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Rule2023-25921

Energy Conservation Program: Test Procedure for Water-Source Heat Pumps

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Published

December 4, 2023

Effective

January 3, 2024

Issuing agencies

Energy Department

Abstract

The U.S. Department of Energy ("DOE") is amending its test procedure for water-source heat pumps to expand the scope of applicability of the test procedure, incorporate by reference a new industry consensus test standard for water-source heat pumps, adopt a seasonal cooling efficiency metric, and specify more representative test conditions used for measuring heating performance. DOE has determined that the amended test procedure will produce results that are more representative of an average use cycle and be more consistent with current industry practice without being unduly burdensome to conduct. Additionally, DOE is adopting provisions governing public representations of efficiency for this equipment.

Full Text

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<title>Federal Register, Volume 88 Issue 231 (Monday, December 4, 2023)</title>
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[Federal Register Volume 88, Number 231 (Monday, December 4, 2023)]
[Rules and Regulations]
[Pages 84188-84232]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-25921]

[[Page 84187]]

Vol. 88

Monday,

No. 231

December 4, 2023

Part II

Department of Energy

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10 CFR Parts 429 and 431

Energy Conservation Program: Test Procedure for Water-Source Heat
Pumps; Final Rule

Federal Register / Vol. 88 , No. 231 / Monday, December 4, 2023 /
Rules and Regulations

[[Page 84188]]

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DEPARTMENT OF ENERGY

10 CFR Parts 429 and 431

[EERE-2017-BT-TP-0029]
RIN 1904-AE05

Energy Conservation Program: Test Procedure for Water-Source Heat
Pumps

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of
Energy.

ACTION: Final rule.

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SUMMARY: The U.S. Department of Energy (``DOE'') is amending its test
procedure for water-source heat pumps to expand the scope of
applicability of the test procedure, incorporate by reference a new
industry consensus test standard for water-source heat pumps, adopt a
seasonal cooling efficiency metric, and specify more representative
test conditions used for measuring heating performance. DOE has
determined that the amended test procedure will produce results that
are more representative of an average use cycle and be more consistent
with current industry practice without being unduly burdensome to
conduct. Additionally, DOE is adopting provisions governing public
representations of efficiency for this equipment.

DATES: The effective date of this rule is January 3, 2024. The
amendments will be mandatory for product testing starting November 29,
2024.
The incorporation by reference of certain material listed in the
rule is approved by the Director of the Federal Register on January 3,
2024.

ADDRESSES: The docket, which includes Federal Register notices, public
meeting attendee lists and transcripts, comments, and other supporting
documents/materials, is available for review at <a href="http://www.regulations.gov">www.regulations.gov</a>.
All documents in the docket are listed in the <a href="http://www.regulations.gov">www.regulations.gov</a>
index. However, not all documents listed in the index may be publicly
available, such as those containing information that is exempt from
public disclosure.
A link to the docket web page can be found at <a href="http://www.regulations.gov/docket/EERE-2017-BT-TP-0029">www.regulations.gov/docket/EERE-2017-BT-TP-0029</a>. The docket web page contains instructions
on how to access all documents, including public comments, in the
docket.
For further information on how to review the docket contact the
Appliance and Equipment Standards Program staff at (202) 287-1445 or by
email: <a href="/cdn-cgi/l/email-protection#9adbeaeaf6f3fbf4f9ffc9eefbf4fefbe8fee9cbefffe9eef3f5f4e9daffffb4fef5ffb4fdf5ec">[email&#160;protected]</a>.

FOR FURTHER INFORMATION CONTACT:
Mr. Troy Watson, U.S. Department of Energy, Office of Energy
Efficiency and Renewable Energy, Building Technologies Office, EE-5B,
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone:
(240) 449-9387. Email: <a href="/cdn-cgi/l/email-protection#08497878646169666b6d5b7c69666c697a6c7b597d6d7b7c6167667b486d6d266c676d266f677e">[email&#160;protected]</a>.
Ms. Kristin Koernig, U.S. Department of Energy, Office of the
General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC
20585-0121. Telephone: (202) 586-3593. Email:
<a href="/cdn-cgi/l/email-protection#7239001b01061b1c5c391d17001c1b15321a035c161d175c151d04">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: DOE incorporates by reference the following
material into 10 CFR parts 429 and 431:

AHRI Standard 600-2023 (I-P), 2023 Standard for Performance Rating of
Water/Brine to Air Heat Pump Equipment, approved September 11, 2023
(``AHRI 600-2023'').
ANSI/ASHRAE Standard 37-2009, Methods of Testing for Rating
Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment,
ASHRAE-approved June 24, 2009 (``ANSI/ASHRAE 37-2009'').
Errata sheet for ANSI/ASHRAE Standard 37-2009, Methods of Testing for
Rating Electrically Driven Unitary Air-Conditioning and Heat Pump
Equipment, March 27, 2019.
ISO Standard 13256-1:1998, Water-source heat pumps--Testing and rating
for performance--Part 1: Water-to-air and brine-to-air heat pumps,
approved 1998 (``ISO 13256-1:1998'').
Properties of Secondary Working Fluids for Indirect Systems, including
Section 2.3 Errata Sheet, Melinder, published 2010 (``Melinder 2010'').

Copies of AHRI 600-2023 are available from the Air-Conditioning,
Heating, and Refrigeration Institute (``AHRI''), 2311 Wilson Blvd.,
Suite 400, Arlington, VA 22201, (703) 524-8800, or by going to
<a href="http://www.ahrinet.org">www.ahrinet.org</a>.
Copies of ANSI/ASHRAE 37-2009 and Errata sheet for ANSI/ASHRAE
Standard 37-2009 are available from the American Society of Heating,
Refrigerating, and Air-Conditioning Engineers (``ASHRAE''), 180
Technology Parkway NW, Peachtree Corners, GA 30092, (404) 636-8400, or
by going to <a href="http://www.ashrae.org">www.ashrae.org</a>. (ASHRAE standards are co-published with
American National Standards Institute (``ANSI'')).
Copies of ISO Standard 13256-1:1998 can be obtained from the
International Organization for Standardization (``ISO''), Chemin de
Blandonnet 8 CP 401, 1214 Vernier, Geneva, Switzerland, +41 22 749 01
11, or online at: <a href="http://www.iso.org/store.html">www.iso.org/store.html</a>.
Copies of Melinder 2010 are available from the International
Institute of Refrigeration (``IIR''), 177 Boulevard Malesherbes 75017
Paris, France; +33 (0)1 42 27 32 35; <a href="http://www.iifiir.org">www.iifiir.org</a>.
See section IV.N of this document for further discussion of these
standards.

Table of Contents

I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Final Rule
III. Discussion
A. Scope of Applicability
1. WSHPs With Cooling Capacity Greater Than or Equal to 135,000
Btu/h
2. Representations for Residential Applications
B. Definition
C. Organization of the Amended DOE Test Procedures
D. Updates to Industry Standards
1. Comments Regarding DOE's Authority
2. Comments Regarding DOE's Test Procedure Development Process
3. Comments Supporting the Adoption of AHRI 340/360-2022
4. Comments Opposing the Adoption of AHRI 340/360-2022
5. Comments Encouraging the Adoption of AHRI 600
6. Finalized DOE Test Procedure
E. Efficiency Metrics
1. IEER
2. ACOP
3. Optional Representations
4. Entering Air Conditions
F. Test Method
1. Airflow and External Static Pressure
2. Capacity Measurement
3. Pump Power Adjustment and Liquid External Static Pressure
4. Test Liquid and Specific Heat Capacity
5. Liquid Flow Rate
6. Refrigerant Line Losses
7. Airflow Measurement
8. Air Condition Measurement
9. Duct Losses
10. Refrigerant Charging
11. Voltage
12. Non-Standard Low-Static Indoor Fan Motors
G. Configuration of Unit Under Test
1. Background and Summary
2. General Comments Received
3. Approach for Exclusion of Certain Components
H. Represented Values and Enforcement
1. Cooling Capacity
2. Enforcement of IEER
I. Test Procedure Costs
J. Effective and Compliance Dates
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Orders 12866, 13563, and 14094
B. Review Under the Regulatory Flexibility Act
1. Description and Estimate of Small Entities Regulated
2. Description and Estimate of Compliance Requirements

[[Page 84189]]

3. Certification Statement
C. Review Under the Paperwork Reduction Act of 1995
D. Review Under the National Environmental Policy Act of 1969
E. Review Under Executive Order 13132
F. Review Under Executive Order 12988
G. Review Under the Unfunded Mandates Reform Act of 1995
H. Review Under the Treasury and General Government
Appropriations Act, 1999
I. Review Under Executive Order 12630
J. Review Under Treasury and General Government Appropriations
Act, 2001
K. Review Under Executive Order 13211
L. Review Under Section 32 of the Federal Energy Administration
Act of 1974
M. Congressional Notification
N. Description of Materials Incorporated by Reference
V. Approval of the Office of the Secretary

I. Authority and Background

Water-source heat pumps (``WSHPs'') are a category of small, large,
and very large commercial package air-conditioning and heating
equipment,\1\ which are included in the list of ``covered equipment''
for which DOE is authorized to establish and amend energy conservation
standards and test procedures. (42 U.S.C. 6311(1)(B)-(D);
6313(a)(1)(G)-(I)) DOE's test procedure for WSHPs is currently
prescribed at title 10 of the Code of Federal Regulations (``CFR'')
part 431.96. The following sections discuss DOE's authority to
establish and amend a test procedure for WSHPs and relevant background
information regarding DOE's consideration of a test procedure for this
equipment.
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\1\ The Energy Policy and Conservation Act, as amended
(``EPCA'') defines ``commercial package air conditioning and heating
equipment'' as air-cooled, water-cooled, evaporatively-cooled, or
water-source (not including ground-water-source) electrically
operated unitary central air conditioners and central air
conditioning heat pumps for commercial application. (42 U.S.C.
6311(8)(A)) EPCA further defines ``small commercial package air
conditioning and heating equipment'' as commercial package air
conditioning and heating equipment that is rated below 135,000 Btu
per hour (cooling capacity); ``large commercial package air
conditioning and heating equipment'' as commercial package air
conditioning and heating equipment that is rated at or above 135,000
Btu per hour and below 240,000 Btu per hour (cooling capacity); and
``very large commercial package air conditioning and heating
equipment'' as commercial package air conditioning and heating
equipment that is rated at or above 240,000 Btu per hour and below
760,000 Btu per hour (cooling capacity). (42 U.S.C. 6311(8)(B)-(D))
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A. Authority

The Energy Policy and Conservation Act, Public Law 94-163, as
amended (``EPCA''),\2\ authorizes DOE to regulate the energy efficiency
of a number of consumer products and certain industrial equipment. (42
U.S.C. 6291-6317) Title III, Part C of EPCA,\3\ added by Public Law 95-
619, Title IV, section 441(a), established the Energy Conservation
Program for Certain Industrial Equipment, which sets forth a variety of
provisions designed to improve energy efficiency. This equipment
includes WSHPs, the subject of this document. (42 U.S.C. 6311(1)(B)-
(D))
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\2\ All references to EPCA in this document refer to the statute
as amended through the Energy Act of 2020, Public Law 116-260 (Dec.
27, 2020), which reflect the last statutory amendments that impact
Parts A and A-1 of EPCA.
\3\ For editorial reasons, upon codification in the U.S. Code,
Part C was redesignated Part A-1.
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The energy conservation program under EPCA consists essentially of
four parts: (1) testing, (2) labeling, (3) Federal energy conservation
standards, and (4) certification and enforcement procedures. Relevant
provisions of EPCA include definitions (42 U.S.C. 6311), test
procedures (42 U.S.C. 6314), labeling provisions (42 U.S.C. 6315),
energy conservation standards (42 U.S.C. 6313), and the authority to
require information and reports from manufacturers (42 U.S.C. 6316; 42
U.S.C. 6296).
The Federal testing requirements consist of test procedures that
manufacturers of covered equipment must use as the basis for: (1)
certifying to DOE that their equipment complies with the applicable
energy conservation standards adopted pursuant to EPCA (42 U.S.C.
6316(b); 42 U.S.C. 6296), and (2) making other representations about
the efficiency of that equipment (42 U.S.C. 6314(d)). Similarly, DOE
uses these test procedures to determine whether the equipment complies
with relevant standards promulgated under EPCA.
Federal energy efficiency requirements for covered equipment
established under EPCA generally supersede State laws and regulations
concerning energy conservation testing, labeling, and standards. (42
U.S.C. 6316(a) and 42 U.S.C. 6316(b); 42 U.S.C. 6297) DOE may, however,
grant waivers of Federal preemption for particular State laws or
regulations, in accordance with the procedures and other provisions of
EPCA. (42 U.S.C. 6316(b)(2)(D))
Under 42 U.S.C. 6314, EPCA sets forth the criteria and procedures
DOE must follow when prescribing or amending test procedures for
covered equipment. EPCA requires that any test procedures prescribed or
amended under this section must be reasonably designed to produce test
results which reflect energy efficiency, energy use or estimated annual
operating cost of a given type of covered equipment during a
representative average use cycle (as determined by the Secretary) and
requires that test procedures not be unduly burdensome to conduct. (42
U.S.C. 6314(a)(2))
EPCA requires that the test procedures for commercial package air
conditioning and heating equipment be those generally accepted industry
testing procedures or rating procedures developed or recognized by the
Air-Conditioning, Heating, and Refrigeration Institute (``AHRI'') or by
the American Society of Heating, Refrigerating and Air-Conditioning
Engineers (``ASHRAE''), as referenced in ASHRAE 90.1, ``Energy Standard
for Buildings Except Low-Rise Residential Buildings'' (``ASHRAE
90.1''). (42 U.S.C. 6314(a)(4)(A)) Further, if such an industry test
procedure is amended, DOE must update its test procedure to be
consistent with the amended industry test procedure, unless DOE
determines, by rule published in the Federal Register and supported by
clear and convincing evidence, that such test procedure would not meet
the requirements in 42 U.S.C. 6314(a)(2) and (3), related to
representative use and test burden. (42 U.S.C. 6314(a)(4)(B))
EPCA also requires that, at least once every 7 years, DOE evaluate
test procedures for each type of covered equipment, including WSHPs, to
determine whether amended test procedures would more accurately or
fully comply with the requirements for the test procedures to not be
unduly burdensome to conduct and be reasonably designed to produce test
results that reflect energy efficiency, energy use, and estimated
operating costs during a representative average use cycle. (42 U.S.C.
6314(a)(1)
In addition, if the Secretary determines that a test procedure
amendment is warranted, the Secretary must publish proposed test
procedures in the Federal Register and afford interested persons an
opportunity (of not less than 45 days' duration) to present oral and
written data, views, and arguments on the proposed test procedures. (42
U.S.C. 6314(b)) If DOE determines that test procedure revisions are not
appropriate, DOE must publish in the Federal Register its determination
not to amend the test procedures. (42 U.S.C. 6314(a)(1)(A)(ii))
DOE undertook this rulemaking in satisfaction of the 7-year-
lookback obligations under EPCA. (42 U.S.C. 6314(a)(1)). As discussed
previously in this document, WSHPs are a category of commercial package
air conditioning and heating equipment. EPCA requires the DOE test
procedures for commercial package air conditioning and heating

[[Page 84190]]

equipment to be the generally accepted industry testing procedure
developed or recognized by AHRI or by ASHRAE, as referenced in ASHRAE
90.1. (42 U.S.C. 6314(a)(4)(A)) EPCA further requires that each time
the referenced industry test procedure is amended in ASHRAE 90.1, DOE
must amend its test procedure to be consistent with the industry
update, unless DOE determines in a rulemaking that there is clear and
convincing evidence that the updated update industry test procedure
would not be representative of an average use cycle or would be unduly
burdensome to conduct. (42 U.S.C. 6314(a)(4)(B)(C)) However, under the
7-year-lookback obligations, there is no ``clear and convincing
evidence'' required in EPCA. Rather, EPCA only requires that DOE
determine whether the amended test procedure would more accurately or
fully comply with the requirements for the test procedure to not be
unduly burdensome to conduct and be reasonably designed to produce test
results that reflect energy efficiency, energy use, and estimated
operating costs during a representative average use cycle. (42 U.S.C.
6314(a)(1))
DOE is publishing this final rule in satisfaction of its statutory
obligations under EPCA. (42 U.S.C. 6314(a)(1)(A))

B. Background

DOE's existing test procedure for WSHPs is specified at 10 CFR
431.96 (``Uniform test method for the measurement of energy efficiency
of commercial air conditioners and heat pumps''). The Federal test
procedure currently incorporates by reference International
Organization for Standardization (``ISO'') Standard 13256-1 (1998),
``Water-source heat pumps--Testing and rating for performance--Part 1:
Water-to-air and brine-to-air heat pumps,'' (``ISO 13256-1:1998'').
DOE initially incorporated ISO 13256-1:1998 as the referenced test
procedure for WSHPs on October 21, 2004 (69 FR 61962), and DOE last
reviewed the test procedure for WSHPs as part of a final rule for
commercial package air conditioners and heat pumps published in the
Federal Register on May 16, 2012 (``May 2012 Final Rule''; 77 FR
28928). In the May 2012 Final Rule, DOE retained the reference to ISO
13256-1:1998 but adopted additional provisions for equipment setup at
10 CFR 431.96(e), which provide specifications for addressing key
information typically found in the installation and operation manuals.
77 FR 28928, 28991.
On June 22, 2018, DOE published a request for information (``RFI'')
to collect information and data to consider amendments to DOE's test
procedure for WSHPs (``June 2018 RFI''). 83 FR 29048.\4\ Subsequently,
on August 30, 2022, DOE published a notice of proposed rulemaking
(``NOPR'') in which DOE responded to stakeholders' comments on the June
2018 RFI and proposed amendments to its test procedure for WSHPs
(``August 2022 NOPR'') 87 FR 53302. In the August 2022 NOPR, DOE
proposed to amend the test procedures for WSHPs to incorporate by
reference AHRI Standard 340/360-2022 (I-P), ``2022 Standard for
Performance Rating of Commercial and Industrial Unitary Air-
conditioning and Heat Pump Equipment'' (``AHRI 340/360-2022'') and
ANSI/ASHRAE Standard 37-2009, ``Methods of Testing for Rating
Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment''
(``ANSI/ASHRAE 37-2009''). Id. at 87 FR 53348. Specifically, DOE
proposed to implement these changes by adding new appendices C and C1
to subpart F of part 431, both titled ``Uniform Test Method for
Measuring the Energy Consumption of Water-Source Heat Pumps.''
(``appendix C'' and ``appendix C1,'' respectively). Id. at 87 FR 53351-
52252. The current DOE test procedure for WSHPs would be relocated to
appendix C without change, and the new test procedure adopting AHRI
340/360-2022 and ANSI/ASHRAE 37-2009 and any other amendments would be
set forth in proposed appendix C1 for determining IEER. Id. at 87 FR
53352-53353. DOE held a public meeting on September 14, 2022 (``NOPR
public meeting'') to present the key proposals from the August 2022
NOPR.
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\4\ An extension of the comment period for the June 2018 RFI was
published July 9, 2018. 83 FR 31704.
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DOE received comments in response to the August 2022 NOPR from the
interested parties listed in Table I.1.

Table I.1--List of Commenters With Written Submissions in Response to the August 2022 NOPR
----------------------------------------------------------------------------------------------------------------
Reference in this final Comment No. in
Commenter(s) rule the docket Commenter type
----------------------------------------------------------------------------------------------------------------
Air-Conditioning, Heating and AHRI..................... 24 Trade Association.
Refrigeration Institute.
Appliance Standards Awareness Project, Joint Commenters......... 27 Efficiency Organizations.
American Council for an Energy-
Efficient Economy.
Northwest Energy Efficiency Alliance... NEEA..................... 25 Efficiency Organization.
New York State Energy Research and NYSERDA.................. 21 State Agency.
Development Authority.
ClimateMaster, Inc..................... ClimateMaster............ 22 Manufacturer.
WaterFurnace International............. WaterFurnace............. 20 Manufacturer.
Enertech Global, LLC................... Enertech................. 19 Manufacturer.
Florida Heat Pump Manufacturing........ FHP...................... 26 Manufacturer.
The Geothermal Exchange Organization... GeoExchange.............. 29 Trade Association.
Madison Indoor Air Quality............. MIAQ..................... 23 Manufacturer.
Trane Technologies..................... Trane.................... 28 Manufacturer.
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A parenthetical reference at the end of a comment quotation or
paraphrase provides the location of the item in the public record.\5\
In addition to the comments listed in Table I.1, DOE also received 2
comments from anonymous individuals, which were considered in the
development of this final rule, but not cited individually. To the
extent that interested parties have provided written comments that are
substantively consistent with any oral comments provided during the
NOPR public meeting, DOE cites the written comments throughout this
final rule.

[[Page 84191]]

Any oral comments provided during the webinar that are not
substantively addressed by written comments are summarized and cited
separately throughout this final rule.
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\5\ The parenthetical reference provides a reference for
information located in the docket of DOE's rulemaking to develop an
amended test procedure for WSHPs. (Docket No. EERE-2017-BT-TP-0029,
which is maintained at <a href="http://www.regulations.gov">www.regulations.gov</a>). The references are
arranged as follows: (commenter name, comment docket ID number, page
of that document).
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In May 2021, ISO published an updated version of Standard 13256-1,
ISO Standard 13256-1 (2021), ``Water-source heat pumps--Testing and
rating for performance--Part 1: Water-to-air and brine-to-air heat
pumps,'' (``ISO 13256-1:2021''). In January 2023, ASHRAE published
ASHRAE 90.1-2022. ASHRAE 90.1-2022 did not update the referenced test
procedure for WSHPs.\6\
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\6\ ASHRAE 90.1-2022 lists ANSI/AHRI/ASHRAE 13256-1: 1998 (2021)
as the test procedure for WSHPs. However, DOE believes ASHRAE
intended to include ``2012'' in the parentheses as that was the most
recent year in which the 1998 version of 13256-1 was redesignated.
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On September 11, 2023, AHRI published a new industry test standard
for WSHPs, titled AHRI Standard 600, ``Standard for Performance Rating
of Water/Brine to Air Heat Pump Equipment'' (``AHRI 600-2023''). DOE
worked with stakeholders (including WSHP manufacturers and efficiency
advocates) as part of the AHRI Geothermal and WSHP standards technical
committee (``STC'') to develop AHRI 600-2023, which addresses many of
the issues in the current WSHP test procedure that DOE raised in the
August 2022 NOPR. The intent of the Geothermal and WSHP STC was for
AHRI 600-2023 to be used for testing WSHPs instead of any versions of
ISO Standards 13256-1.

II. Synopsis of the Final Rule

In this final rule DOE is establishing new appendices C and C1 to
subpart F of part 431. The current DOE test procedure for WSHPs is
relocated to appendix C without change. The amended test procedure for
WSHPs is established in a new appendix C1, which includes the following
amended test procedure requirements for WSHPs for measuring the updated
efficiency metrics: (1) integrated energy efficiency ratio (``IEER'')
for WSHPs using AHRI 600-2023; and (2) applied coefficient of
performance (``ACOP'') using AHRI 600-2023. Use of the amended test
procedure in appendix C1 will not be required until such time as
compliance is required with amended energy conservation standards for
WSHPs denominated in terms of IEER, should DOE adopt such standards.
Additionally, DOE is expanding the scope of the test procedure to
include WSHPs with capacities between 135,000 and 760,000 British
thermal units per hour (``Btu/h''), as well as specifying the
components that must be present for testing and amending certain
provisions related to representations and enforcement in 10 CFR part
429.
As discussed in this final rule, DOE has concluded that the amended
test procedure in appendix C1 (incorporating by reference the most
recent industry consensus test standard for WSHPs, AHRI 600-2023)
provides more representative results and more fully complies with the
requirements of 42 U.S.C. 6314(a)(2) than testing with the current
Federal test procedure (based on ISO 13256-1:1998).
The adopted amendments are summarized in Table II.1 and compared to
the test procedure provisions in place prior to the amendment, as well
as the reason for the adopted change.

Table II.1--Summary of Changes in the Amended Test Procedure
------------------------------------------------------------------------
Amended test
Current DOE test procedure procedure Attribution
------------------------------------------------------------------------
Located in 10 CFR 431.96........ Current test Readability of
procedure moved test procedure.
to appendix C to
10 CFR 431.96 and
amended test
procedure
established in
appendix C1 to 10
CFR 431.96.
Scope is limited to units with a Expands the scope Harmonize with
cooling capacity less than of the test scope of test
135,000 Btu/h. procedure to procedure for
additionally water-cooled
include units commercial
with a cooling unitary air
capacity greater conditioners.
than or equal to
135,000 Btu/h and
less than 760,000
Btu/h in 10 CFR
431.96.
Incorporates by reference ISO Incorporates by Improve
13256-1:1998. reference AHRI representativenes
600-2023 into s of test
appendix C1. procedure.
Includes provisions for Includes Improve
determining EER metric. provisions for representativenes
determining IEER s of test
by incorporating procedure.
by reference AHRI
600-2023 into
appendix C1.
Specifies test condition of 68 Changes the test Improve
[deg]F for measuring condition for representativenes
coefficient of performance ACOP to 50 s of test
(``COP''). [deg]F, by procedure.
incorporating by
reference AHRI
600-2023 into
appendix C1.
Does not include WSHP-specific Includes Establish WSHP-
provisions for determination of provisions in 10 specific
represented values in 10 CFR CFR 429.43 provisions for
429.43. specific to WSHPs determination of
for determining represented
represented values.
values.
Does not include WSHP-specific Adopts product- Establish
enforcement provisions in 10 specific enforcement
CFR 429.134. enforcement provisions for
provisions for DOE testing of
WSHPs regarding WSHPs.
verification of
cooling capacity,
testing of
systems with
specific
components, and
IEER testing
conducted by DOE.
------------------------------------------------------------------------

DOE has determined that the test procedure in appendix C, as
described in section III of this final rule regarding the establishment
of appendix C, does not alter the measured efficiency of WSHPs or
require retesting solely as a result of the establishment of appendix
C. Additionally, DOE has determined that the establishment of appendix
C will not increase the cost of testing.
DOE has determined that the amended test procedure adopted in
appendix C1 does alter the measured efficiency of WSHPs and would
increase the cost of testing relative to the current Federal test
procedure, as discussed further in section III.I of this document.
However, as stated, use of appendix C1 will not be required until the
compliance date of any amended standards denominated in terms of IEER,
should DOE adopt such standards. DOE has also determined that the
amended test procedure will not be unduly burdensome to conduct.
For units with cooling capacity greater than or equal to 135,000
Btu/h and less than 760,000 Btu/h newly added within scope of the WSHP
test procedure, testing according to the established test procedure for
purposes of certifications of compliance will not

[[Page 84192]]

be required until the compliance date of any energy conservation
standards for such equipment, should DOE adopt such standards. However,
if a manufacturer chooses to make representations of the energy
efficiency or energy use of such equipment, beginning 360 days after
publication of the final rule in the Federal Register, the manufacturer
will be required to base such representations on the DOE test
procedure. (42 U.S.C. 6314(d)(1))
The effective date for the amended test procedure adopted in this
final rule is 30 days after publication of this document in the Federal
Register. Discussion of DOE's actions are addressed in detail in
section III of this document.

III. Discussion

A. Scope of Applicability

This rulemaking applies to WSHPs, which are a category of small,
large, and very large commercial package air-conditioning and heating
equipment. (See 42 U.S.C. 6311(1)(B)-(D)) In its regulations, DOE
defines WSHP as ``a single-phase or three-phase reverse-cycle heat pump
that uses a circulating water loop as the heat source for heating and
as the heat sink for cooling. The main components are a compressor,
refrigerant-to-water heat exchanger, refrigerant-to-air heat exchanger,
refrigerant expansion devices, refrigerant reversing valve, and indoor
fan. Such equipment includes, but is not limited to, water-to-air
water-loop heat pumps.'' 10 CFR 431.92.
1. WSHPs With a Cooling Capacity Greater Than or Equal to 135,000 Btu/h
The current Federal WSHP test procedure and energy conservation
standards apply to WSHPs with a rated cooling capacity below 135,000
Btu/h. 10 CFR 431.96, Table 1 and 10 CFR 431.97, Table 3. In the August
2022 NOPR, DOE proposed to expand the scope of applicability of the
test procedure to include WSHPs with a cooling capacity between 135,000
and 760,000 Btu/h. 87 FR 53302, 53307. Specifically, DOE proposed to
update Table 1 to 10 CFR 431.96 to include WSHPs with a cooling
capacity greater than or equal to 135,000 Btu/h and less than 240,000
Btu/h under Large Commercial Package Air-Conditioning and Heating
Equipment; and to include WSHPs with a cooling capacity greater than or
equal to 240,000 Btu/h and less than 760,000 Btu/h under Very Large
Commercial Package Air-Conditioning and Heating Equipment. Id. In the
August 2022 NOPR, DOE tentatively determined that, based on the
presence on the market of units over 135,000 Btu/h with efficiency
ratings and the identification of laboratories capable of testing such
units, such testing would not be unduly burdensome. Id. at 87 FR 53306.
Additionally, DOE stated that expanding the scope of DOE's test
procedure for WSHPs to include equipment with a cooling capacity
between 135,000 Btu/h and 760,000 Btu/h would ensure that
representations for all WSHPs are made using the same test procedure
and that ratings for equipment in this cooling capacity range are
appropriately representative. Id. at 87 FR 53306-53307. DOE requested
comments on the proposed expansion of the scope of applicability of the
Federal test procedure to include WSHPs with a cooling capacity between
135,000 and 760,000 Btu/h. Id. at 87 FR 53307.
In response to the June 2022 NOPR, some commenters expressed
concern with the proposal to expand the scope of the test procedure.
AHRI commented that it is concerned with DOE's proposal to expand
testing coverage and update test procedures without taking steps to
measure the impact on manufacturers and third-party test labs. (AHRI,
No. 24 at pp. 2-3) AHRI asserted that the August 2022 NOPR does not
show evidence of DOE's participation in the critical consensus process
required for developing test procedures and improving efficiency for
ASHRAE 90.1, which involves conversations regarding lab capabilities,
product availability, and product efficiencies. (Id.)
AHRI further commented that the impact on manufacturers of DOE's
proposed test coverage expansion has not been quantified. (Id. at p. 3)
AHRI stated that it expects third-party test labs will not be able to
accommodate the expanded scope to include equipment up to 760,000 Btu/
h, as such an expansion of scope would require test labs to increase
their testing capacity from 3 gallons per minute (``GPM'') per ton
(``GPM/ton'') at 50 [deg]F to nearly 200 GPM. (Id.) AHRI commented that
the additional constraints placed on test labs would cause delays in
testing other equipment as well as WSHPs. (Id.)
Similarly, ClimateMaster opposed DOE's proposal to include WSHP
equipment with capacities greater than 135,000 Btu/h within the scope
of the test procedure due to the cost burden that ClimateMaster
asserted would be imposed on manufacturers and consumers.
(ClimateMaster, No. 22 at p. 2) ClimateMaster stated that these larger
model sizes account for only 0.4 percent of its overall market volume
from 2019 to 2021. (Id.) ClimateMaster presented data showing that
adding the higher-capacity models to the scope of the test procedure
would increase the certification cost by $184,000 per year to
accommodate testing and equipment costs. (Id.) ClimateMaster further
commented that third-party compliance labs are unable to test equipment
above 420,000 Btu/h, which would render DOE's proposal to test WSHPs
that reach 760,000 Btu/h impossible. (Id.) ClimateMaster noted that the
increased cost burden needed to accommodate such a small percentage of
affected equipment would negatively affect consumers as well as
manufacturers. (Id.) ClimateMaster recommended that DOE maintain the
scope of applicability of the Federal test procedure to only include
WSHPs with cooling capacity below 135,000 Btu/h. (Id. at p. 3)
FHP commented that its main concern regarding DOE's proposal to
expand the scope of applicability is lab availability. (FHP, No. 26 at
p. 2) FHP stated that it has found only a limited supply of WSHP
testing facilities, none of which have a capacity to test equipment
over 480,000 Btu/h. (Id.) FHP recommended that DOE provide a list of
testing facilities for WSHPs with a cooling capacity greater than
135,000 Btu/h, stating that multiple testing facilities must be
available to ensure that an increased demand for large unit testing
does not also cause spikes in testing costs due to supply and demand
pressures. (Id.) FHP further commented that WSHPs with capacities above
135,000 Btu/h account for less than 1 percent of the market share.
(Id.)
MIAQ commented that it is concerned DOE has not quantified the
impact on manufacturers and third-party labs of expanding the scope of
coverage to larger equipment. (MIAQ, No. 23 at p. 3) MIAQ stated that
conversations regarding lab capabilities and product availability and
efficiency occur during the consensus process required for developing
test procedures in ASHRAE 90.1. (Id.) MIAQ stated that the water volume
required for testing larger capacities up to 760,000 Btu/h may limit
testing. (Id.) More specifically, MIAQ stated that testing a 760,000
Btu/h WSHP would require approximately 200 GPM of 50 [deg]F water,
which MIAQ stated would require large chillers to maintain the water at
the correct temperature. (Id.) MIAQ also noted that due to the
increased need for larger spaces capable of testing such equipment,
there could be bottlenecks at third-party test labs, which also test
other categories of commercial package air conditioning and heating
equipment. (Id.)

[[Page 84193]]

WaterFurnace stated that there are no known WSHP products with a
cooling capacity above approximately 360,000 Btu/h nor any test
facilities capable of testing such WSHPs at the required conditions for
IEER. (WaterFurnace, No. 20 at p. 6) WaterFurnace commented that DOE
did not justify regulating this larger equipment and that doing so
would be a burden on the industry and testing facilities. (Id.)
Other commenters supported the proposal to expand the scope of the
WSHP test procedure. The Joint Commenters, NEEA, and NYSERDA supported
DOE's proposal to include WSHPs with cooling capacities between 135,000
and 760,000 Btu/h in the scope of the test procedure. (Joint
Commenters, No. 27 at p. 1; NEEA, No. 25 at p. 2; NYSERDA, No. 21 at p.
2) The Joint Commenters stated that they believe it is important that
equipment in this capacity range be testing using a standardized test
procedure and that expanding the scope of the test procedure would
bring it into alignment with test procedures for other commercial
package air-conditioning and heating equipment. (Joint Commenters, No.
27 at p. 1)
NEEA commented that, while this size range may account for
relatively few annual sales, expanding the test procedure to larger
capacity equipment would ensure that large equipment is fairly rated
and regulated and held to the same standards as smaller equipment of
the same type. (NEEA, No. 25 at p. 2)
NYSERDA asserted that expanding the scope is a feasible and
necessary change to ensure that WSHPs of varying sizes are consistently
tested according to industry standards, which will demonstrate to
customers that WSHPs--especially geothermal WSHPs--are reliable and
thus enable WSHP market growth. (NYSERDA, No. 21 at p. 2)
As discussed in the August 2022 NOPR, DOE has identified numerous
model lines of WSHPs with a cooling capacity over 135,000 Btu/h from a
wide variety of manufacturers. 87 FR 53302, 53306. The manufacturer
literature for all identified model lines includes efficiency
representations that are explicitly based on ISO 13256-1:1998, the
current industry standard, indicating efficiency representations can be
made for these models using an industry consensus test procedure for
WSHPs. Id.
In response to comments from AHRI, Climate Master, and
WaterFurnace, as discussed in the August 2022 NOPR, DOE is aware of
several independent test labs that have the capability to test WSHPs
with a cooling capacity over 135,000 Btu/h. Id. DOE conducted
investigative testing on multiple WSHP models with a cooling capacity
over 135,000 Btu/h at one such independent test lab and did not
encounter any difficulties specific to units in this capacity range.
Id. Regarding comments by ClimateMaster and FHP stating that test labs
cannot test units greater than 420,000 Btu/h and 480,000 Btu/h,
respectively, comments submitted by WaterFurnace indicate that the
largest models currently available on the market are 360,000 Btu/h,
which DOE research corroborates. As such, any capacity limitations for
testing as asserted by ClimateMaster and FHP would not impact any
models currently on the market.
Further, DOE notes that AHRI 600-2023 includes provisions for
testing units with capacities over 135,000 Btu/h. Both ASHRAE 90.1 and
DOE regulations cover other categories of commercial air conditioning
and heating equipment, including water-cooled commercial unitary air
conditioners (``WCUACs''), with a cooling capacity up to 760,000 Btu/h.
As discussed in the August 2022 NOPR, DOE has determined that testing
WSHPs with a cooling capacity over 135,000 Btu/h would be of comparable
burden to testing other commercial air conditioning and heating
equipment of similar capacity, such as WCUACs. Id.
Regarding comments on the potential burden of testing such units,
EPCA does not require DOE to consider only burden-reducing options, but
rather requires only that the test procedure must not be unduly
burdensome to conduct. Expanding the scope of the test procedure to
include larger equipment would not necessitate certification unless DOE
were to establish standards for such equipment. Until such a time, an
expansion of scope for the test procedure would require only that if
manufacturers choose to make optional representations of efficiency for
WSHPs with a cooling capacity over 135,000 Btu/h, that such optional
representations be made in accordance with the DOE test procedure.
Further, DOE notes that representations for WSHPs can be made either
based on testing (in accordance with 10 CFR 429.43(a)(1)) or based on
alternative efficiency determination methods (``AEDMs'') (in accordance
with 10 CFR 429.43(a)(2)). An AEDM is a computer modeling or
mathematical tool that predicts the performance of non-tested basic
models. These computer modeling and mathematical tools, when properly
developed, can provide a means to predict the energy usage or
efficiency characteristics of a basic model of a given covered product
or equipment and reduce the burden and cost associated with testing.
Whereas DOE requires at least two units to be tested per basic model
when represented values are determined through testing, DOE requires
each AEDM to be validated by tests of only two WSHP basic models of any
capacity (in accordance with 10 CFR 429.70(c)(2)). Based on DOE's
observation of the prevalence of use of AEDMs for WSHP and similar
equipment for which energy conservation standards currently apply
(i.e., for equipment with a cooling capacity no greater than 135,000
Btu/h), DOE expects that representations of efficiency could be
determined through the use of AEDMs for the majority of models with a
cooling capacity over 135,000 Btu/h. As such, DOE expects an expansion
of scope for the DOE test procedure to include equipment with a cooling
capacity over 135,000 Btu/h would not necessitate the testing of many
such larger units. Therefore, testing would not be as burdensome as
noted by commenters.
Based on the presence on the market of units over 135,000 Btu/h,
the identification of laboratories capable of testing such units, DOE's
observation that representations of efficiency for such equipment are
currently being made, and the inclusion of units over 135,000 Btu/h
within the scope of the most recent industry consensus test standard
for WSHPs (AHRI 600-2023), DOE has determined that testing units with a
cooling capacity over 135,000 Btu/h is feasible and would not be unduly
burdensome. As discussed, expanding the scope of DOE's test procedure
for WSHPs to include equipment with a cooling capacity between 135,000
Btu/h and 760,000 Btu/h would ensure that representations for all WSHPs
are made using the same test procedure and that ratings for equipment
in this cooling capacity range are appropriately representative.
For the reasons discussed in the proceeding paragraphs and in the
August 2022 NOPR, DOE is expanding the scope of applicability of the
WSHP test procedure to include WSHPs with a cooling capacity between
135,000 and 760,000 Btu/h consistent with the scope of AHRI 600-2023.
Specifically, DOE is updating Table 1 to 10 CFR 431.96 to include WSHPs
with a cooling capacity greater than or equal to 135,000 Btu/h and less
than 240,000 Btu/h under Large Commercial Package Air-Conditioning and
Heating Equipment and to include WSHPs with a cooling capacity greater
than or equal to 240,000 Btu/h and less than 760,000 Btu/h under Very
Large

[[Page 84194]]

Commercial Package Air-Conditioning and Heating Equipment.
As previously discussed, DOE does not currently specify energy
conservation standards for WSHPs with a cooling capacity over 135,000
Btu/h. DOE would consider any future standards applicable to WSHPs over
135,000 Btu/h in a separate energy conservation standards rulemaking.
Manufacturers of WSHPs with a cooling capacity over 135,000 Btu/h would
not be required to test WSHPs with a cooling capacity over 135,000 Btu/
h until such time as compliance with standards for this equipment were
required, should DOE adopt such standards. DOE notes, however, that
beginning 360 days after this final rule publishes in the Federal
Register, any voluntary representations with respect to energy use or
efficiency must be based on the test procedure in appendix C, and any
voluntary representations of IEER or ACOP must be based on the test
procedure in appendix C1.
2. Representations for Residential Applications
Sections 6.5 and 6.6 of AHRI 600-2023 state that provisions for
determination of residential cooling capacity and efficiency are to be
added in a future revision. In the August 2022 NOPR, DOE proposed to
allow optional energy efficiency ratio (``EER'') and COP
representations at the full-load and part-load EWT conditions specified
in Table 1 of ISO 13256-1:1998 per the DOE test procedure proposed in
appendix C1. 87 FR 53302, 53313. DOE notes that the residential
representations discussed in AHRI 600-2023 are separate from the
proposed optional representations from the August 2022 NOPR, as test
provisions in AHRI 600-2023 specify separate air and liquid external
static pressures to be used during testing to develop ratings for
residential applications. However, the residential representations have
not yet been fully developed for WSHPs, as indicated in sections 6.5
and 6.6 of AHRI 600-2023. Therefore, DOE is not adding any provisions
regarding residential representations in this final rule but will
continue to work with the AHRI 600 committee to develop such
provisions.

B. Definition

As discussed, WSHPs are a category of commercial package air-
conditioning and heating equipment. The current definition for ``water-
source heat pump'' does not explicitly state that it is ``commercial
package air-conditioning and heating equipment.'' This is inconsistent
with the definitions of most other categories of commercial package
air-conditioning and heating equipment (e.g., computer room air
conditioner, single package vertical air conditioner, variable
refrigerant flow multi-split air conditioner). See 10 CFR 431.92.
To provide consistency with other definitions of specific
categories of commercial package air-conditioning and heating
equipment, DOE proposed in the August 2022 NOPR to amend the definition
of ``water-source heat pump'' to explicitly indicate that WSHPs are a
category of commercial package air-conditioning and heating equipment.
87 FR 53302, 53307. This proposed clarification to the ``water-source
heat pump'' definition would not change the scope of equipment covered
by the definition.
In addition, the current definition for WSHPs lists the main
components of a WSHP and it includes ``indoor fan'' on that list. See
10 CFR 431.92. DOE discussed in the August 2022 NOPR that it has
identified coil-only WSHPs on the market that rely on a separately
installed furnace or modular blower for indoor air movement. 87 FR
53302, 53307. To clarify that coil-only WSHPs are covered under the
WSHP definition, DOE proposed to amend the WSHP definition to make
clear that an indoor fan is not an included component for coil-only
WSHPs. Id. Specifically, DOE proposed to include the parenthesized
statement ``except that coil-only units do not include an indoor fan''
in the sentence listing the main components in the proposed WSHP
definition. Id.
DOE requested comment on the proposed change to the definition of
WSHP to explicitly indicate that WSHP is a category of commercial
package air-conditioning and heating equipment and to clarify that the
presence of an indoor fan does not apply to coil-only units. Id.
ClimateMaster generally agreed with DOE's proposed definition of
WSHP, but requested clarity on what constitutes a commercial system.
(ClimateMaster, No. 22 at p. 3) ClimateMaster commented that other
industry test programs clearly demarcate the difference between systems
through listed capacity. (Id.) ClimateMaster noted that the current
definition includes only packaged systems but that DOE's proposed
amendments in the August 2022 NOPR specified procedures for testing
split systems. (Id.) ClimateMaster stated that it is not able to
determine with the current definition what exact products would fall
under the certification program and how DOE would enforce which
products are covered by the applicable standards. (Id.) ClimateMaster
also stated that there were non-reversible WSHP products that operate
as either cooling only units or utilize a hydronic coil that are not
covered by the current definition. ClimateMaster stated that provisions
should be made for this equipment type. (Id.)
WaterFurnace questioned whether it would be necessary to change the
definition of WSHP if DOE were to maintain the method of test based on
ISO 13256 and AHRI 600. (WaterFurnace, No. 20 at p. 6) WaterFurnace
recommended using the term ``heat pump'' in lieu of ``air conditioner
and heating equipment,'' which WaterFurnace asserted is technically
inaccurate. (Id.)
Regarding ClimateMaster's request for clarity regarding the
definition, DOE notes that all products that meet the WSHP definition,
with sizes less than 760,000 Btu/h cooling capacity (see discussion in
section III.A of this final rule), would be considered a WSHP,
regardless of whether the models are marketed and distributed in
commerce for commercial or residential applications. The definition of
WSHPs includes both single-package and split-system equipment.
Regarding WaterFurnace's comment on whether it would be necessary
to change the definition of WSHP if DOE were to maintain the method of
test based on ISO 13256 and AHRI 600, the DOE definition of WSHP serves
to specify models that are within the scope of coverage of DOE's
regulations and is independent of the test procedure being used for
WSHPs. DOE also notes in response to WaterFurnace's comment that the
definition of WSHP already uses the term ``heat pump'' to define WSHP
and that the term ``commercial package air-conditioning and heating
equipment'' is being added to the definition only to indicate the
larger type of equipment, as defined in the EPCA, of which WSHPs are a
category.
Regarding ClimateMaster's comment that the current definition does
not cover units that are not reversible, DOE considers water-source
heat pumps to include only models with reverse-cycle heating;
therefore, DOE is not removing the ``reverse-cycle'' provision from the
WSHP definition.
For the reasons discussed, DOE is adopting an amended definition of
WSHP that is identical to the definition proposed in the August 2022
NOPR, as follows:
Water-source heat pump means commercial package air-conditioning
and heating equipment that is a single-phase or three-phase reverse-
cycle heat pump that uses a circulating water loop as the heat source
for heating and as the

[[Page 84195]]

heat sink for cooling. The main components are a compressor,
refrigerant-to-water heat exchanger, refrigerant-to-air heat exchanger,
refrigerant expansion devices, refrigerant reversing valve, and indoor
fan (except that coil-only units do not include an indoor fan). Such
equipment includes, but is not limited to, water-to-air water-loop heat
pumps.

C. Organization of the Amended DOE Test Procedures

In this final rule, DOE is relocating and centralizing the current
test procedure for WSHPs to a new appendix C to subpart F of part 431
and establishing an amended test procedure for WSHPs in a new appendix
C1 to subpart F of part 431. Appendix C maintains the substance of the
current test procedure and continues to reference ISO 13256-1:1998 and
provide for determining EER and COP. Appendix C also includes the
additional test provisions for equipment set-up currently codified at
10 CFR 431.96(e). As discussed, WSHPs are required to be tested
according to appendix C until such time as compliance is required with
an amended energy conservation standard based on the amended test
procedure in appendix C1, should DOE adopt such a standard.
DOE is also establishing an amended test procedure for WSHPs in a
new appendix C1 to subpart F of part 431 that includes provisions for
determining IEER and ACOP by incorporating by reference AHRI 600-2023,
as discussed further throughout this document. WSHPs are not required
to be tested according to appendix C1 until such time as compliance is
required with an amended energy conservation standard denominated in
terms of the IEER metric, should DOE adopt such a standard; although,
any voluntary representations of IEER prior to the compliance date of
any such standard must be based on testing according to appendix C1.

D. Updates to Industry Standards

As noted in section I.B. of this document, the DOE test procedure
currently incorporates by reference ISO 13256-1:1998 and includes
additional provisions for equipment set-up at 10 CFR 431.96(e), which
provide specifications for addressing key information typically found
in the installation and operation manuals. In the August 2022 NOPR, DOE
proposed to adopt an amended test procedure for WSHPs in a new appendix
C1 that would incorporate by reference AHRI 340/360-2022 for measuring
efficiency using IEER. 87 FR 53302, 53311. Because AHRI 340/360-2022
references ANSI/ASHRAE 37-2009 for test provisions, DOE also proposed
to incorporate by reference relevant sections of ANSI/ASHRAE 37-2009 in
its amended test procedure for WSHPs. Id. at 87 FR 53312. Compared to
the current test procedure, the key substantive changes that would
result from DOE adopting the proposed test procedure included the
following:
(1) A new energy efficiency descriptor, IEER, which incorporates
part-load cooling performance;
(2) Modified test conditions for determining COP;
(3) Minimum external static pressure (``ESP'') requirements,
instructions for setting airflow and ESP, and tolerances for airflow
and ESP, and
(4) Specified liquid ESP requirements for units with integral pumps
and a method to account for total pumping effect for units without
integral pumps. Id. at 87 FR 53305.
In response to this proposal, DOE received multiple comments
(summarized in the following sub-sections) urging DOE not to
incorporate by reference AHRI 340/360-2022 as the test procedure for
WSHPs, to continue to collaborate with industry on finalizing AHRI 600,
and to instead adopt the revised industry test standard resulting from
work on AHRI 600. As previously noted, after publication of the August
2022 NOPR, DOE worked with the AHRI Geothermal and WSHP STC to develop
a revised version of AHRI 600 (AHRI 600-2023) to address the issues DOE
raised in the August 2022 NOPR. As discussed further throughout this
section, AHRI 600-2023 includes a method to determine IEER for WSHPs
similar to that proposed in the August 2022 NOPR and addresses many of
the concerns expressed by commenters in response to the August 2022
NOPR. As discussed, AHRI 600-2023 is intended to serve as the primary
industry test procedure for WSHPs going forward and it does not
reference any versions of ISO Standard 13256-1. Instead, AHRI 600-2023
references ANSI/ASHRAE 37-2009 and includes sufficient provisions for
testing WSHPs that references to test provisions in ISO Standard 13256-
1 or AHRI 340/360-2022 are not needed.
As discussed further throughout this section, in this final rule,
DOE is adopting an amended test procedure that incorporates by
reference AHRI 600-2023, with minor differences as explained further
throughout the following sections of this document.
In the following sections, DOE summarizes comments received in
response to the August 2022 NOPR with regard to industry standards.
1. Comments Regarding DOE's Authority
As discussed previously in this document, with respect to small,
large, and very large commercial package air conditioning and heating
equipment (of which WSHPs are a category), EPCA directs that when the
generally accepted industry testing procedures or rating procedures
developed or recognized by AHRI or by ASHRAE, as referenced in ASHRAE
90.1, are amended, the Secretary shall amend the DOE test procedure
consistent with the amended industry test procedure or rating procedure
unless the Secretary determines, by clear and convincing evidence, that
to do so would not meet the requirements for test procedures to produce
results representative of an average use cycle and is not unduly
burdensome to conduct. (42 U.S.C. 6314(a)(4)(A)-(B))
In response to the August 2022 NOPR, AHRI, MIAQ, and WaterFurnace
expressed concern with DOE's proposal to adopt a test procedure
different from the industry standard (i.e., ISO 13256-1:1998 and the
not yet published AHRI 600 standard), and the procedure cited in ASHRAE
90.1. (AHRI, No. 24 at pp. 1-2; MIAQ, No. 23 at pp. 1-2; WaterFurnace,
No. 20 at p. 1) AHRI, MIAQ, and WaterFurnace noted that EPCA explicitly
directs DOE to adopt the industry consensus test procedure cited in
ASHRAE 90.1 and asserted that EPCA precludes DOE from adopting as a
national standard a wholly different test procedure from that cited in
ASHRAE 90.1. (Id.) These commenters urged DOE to adopt a revised test
method only after it has been published by AHRI and adopted by ASHRAE
in ASHRAE 90.1. (Id.)
MIAQ asserted further that EPCA requires DOE to justify by clear
and convincing evidence each amendment or difference between AHRI 340/
360-2022 and ISO 13256-1:1998. (MIAQ, No. 23 at p. 2) MIAQ commented
that DOE has determined in past rulemakings that ISO 13256-1 is cost
effective and representative of energy use. (Id.) MIAQ stated that any
deviation from ASHRAE 90.1 requires quantification of the burden and
that only modifications that reduce testing burden on manufacturers can
be considered. (Id. at p. 3)
AHRI and MIAQ commented that DOE and outside stakeholders have been
developing a consensus-based revision to the test procedure for
commercial packaged air conditioners and heat pumps (``CUAC/HPs'').
(AHRI,

[[Page 84196]]

No. 24 at p. 2; MIAQ, No. 23 at p. 2) AHRI and MIAQ further stated that
after AHRI 600 has been finalized and adopted, AHRI will introduce the
new test procedure to ASHRAE 90.1 to begin the procedural process for
updates. (AHRI, No. 24 at p. 3; MIAQ, No. 23 at p. 2) AHRI and MIAQ
commented that waiting to harmonize standards would establish
consistent energy efficiency levels and design requirements between
industry and Federal requirements, as well as comparable metrics and
scope. (AHRI, No. 24 at p. 3; MIAQ, No. 23 at pp. 2-3) AHRI and MIAQ
recommended that DOE continue to work with AHRI and other stakeholders
to finalize AHRI 600 and support a proposed amendment to ASHRAE 90.1,
which DOE could adopt as the national test procedure during the next
rulemaking. (AHRI, No. 24 at p. 4; MIAQ, No. 23 at pp. 3, 9)
ClimateMaster commented that DOE has not followed a cooperative
approach to improve the test methods as proposed in the August 2022
NOPR. (ClimateMaster, No. 22 at p. 1) ClimateMaster asserted that this
seems to violate EPCA, which requires DOE to adopt the test procedure
cited in ASHRAE 90.1. (Id.)
With regard to comments asserting that DOE does not have the
authority to adopt a test procedure prior to its inclusion in ASHRAE
90.1, EPCA provides DOE with authority to adopt an amended test
procedure in satisfaction of EPCA's 7-year-lookback review requirement
for test procedures. (42 U.S.C. 6314(a)(1)(A)). Under its 7-year-
lookback review, DOE must ensure that test procedures established are
reasonably designed to produce test results which reflect energy
efficiency, energy use, and estimated operating costs during a
representative average use cycle and are not unduly burdensome to
conduct. (42 U.S.C. 6314(a)(2)) During its 7-year lookback review, DOE
is directed by EPCA to evaluate whether an amended test procedure would
more accurately or fully comply with those requirements, and if DOE
determines an amended test procedure would do so, then DOE is required
to prescribe such test procedures for the equipment class. (42 U.S.C.
6314(a)(1)(A)) It is important to note that under the 7-year lookback
DOE does not need clear and convincing evidence that an amended test
procedure would more accurately or fully comply with EPCA's
requirements. (Id.) Rather, DOE must show that the amended test
procedure is reasonably designed to produce test results which reflect
energy efficiency, energy use, and estimated operating costs during a
representative average use cycle and are not unduly burdensome to
conduct. (42 U.S.C. 6314(a)(2)) For example, a test procedure
referenced by ASHRAE 90.1 may not be reasonably representative because
more representative test procedures are available. And a test procedure
that was reasonably representative in the past may become unreasonably
representative when newly available test procedures allow for better,
more complete measurements. DOE's 7-year-lookback review under EPCA
ensures that DOE is not bound to an industry test procedure that has
not been updated and is no longer representative of current equipment.
DOE notes that submitted comments from AHRI, WaterFurnace,
ClimateMaster, and MIAQ do not mention DOE's 7-year-lookback review and
therefore only engaged with the review process under 42 U.S.C.
6314(a)(4)(A). AHRI stated in its written comment that DOE is mandated
to adopt an industry test procedure only after that test procedure is
adopted in ASHRAE 90.1 but identified no such mandate within the
statute itself. It is important to note that the 7-year-lookback review
language at issue here was added to EPCA in EISA 2007, well after the
relevant ASHRAE 90.1 test procedure language was added in 1992.
(Compare Sec. 302 of EISA 2007, Pub. L. 110-140, 121 STAT. 1552 (Dec.
19, 2007) with Sec. 121 of the Energy Policy Act of 1992, Pub. L. 106-
486, 106 STAT. 2808 (Oct. 24, 1992)). Therefore, the most natural
reading of the two provisions together is that Congress intended to add
the 7-year-lookback review to those triggers for review of test
procedures that already existed. The language of the 7-year-lookback
review applies generally to all covered equipment. Rather than restrict
DOE to an outdated test procedure in the manner the industry commenters
suggest, EPCA instead compels DOE to use due diligence to review the
totality of relevant and available information before settling on
appropriate energy conservation standards and test procedures.
As a result, it is appropriate for DOE to consider in its 7-year-
lookback whether amendments to the test procedure would more accurately
produce test results which reflect energy efficiency, energy use, and
estimated operating costs during a representative average use cycle and
would not be unduly burdensome to conduct even without an update to
AHSRAE 90-1. DOE finds here that the test procedure provided in the
updated industry consensus test standard for WSHPs (AHRI 600-2023), and
therefore the test procedure specified in the regulatory text of this
final rule, is more representative without incurring undue burden, as
discussed below, thereby satisfying EPCA's requirements.
DOE acknowledges that DOE has previously stated that it will only
consider an update to ASHRAE 90.1 that modifies the referenced industry
test procedure to be a trigger under that provision of the statute, as
opposed to an update of just the industry test procedure itself. (See
e.g., 86 FR 35668, 35676 (July 7, 2021)). DOE stands by that position
regarding what constitutes a triggering event in the context of ASHRAE
equipment and does not consider the provisions in 42 U.S.C. 6314(a)(4)
to have been triggered. However, that does not preclude DOE from
considering an amended test procedure when reviewing DOE's test
procedures under EPCA's 7-year-lookback provision. Not only does DOE
have discretion to do so, but it has a statutory duty to do so, to
ensure that its test procedures produce results that are representative
of an average use cycle and are not unduly burdensome to conduct.
DOE has determined that the test procedure adopted in this final
rule for WSHPs would improve the representativeness of the current
Federal test procedure for WSHPs and would not be unduly burdensome.
Specifically, DOE has concluded that testing WSHPs in accordance with
AHRI 600-2023 would provide more representative results and more fully
comply with the requirements of paragraph (2) of 42 U.S.C. 6314(a) than
testing in accordance with the currently referenced standard ISO 13256-
1:1998, as discussed in more detail in section III.D.6 of this final
rule. And while clear and convincing evidence is not needed when
amending a test procedure under the 7-year-lookback, DOE finds that the
test procedure amendments adopted here are supported by clear and
convincing evidence as outlined in this final rule. DOE discusses the
specific test procedure updates included in appendix C1, resulting from
the incorporation by reference of AHRI 600-2023, in sections III.E and
III.F of this final rule. Therefore, DOE is adopting an amended test
procedure for WSHPs that incorporates by reference AHRI 600-2023, with
minor deviations. With regard to the assertion by AHRI and MIAQ that
any deviation from ASHRAE 90.1 requires quantification of the burden,
and MIAQ's assertion that only modifications that reduce testing burden
on manufacturers can be considered, DOE does not agree that EPCA
requires DOE to consider only deviations that

[[Page 84197]]

would reduce burden. Rather, EPCA requires only that DOE ensure that
test procedures established are not unduly burdensome to conduct. (42
U.S.C. 6314(a)(2))
With regard to the assertion by AHRI and MIAQ that EPCA requires
DOE to justify by clear and convincing evidence each amendment or
difference from the industry test procedure referenced by ASHRAE 90.1,
DOE does not agree that EPCA requires such a line-by-line assessment of
an amended test procedure. First, as stated previously, there is no
requirement for clear and convincing evidence in EPCA for a test
procedure amendment under the 7-year-lookback. Additionally, if DOE
were amending a test procedure pursuant to the ASHRAE trigger, EPCA
requires only that DOE shall amend the test procedure for the product
as necessary to be consistent with the amended industry test procedure
or rating procedure unless it determines, supported by clear and
convincing evidence, that to do so would not meet the requirements of
EPCA (42 U.S.C. 6314 (a)(4)(B)). If DOE makes such a determination, DOE
may establish an amended test procedure, but there is no requirement
for DOE to show, by clear and convincing evidence, that DOE's amended
test procedure is reasonably designed to produce test results which
reflect energy efficiency, energy use, and estimated operating costs
during a representative average use cycle and are not unduly burdensome
to conduct. (See 42 U.S.C. 6314(a)(2)). Additionally, if DOE does not
make such a determination, there is no requirement that DOE show, by
clear and convincing evidence, that an amended test procedure, which is
consistent with the industry test procedure, is reasonably designed to
produce test results which reflect energy efficiency, energy use, and
estimated operating costs during a representative average use cycle and
are not unduly burdensome to conduct.
2. Comments Regarding DOE's Test Procedure Development Process
In response to the June 2022 NOPR, DOE received comments regarding
its rulemaking development process. AHRI recommended that DOE follow a
transparent, cooperative, or consensus-based regulatory development
process. (AHRI, No. 24 at p. 4) AHRI commented that, in the past, DOE
has had difficulty duplicating test results without the help and
guidance of manufacturers and AHRI testing facilities and that the
complex controls and operational characteristics of WSHP equipment
require manufacturer and testing facility experience to test properly.
(Id.) AHRI acknowledged that DOE has tested 15 units from the WSHP
industry but stated that DOE did not release the data and results of
the testing. (Id.) AHRI expressed further concern that the testing
cited in the August 2022 NOPR was not shared with the relevant AHRI
committee and requested that DOE share the results of its findings with
stakeholders in order to allow for validation and review. (Id. at pp.
2, 4)
AHRI recommended that DOE work with industry on finalizing AHRI
600, conduct any necessary testing or calculations to develop a
document agreed upon by DOE and relevant stakeholders, and follow the
proper procedures to introduce the finalized test procedure and updated
efficiency standards in ASHRAE 90.1. (Id.) AHRI commented that it will
support the necessary updates to the Federal procedure and metrics
after DOE takes the aforementioned steps. (Id.)
ClimateMaster commented that DOE did not follow a cooperative
process to improve the test methods for WSHPs and that neither AHRI nor
the WSHP industry was consulted in a working group setting with other
stakeholders, which was inconsistent with past and current industry
approaches. (ClimateMaster, No. 22 at p. 1)
WaterFurnace commented that it believed a more transparent and
consensus-based development process is warranted before DOE implements
new WSHP test procedures and that DOE should seek industry and AHRI
input in order to validate and review the testing results.
(WaterFurnace, No. 20 p. 2) WaterFurnace recommended that DOE implement
an Appliance Standards and Rulemaking Federal Advisory Committee
(``ASRAC'') Working Group for all future undertakings to propose
substantial changes in regulatory policy so as to work out complex
issues in a common forum with industry and AHRI. (Id.)
With respect to the comments from AHRI, ClimateMaster, and
WaterFurnace, DOE notes that it may establish a negotiated rulemaking
working group under ASRAC in accordance with the Federal Advisory
Committee Act (``FACA'') and the Negotiated Rulemaking Act (``NRA'') (5
U.S.C. 561-570, Pub. L. 104-320) to negotiate proposed test procedures
and amended energy conservation standards if DOE determines that the
use of the negotiated rulemaking process is in the public interest
according to the requirements of FACA and in a manner consistent with
the requirements of the NRA. However, in this rulemaking, DOE is
following the traditional rulemaking notice-and-comment process.
DOE recognizes the benefits of developing test procedures through a
consensus-based process and notes that DOE has participated in the AHRI
process and has worked with the AHRI Geothermal and WSHP STC in
developing AHRI 600-2023, which is incorporated by reference in this
final rule. As noted in the August 2022 NOPR, DOE has participated in
AHRI committee meetings working to develop AHRI 600 since 2019. See 87
FR 53302, 53308-53309. In particular, DOE brought up many of the
concerns raised in August 2022 NOPR in ISO 13256-1 and AHRI 600
meetings for several years prior to the publication of the August 2022
NOPR, but the committees declined to address these issues in the draft
industry test procedures at that time. At the time of drafting of the
August 2022 NOPR, AHRI 600 was still in development and had not yet
published. In the August 2022 NOPR, DOE outlined its understanding that
the intent of AHRI 600 would be to provide a method for calculation of
IEER for WSHPs based on testing conducted according to ISO 13256-
1:1998. Id. at 87 FR 53309. In the August 2022 NOPR, DOE tentatively
concluded that the general methodology in AHRI 600 for determining IEER
is appropriate. Id. However, DOE identified several aspects of the
methodology that warrant further modifications. Id. In the August 2022
NOPR, DOE noted that it could not speculate as to the substantive
outputs of the ISO 13256-1 National deviation and the AHRI 600
committee's efforts. Id. Consistent with DOE's procedure for notice-
and-comment rulemakings, DOE also conducted the NOPR public meeting
that provided opportunity for stakeholders to provide feedback on DOE's
proposals. The feedback DOE received in both NOPR public meeting
comments and written comments was considered in subsequent AHRI 600
committee meetings and drafting of this final rule.
Since the publication of the August 2022 NOPR, DOE continued to
work with industry in AHRI 600 committee, as recommended by commenters,
to address the test procedure concerns DOE raised in the August 2022
NOPR with the intent that a revised industry test procedure specific to
WSHPs could be adopted in a final rule. Rather than continue to
simultaneously modify and maintain ISO 13256-1 and AHRI-600, the
committee members voted to merge them into a comprehensive unified test
procedure, AHRI 600. More specifically, the methodology specified in
ISO 13256-1 has been incorporated into

[[Page 84198]]

AHRI 600-2023. Therefore, AHRI 600-2023 does not reference ISO 13256-1.
Regarding AHRI's comment about sharing data, DOE presented the
results of its testing in the August 2022 NOPR. Id. at 87 FR 53314-
53317. Based on participation in AHRI 600 committee meetings following
the August 2022 NOPR, additional data from DOE's investigative testing
was not needed for the committee to reach resolution on the content of
AHRI 600-2023.
On September 11, 2023, AHRI 600-2023 was published. DOE notes that
the statutory deadline for publishing a test procedure final rule for
WSHPs was May 16, 2019. (42 U.S.C. 6314(a)(1)) Given EPCA's statutory
requirement to review the appropriate test procedures for WSHPs every
seven years, DOE has concluded that it would be neither appropriate nor
permissible to delay the current rulemaking for the WSHP test procedure
until after ASHRAE 90.1 adopts AHRI 600-2023 as the test procedure for
WSHPs. To avoid any further delay, DOE is adopting a test procedure for
WSHPs that incorporates by reference AHRI 600-2023, with minor
deviations.
3. Comments Supporting the Adoption of AHRI 340/360-2022
In response to the June 2022 NOPR, some commenters supported
adopting AHRI 340/360-2022 in the WSHP test procedure. NEEA generally
supported DOE's efforts to align the WSHP test procedure with other
water-cooled unitary systems, including by integrating fan energy into
the test procedure for ducted WSHPs. (NEEA, No. 25 at p. 1) In
particular, NEEA supported DOE's proposal to align the WSHP test
procedure with AHRI 340/360-2022 and ANSI/ASHRAE 37-2009. (Id. at p. 2)
NEEA stated that aligning the testing of WSHPs with ANSI/ASHRAE 37-2009
would ensure that WSHP ratings will be consistent with other water-
cooled and direct expansion cooling systems. (Id.) NEEA also supported
the introduction of an IEER metric rather than rating only with EER.
(Id.) NEEA stated that the proposed test procedure would impact the
current modeling approach for WSHP standard reference systems used to
determine total system performance ratio in the 2018 Washington State
Energy Code, but NEEA acknowledged that potential advancements to the
test procedure and ratings metric would provide an important
improvement in representativeness for this equipment. (Id. at p. 1)
NYSERDA generally supported DOE's proposed amendments for the WSHP
test procedure and concurred with DOE's tentative determination that
the changes would improve the representativeness of the WSHP test
procedure. (NYSERDA, No. 21 at pp. 1-2) NYSERDA asserted that this
would spur growth in the market for WSHPs, including geothermal heat
pumps. (Id. at p.2)
As discussed previously, in this final rule, DOE is incorporating
by reference AHRI 600-2023 into appendix C1 in lieu of incorporating by
reference AHRI 340/360-2022 as proposed in the August 2022 NOPR. DOE
notes, however, that the majority of the technical content from the
proposed test procedure in the August 2022 NOPR remains consistent in
the test procedure finalized in this final rule. Any changes to
technical provisions from the August 2022 NOPR proposal were due to
industry consensus culminating in the AHRI 600-2023 standard.
Throughout this final rule, DOE discusses in detail the technical
differences between the test procedure proposed in the August 2022 NOPR
and the version finalized in this final rule.
4. Comments Opposing the Adoption of AHRI 340/360-2022
Other commenters opposed the proposal in the August 2022 NOPR to
adopt AHRI 340/360-2022 in the WSHP test procedure. AHRI and MIAQ
expressed concern that the impact on manufacturers of DOE's proposal to
update the WSHP test procedure has not been quantified. (AHRI, No. 24
at p. 2; MIAQ, No. 23 at p. 3) AHRI and MIAQ stated that the capability
of testing WSHPs to AHRI 340/360-2022 has not been assessed by third-
part test labs. (Id.)
AHRI and MIAQ noted that an ASRAC Working Group has been formed in
an effort to negotiate test procedures and energy efficiency standards
for CUAC/HPs, the scope of which stands to result in significant
modifications to AHRI 340/360-2022 and the efficiency measures for such
equipment. (AHRI, No. 24, at p. 2; MIAQ, No. 23 at p. 2) AHRI and MIAQ
further noted, however, that WSHPs are outside the scope of these
efforts, potentially leaving a significant gap in ratings (i.e., were
WSHPs to be rated using AHRI 340/360). (Id.)
WaterFurnace expressed concern regarding DOE's sampling and testing
procedure for modifying AHRI 340/360, especially considering the
complexity of the product's controls and operational characteristics
and taking into account past instances in which DOE has struggled to
duplicate test results without manufacturer and AHRI testing support.
(WaterFurnace, No. 20 at p. 2)
WaterFurnace agreed with AHRI's concerns that the impact on
manufacturers of DOE's proposal to update test procedures has not been
adequately quantified, nor was it clear whether third-party test labs
have the capability to accommodate the proposed changes. (Id. at p. 2)
WaterFurnace, ClimateMaster, Enertech, and FHP all expressed
concern that DOE's proposal to test WSHPs using AHRI 340/360-2022 would
require manufacturers to test WSHPs to two different test standards
because geothermal applications for WSHPs would still require testing
to ISO 13256-1. (WaterFurnace, No. 20 at p. 3; ClimateMaster, No. 22 at
p. 1; Enertech, No. 19 at p. 1; FHP, No. 26 at p. 3) WaterFurnace noted
that ISO 13256-1 is already referenced in several Federal, State, and
local codes. (WaterFurnace, No. 20 at p. 3) WaterFurnace and
ClimateMaster stated that implementing a dual certification process
would be burdensome for manufacturers. (WaterFurnace, No. 20 at p. 3;
ClimateMaster, No. 22 p. 1) Enertech also noted that Federal and State
tax credits specifically reference ISO/AHRI 13256-1:1998 for efficiency
ratings and that the ENERGY STAR specifications directly reference the
ISO 13256-1:1998 standard for the ENERGY STAR Tier 3 efficiency
requirements. (Enertech, No. 19 at p. 1)
WaterFurnace asserted that DOE underestimated the significance and
the burden that the proposed changes to the WSHP test procedure would
impose upon manufacturers and industry players. (WaterFurnace, No. 20
at p. 3) WaterFurnace identified the following assumptions and
shortcomings in AHRI 340/360-2022 that it stated were not appropriately
addressed in the August 2022 NOPR:
(1) While the August 2022 NOPR stated that IEER can be calculated
and an interpolation can be performed using existing data from ISO
13256-1, WaterFurnace determined that the entering air, water flow,
external static and airflow conditions differ from AHRI 340/360-2022,
which will therefore require additional testing by the manufacturer and
the implementation of a new certification program;
(2) Currently, performance mapping capability is available across a
wide range of entering water temperatures (``EWT'') used in modeling
software such as EQuest and DOE's EnergyPlus, and all of this detail
would be lost with the implementation of AHRI 340/360-2022 because it
only presents a single IEER cooling metric and a single heating point;

[[Page 84199]]

(3) Provisions should be added under AHRI 340/360-2022 for hybrid
heat pumps, which are unique in their capability for refrigerant
cooling with other non-refrigerant heating capability;
(4) Provisions should be added under AHRI 340/360-2022 for split
configurations, which are offered for smaller WSHPs;
(5) Provisions should be added under AHRI 340/360-2022 for small
WSHPs with non-ducted applications (e.g., console units), along with
language that takes into account the fact that many of these units are
installed into residential buildings with substantial heating that
would not fit the AHRI 340/360-2022 conditions;
(6) While DOE proposed to adopt heating test conditions for WSHPs
that are not specified in AHRI 340/360-2022, this overlooks other
testing requirements and language that would need to be addressed
(e.g., minimum and maximum operating conditions) in order to adequately
add heating tests to a cooling-only standard;
(7) Provisions should be added under AHRI 340/360-2022 for
antifreeze blends and their fluid characteristics (i.e., alcohols,
salts, and glycols);
(8) Test procedures would need to be modified to account for
smaller WSHP units, as AHRI 340/360-2022 requires an airflow tolerance
of less than 3 percent and is thus designed around larger product
designs with drives and adjustable sheaves that accommodate this
airflow capability;
(9) Although AHRI 340/360-2022 is primarily an air-source standard
that utilizes air and refrigerant enthalpy test methods, water-source
equipment is more consistently and accurately tested with a liquid
enthalpy test method and would need to use air or refrigerant enthalpy
only as secondary methods--and, furthermore, this process would be
inconsistent with part load measurements under AHRI 340/360-2022;
(10) Manufacturer-specified liquid flow rate is preferred over the
AHRI 340/360-2022 method of setting liquid flow rate using a 10 [deg]F
temperature rise to establish flow rates;
(11) Continuous 24/7 fan operation is an outdated idea according to
ASHRAE 90.1; and
(12) Issues addressed by Working Groups under ASRAC will likely
result in massive changes to AHRI 340/360 regarding air-side
measurements and will take focus away from necessary modifications to
provisions for water-cooled units and, thus, changes for water-cooled
units to AHRI 340/360 will likely be of secondary importance to the
ASRAC committee. (Id. at pp. 3-4)
WaterFurnace also commented that because AHRI 340/360-2022 is
primarily an air-source standard, AHRI 340/360-2022's comparatively
small water-cooled section is used to certify approximately 1,000 units
per year in contrast to the 200,000 unit sales per year under the AHRI/
ISO 13256 certification programs. (Id. at p. 5) Therefore, WaterFurnace
noted that moving testing of WSHPs (with much higher shipments) to the
smaller water-cooled section of AHRI 340/360-2022 would not be logical
considering the noted changes required. (Id.)
WaterFurnace commented that changing to a different AHRI 340/360-
2022 standard and separating out geothermal applications to ISO 13256
would be disruptive to both the water-source and geothermal industries
at a time when the use of heat pumps is being encouraged by national,
state, and local regulations as a carbon-reduction solution. (Id.)
WaterFurnace stated that tax credits and rebates based upon AHRI/ISO
13256 performance have been legislatively codified and will be
difficult to change, and further noted that the Inflation Reduction Act
references ASHRAE 90.1 and AHRI/ISO 13256 as a measurement of
performance. (Id. at p. 6) WaterFurnace stated that other governmental
programs such as ENERGY STAR have specifications and benefits based on
AHRI/ISO 13256 performance certification and that decarbonization
policy programs by utilities, cities, and states rely on such
certification as well. (Id.)
ClimateMaster commented that DOE would need to address the
following issues with AHRI 340/360-2022:
(1) AHRI 340/360-2022 needs to be updated to include the appendix
C1 additions, a process that will likely be delayed by a current ASRAC
working group undertaking to amend the current AHRI 340/360-2022 test
procedures with a focus on air-source equipment;
(2) AHRI 340/360-2022 does not include test requirements for water-
source heating;
(3) AHRI 340/360-2022 does not include test provisions for non-
ducted equipment;
(4) The airflow setting and tolerance specified by AHRI 340/360-
2022 does not cover or is incompatible with current WSHP equipment;
(5) AHRI 340/360-2022 does not include a pump power adder for all
equipment sizes, nor is DOE's proposal to utilize the pump power adder
in AHRI 920 representative of installed WSHP systems;
(6) AHRI 340/360-2022 does not include glycols or antifreeze
solutions in the method of test, and the recommended solution is not
representative of the fluids used for WSHPs in the field or test
laboratories currently used in the development, qualification, and
compliance processes; and
(7) The refrigerant charging requirements included in AHRI 340/360-
2022 are not applicable, accurate, or relevant to WSHP systems.
(ClimateMaster, No. 22 at pp. 1-2)
Enertech commented that AHRI 340/360-2022 lacks testing parameters
for water source heating, testing parameters for non-ducted equipment,
testing methods utilizing antifreeze blends, and parameters for pump
power adder for small equipment. (Enertech, No. 19 at p. 1) Enertech
noted that AHRI 340/360-2022 requires a <plus-minus>3 percent airflow
tolerance during testing, which Enertech asserted is unrealistic for
small-capacity equipment. (Id.) For these reasons, Enertech disagreed
that new efficiency ratings could be interpolated from conditions
common to the WSHP industry and asserted that new testing would be
required for all products offered by any manufacturer. (Id.) Enertech
stated that adopting AHRI 340/360-2022 as the DOE test procedure for
WSHPs would result in long-term disruptions to the geothermal and WSHP
industries. (Id. at p. 2)
FHP commented that adopting test methods per AHRI 340/360-2022
would require additional testing effort, time, and resources, and would
result in additional costs to the industry. (FHP, No. 26 at p. 3) FHP
commented further that AHRI 340/360-2022 contains differences in
standard test conditions that would require additional testing as well
as changes to (1) the design of the units to ensure 10 [deg]F
temperature rise on the water side and (2) the fan/motor selections and
programs to maintain the proper air flow at defined static pressures
and airflow tolerances. (Id.) FHP stated that the use of two standards
may split the current WSHP product designs, thereby adding permanent
design burden to current product offerings. (Id.)
FHP stated that the proposed changes to the WSHP test procedure
could be the most impactful regulatory issue for the WSHP industry and
that the industry's resources are completely dedicated to the
development of equipment that uses low-global warming potential
refrigerants through January 1, 2025. (FHP, No. 26 at p. 5) FHP
expressed concern about the impact of moving to an entirely new test
procedure that would require re-testing, re-designing, and potentially
re-certifying most of its basic model groups. (Id.) FHP also

[[Page 84200]]

expressed concerns about the additional resources and maintenance
potentially required by having two separate product designs and
validations for WSHPs. (Id.)
FHP also stated that current AEDMs are based on the leading
industry standard for these types of equipment. (Id. at p. 2) More
specifically, FHP stated that its current AEDM is based on the ISO
13256-1:1998 test standard and that DOE's proposal to reference AHRI
340/360-2022 as the test procedure for WSHPs would require additional
testing and new AEDMs. (Id.) FHP commented that even reduced testing to
validate AEDMs would be unduly burdensome for such a small market.
(Id.)
During the public meeting, AAON commented that the amount of
testing in the proposed test procedure was rather extreme and asked DOE
to share the testing burden assessment. (Public Meeting Transcript, No.
17 at p. 60)
GeoExchange commented that manufacturers of geothermal heat pumps
have significant concerns with the August 2022 NOPR as written and
believe it will subject WSHPs and geothermal heat pumps to competing
and inconsistent certification standards. (GeoExchange, No. 29 at p. 1)
GeoExchange commented that these issues will complicate production of
these products and increase costs for consumers. (Id.) GeoExchange
stated that the timing of the August 2022 NOPR coincides with efforts
by the industry to complete work on its development of a standard that
recognizes the overlap between different applications of heat pump
technology and minimizes unnecessary disruptions for manufacturers.
(Id.)
DOE appreciates these comments regarding the proposal to adopt AHRI
340/360-2022 in the WSHP test procedure. As discussed, in this final
rule, DOE is no longer adopting AHRI 340-360-2022 and is adopting
instead an amended test procedure for WSHPs that incorporates by
reference AHRI 600-2023. Because AHRI 600-2023 was developed through an
industry consensus process subsequent to the timing of the August 2022
NOPR comment period, DOE surmises that the testing approach specified
in AHRI 600-2023 represents the prevailing industry consensus regarding
the most appropriate method of testing WSHPs and addresses the issues
raised by commenters regarding DOE's proposal to adopt AHRI 340/360-
2022 as the test procedure for WSHPs. See sections III.E and III.F of
this final rule for discussion of specific test procedure topics raised
by interested parties in response to the August 2022 NOPR.
Further, in response to the test burden comments, DOE did quantify
per-test burden of the proposed test procedure in the August 2022 NOPR
and found that the proposed test procedure was not unduly burdensome to
conduct. 87 FR 53302, 53340. A similar analysis is presented in this
final rule (see section III.I of this document for details), and the
same conclusion is reached. Additionally, as discussed in this
document, DOE is adopting a test procedure incorporating by reference
the industry consensus test standard, AHRI 600-2023. Therefore, DOE has
determined that the amended test procedure will not increase burden as
compared to the latest draft industry consensus test standard.
5. Comments Encouraging the Adoption of AHRI 600
Numerous commenters encouraged DOE to adopt AHRI 600 in an amended
WSHP test procedure in response to the August 2022 NOPR. AHRI
recommended that DOE refrain from adopting AHRI 340/360-2022 for WSHPs
in favor of continuing to collaborate with industry on finalizing AHRI
600. (AHRI, No. 24 at p. 4) AHRI commented that AHRI 600 has been under
development for several years and that, despite some delays, is
steadily progressing. (Id.) AHRI commented that during the discussions
for the development of AHRI 600, the committee considered applying AHRI
340/360-2022 to calculate IEER. (Id.) AHRI commented that it continues
to improve AHRI 600 test procedures (e.g., by resolving issues to fan
power, external static pressure, water temperature, and subsequent
efficiency levels) and that AHRI will continue committing to frequent
meetings to satisfactorily resolve the issues raised in August 2022
NOPR. (Id.)
WaterFurnace stated that AHRI 600 draft standard was released in
October 2022 and achieves the objectives of the August 2022 NOPR
without industry distractions. (WaterFurnace, No. 20 p. 5) WaterFurnace
commented that AHRI 600 standard is on track for committee review by
October 31, 2023. (Id.)
WaterFurnace stated that the quickest way to implement appropriate
changes to WSHP test procedures would be to adopt versions of AHRI 600
and ISO 13256-1, as modifying test procedures to comply with AHRI 340/
360-2022 would entail substantial changes that will delay the
implementation process. (Id. at p. 4)
WaterFurnace commented that it supports development of AHRI 600
test procedure and recommended that the DOE test procedure reference it
directly instead of AHRI 340/360-2022. (Id. at p. 5) WaterFurnace
stated that the AHRI 600 standard can resolve most of the issues DOE
identified in the August 2022 NOPR regarding the current WSHP test
procedure. (Id.) WaterFurnace recommended that DOE re-evaluate the
August 2022 NOPR proposal and support WaterFurnace's proposal to
quickly adopt AHRI 600 and the national deviation updates to AHRI/ISO
13256. (Id. at p. 11) WaterFurnace commented that doing so will help
industry achieve DOE's desired goals faster and with less disruption.
(Id.)
WaterFurnace commented that it supports implementation of an
updated AHRI/ISO 13256:1998 with a targeted national deviation and
revised annexes. (Id. at p. 5) WaterFurnace commented that an updated
AHRI/ISO 13256:1998 with a targeted national deviation can solve
specific issues mentioned in the August 2022 NOPR regarding AHRI/ISO
13256 with changes that would not be substantial, stating that the
method of testing WaterFurnace follows aligns with the August 2022
NOPR. (Id.) WaterFurnace commented that many of the issues raised by
DOE center on specific issues and test methods currently in use that
can be documented and solved with a national deviation from AHRI/ISO
13256. (Id.) WaterFurnace stated that it has developed a draft of this
national deviation that will address the noted shortcomings and can be
completed in a similar time frame as AHRI 600 approval. (Id.)
ClimateMaster commented that DOE's proposal to move WSHPs to AHRI
340/360-2022 would create too significant a change in the industry and
instead recommended considering AHRI 600, which uses existing ISO/AHRI
13256-1 certified data to mathematically calculate the system IEER.
(ClimateMaster, No. 22 at p. 1) ClimateMaster further commented that
DOE should consider updating the ISO/AHRI 13256-1:1998 standard to
include national deviations to address specific issues such as: (1)
modifying refrigerant charging and airflow/ESP requirements; and (2)
the need to include a reference to ASHRAE 37 and provisions for air
sampling for air-side capacity measurements. (Id. at p. 2)
Enertech suggested adopting AHRI 600 for calculating IEER rather
than the AHRI 340/360-2022 method. (Enertech, No. 19 at p. 2)
MIAQ recommended that DOE work with industry to finalize AHRI
Standard 600, conduct any necessary testing/calculations to develop a
crosswalk, and follow proper procedures to introduce the finalized
procedure and updated

[[Page 84201]]

efficiency standards in ASHRAE 90.1. (MIAQ, No. 23 at p. 9)
Trane recommended that DOE move from a full-load metric and test
procedure to one that is more representative of an energy use cycle,
such as a part-load test procedure. (Trane, No. 28 at p. 3) Trane
commented that the most accurate and representative test procedure is
AHRI 600, not AHRI 340/360-2022 as proposed in the August 2022 NOPR.
(Id.) Trane noted that AHRI 600 draft is now published and seeking
public comments for the final version. (Id. at p. 2)
As discussed, in this final rule, DOE is adopting an amended test
procedure for WSHPs incorporating by reference AHRI 600-2023. As noted
in the previous discussion, the methodology specified in ISO 13256-1
has been incorporated into the AHRI 600-2023, which represents the
latest industry consensus test standard for WSHPs and moves away from
using ISO 13256-1, thus rendering unnecessary a national deviation to
ISO 13256-1. Having been developed through an industry consensus
process subsequent to the timing of the August 2022 NOPR comment
period, DOE surmises that the testing approach specified in AHRI 600-
2023 represents the prevailing industry consensus regarding the most
appropriate method of testing WSHPs.
6. Finalized DOE Test Procedure
In summary, DOE is adopting an amended test procedure for WSHPs
that incorporates by reference AHRI 600-2023, with minor deviations, in
this final rule. DOE has determined that the test methods specified in
AHRI 600-2023 (which are largely consistent with the provisions adopted
in appendix C1 of this final rule) would produce test results that
better reflect energy efficiency of WSHPs during a representative
average use cycle than the current DOE test procedure and ISO 13256-
1:1998. DOE notes that the IEER metric is representative of cooling
efficiency for WSHPs on an annual basis and is more representative than
the current EER metric, which captures the system performance at a
single, full-load operating point. DOE also notes that the other test
procedure amendments incorporated in this final rule better ensure
accurate and repeatable measurements and ensure that representative
test conditions are maintained during testing. These changes include:
(1) Minimum ESP requirements, instructions for setting airflow and
ESP, and tolerances for airflow and ESP;
(2) Operating tolerance for voltage;
(3) Different indoor air conditions for testing;
(4) Refrigerant charging instructions for cases where they are not
provided by the manufacturer;
(5) Use of the primary capacity measurement (i.e., indoor air
enthalpy method) as the value for capacity, and different provisions
for required agreement between primary and secondary capacity
measurements;
(6) Provisions for split systems, such as accounting for compressor
heat and refrigerant line losses;
(7) Measurement of duct losses for ducted units;
(8) Standardized heat capacity of water and brine; and
(9) A calculation for discharge coefficients.
The subsequent sections of this final rule discuss aspects of the
finalized test procedure that differ from the proposal in the August
2022 NOPR. DOE has determined that these updates improve the
representativeness of the test procedure for WSHPs. These include but
are not limited to:
(1) Updated pump power adder, developed during the AHRI 600-2023
process;
(2) ESP requirements for large units >65,000 Btu/h consistent with
levels from the December 2022 term sheet of recommendations regarding
test procedures for air-cooled commercial unitary air conditioners and
heat pumps (``ACUACs and ACUHPs''), referred to hereafter as ``the
ACUAC and ACUHP Working Group TP Term Sheet'' (See Document No. 65 in
Docket No. EERE-2022-BT-STD-0015);
(3) No option to physically test at the IEER conditions and to
instead require testing at all three ISO 13256-1:1998 conditions;
(4) Updated part-load EWT;
(5) Specifying a maximum water flow rate instead of fixed inlet and
outlet water conditions;
(6) Different test provisions for coil-only units, including
adjustments to default fan power;
(7) Different required fluid--a methanol solution--and different
fluid properties specified;
(8) Some changes to airflow provisions, which are consistent with
DOE's test procedure for central air conditioners and heat pumps at
appendix M1 to subpart B of 10 CFR part 430 instead of AHRI 340/360-
2022;
(9) IEER cyclic degradation equation that does not assume
continuous fan operation; and
(10) Heating test temperature of 50 [deg]F instead of 55 [deg]F.
As discussed, DOE recognizes that the test method in AHRI 600-2023
and incorporated by reference into appendix C1 represents an industry
consensus test procedure that is likely to be considered for future
updates to ASHRAE 90.1.
Accordingly, for the foregoing reasons and those discussed in the
subsequent sections of this final rule, DOE is incorporating by
reference AHRI 600-2023 into the amended Federal test procedure for
WSHPs. DOE has determined that the amended test procedure is reasonably
designed to produce results that are representative of the energy
efficiency of that covered equipment during an average use cycle and is
not unduly burdensome to conduct. DOE notes also that use of appendix
C1 will not be required until the compliance date of any amended
standards denominated in terms of IEER, should DOE adopt such
standards.

E. Efficiency Metrics

1. IEER
As discussed previously, DOE's current test procedure for WSHPs
measures cooling-mode performance in terms of the EER metric, the
current regulatory metric. 10 CFR 431.96. EER captures WSHP performance
at a single, full-load operating point in cooling mode (i.e., a single
EWT) and does not provide a seasonal or load-weighted measure of energy
efficiency. A seasonal metric is a weighted average of the performance
of cooling or heating systems at different outdoor conditions intended
to represent average efficiency over a full cooling or heating season.
Several categories of commercial package air-conditioning and heating
equipment are rated using a seasonal or part-load metric, such as IEER.
IEER is a weighted average of efficiency at four load levels
representing 100, 75, 50, and 25 percent of full-load capacity, each
measured at a specified outdoor condition that is representative of
field operation at the given load level. In general, the IEER metric
provides a more representative measure of field performance than EER by
weighting the full-load and part-load efficiencies by the average
amount of time equipment spends operating at each load level. Table 1
of ISO 13256-1:1998, the industry test standard incorporated by
reference into DOE's current WSHP test procedure, and Table 2 of ISO
13256-1:2021 both specify EWT conditions to be used for developing
part-load ratings of EER for WSHPs with capacity control (tested at
minimum compressor speed). However, part-load EER ratings are not
addressed in the current DOE test procedure. Further, each part-load
rating captures operation only at a single compressor speed and EWT

[[Page 84202]]

condition rather than operation across a range of temperatures and
compressor speeds, as would be captured by an IEER metric. Neither ISO
13256-1:1998 nor ISO 13256-1:2021 include seasonal metrics.
In the August 2022 NOPR, DOE tentatively determined that use of a
seasonal efficiency metric would be more representative of the average
use cycle of a unit as compared to the current EER metric. 87 FR 53302,
53313. Accordingly, DOE proposed to adopt certain provisions of AHRI
340/360-2022 and use the IEER metric specified in section 6.2 of AHRI
340/360-2022 for WSHPs. Id. Specifically, DOE proposed that IEER for
WSHPs be calculated based on the EWT conditions specified in Table 9 of
AHRI 340/360-2022 (i.e., 85 [deg]F, 73.5 [deg]F, 62 [deg]F, and 55
[deg]F). Id. DOE referred to the approach of testing at these AHRI 340/
360-2022 EWTs as ``option 1'' in the August 2022 NOPR. Id. at 87 FR
53316.
In addition, DOE acknowledged in the August 2022 NOPR that adopting
the IEER metric for WSHPs would increase the number of required
cooling-mode tests from one to four. Id. at 87 FR 53313. DOE also
discussed its understanding that the future updated version of AHRI 600
would provide for calculating IEER from test results measured at the
EWTs specified in Table 1 of ISO 13256-1:1998. Id. DOE stated that
determining IEER via interpolation and extrapolation from testing at
the ISO 13256-1:1998 EWTs, rather than from additional testing at the
IEER EWTs specified in AHRI 340/360-2022, may reduce overall testing
burden for manufacturers. Id. at 87 FR 53314. Consistent with this
approach, DOE also proposed to allow determination of IEER via
interpolation and extrapolation (``option 2'') based on testing at the
full-load and part-load EWT conditions specified in Table 1 of ISO
13256-1:1998 (i.e., 86 [deg]F, 77 [deg]F, and 59 [deg]F for full-load
tests and 86 [deg]F, 68 [deg]F, and 59 [deg]F for part-load tests). Id.
at 87 FR 53316. DOE proposed that the tests for option 2 would be
performed using the same test provisions (aside from the EWTs) from
AHRI 340/360-2022, ANSI/ASHRAE 37-2009, and sections 2 through 4 and 7
of proposed appendix C1 as the tests for option 1. Id.
In the August 2022 NOPR, DOE presented test data that indicated
that determining EER by interpolating/extrapolating cooling capacity
and total power would result in closer agreement to tested values than
directly interpolating/extrapolating EER. Id. at 87 FR 53314-53315.
Based on these findings, DOE proposed to specify interpolation/
extrapolation using the cooling capacity and total power as opposed to
EER directly. Id. at 87 FR 53316. DOE also presented data in the August
2022 NOPR indicating that for variable-speed WSHPs with higher (i.e.,
better) EER performance at intermediate compressor speeds than at
maximum or minimum compressor speeds, the proposed interpolation and
extrapolation method would result in a lower (i.e., worse) calculated
IEER than testing at the IEER conditions specified in AHRI 340/360-
2022. Id. at 87 FR 53315-53316. DOE discussed its understanding from
participation in AHRI 600 committee meetings that many manufacturers
would prefer the option to use the interpolation and extrapolation
method for variable-speed WSHPs, even if it results in lower IEER
ratings, because it would result in less overall testing burden than
testing at each of the AHRI 340/360-2022 conditions. Id. at 87 FR
53316.
DOE also proposed that if represented values for a basic model are
determined with an AEDM, the AEDM could use either option 1 or option 2
for determining IEER per the proposed test procedure in appendix C1.
Id.
DOE requested comment on the proposal to allow determination of
IEER using two different methods: (1) testing in accordance with AHRI
340/360-2022; or (2) interpolation and extrapolation of cooling
capacity and power values based on testing in accordance with the
proposed test procedure at the EWTs specified in Table 1 of ISO 13256-
1:1998. Id. DOE sought feedback on the proposed method for calculating
IEER via interpolation and extrapolation, and on whether this approach
would serve as a potential burden-reducing option as compared to
testing at the AHRI 340/360-2022 conditions. Id. DOE also requested
comment on whether the proposed methodology to determine IEER based on
interpolation and extrapolation is appropriate for variable-speed
units. Id. DOE noted it would consider requiring variable-speed
equipment be tested only according to AHRI 340/360-2022 and, thus,
testing physically at the IEER EWTs, if suggested by commenters. Id.
Finally, DOE sought feedback on whether the proposed interpolation and
extrapolation method should be based on testing at the ISO 13256-1:2021
EWTs (which differ from the ISO 13256-1:1998 EWTs for certain test
points). Id.
Some commenters opposed DOE's proposals regarding the IEER metric
in the August 2022 NOPR. ClimateMaster, MIAQ, and WaterFurnace
recommended that DOE adopt the test methods specified in AHRI 600
instead of AHRI 340/360-2022 for calculating the IEER of WSHPs.
(ClimateMaster, No. 22 at pp. 3-5; MIAQ, No. 23 at p. 4; Waterfurnace,
No. 20 at pp. 6-7) MIAQ stated that AHRI 600 will provide a method for
calculating a seasonal cooling efficiency metric for WSHPs (i.e., IEER)
based on testing conducted according to ISO 13256-1:1998. (MIAQ, No. 23
at p. 4) MIAQ stated that that the estimated AHRI 600 approval date of
October 1, 2023 would meet DOE's timeline for adopting the standard.
(Id.) ClimateMaster commented that adopting the test methods specified
in AHRI 340/360-2022 would require manufacturers to certify products
under two programs (i.e., AHRI 340-360 and ISO/AHRI 13256), which is
unprecedented in the industry, and would pose challenges for
manufacturers, third-party labs, and partners to test and maintain two
certification programs. (ClimateMaster, No. 22 at p. 3)
ClimateMaster recommended that DOE utilize data created through ISO
13256-1:1998 to interpolate per the procedure provided in AHRI 600.
(ClimateMaster, No. 22 at p. 4) ClimateMaster disagreed with DOE's
proposal for ``option 2'' to interpolate and extrapolate cooling
capacity and total power instead of directly interpolating/
extrapolating EER and argued that the method in the draft AHRI 600 at
the time should be used, which is based on directly interpolating/
extrapolating EER. (Id.) ClimateMaster further argued that the
difference between the two methodologies is within the uncertainty of
measurement for testing WSHPs and, therefore, that DOE's proposed
deviation from the methodology in AHRI 600 (at the time) is
unnecessary. (Id.) ClimateMaster further commented that their analysis
of a random sample of performance data for five systems tested in their
labs showed that, on average, interpolating/extrapolating based on EER
resulted in slightly more accurate numbers than interpolating/
extrapolating based on capacity and power. (Id. at pp. 4-5)
ClimateMaster recommended that DOE maintain the existing ISO 13256-
1:1998 standard until the WSHP industry adopts the updated standard and
suggested that DOE adopting a national deviation of ISO 13256-1:2021
would be practical as long manufacturers are given significant time to
adopt the new test procedure. (ClimateMaster, No. 22 at p. 5)
ClimateMaster commented that there are several changes introduced in
ISO 13256-1:2021 that it believes provide a more effective performance
map for a

[[Page 84203]]

WSHP system, but that this standard has not yet been adopted by the
WSHP industry. (Id.) ClimateMaster further commented that the EWTs
utilized for determining IEER via interpolation/extrapolation are
irrelevant as long as DOE requires that the entering air temperatures
and other items are inconsistent from the current ISO 13256-1:1998 test
program. (Id.)
Regarding DOE's request for comment on variable-speed unit testing,
ClimateMaster commented that DOE's test results from the units sampled
and tested at a third-party lab should be shared with stakeholders for
review and comment--particularly regarding variable speed units, as
most of these require hardware and software from the manufacturer to
allow for proper testing, and test instructions were not provided to
DOE for the department's testing of variable-speed units as would be
done for normal certification testing. (ClimateMaster, No. 22 at p. 4)
MIAQ commented that the proposed interpolation and extrapolation
method should be based on testing at the ISO 13256-1:2021 EWTs. (MIAQ,
NO. 23 at p. 4) Regarding the proposed ``option 2'' approach for
determining IEER via interpolation/extrapolation for variable-speed
units, MIAQ recommended DOE use the latest edition of ISO 13256-1:2021
as the test procedure and continue to use AHRI 340/360-2022 for IEER
calculations. (Id.)
Other commenters supported DOE's proposals regarding the IEER
metric in the August 2022 NOPR. The Joint Commenters supported adopting
a part-load metric to measure cooling efficiency performance, stating
that WSHPs, like many other commercial air conditioners and heat pumps,
operate a significant percent of the time at part-load conditions, and
that a part-load metric could incentivize designs that reduce annual
energy consumption. (Joint Commenters, No. 27 at pp. 1-2) The Joint
Commenters recommended DOE ensure that an adopted part-load metric
reflects the total cooling provided divided by the total energy
consumed and noted that they have previously commented that the IEER
metric likely does not reflect the total cooling provided divided by
the total energy consumed, and instead weights efficiencies calculated
at different load-points. (Id.)
NEEA supported DOE's proposed transition from regulating WSHP
efficiency based on a full-load EER metric to a multi-capacity IEER
metric. (NEEA, No. 25 at p. 2) NEEA commented that an IEER metric is
more representative of overall equipment performance, and that
optimizing part-load efficiencies is beneficial to both consumers and
utilities because heating/cooling equipment operates at peak capacity
for a small number of hours. (Id.) NEEA recommended that DOE move to
the IEER metric for regulatory purposes while still encouraging
manufacturers to also publish full-load EER data, given the importance
of EER data for peak load performance and planning for utilities. (Id.)
NEEA commented that it is encouraged by DOE's monitoring of the
development of the AHRI Standard 600 and stated that this standard will
allow for even more representative ratings of regional seasonal heating
and cooling efficiencies. (Id.)
NYSERDA supported DOE's proposal to adopt for WSHPs the testing
methods specified in AHRI 340/360-2022 for calculating IEER, stating
that a seasonal efficiency metric is more representative of the part-
load operation and varying temperature conditions seen in actual field
performance of WSHPs. (NYSERDA, No. 21 at p. 2)
As discussed in section III.D, DOE is incorporating by reference
AHRI 600-2023 into its amended WSHP test procedure. Section 6.3 of AHRI
600-2023 uses a method for determining IEER that is similar to the
interpolation method proposed in the August 2022 NOPR, including tests
at three EWTs, interpolating from those EWTs to the IEER EWTs specified
in AHRI 340/360-2022, and adjusting the efficiency from the tested and
interpolated load percentages to the IEER load percentages.
With regards to ClimateMaster's comment on the interpolation
methodology (i.e., interpolating the capacity and power vs.
interpolating EER directly), DOE discussed this issue with stakeholders
in AHRI 600 meetings after publication of the August 2022 NOPR, and
section 6.3.4 of AHRI 600-2023 includes interpolation of capacity and
power, consistent with the approach proposed in the August 2022
NOPR.\7\ Having been developed through an industry consensus process
subsequent to the timing of the August 2022 NOPR comment period, DOE
surmises that the interpolation approach specified in AHRI 600-2023
represents the prevailing industry consensus regarding the most
appropriate method of performing the interpolation of capacity and
power and addresses the issues raised by commenters regarding DOE's
proposed methodology for the interpolation method in the August 2022
NOPR.
---------------------------------------------------------------------------

\7\ As discussed later in this section, the lowest EWT in AHRI
600-2023 is 50 [deg]F, which is lower than the lowest IEER EWT (55
[deg]F), such that the AHRI 600-2023 approach does not require
extrapolation for determining IEER.
---------------------------------------------------------------------------

With regards to the comment from the Joint Commenters recommending
that DOE adopt a part-load metric that reflects the total cooling
provided divided by the total energy consumed, DOE notes that no
industry test procedures for WSHPs include a metric using such an
equation format instead of the equation format for IEER (which is a
weighted average of EERs at four different EWTs) and the Joint
Commenters did not provide sufficient information to support
development of such an equation format for WSHPs. Therefore, at this
time, DOE has concluded that it lacks the necessary information to
adopt an integrated metric other than IEER for WSHPs.
While much of the methodology to determine IEER adopted in this
final rule is consistent technically with the proposal from the August
2022 NOPR, DOE notes the following differences between the approach
adopted in this final rule (consistent with AHRI 600-2023) and the
proposals in the August 2022 NOPR:
(1) Removal of option for testing directly at IEER EWTs. In this
final rule, DOE is not adopting the proposed option 1 methodology of
directly testing at the IEER EWTs (i.e., 85 [deg]F, 73.5 [deg]F, 62
[deg]F, 55 [deg]F). Rather, consistent with section 6.3 of AHRI 600-
2023, the test procedure adopted in this final rule specifies that IEER
is determined via interpolation from tests at ISO 13256-1 EWTs, which
is similar to option 2 as proposed in the August 2022 NOPR. With
regards to NYSERDA's comment supporting adopting AHRI 340/360-2022 to
calculate IEER, DOE notes that the methodology specified in AHRI 600-
2023 is very similar and produces near identical results to the
methodology of AHRI 340/360-2022, as demonstrated through DOE's data
presented in the August 2022 NOPR. See 87 FR 53302, 53316.
(2) Change in full-load test EWTs. The full-load test temperatures
used for interpolation in section 6.2.1 of AHRI 600-2023 are consistent
with ISO 13256-1:2021 (i.e., 86 [deg]F, 68 [deg]F, 50 [deg]F) instead
of ISO 13256-1:1998 (i.e., 86 [deg]F, 77 [deg]F, 59 [deg]F), which was
proposed in the August 2022 NOPR. This is also consistent with the
comment from MIAQ that encouraged the use of ISO 13256-1:2021 EWTs.
(3) Change in part-load test EWTs. The part-load test EWTs used for
interpolation in section 6.3.2 of AHRI 600-2023 are the same as the
full-load EWTs (i.e., 86 [deg]F, 68 [deg]F, 50 [deg]F). This differs
from the approach in the August 2022 NOPR, which proposed to align

[[Page 84204]]

with the EWTs specified in ISO 13256-1:1998 (i.e., 86 [deg]F, 77
[deg]F, and 59 [deg]F for full-load tests; 86 [deg]F, 68 [deg]F, and 59
[deg]F for part-load tests). MIAQ encouraged the use of ISO 13256-
1:2021, which specifies part-load test EWTs of 77 [deg]F, 59 [deg]F,
and 41 [deg]F. The part-load EWTs in section 6.3.2 of AHRI 600-2023 (86
[deg]F, 68 [deg]F, 50 [deg]F) are not consistent with either the 1998
or 2021 versions of ISO 13256-1, and instead reflect the conclusion of
discussions in AHRI 600 committee meetings that conducting part-load
tests at the same EWTs as full-load tests would reduce testing burden
(by reducing the number of times the water temperature would need to be
reconditioned between tests) and better align with the IEER methodology
in AHRI 340/360-2022. DOE surmises that the part-load EWTs specified in
section 6.3.2 of AHRI 600-2023 represent the prevailing industry
consensus regarding the most appropriate EWTs for testing WSHPs. In
addition, as compared to the part-load EWTs proposed in the August 2022
NOPR (the lowest of which was 59 [deg]F), the lowest part-load EWT in
AHRI 600-2023 (50 [deg]F) is lower than the lowest IEER EWT (55
[deg]F). Therefore, use of the part-load EWTs in AHRI 600-2023 means
that all IEER EWTs can be interpolated from the tested EWTs, instead of
requiring any extrapolation. As a result, in this final rule DOE is
adopting the part-load EWTs as outlined in the AHRI 600-2023 through
incorporation by reference.
(4) Updated provisions for variable speed units. The approach for
determining IEER for variable-speed WSHPs specified in AHRI 600-2023
differs from the approach proposed in the August 2022 NOPR in that
additional tests are required at intermediate compressor speeds.
Specifically, section 6.3.2 of AHRI 600-2023 requires that three tests
be performed at each EWT, at the three following compressor speeds: (1)
maximum compressor speed (i.e., full-load test); (2) minimum compressor
speed; and (3) an intermediate compressor speed that reflects the
compressor stage with a capacity closest to half-way between the
capacities measured at the minimum and maximum compressor speeds. This
third test reduces the range of compressor speeds over which
interpolation must be conducted (i.e., interpolating between
intermediate compressor speed and maximum or minimum compressor speeds,
instead of between maximum compressor speed and minimum compressor
speed), thus reducing the extent to which interpolated results might
differ from unit performance at the IEER EWTs. DOE surmises that the
approach for variable speed units specified in section 6.3.2 of AHRI
600-2023 represents the prevailing industry consensus regarding the
most appropriate method. Therefore, in this final rule, DOE is adopting
the IEER determination method for variable-speed units from AHRI 600-
2023 through incorporation by reference into appendix C1 of section
6.3.2. Additionally, DOE presumes this updated methodology resolves
Climatemaster's request for DOE's variable speed test data, as DOE is
adopting the industry consensus methodology.\8\
---------------------------------------------------------------------------

\8\ Section 6.3.2.4 of AHRI 600-2023 further specifies that if
the continuous capacities of two compressor modulation levels
allowed by the controls at a single set of operating conditions are
equidistant from the arithmetic mean of the capacities from the
minimum and maximum compressor modulation levels at the same set of
operating conditions, the intermediate compressor modulation level
used for testing is the compressor modulation level with the lower
capacity.
---------------------------------------------------------------------------

(5) Change in cyclic degradation equation. See section III.E.1.a of
this document for detailed discussion.
Finally, DOE is defining ``IEER'' in 10 CFR 431.92 as a weighted
average calculation of mechanical cooling EERs determined for four load
levels and corresponding rating conditions, expressed in Btu/watt-hour
and that IEER is measured per appendix C1 to subpart F of part 431 for
water-source heat pumps.
a. Cyclic Degradation
In the August 2022 NOPR, DOE proposed to adopt specific sections of
AHRI 340/360-2022 in its amended test procedure for WSHPs, including
section 6.2.3.2. 87 FR 53302, 53327. Equation 4 in section 6.2.3.2 of
AHRI 340/360-2022 is used to calculate part-load EER for a unit that
needs to cycle in order to meet the 75-percent, 50-percent, and/or 25-
percent load conditions required for the IEER metric. Id. Cycling is
the term used to describe the process in which a unit's compressor is
repeatedly turned off and on in order to meet a load that is lower than
the unit's capacity at its lowest compressor stage. Id. Equation 4 of
AHRI 340/360-2022 multiplies only the compressor power and condenser
section power by the load factor and the coefficient of degradation,
while the indoor fan power and controls power are not multiplied by
these variables. Id. This means that equation 4 of AHRI 340/360-2022
assumes that the indoor fan continues to operate when the compressor
cycles off. Id.
DOE requested comment on the proposal to adopt the cyclic
degradation equation specified in section 6.2.3.2 of AHRI 340/360-2022
for WSHPs, which assumes continuous indoor fan operation when the
compressor cycles off. Id. at 87 FR 53328.
ClimateMaster commented that the assumption of continuous fan
operation in the AHRI 340/360 IEER calculations is neither
representative of field operation nor is it in alignment with guidance
provided by ASHRAE 90.1. (ClimateMaster, No. 22 at p. 3) ClimateMaster
stated that, according to data it collected through consumer surveys,
16 percent of installed systems cycle fan operation with the
compressor, 52 percent operate the fan continuously while a building is
occupied but cycle the fan with the compressor when unoccupied, and
only 14 percent of installed WSHPs run the fan continuously regardless
of occupancy and compressor operation, while the remaining 18 percent
responded that they were unaware of how their WSHP system cycles
operated. (Id. at p. 3) ClimateMaster recommended that DOE instead use
AHRI 600 method that does not assume continuous fan operation. (Id. at
p. 8) ClimateMaster commented that, for WSHPs that are installed to
operate the fan continuously, models with a multi-speed motor will
operate at the cooling fan speed, while variable-speed models have an
option to adjust the continuous fan speed to a lower value. (Id.)
WaterFurnace commented that supporting ISO 13256 and AHRI 600 would
solve the issue. (WaterFurnace, No. 20 at p. 8) WaterFurnace stated
that continuous indoor fan operation is not the most appropriate logic
in cooling-dominated environments and recommended demand controls
ventilation as a better use of energy that improves latent moisture
removal. (Id.)
In response to these comments, DOE notes that section 6.3.6.4 of
AHRI 600-2023 has an equation similar to equation 4 of AHRI 340/360-
2022, but the equation in AHRI 600-2023 assumes that the indoor fan
stops operating whenever the compressor cycles off. The data provided
by ClimateMaster suggest that the vast majority of installed WSHPs do
not operate the fan continuously in all operating modes, but that many
installed WSHPs do operate the fan continuously during occupied hours
(i.e., regardless of whether the compressor is cycled on or off). At
the time of publication of the August 2022 NOPR, there were no WSHP
industry consensus test procedures that included IEER. However, at this
time, DOE surmises that the method in section 6.3.6.4 of AHRI 600-2023,
which assumes the fan does not run when the compressor is cycled off,
represents

[[Page 84205]]

industry consensus on the appropriate method for determining IEER for
WSHPs. At this time, DOE has concluded that it lacks sufficient
information to justify deviating from the approach in AHRI 600-2023
regarding fan operation. DOE is therefore incorporated by reference the
cyclic degradation equation from section 6.3.6.4 of AHRI 600-2023 into
its amended test procedure in this final rule.
2. ACOP
DOE's current test procedure for WSHPs measures heating-mode
performance in terms of the COP metric. COP is a full-load heating
efficiency metric for WSHP water-loop applications, meaning that it
represents the heating efficiency for a WSHP operating at its maximum
capacity at an EWT that is typical of heating operation in water-loop
applications. DOE's current test procedure specifies an EWT of 68
[deg]F for measuring COP. 10 CFR 431.96.
In the August 2022 NOPR, DOE discussed its understanding that while
in the past water-loop temperatures were maintained at temperatures
above 60 [deg]F via heat provided by a system boiler, in current
practice WSHP installations are typically controlled to allow water-
loop temperatures to drop to temperatures closer to 50 [deg]F. 87 FR
53302, 53316. Therefore, while the current EWT of 68 [deg]F for the COP
metric may have been more representative of how WSHP systems were
controlled in the past (i.e., with a boiler maintaining water-loop
temperatures above 60 [deg]F), DOE tentatively determined in the August
2022 NOPR that the EWT specified for determining COP should be no
higher than the lowest EWT used in the IEER metric, which is 55 [deg]F
(for the 25-percent load point). Id. Therefore, DOE tentatively
concluded in the August 2022 NOPR that the COP metric would be more
representative of water-loop WSHP applications if based on an EWT of 55
[deg]F. Id. at 87 FR 53317. Accordingly, in the August 2022 NOPR, DOE
proposed use an EWT of 55 [deg]F for the COP metric in appendix C1. Id.
DOE also considered whether an EWT below 55 [deg]F, specifically 50
[deg]F, might be more representative for determining COP, depending
upon typical heating conditions for water-loop WSHPs. Id. However, DOE
noted in the August 2022 NOPR that it lacked data or evidence
indicating that 50 [deg]F would be a more representative heating EWT
than 55 [deg]F for WSHPs. Id.
Additionally, DOE proposed to include an alternate method in
appendix C1 that would allow manufacturers to determine COP at the
proposed EWT of 55 [deg]F by interpolation from results of testing at
the EWTs specified in Table 2 of ISO 13256-1:1998 (i.e., 50 [deg]F and
68 [deg]F). Id. In the August 2022 NOPR, DOE presented the results of
investigative testing demonstrating that COP calculated from
interpolated values of cooling capacity and total power differed from
measured COP by an average of less than 1 percent. Id. Based on these
test results, DOE tentatively concluded that determining COP at 55
[deg]F via interpolation from testing at the ISO 13256-1:1998 EWTs (in
accordance with DOE's proposed test procedure) would provide
appropriately representative results that are comparable to testing at
55 [deg]F. Id.
In summary, DOE proposed in section 6.2 of the proposed appendix C1
to allow that COP for WSHPs can be calculated from either of two
methods: (1) ``option A''--testing at 55 [deg]F; or (2) ``option B''--
interpolation of heating capacity and power values based on testing in
accordance with the proposed test procedure at EWTs of 50 [deg]F and 68
[deg]F. Id.
DOE sought comment and data on the representativeness of 55 [deg]F
as the EWT condition for determining COP. Id. Specifically, DOE
requested feedback and data on whether a lower EWT, such as 50 [deg]F,
would be more representative of heating operation of WSHPs. Id. DOE
stated that it would further consider any alternate EWT suggested by
comments in developing any final rule. Id. DOE also requested comment
on the proposal to allow determination of COP using the two different
methods. Id. Specifically, DOE sought feedback on the proposed method
for calculating COP via interpolation and on whether this approach
would serve as a potential burden reducing option as compared to
testing at 55 [deg]F. Id.
In response to the August 2022 NOPR, ClimateMaster recommended that
DOE maintain use of the ISO 13256-1:1998 EWT of 68 [deg]F as the basis
for the regulated metric, asserting that this would take into account
the fact that building designers select and simulate system equipment
and performance based upon data published by manufacturers.
(ClimateMaster, No. 22 at p. 5) ClimateMaster stated that the EWT used
for heating operation in a WSHP is dependent on many factors (e.g.,
building design, location, system design, system operation, and
building occupancy or use) and that, due to these factors, there are no
data available to determine the representativeness of 55 [deg]F as the
EWT condition in contrast to a lower or higher EWT. (Id.)
Regarding DOE's proposal to allow two different options for
determining COP, ClimateMaster stated that it disagreed with both
proposed options for allowing determination of COP, stating that
neither option would provide a reduction in burden considering DOE's
proposal to change entering air temperatures. (Id.) ClimateMaster
further commented that the proposed changes would require the industry
to test under multiple standards to meet both certification programs.
(Id. at pp. 5-6)
MIAQ recommended aligning the EWT conditions with the latest
edition of ISO standard EWT conditions. (MIAQ, No. 23 at p. 4)
WaterFurnace commented that non-expansion valve products typically
cannot operate below an EWT of 60 [deg]F and that a percentage of the
market has always had limited water temperature range capability.
(WaterFurnace, No. 20 at p. 7) WaterFurnace also commented that
adopting ISO 13256-1 and AHRI 600 would solve the issue of COP test
temperature. (Id.)
Regarding considerations for selecting the EWT condition for
determining COP, FHP commented that the use of higher EWTs is focused
on water loop condition only and the move to electrification for
commercial buildings will shift commercial designs for water source
products toward ground coupled systems, driving temperatures closer to
ISO 13256-1 ground loops conditions (e.g., 32 [deg]F entering water).
(FHP, No. 26 at p. 4)
NYSERDA agreed with DOE's proposal to adopt an EWT of 55 [deg]F or
lower, stating that geothermal technology research and development
undertaken by NYSERDA and the Cleaner, Greener Communities Program in
Syracuse revealed the average EWT for the average mixed-use building
was 48 [deg]F when heating. (NYSERDA, No. 21 at p. 3) NYSERDA commented
that it had collected data supporting that the average building
consistently uses EWTs of 55 [deg]F or lower and presented these data
in a table that suggested the current EWT test condition of 68 [deg]F
is unrepresentatively high. (Id. at pp. 3-4)
In response to WaterFurnace's comment that some products cannot
operate below 60 [deg]F, DOE notes that the heating temperatures in
section 6.2.1 of AHRI 600-2023 include temperatures below 60 [deg]F, at
50 [deg]F and 32 [deg]F. Inclusion of these EWTs in the updated
industry standard suggests that there is industry agreement that WSHPs
can generally operate below 60 [deg]F. DOE is not aware of any WSHPs
that cannot operate in heating mode at 50 [deg]F and notes that the
issue was not raised in

[[Page 84206]]

AHRI 600 committee meetings after the August 2022 NOPR. As discussed
earlier in this section, comments from other interested parties also
supported the use of a lower temperature.
As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023. Section 6.2.1 of AHRI 600-
2023 includes EWTs of 68 [deg]F, 50 [deg]F, and 32 [deg]F for measuring
COP. Additionally included in section 6.4.5 of AHRI 600-2023 is a new
metric, ACOP, which is only measured at 50 [deg]F. This new metric is
similar to COP but includes provisions accounting for system pump
power, which better accounts for total energy use of WSHPs and aligns
with changes made to the cooling efficiency metric (see section III.F.3
of this document for more details). Further, ACOP is included in
section 7.1 of AHRI 600-2023 as a minimum requirement for published
ratings. Therefore, ACOP, measured at 50 [deg]F, is the heating metric
required for WSHPs according to AHRI 600-2023. Having been developed
through an industry consensus process subsequent to the timing of the
August 2022 NOPR comment period, DOE surmises that ACOP tested at an
EWT of 50 [deg]F specified in AHRI 600-2023 represents the prevailing
industry consensus regarding the most appropriate metric for measuring
heating performance. Therefore, in this final rule, DOE is
incorporating by reference sections 6.2.1 and 6.4.5 of AHRI 600-2023
into appendix C1 adopting the ACOP metric, tested at an EWT of 50
[deg]F.
DOE notes that no heating EWT of 55 [deg]F is included in section
6.2.1 of AHRI 600-2023 and, instead, Table 8 of the document maintains
the same heating test temperatures as ISO 13256-1:1998 (68 [deg]F, 50
[deg]F, and 32 [deg]F). Therefore, due to the lack of support of a test
temperature at 55 [deg]F, the exclusion of that temperature in AHRI
600-2023, and the support for aligning with ISO 13256-1:1998 test
temperatures (which include 50 [deg]F), DOE is finalizing the ACOP
metric based on a test at 50 [deg]F, consistent with AHRI 600-2023.
As discussed, use of the amended test procedure in appendix C1 and
rating to ACOP at 50 [deg]F are not required until the compliance date
of amended standards denominated in terms of ACOP, should DOE adopt
such standards. DOE is defining ``ACOP'' in 10 CFR 431.92 as the ratio
of the heating capacity to the power input, including system pump
power, for water-source heat pumps and that ACOP is expressed in watts
per watt and determined according to appendix C1 of subpart F of part
431.
Because AHRI 600-2023 requires a heating test at 50 [deg]F, there
is no need for an interpolation method to determine ACOP at an EWT
different from the tested EWT, and, therefore, AHRI 600-2023 includes
no such interpolation method for ACOP. Correspondingly, because DOE is
incorporating by reference AHRI 600-2023 into appendix C1 to require a
heating test be conducted at 50 [deg]F and to adopt the ACOP metric
based on the same EWT, the COP interpolation method proposed in the
August 2022 NOPR is no longer applicable. Therefore, DOE is not
adopting an interpolation method for determining ACOP in this final
rule.
3. Optional Representations
In the August 2022 NOPR, DOE proposed provisions to allow for
optional representations of EER conducted per the proposed test
procedure (sections 2 through 4 and 7 of proposed appendix C1) at the
full-load and part-load EWT conditions specified in Table 1 of ISO
13256-1:1998 (i.e., full load tests at 86 [deg]F, 77 [deg]F, and 59
[deg]F and part-load tests at 86 [deg]F, 68 [deg]F, and 59 [deg]F). 87
FR 53302, 53314. Additionally, DOE proposed provisions to provide for
optional representations of COP based on testing conducted per the
proposed test procedure (sections 2 through 4 and 7 of proposed
appendix C1) at the full-load and part-load EWT conditions specified in
Table 2 of ISO 13256-1:1998 (i.e., 68 [deg]F, 50 [deg]F, 41 [deg]F, and
32 [deg]F). Id. at 87 FR 53317.
AHRI 600-2023 includes provisions allowing for optional
representations of EER and COP in sections 6.3.12 and 6.4.7,
respectively. Optional representations can be made at any of the
cooling and heating full-load and part-load EWT conditions in Table 8
of AHRI 600-2023. DOE notes that the AHRI 600-2023 includes new metrics
applied energy efficiency ratio (``AEER'') and ACOP (see section
III.E.2 of this final rule for more details about ACOP). Each of these
metrics include a power adder representing system pumps and the adder
for AEER also includes cooling tower power. DOE notes that AHRI 600-
2023 does not have provisions for optional representations of these
metrics and instead requires them to be published. The optional
representations of EER and COP allowed for by AHRI 600-2023 do not
include the power adder for system pumps and cooling tower power.
As discussed in section III.E.1 and III.E.2 of this final rule, DOE
is incorporating by reference AHRI 600-2023 for IEER and ACOP into
appendix C1 as the cooling and heating metrics for WSHPs. The IEER
metric as determined according to AHRI 600-2023 includes a power adder
for system pumps and cooling tower power. DOE notes that the metrics it
is adopting are intended to best reflect WSHP performance, using
representative EWTs and including power for all components that are
needed for operation of WSHP systems in a representative application
(i.e., external pumps and cooling towers). Optional representations of
EER and COP are intended to provide more information to consumers
across a range of temperature conditions such that performance can be
assessed for specific applications. DOE is adopting the provisions for
optional representations of EER and COP from sections 6.3.12 and 6.4.7
from AHRI 600-2023 by incorporating by reference AHRI 600-2023 into
appendix C1. These provisions allow optional representations to be made
consistent with AHRI 600-2023 at full-load or part-load at any of the
standard rating conditions for WSHPs (i.e., 86 [deg]F, 68 [deg]F, and
50 [deg]F for cooling and 68 [deg]F, 50 [deg]F, and 32 [deg]F for
heating). DOE notes that these temperatures vary slightly from the
proposals in the August 2022 NOPR for optional representations, but
represent the same intent of allowing for optional representations of a
range of operating conditions. Having been developed through an
industry consensus process subsequent to the timing of the August 2022
NOPR comment period, DOE has determined that the EWTs specified in AHRI
600-2023 represent the prevailing industry consensus regarding the most
appropriate EWTs for optional performance test points.
4. Entering Air Conditions
The current DOE WSHP test procedure references ISO 13256-1:1998,
which specifies in Table 1 that EER is measured with entering air at 27
[deg]C (80.6 [deg]F) dry-bulb temperature and 19 [deg]C (66.2 [deg]F)
wet-bulb temperature and in Table 2 that COP is measured with entering
air at 20 [deg]C (68 [deg]F) dry-bulb temperature and 15 [deg]C (59
[deg]F) wet-bulb temperature.
In the August 2022 NOPR, DOE proposed to use the entering air
conditions in Table 6 of AHRI 340/360-2022, which specify that cooling
tests are measured with entering air at 80 [deg]F dry-bulb temperature
and 67 [deg]F wet-bulb temperature heating tests are measured with
entering air at 70 [deg]F dry-bulb temperature and a maximum of 60
[deg]F wet-bulb temperature. 87 FR 53302, 53318. DOE discussed in the
August 2022 NOPR that the entering air conditions specified in AHRI
340/360-2022 are similar to the conditions specified in ISO 13256-
1:1998 and ISO 13256-1:2021, differing for cooling by

[[Page 84207]]

0.6 [deg]F for dry-bulb temperature and 0.8 [deg]F for wet-bulb
temperature and for heating by 2 [deg]F for dry-bulb temperature and 1
[deg]F for wet-bulb temperature. Id. DOE surmised that these
differences are likely due to the conditions in ISO 13256-1 (1998 and
2021 versions) being specified in terms of degrees Celsius, whereas the
conditions in AHRI 340/360-2022 are specified in degrees Fahrenheit.
Id. DOE also noted that the entering air conditions specified in AHRI
340/360-2022 are the same as in previous versions of AHRI 340/360,
including AHRI 340/360-2007, which is referenced in the current DOE
test procedure for CUAC/HP equipment. Id. Further, the most common
application for WSHPs (and the application DOE understands that the
WSHP industry is intending to represent via use of the IEER metric in
AHRI 600) is commercial buildings, similar to CUAC/HP equipment. Id.
Therefore, DOE tentatively determined in the August 2022 NOPR that the
entering air conditions in AHRI 340/360-2022 are appropriately
representative of the average conditions in which WSHPs operate in the
field. Id.
DOE requested comment on its proposal to specify use of the cooling
entering air conditions from AHRI 340/360-2022 (i.e., 80 [deg]F dry-
bulb temperature and 67 [deg]F wet-bulb temperature) and the heating
entering air conditions from AHRI 340/360-2022 (i.e., 70 [deg]F dry-
bulb temperature and a maximum of 60 [deg]F wet-bulb temperature). Id.
In response to the August 2022 NOPR, ClimateMaster recommended that
DOE keep the existing entering air temperature conditions for both
heating and cooling tests from ISO 13256-1:1998 to avoid the
requirement to test equipment under two separate certification
programs. (ClimateMaster, No. 22 at p. 6) ClimateMaster stated that the
use of 80.6 [deg]F and 66.2 [deg]F entering air conditions for cooling
would be more conservative (i.e., result in lower efficiency ratings)
than those at 80 [deg]F and 67 [deg]F as specified in AHRI 340/360-
2022. (Id.)
WaterFurnace commented that adopting ISO 13256 and AHRI 600 would
solve the issue of which entering air conditions to use. (WaterFurnace,
No. 20 at p. 7) WaterFurnace further commented that DOE's proposal
would essentially require all new testing due to the different entering
air conditions. (Id.) WaterFurnace stated that the existing entering
air conditions of AHRI/ISO 13256 could be used and would result in a
more conservative performance prediction. (Id.)
MIAQ commented that it generally agrees with DOE's proposal to
adopt the entering air conditions in AHRI 340/360-2022. (MIAQ, No. 23
at p. 5)
As discussed, DOE is adopting provisions for determining IEER and
ACOP by incorporating by reference AHRI 600-2023 into appendix C1. The
entering air conditions in section 6.2.1 of AHRI 600-2023 align with
the entering air conditions specified in AHRI 340/360-2022 (and
therefore align with DOE's August 2022 NOPR proposal). DOE surmises
that inclusion of the AHRI 340/360-2022 entering air conditions in AHRI
600-2023 indicates industry consensus with these test conditions.
Therefore, DOE is adopting provisions for determining IEER and ACOP
consistent with AHRI 600-2023, including entering air conditions of 80
[deg]F dry bulb and 67 [deg]F wet bulb for cooling tests and 70 [deg]F
dry bulb and a maximum of 60 [deg]F wet bulb for heating tests, in this
final rule, by incorporating by reference into appendix C1 section
6.2.1 of AHRI 600-2023.

F. Test Method

1. Airflow and External Static Pressure
a. Fan Power Adjustment and Required Air External Static Pressures
For ducted units, the current DOE WSHP test procedure, which
incorporates by reference ISO 13256-1:1998, specifies a fan power
adjustment calculation that does not account for fan power used for
overcoming external resistance. As a result, the calculation of
efficiency includes only the fan power required to overcome the
internal resistance of the unit. In addition, ISO 13256-1:1998 does not
specify ESP requirements for ducted equipment, instead allowing
manufacturers to specify a rated ESP. In the August 2022 NOPR, DOE
proposed provisions to reflect fan power to overcome a representative
ESP when calculating efficiency for ducted units to account for the
impacts of ESP typically encountered in the field. 87 FR 53302, 53321.
DOE determined that, to best reflect field operation, ducted WSHPs
should be tested with minimum ESPs, the power for overcoming ESP should
be included in efficiency calculations, and all equipment should be
tested with an ESP upper tolerance. Id. DOE determined that the method
in AHRI 340/360-2022 is more representative of field energy use than
the methods used in ISO 13256-1:1998 for WSHPs. Id. DOE proposed to
adopt AHRI 340/360-2022 for WSHPs, including section 6.1.3.3 and Table
7 of AHRI 340/360-2022, which specify minimum ESPs for ducted units, a
tolerance on ESP of -0.00/+0.05 in H<INF>2</INF>O, and no fan power
adjustment. Id. DOE requested comment on the proposal to adopt
provisions from AHRI 340/360-2022 such that for ducted units testing
would be conducted within tolerance of the AHRI 340/360-2022 minimum
ESP requirements, and efficiency ratings would include the fan power
measured to overcome the tested ESP. Id. at 87 FR 53322.
In response to the August 2022 NOPR, ClimateMaster recommended that
DOE keep the existing ISO 13256-1:1998 standard and develop an IEER
rating per AHRI 600 that offers provisions for complying with the
required minimum external pressure as given in AHRI 340/360-2022.
(ClimateMaster, No. 22 at p. 6) ClimateMaster stated that there are
multiple reasons why the current ISO 13256-1:1998 standard excludes
external static pressure, including that the methodology was created to
rate different motor options for varying static requirements in the
market space, which is especially problematic with non-variable speed
motors as they are limited in output capability over a narrow static
range. (Id.) MIAQ recommended DOE reference the ESP requirements in the
latest edition of ISO 13256-1. (MIAQ, No. 23 at p. 5) WaterFurnace
commented that supporting ISO 13256 and AHRI 600 would solve the issue
and that it believes the required information can be calculated from
AHRI/ISO 13256 data without retesting. (WaterFurnace, No. 20 at p. 7)
WaterFurnace additionally commented that the minimum ESP requirements
specified in AHRI 340/360 are adequate for most commercial WSHPs
because most are installed with common plenum returns with little to no
return ductwork. (Id.)
FHP recommended that instead of requiring testing at minimum ESP
requirements, DOE develop a revised fan power adjustment that
incorporates accurate fan efficiencies and allows testing at a range of
ESPs but adjusts fan performance to reflect performance at the minimum
ESPs specified in AHRI 340/360-2022. (FHP, No. 26 at pp. 3-4) FHP
asserted that such a revised fan power adjustment would allow for
variations in tested ESP to achieve rated airflow to account for
limitations of the fan-motor combination and variation in manufacturing
tolerances, while still ensuring ratings are based on an ESP more
representative than zero ESP. (Id.)
The Joint Commenters supported DOE's proposal that WSHPs be tested
at the ESPs specified in the proposed test procedure. (Joint
Commenters, No. 27 at p. 2) The Joint Commenters stated that
maintaining the current test procedure,

[[Page 84208]]

which applies a correction factor that adjusts fan power measured at
the manufacturer-specified ESP is adjusted down to reflect fan power at
zero ESP and incentivizes testing with higher-than-representative ESPs,
would be inconsistent with the recommendation in the ASRAC Fans and
Blowers Working Group term sheet to capture fan energy more fully
across commercial HVAC product categories. (Id.)
NEEA supported DOE's proposal to include additional fan energy in
the WSHP efficiency metric, but also encouraged DOE to consider
increasing the proposed ESP requirements to be more representative of
current industry practice. (NEEA, No. 25 at pp. 2-3) NEEA stated that
during the 2015 CUAC/HP energy conservation standard ASRAC
negotiations, DOE's energy use analysis used ESP values 2 to 3 times
higher than the ESP requirements in the current test procedure because
DOE found the values to be more realistic and representative of field
conditions. (Id. at p. 3) NEEA further recommended that DOE consider
aligning WSHP ESP requirements with the updated CUAC/HP ESP
requirements when they are finalized by the ASRAC Working Group. (Id.)
With regards to these comments, DOE notes that section 5.5.1 of
AHRI 600-2023 includes ESPs to be used for testing for ducted units.
The ESPs are equivalent to those outlined in AHRI 340/360-2022 for
units less than 75,000 Btu/h cooling capacity, but the ESPs for units
above 75,000 Btu/h cooling capacity (i.e., 0.75 in. H<INF>2</INF>O for
units from 75,000 Btu/h to 134,000 Btu/h; 1.00 in. H<INF>2</INF>O for
units from 135,000 Btu/h to 280,000 Btu/h; and 1.50 in. H<INF>2</INF>O
for units greater than 280,000 Btu/h) are significantly higher than
those in AHRI 340/360-2022 and align with the ESP requirements
recommended in the ACUAC and ACUHP Working Group TP Term Sheet. (See
Document No. 65 in Docket No. EERE-2022-BT-STD-0015) Section 5.7 of
AHRI 600-2023 also includes a tolerance of ESP of -0.00/+0.05 in
H<INF>2</INF>O and sections 6.3 and 6.4 of AHRI 600-2023 include no fan
power adjustment. DOE notes also that the approach set forth in AHRI
600-2023 is mostly consistent with the approach proposed in the August
2022 NOPR, with the only difference being higher ESP requirements for
units greater than 75,000 Btu/h in cooling capacity. DOE has determined
that the inclusion of ESP requirements, an ESP tolerance, and no fan
power adjustment in AHRI 600-2023 represents industry consensus that
these provisions provide the most appropriate and representative method
for testing WSHPs. As discussed in section III.D of this final rule,
DOE is incorporating by reference AHRI 600-2023 into appendix C1,
including these ESP provisions. DOE notes that including these
provisions is consistent with commenters' suggestions to adopt AHRI
600.
Regarding the higher ESP requirements for units with a cooling
capacity greater than 75,000 Btu/h, adopting these values is consistent
with NEEA's recommendation to align with the recommendations from the
ASRAC Working Group for test procedures for CUAC/HPs. These ESP
requirements were developed as part of a joint effort between
manufacturers, efficiency advocates, utilities, and DOE to create a
more representative efficiency metric for CUACs/HPs. DOE understands
that WSHPs greater than 75,000 Btu/h are installed in similar
applications to CUACs/HPs and, as such, DOE finds the AHRI 600-2023 ESP
requirements to be representative for WSHPs with a cooling capacity
greater than 75,000 Btu/h.
DOE notes that the ACUAC and ACUHP Working Group TP Term Sheet
recommends an ESP requirement of 0.75 in. H<INF>2</INF>O for units with
a cooling capacity between 65,000 to 135,000 Btu/h, while the lower
capacity limit for this requirement in section 5.5.1 of AHRI 600-2023
is 75,000 Btu/h. Based on discussions in AHRI 600 committee meetings,
DOE understands that there are WSHP model lines that span up to 6 tons
that typically use fan/motor combinations that are designed for lower
ESP applications and cannot operate at the rated airflow at an ESP as
high as 0.75 in. H<INF>2</INF>O. Therefore, AHRI 600-2023 specifies a
lower capacity limit for this ESP requirement of 75,000 Btu/h rather
than 65,000 Btu/h so that these 6-ton models are tested with a more
representative ESP. DOE understands this issue to be unique to WSHPs
and does not apply to ACUACs and ACUHPs, for which models with a
cooling capacity between 65,000 Btu/h and 75,000 Btu/h typically have
different designs than three-phase ACUACs and ACUHPs (which typically
have comparable designs to CAC/HPs) and are typically designed for
installations for which an ESP of 0.75 in. H<INF>2</INF>O is
representative. Therefore, in this final rule, DOE is incorporating by
reference the requirements specified in Table 7 of section 5.5.1 of
AHRI 600-2023 for all WSHPs with a cooling capacity less than 760,000
Btu/h.
With regard to comments from ClimateMaster and FHP expressing
concern over ability of different fan/motor combinations to test at an
ESP requirement at the rated airflow, DOE notes that this issue is
addressed by the provisions for (1) non-standard high-static indoor fan
motors and fan/motor combinations proposed in the August 2022 NOPR,
included in section D4 of AHRI 600-2023 (discussed in section III.G.3
of this final rule); and (2) non-standard low-static motors included in
sections 3.2.30 and 5.7.4.3 of AHRI 600-2023 (discussed in section
III.F.12 of this final rule). DOE has concluded that the inclusion of
ESP requirements and provisions in AHRI 600-2023 for (1) non-standard
high-static indoor fan motors and fan/motor combinations and (2) non-
standard low-static motors reflect industry consensus that these
provisions provide an appropriate method for testing and rating WSHPs.
DOE notes that section 5.5.1.2 of AHRI 600-2023 specifies a minimum
ESP of 0.5 in. H<INF>2</INF>O for residential representations, but that
the residential representations have not yet been fully developed for
WSHPs (see section III.A.2 of this document for more details). DOE will
continue to work with AHRI 600 committee to develop provisions for
determining such ratings.
b. Setting Airflow and ESP
DOE's current WSHP test procedure does not include provisions on
how to simultaneously set airflow and ESP because there are no required
ESPs for testing. Because DOE proposed to include minimum ESPs in its
test procedure in the August 2022 NOPR, it also proposed provisions to
address how to simultaneously set airflow and ESP. 87 FR 53302, 53322-
53324. The proposals were broken into three groups:
(1) For ducted units with continuously variable speed fans, DOE
proposed to use relevant provisions from AHRI 340/360-2022 in sections
6.1.3.3 through 6.1.3.5.
(2) For ducted units with discrete step fans, DOE proposed
instructions for setting the fan speed in the scenario in which: (1)
tolerances for airflow and ESP could not be met simultaneously, and (2)
adjacent fan control settings result in airflow or ESP too low at the
lower fan control setting and too high at the higher fan control
setting.
(3) For non-ducted units, DOE proposed units to be tested with a
target ESP of 0.00 in H<INF>2</INF>O within a tolerance of -0.00/+0.05
in H<INF>2</INF>O.

Id.

For all three types of units, the proposed airflow tolerance was 3
percent. Id.
DOE requested comment on the proposed adoption of provisions from
AHRI 340/360-2022 for setting airflow and ESP for testing WSHP units
with

[[Page 84209]]

continuously variable speed fans. Id. at 87 FR 53323. DOE also
requested comment on its proposed instructions (distinct from
provisions in AHRI 340/360-2022) for setting airflow and ESP for ducted
WSHP units with discrete-step fans. Id. Finally, DOE requested comment
on its proposal for setting airflow and ESP for non-ducted WSHP units.
Id. at 87 FR 53324.
In response to the August 2022 NOPR, ClimateMaster recommended that
DOE work with industry to create a national deviation of ISO 13256-
1:1998 that adopts the applicable parts of AHRI 340/360 for fully
variable-speed motor systems and systems with adjustable sheaves, while
still providing separate provisions for setting airflow for fan motor
systems that are not continuously variable. (ClimateMaster, No. 22 at
p. 7) ClimateMaster stated that it disagrees with the use of AHRI 340/
360-2022 for all indoor blower systems, arguing that these provisions
were developed to accommodate only continuously variable-speed blower
systems and asserted that the proposed 3 percent tolerance would not be
feasible for larger WSHP systems without continuously variable motors
or WSHPs with discrete-step or constant volume fan motors. (Id. at p.
6) ClimateMaster stated that Table B1 of the AHRI WSHP Operations
Manual \9\ specifies a 5 percent airflow tolerance for discrete-step
motors. (Id. at p. 7) ClimateMaster further commented that the
provisions for setting airflow in AHRI 210/240-2023 are more
appropriate for the fan motors utilized in most WSHP systems (i.e., not
continuously variable), stating that the AHRI 210/240-2023 provisions
use manufacturer-specified fan motor settings and allow airflow to
decrease to 10 percent below the target airflow. (Id. at p. 7)
---------------------------------------------------------------------------

\9\ DOE notes that the AHRI WSHP Certification Operations Manual
is available at: <a href="https://www.ahrinet.org/sites/default/files/2022-06/WSHP_OM.pdf">https://www.ahrinet.org/sites/default/files/2022-06/WSHP_OM.pdf</a> (Last accessed April 25, 2023).
---------------------------------------------------------------------------

FHP commented that the combination of a minimum ESP requirement and
a 3 percent airflow tolerance would require additional testing and
significant design constraints and changes at the component level for
WSHPs with direct-drive motors and questioned whether a 3 percent
airflow tolerance at a minimum ESP requirement is technologically
feasible. (FHP, No. 26 at p. 4) FHP further commented that units with
constant-torque direct-drive fan motors (e.g., permanent split
capacitor (``PSC'') motors, electrically commutated motors (``ECMs''))
do not allow for adjustments to airflow without adjustments to ESP,
making it difficult to consistently hit the airflow target within 3
percent. (Id.) FHP also noted that the AHRI WSHP Operations Manual
allows for adjustments to ESP to meet a 5-percent airflow tolerance for
these systems. (Id.)
WaterFurnace commented that adopting ISO 13256 and AHRI 600 would
solve the issue. (WaterFurnace, No. 20 at p. 8) WaterFurnace stated
that a test procedure for models fans with ECMs would have to be added
to AHRI 340/360 because the standard does not address setting airflow
and ESP for such models, which it stated are typical for smaller WSHPs.
(Id.) MIAQ recommended DOE reference the latest edition of ISO 13256-1,
stating that this standard is the industry test procedure currently
used by manufacturers and laboratories for WSHP testing. (MIAQ, No. 23
at p. 5)
ClimateMaster stated that the WSHP Operations Manual covers
available provisions with what they consider to be a proper allowance
for airflow variation and that non-ducted WSHPs are available with
motors that have multiple set speeds either through software or by
utilizing a tapped motor winding. (ClimateMaster, No. 22 at p. 7)
ClimateMaster stated that these provisions are slightly different from
those proposed in the August 2022 NOPR and requested further
clarification to the meaning of ``as close as possible''. (Id.)
ClimateMaster noted that they expect that the speed tap specified by
the manufacturer would be utilized and that, if this is the case, then
there should not be any concern if the airflow is ``as close as
possible'' to the rated point. (Id.)
In response to the comment from ClimateMaster, DOE notes that the
``as close to the target as possible'' language in the August 2022 NOPR
is used in situations when the airflow and ESP requirements cannot be
simultaneously met. Specifically, for non-ducted units, the August 2022
NOPR provisions specify that if airflow and ESP requirements cannot be
met simultaneously, the ESP requirement takes precedence (i.e., ESP
must be maintained within tolerance) and the airflow is maintained as
close as possible to the target airflow (but outside of tolerance).
Section 5.8 of AHRI 600-2023 similarly specifies that in this situation
the ESP must be maintained within tolerance and that there is no
condition tolerance for airflow.
As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023 into appendix C1. This
includes sections 5.7 and 5.8 of AHRI 600-2023. This language includes
provisions generally consistent with provisions outlined in the August
2022 NOPR, specifically a tolerance of 3 percent for setting airflow,
separate provisions for continuously variable speed fans and discrete-
step fans, and a method for non-ducted units. Section 5.7 of AHRI 600-
2023 also includes provisions for setting airflow and ESP for constant-
volume fans, but DOE notes that these provisions were not proposed in
the August 2022 NOPR and are consistent with provisions in appendix M1
for central air conditioners and heat pumps.
Regarding commenter's concerns about models with non-continuously-
variable fan motors, the comments received suggest that the commenters
interpreted DOE's proposal to be adopting the provisions for setting
airflow and ESP in AHRI 340/360-2022 without modification. However, as
discussed in the August 2022 NOPR, DOE proposed additional provisions
to allow a larger airflow tolerance for models with non-continuously-
variable fan motors that align more closely with the provisions for
setting airflow in AHRI 210/240-2023 (as recommended by ClimateMaster).
See 87 FR 53302, 53323. Similar provisions are included in AHRI 600-
2023. DOE has concluded that these provisions, along with the
previously mentioned provisions for constant-volume fans, provide an
appropriate method for setting airflow and ESP for WSHPs of all fan
motor types.
DOE has determined that incorporating by reference AHRI 600-2023
for setting airflow and ESP addresses commenters' concerns. DOE
surmises that the inclusion of these provisions for setting airflow and
ESP in AHRI 600-2023 indicates industry consensus that these provisions
provide an appropriate method for testing WSHPs. Therefore, in this
final rule, DOE is incorporating by reference into appendix C1 sections
5.7 and 5.8 of AHRI 600-2023 for setting airflow and ESP.
c. Coil-Only Units
For units without integral fans (i.e., coil-only units), section
4.1.3.1 of ISO 13256-1:1998, which is referenced in the current DOE
WSHP test procedure, specifies that a fan power adjustment be added to
the total power of the unit, and that this value be added to the
heating capacity and subtracted from the cooling capacity. The fan
power adjustment equation to determine fan power estimates fan power to
overcome internal pressure drop within the unit, using a similar
methodology to the fan power adjustment equation used for

[[Page 84210]]

units with integral fans to subtract out the fan power to overcome ESP.
As discussed in section III.F.1.a of this final rule, the amended test
procedure adopted in appendix C1 (incorporating by reference AHRI 600-
2023) does not use a fan power adjustment for units with integral fans
and requires testing at representative minimum external static
pressures and ratings reflect performance at the tested ESP.
As part of DOE's proposal to adopt AHRI 340/360-2022, in the August
2022 NOPR, DOE proposed to adopt sections 6.1.1.6, 6.1.3.3 and 6.1.3.4
of AHRI 340/360-2022, which contain provisions for how to test coil-
only units. 87 FR 53302, 53322. In particular, section 6.1.3.3.4
specifies that coil-only units shall not have a pressure drop exceeding
0.30 in H<INF>2</INF>O for the full load cooling test. Section
6.1.3.4.6 outlines that coil-only units are to be tested at
manufacturer specified airflow rates, not exceeding 450 standard cubic
feet per minute (``scfm'') per ton of cooling capacity and if there is
no manufacturer specified airflow rate, they are to be tested at 400
scfm per ton of rated cooling capacity. Finally, section 6.1.1.6
specifies that 1,250 Btu/h per 1,000 scfm is to be removed from the
measured cooling capacity and 365 Watts (``W'') per 1,000 scfm is to be
added to the measured power for ducted coil-only units.
AHRI 600-2023 includes provisions for coil-only units, which are
defined as units without an indoor fan or separate designated air
mover. The provisions are nearly identical to those proposed in the
August 2022 NOPR. Section 5.5.2 specifies that coil-only units shall
not have a pressure drop exceeding 0.30 in H<INF>2</INF>O for the full-
load cooling test. Section 5.6.3 outlines that coil-only units are to
be tested at manufacturer specified airflow rates, not exceeding 450
scfm per ton of cooling capacity and if there is no manufacturer
specified airflow rate, they are to be tested at 400 scfm per ton of
rated cooling capacity. Finally, sections 6.3.3.4 and 6.4.3.4 specify
that for ducted coil-only units, measured capacity is adjusted by 1,245
Btu/h per 1,000 scfm (subtracted from cooling capacity and added to
heating capacity) and measured power is adjusted by adding 365 W per
1,000 scfm. Additionally, AHRI 600-2023 includes provisions for non-
ducted coil only units--for these, the values are 940 Btu/h per 1,000
scfm for capacity adjustment and 275 W per 1,000 scfm for power adder
respectively.
DOE notes that the provisions outlined in AHRI 600-2023 are
consistent with those proposed in the August 2022 NOPR except for a
minor deviation in the capacity reduction for ducted coil-only units
and the inclusion of provisions for non-ducted coil-only units. Based
on discussion in AHRI 600 committee meetings, DOE understands that non-
ducted coil-only WSHP models exist on the market, and therefore, DOE
has determined that the addition of provisions for testing such units
is warranted. As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023 into appendix C1. This
includes section 5.5.2, 5.6.3, and 6.3.3.4 of AHRI 600-2023. DOE notes
the inclusion of these provisions in AHRI 600-2023 indicates industry
consensus with these provisions and provides an appropriate method for
testing coil-only WSHPs. Therefore, DOE is incorporating by reference
into appendix C1 the provisions for coil-only units from AHRI 600-2023
in this final rule.
2. Capacity Measurement
The current DOE WSHP test procedure, through adoption of section
6.1 of ISO 13256-1:1998, specifies that total cooling and heating
capacities are to be determined by averaging the results obtained using
two test methods: the liquid enthalpy test method for the liquid side
tests and the indoor air enthalpy test method for the air side tests.
10 CFR 431.96. For non-ducted equipment, section 6.1 of ISO 13256-
1:1998 includes an option for conducting the air-side tests using the
calorimeter room test method instead of the air enthalpy test method.
Section 6.1 of ISO 13256-1:1998 also specifies that, for a test to be
valid, the results obtained by the two methods used must agree within 5
percent. ANSI/ASHRAE 37-2009 is similar to the test method in ISO
13256-1:1998. ANSI/ASHRAE 37-2009 requires two capacity measurements
for units with cooling capacity less than 135,000 Btu/h; the first
method of measurement (i.e., the primary method) is used as the
determination of the unit's capacity, while the second measurement
(i.e., the secondary method) is used to confirm rather than to be
averaged with the primary measurement (see section 10.1 and Table 1 of
ANSI/ASHRAE 37-2009).
In the August 2022 NOPR, DOE proposed to adopt specific sections of
AHRI 340/360-2022 for use in the WSHP test procedure, including section
E6, which specifies test methods for capacity measurement. 87 FR 53302,
53325-53327. Section E6.1 of AHRI 340/360-2022 requires use of the
indoor air enthalpy method specified in section 7.3 of ANSI/ASHRAE 37-
2009 as the primary method for capacity measurement. This is the
measurement used to determine capacity, as required in section 10.1.2
of ANSI/ASHRAE 37-2009. Section E6.2.2 of AHRI 340/360-2022 requires
use of one of the applicable ``Group B'' methods specified in Table 1
of ANSI/ASHRAE 37-2009 as a secondary method for capacity measurement.
The group B methods that are applicable to WSHPs are the outdoor liquid
coil method (similar to the liquid enthalpy method included in the 1998
and 2021 versions of ISO 13256-1), the refrigerant enthalpy method, and
the compressor calibration method. Section E6.4.2 of AHRI 340/360-2022
requires that the primary and secondary measurements match for full-
load cooling and heating tests, within 6 percent of the primary
measurement. No match is required between primary and secondary
measurements for part-load cooling tests. DOE proposed to adopt all of
these provisions by incorporating by reference AHRI 340/360-2022. Id.
at 87 FR 53325. DOE requested comment on this approach to adopt the
provisions in AHRI 340/360-2022 and ANSI/ASHRAE 37-2009 regarding
primary and secondary capacity measurements. Id. at 87 FR 53326.
In response to the August 2022 NOPR, ClimateMaster commented that
it agrees with the intent of DOE's proposed approach but disagrees with
some specifics and recommended that DOE work with industry to create a
national deviation of ISO 13256-1:1998 that adopts the provisions of
ANSI/ASHRAE 37-2009 for primary and secondary capacity measurements,
with certain modifications. (ClimateMaster, No. 22 at pp. 7-8)
ClimateMaster commented additionally that it disagrees with the
provisions in AHRI 340/360-2022 that only require agreement between the
primary and secondary capacity measurements for full-load tests. (Id.
at p. 8) ClimateMaster noted that the current ISO standard allows for a
5 percent tolerance between the two measurements, and that in its
internal testing ClimateMaster strives for agreement within 3-4
percent, stating that anything over that limit indicates an issue in
equipment setup and/or the measurement system. (Id.) ClimateMaster
commented that neglecting to include a match requirement for part-load
tests could lead to inaccurate representations of system performance.
(Id.)
ClimateMaster further commented that the uncertainty of measurement
for the liquid coil method is lower than for the indoor air enthalpy
method, and that the WSHP industry considers the liquid coil method to
be the more accurate measurement method. (Id.) ClimateMaster also
stated that the liquid coil method does not include the

[[Page 84211]]

limitations regarding refrigerant sub-cooling that are specified for
the refrigerant enthalpy method (in section 7.5.1.3 of ANSI/ASHRAE 37-
2009), and stated that low values of refrigerant subcooling are
typically seen in part-load tests. (Id.) ClimateMaster commented that
it disagrees with section 7.6.1.2 of ANSI/ASHRAE 37-2009 because this
provision specifies that the outdoor liquid coil method cannot be used
for outdoor compressor systems, and therefore makes the refrigerant
enthalpy method necessary as the secondary capacity measurement method
for such systems. (Id.) ClimateMaster stated that while it agrees in
theory that the compressor and associated refrigerant lines will lose
heat when an uninsulated compressor section is installed outdoors,
requiring the use of the refrigerant enthalpy method is not
representative of installed outdoor compressor systems because for
testing the outdoor section of a split WSHP system is installed in the
same psychrometric room as the indoor air handler. (Id.) ClimateMaster
added that there are currently no specified outdoor conditions or
requirements for placement of the outdoor unit in a differently
conditioned room and that the difference between the current liquid
coil method and the proposed refrigerant enthalpy method is negligible
without specifying conditions more thoroughly. (Id.) ClimateMaster
further commented that the insulation requirements in ANSI/ASHRAE 37-
2009 only specify 1 inch of fiberglass insulation and do not specify a
minimum R-value for the insulation. (Id.)
In summary, ClimateMaster recommended that DOE adopt the indoor air
enthalpy method for the primary capacity measurement, and that the
outdoor coil liquid method be used for the secondary capacity
measurement if the unit either (1) meets the requirements of section
7.6.1.2 of ANSI/ASHRAE 37-2009 using fiberglass insulation or an
equivalent material with an R-value of 8.0, or (2) is an outdoor unit
installed in the same test chamber as the indoor coil. (Id.)
ClimateMaster further recommended a requirement for agreement within 5
percent between primary and secondary capacity measurements for full-
load and part-load tests. (Id.)
MIAQ commented that DOE's proposed approach in the August 2022 NOPR
of adopting the provisions in AHRI 340/360 and ANSI/ASHRAE 37-2009
regarding primary and secondary capacity measurements deviates from the
industry test procedure ISO 13256-1 and therefore will require
manufactures to retest their products, resulting in increased burden.
(MIAQ, No. 23 at p. 6)
WaterFurnace commented that adopting ISO 13256 and AHRI 600 would
solve the issue and that the liquid enthalpy test method is widely
accepted as the most accurate method for capacity measurement for
WSHPs. (WaterFurnace, No. 20 at p. 8)
As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023 into Appendix C1, including
provisions in Section 5.2 of AHRI 600-2023 regarding primary and
secondary capacity measurement methods. Specifically, Section 5.2
states that the indoor air enthalpy method be used as the primary
measurement of capacity, and that secondary capacity measurements be
conducting using one of the following methods: outdoor liquid coil
method, refrigerant enthalpy method, or compressor calibration method.
Section 5.2.2 of AHRI 600-2023 also states that, when using the outdoor
liquid coil method, the secondary measurement must agree within 6
percent of the primary measurement of capacity on all tests, including
part-load tests. Incorporating by reference this language addresses
comments in response to the August 2022 NOPR that DOE should adopt AHRI
600. The provisions in AHRI 600-2023 also address ClimateMaster's
concerns about not having a match for part-load tests because AHRI 600-
2023 does require a match between primary and secondary capacity
measurements for part-load tests if the outdoor liquid coil method is
used.
Regarding agreement between primary and secondary measurements, DOE
has concluded that the requirement in AHRI 600-2023 that secondary
capacity measurements agree within 6 percent of primary capacity
measurements (consistent with AHRI 340/360-2022, which DOE proposed to
reference in the August 2022 NOPR) provides a representative measure of
efficiency for WSHPs.
Regarding ClimateMaster's concerns about the outdoor liquid coil
method provisions in ANSI/ASHRAE 37-2009, DOE notes that section
5.2.2.1.1 of AHRI 600-2023 specifies to follow all requirements in
section 7.6 of ANSI/ASHRAE 37-2009 when using the outdoor liquid coil
method and does not include any provisions that deviate from ANSI/
ASHRAE 37-2009 with regard to outdoor compressor systems or insulation
R-value. Regarding ClimateMaster's concern that ANSI/ASHRAE 37-2009
requires use of the refrigerant enthalpy method for secondary capacity
measurements for systems in which the compressor is located outdoors,
DOE further notes that for a split system WSHP with the compressor and
liquid coil contained in the outdoor unit intended for outdoor
installation, shell losses from the compressor could impact capacity
measurements using the outdoor liquid coil method but would not impact
capacity measurements using the refrigerant enthalpy method. Therefore,
at this time, DOE does not have sufficient evidence or justification to
deviate from the provisions in AHRI 600-2023 regarding the outdoor
liquid coil method and has concluded that these provisions provide for
appropriate and representative measurements of efficiency for WSHPs.
Additionally, AHRI 600-2023 was developed through an industry
consensus process subsequent to the timing of the August 2022 NOPR
comment period, and DOE surmises that the capacity measurement approach
specified in section 5.2 of AHRI 600-2023 sufficiently addresses the
concerns raised in comments to the August 2022 NOPR. Consequently, DOE
is incorporating by reference into appendix C1 section 5.2 of AHRI 600-
2023 regarding primary and secondary capacity measurements in this
final rule.
3. Pump Power Adjustment and Liquid External Static Pressure
ISO 13256-1:1998 does not reflect the pump power needed to overcome
liquid ESP from the water loop that pipes water to and from the WSHP.
Instead, section 4.1.4 of ISO 13256-1:1998 includes a pump power
adjustment (which assumes a pump efficiency of 0.3 for all units) to be
applied such that only the pump power required to overcome the liquid
internal static pressure of the unit is included in calculation of
efficiency ratings. ISO 13256-1:1998 also does not specify any liquid
ESP requirements for testing. The exclusion of pump power to overcome
ESP from system water loop piping in ISO 13256-1:1998 ratings results
in higher efficiency ratings than would be measured if ratings
reflected pump power to overcome ESP. ISO 13256-1:1998 also does not
specify a minimum liquid ESP during testing for units with integral
pumps. For units without integral pumps, the pump power adjustment in
ISO 13256-1:1998 estimates pump power at zero liquid external static
pressure.
As discussed previously, ISO 13256-1:1998 was updated. However, the
pump power and liquid ESP provisions in sections 5.1.4 and 5.1.6 of ISO

[[Page 84212]]

13256-1:2021 are the same as those in sections 4.1.4 and 4.1.6 of ISO
13256-1:1998.
In the August 2022 NOPR, DOE proposed to adopt provisions for WSHPs
in appendix C1 that align with the recently adopted provisions for
water-source dedicated outdoor air systems (``DOASes''). 87 FR 53302,
53328-53329. The proposed provisions would require that all WSHPs with
an integral pump be tested with a liquid ESP of 20 ft of water column,
with a -0/+1 ft condition tolerance and a 1 ft operating tolerance. Id.
at 87 FR 53328. For units without integral pumps, DOE proposed to
require that a ``total pumping effect'' (calculated using the same
equation as in section 6.1.6.4 of AHRI 920-2020) be added to the unit's
measured power to account for the pump power to overcome the internal
static pressure of the unit and a liquid ESP of 20 ft of water column.
Id. at 87 FR 53328-53329. Further, DOE proposed to require that the
measured pump power or the pump effect addition, as applicable, be
included in the condenser section power for units of all capacities
when performing cyclic degradation during calculation of IEER. Id. at
87 FR 53329. DOE requested commented on the proposed provisions to
account for pump power to overcome both internal pressure drop and a
representative level of liquid ESP for WSHPs with and without integral
pumps. Id. DOE specifically requested comment on the representativeness
of 20 ft of water column as the liquid ESP for WSHPs. Id.
In response to the August 20222 NOPR, ClimateMaster disagreed with
DOE's proposed values for the liquid ESP for WSHPs, arguing that the
pumping and cooling tower fan power adder specified in AHRI 920-2020 is
incorrect. (ClimateMaster, No. 22 at p. 8) ClimateMaster commented
that, according to a 2014 study conducted by S. Kavanaugh and K.
Rafferty, pumping power for a closed loop ground-source heat pump
(``GSHP'') system can reach 3.75 W/kBtu/h but not exceed 10 W/1kBtu/h,
and that the values given in AHRI 920 are much higher than these values
and are thus not representative of an installed system. (Id. at pp. 8-
9) ClimateMaster recommended that DOE use the approach in AHRI 600,
which includes pumping power for the internal pressure drop and adds a
representative value for building pump and cooling tower operation.
(Id. at p. 9) ClimateMaster commented that this AHRI 600 power adder
for building pump and cooling tower energy consumption is based on the
results of an analysis conducted of typical closed loop systems during
the development of the AHRI 600 standard, which resulted in calculated
power adders of 5.5 W/kBtu/h for full-load conditions and 1 W/kBtu/h
for part-load conditions. (Id.)
FHP commented that the work done by the AHRI 600 working group took
a more accurate approach to today's systems that allows for varying the
fans and pumping energy required during part-load conditions. (FHP, No.
26 at p. 5) FHP recommended that DOE review the values assigned to
tower/pump penalty in AHRI 600 for guidance on this topic, stating that
a single-head pressure as a means of estimating the pumping penalty
does not allow for the variations expected at part-load conditions.
(Id.) WaterFurnace commented that adopting ISO 13256 and AHRI 600 would
solve the issue, noting that the pump power is accounted for in AHRI
600. (WaterFurnace, No. 20 at p.8)
As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023 into appendix C1. AHRI 600-
2023 includes provisions to separately account for pump power to
overcome liquid internal and external static pressure.
Sections 6.3.3 and 6.4.3 of AHRI 600-2023 specify to include pump
power to overcome the liquid internal static pressure of the WSHP in
all cooling and heating ratings. The calculation for pump power
adjustment to account for liquid internal static pressure uses a
similar methodology to ISO 13256-1:1998, but uses a higher pump
efficiency of 75% (as compared to 30% in ISO 13256-1:1998) to better
represent the efficiency of system pumps in commercial water-loop
installations. Specifically, for units without integral pumps, the AHRI
600-2023 approach adds pump power to overcome liquid internal static
pressure. For units with integral pumps, section 5.4.13 of AHRI 600-
2023 specifies a liquid ESP value of zero to use when testing WSHPs
with an integral pump for commercial ratings and specifies to test at
the minimum liquid ESP if the minimum is higher than zero ESP. In the
case of testing a unit with an integral pump at a liquid ESP above
zero, sections 6.3.3 and 6.4.3 of AHRI 600-2023 specify to subtract
pump power to overcome liquid ESP using a similar methodology to the
approach for calculating pump power adjustment for units without
integral pumps.
Sections 6.3.7 (for IEER), 6.3.11 (for AEER), and 6.4.4 (for ACOP)
of AHRI 600-2023 specify to include power to account for power required
for a system pump to overcome liquid ESP representative of a commercial
water-loop installations. As discussed in section III.E.3 of this final
rule, AHRI 600-2023 specifies these provisions to account for system
pump power for calculation of AEER, IEER, and ACOP, but not for
optional representations of EER and COP.
The provisions for accounting for pump power (to overcome liquid
internal and external static pressure) were developed in AHRI 600
committee meetings after publication of the August 2022 NOPR. While the
AHRI 600-2023 approach is not the same as that proposed in the August
2022 NOPR in that it uses a different calculation method and assumes a
different liquid ESP, it is consistent with the August 2022 NOPR
proposal to include power to represent power consumed by pumps to
overcome both liquid internal and external static pressure. The AHRI
600-2023 pump power adders are different than those suggested by
ClimateMaster. However, having been developed through an industry
consensus process subsequent to the timing of the August 2022 NOPR
comment period, DOE surmises that the pump power approach specified in
AHRI 600-2023 represents the prevailing industry consensus regarding
the most appropriate method for addressing pump power. Further, DOE has
concluded based on discussion in AHRI 600 committee meetings that the
AHRI 600-2023 pump power approach is representative of typical water-
loop WSHP applications. As a result, in this final rule, DOE is
incorporating by reference into appendix C1 the methods specified in
AHRI 600-2023 for accounting for pump power.
DOE notes that section 5.4.13.2 of AHRI 600-2023 specifies a
minimum liquid ESP of 7.0 psi for residential representations. However,
the residential representations have not yet been fully developed for
WSHPs (see section III.A.2 of this document for more details). DOE will
continue to work with the AHRI 600 committee to develop provisions for
determining such ratings.
4. Test Liquid and Specific Heat Capacity
The current DOE WSHP test procedure, through adoption of section
4.1.9 of ISO 13256-1:1998, requires the test liquid for water-loop heat
pumps and ground-water heat pumps to be water, and the test liquid for
ground-loop heat pumps to be a 15 percent solution by mass of sodium
chloride in water (i.e., brine). 10 CFR 431.96. Further, the liquid
enthalpy test method in Annex C of ISO 13256-1:1998, which is included
in the current DOE WSHP test procedure, requires the use of the

[[Page 84213]]

specific heat capacity of the test liquid for calculating cooling and
heating capacity but does not specify a value or method for calculating
the specific heat capacity.
Section 5.1.7 of ISO 13256-1:2021 requires that the test liquid for
the low temperature heating test (i.e., EWT of 32 [deg]F) must be a
brine of the manufacturer's specification, while the test liquid for
all other tests may be water or a brine of a composition and
concentration specified by the manufacturer. ISO 13256-1:2021 does not
specify a value or method for calculating the specific heat capacity of
any test liquids.
In the August 2022 NOPR, DOE proposed in section 4.1 of proposed
appendix C1 that the test liquid for all tests other than the proposed
optional ``HFL3'' \10\ low temperature heating test (i.e., EWT of 32
[deg]F) must be water, unless the manufacturer specifies to use a brine
of 15-percent solution by mass of sodium chloride in water. 87 FR
53302, 53329. DOE also proposed in section 4.1 of proposed appendix C1
that the test liquid for the optional HFL3 low temperature heating test
must be a brine of 15-percent solution by mass of sodium chloride in
water. Id. Ground-loop applications of WSHPs typically use brine in the
liquid loop because, in cold weather, the liquid temperature can reach
32 [deg]F (i.e., the temperature at which water freezes) in places. A
15-percent solution by mass of sodium chloride in water can withstand
temperatures as low as 14 [deg]F before freezing. Allowing the use of
brine for testing would provide manufacturers the flexibility of
providing ratings more representative of ground-loop applications.
Therefore, DOE proposed to require brine as the liquid for the optional
HFL3 low temperature heating test (conducted with an EWT of 32 [deg]F),
consistent with section 4.1.9 of ISO 13256-1:1998 and section 5.1.7 of
ISO 13256-1:2021, to avoid the liquid freezing during the test. Id.
---------------------------------------------------------------------------

\10\ ``HFL3'' is the nomenclature used to define the 32 [deg]F
full-load heating test that DOE proposed to add in appendix C1.
---------------------------------------------------------------------------

In the August 2022 NOPR, DOE tentatively concluded that a 15-
percent solution by mass of sodium chloride, as specified in section
4.1.9.2 of ISO 13256-1:1998, is a representative brine composition and
concentration for applications needing brine (e.g., ground-loop), and
that consumers can make more representative comparisons between models
when all models are rated with the same brine composition and
concentration. Id.
As discussed in section III.D.2 of the August 2022 NOPR, DOE
proposed to adopt specific sections of AHRI 340/360-2022 in its test
procedure for WSHPs. Id. AHRI 340/360-2022 in turn references the test
method in ANSI/ASHRAE 37-2009, in which section 12.2.1 requires that
thermodynamic properties of liquids be obtained from the ASHRAE
Handbook--Fundamentals.\11\ The ASHRAE Handbook--Fundamentals specifies
specific heat capacity values for water and for a brine of 15 percent
solution by mass of sodium chloride at multiple temperatures. The
absence of provisions in ISO 13256-1:1998 for how to determine specific
heat capacity for test liquids creates the potential for variation in
measured values based on how specific heat capacity is determined.
Therefore, to minimize any such variation, DOE instead proposed in the
August 2022 NOPR to adopt relevant provisions of ANSI/ASHRAE 37-2009.
Id. DOE tentatively determined that the specifications in ANSI/ASHRAE
37-2009 would be appropriate for testing WSHPs because they are the
generally accepted industry method used for testing similar equipment,
such as WCUACs. Id.
---------------------------------------------------------------------------

\11\ The ASHRAE Handbook--Fundamentals is available at: <a href="https://www.ashrae.org/technical-resources/ashrae-handbook">https://www.ashrae.org/technical-resources/ashrae-handbook</a>.
---------------------------------------------------------------------------

In the August 2022 NOPR, DOE requested comment on the proposed
requirements for using water or a brine of 15-percent solution by mass
of sodium chloride as the test liquid. Id. DOE also requested comment
on the representativeness and test burden associated with permitting
the use of different liquids for different tests. Id. Finally, DOE
requested comments on the proposal to utilize the thermodynamic
properties specified in ANSI/ASHRAE 37-2009 through DOE's proposed
incorporation by reference of AHRI 340/360-2022. Id.
In response to the August 2022 NOPR, MIAQ commented that sodium
chloride is not a common anti-freeze and that propylene and ethylene
glycol are more common. (MIAQ No. 23 at p. 6) MIAQ commented that it is
unsure if nationally recognized testing laboratories \12\ are equipped
to deal with 15-percent solution by mass of sodium chloride as the test
liquid. (Id.) MIAQ stated that specifying a particular antifreeze
rather than relevant thermal properties for the test fluid hinders
innovation and generates a heavy burden to develop and test with the
specified medium. (Id.) MIAQ argued that specifying sodium chloride as
the test liquid may require redesign of the units to avoid corrosion.
(Id.)
---------------------------------------------------------------------------

\12\ MIAQ used the abbreviation NRL, but DOE expects that the
intended term was NRTL, the acronym for nationally recognized
testing laboratory.
---------------------------------------------------------------------------

WaterFurnace commented that supporting ISO 13256 and AHRI 600 would
solve the issue. (WaterFurnace No. 20 at p. 8) WaterFurnace stated that
it prefers to use methanol or ethanol as the test liquid because sodium
chloride can damage lab equipment. (Id.)
ClimateMaster supported DOE's proposal to make provisions for low
temperature testing but disagreed with the proposed fluid for testing.
(ClimateMaster, No. 22 at p. 9) ClimateMaster stated that sodium
chloride is not representative of a brine solution used in water-source
applications in the field and is a carryover from a test liquid used in
older standards such as AHRI 330-98, which was corrosive to test lab
facilities and caused premature wear of hydronic components. (Id.)
ClimateMaster recommended that DOE work with industry to create a
national deviation of 13256-1:1998 that includes provisions for the use
of a 15-percent solution by mass of methanol in water involving a
specific gravity of methanol at 0.976 with a solution temperature of 68
[deg]F. (Id.) ClimateMaster stated that this fluid is commonly used in
the industry and has been an available option in the AHRI 13256-1:1998
certification program since its inception, and if DOE does not select
this solution, an alternative option would be a 20-percent solution of
propylene glycol, which is also commonly used in the industry. (Id.)
ClimateMaster supported DOE's proposal to require a standard set of
properties for consistent performance calculations but disagreed that
the only reference allowed for sink or source liquids can be the 2001
ASHRAE Handbook, stating that it does not include properties for
alternative testing fluids, such as methanol in water, and therefore
limits the available options for testable brine solutions. (Id.)
ClimateMaster recommended that DOE provide provisions under a national
deviation of ISO 13256-1:1998 while allowing for the use of other
established property databases in addition to the 2001 ASHRAE handbook,
such as the published data from Melinder 2010.\13\ (Id.) WaterFurnace
agreed with the need for a specified source of properties and commented
that supporting ISO 13256

[[Page 84214]]

and AHRI 600 would solve the issue. (WaterFurnace, No. 20 at p. 8)
---------------------------------------------------------------------------

\13\ Properties of Secondary Working Fluids for Indirect
Systems, Melinder, 2010 (``Melinder 2010'').
---------------------------------------------------------------------------

As discussed in section III.D of this final rule, DOE is
incorporating by reference AHRI 600-2023 in appendix C1. Section 5.4.14
of AHRI 600-2023 specifies that all cooling and heating tests be
conducted with a 15 percent solution by mass of methanol in water, with
a tolerance of 2 percentage points on the solution concentration and
requires that the concentration be verified prior to and after
completion of all standard rating tests. Section 5.4.14 of AHRI 600-
2023 also specifies to use Melinder 2010 as the source for all
thermodynamic properties of the test liquid. Finally, sections 6.3.3.2
a

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