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Proposed Rule2022-17075

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

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Published

August 30, 2022

Issuing agencies

Energy Department

Abstract

The U.S. Department of Energy ("DOE") proposes to amend its test procedures for water-source heat pumps, with the main changes being ones to expand the scope of applicability of the test procedure, reference different industry standards than currently referenced, change to a seasonal cooling efficiency metric, and change the test conditions used for the heating metric. DOE has tentatively determined that the amended test procedure would produce results that are more representative of an average use cycle and more consistent with current industry practice without being unduly burdensome to conduct. DOE seeks comment from interested parties on this proposal.

Full Text

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<title>Federal Register, Volume 87 Issue 167 (Tuesday, August 30, 2022)</title>
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[Federal Register Volume 87, Number 167 (Tuesday, August 30, 2022)]
[Proposed Rules]
[Pages 53302-53359]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-17075]

[[Page 53301]]

Vol. 87

Tuesday,

No. 167

August 30, 2022

Part IV

Department of Energy

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10 CFR Parts 429 and 431

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

Federal Register / Vol. 87, No. 167 / Tuesday, August 30, 2022 /
Proposed Rules

[[Page 53302]]

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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: Notice of proposed rulemaking and request for comment.

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SUMMARY: The U.S. Department of Energy (``DOE'') proposes to amend its
test procedures for water-source heat pumps, with the main changes
being ones to expand the scope of applicability of the test procedure,
reference different industry standards than currently referenced,
change to a seasonal cooling efficiency metric, and change the test
conditions used for the heating metric. DOE has tentatively determined
that the amended test procedure would produce results that are more
representative of an average use cycle and more consistent with current
industry practice without being unduly burdensome to conduct. DOE seeks
comment from interested parties on this proposal.

DATES:
Comments: DOE will accept comments, data, and information regarding
this proposal no later than October 31, 2022. See section V, ``Public
Participation,'' for details.
Public Meeting: DOE will hold a public meeting via webinar on
Wednesday, September 14, 2022, from 1:00 p.m. to 3:00 p.m. See section
V, ``Public Participation,'' for webinar registration information,
participant instructions, and information about the capabilities
available to webinar participants.

ADDRESSES: Interested persons are encouraged to submit comments using
the Federal eRulemaking Portal at <a href="http://www.regulations.gov">www.regulations.gov</a>, under docket
number EERE-2017-BT-TP-0029. Follow the instructions for submitting
comments. Alternatively, interested persons may submit comments,
identified by docket number EERE-2017-BT-TP-0029 and/or RIN 1904-AE05,
by any of the following methods:
Email: <a href="/cdn-cgi/l/email-protection#0453574c543634353350543434363d4461612a606b612a636b72">[email&#160;protected]</a>. Include the docket number EERE-
2017-BT-TP-0029 and/or RIN 1904-AE05 in the subject line of the
message.
Postal Mail: Appliance and Equipment Standards Program, U.S.
Department of Energy, Building Technologies Office, Mailstop EE-5B,
1000 Independence Avenue SW, Washington, DC 20585-0121. If possible,
please submit all items on a compact disc (``CD''), in which case it is
not necessary to include printed copies.
Hand Delivery/Courier: Appliance and Equipment Standards Program,
U.S. Department of Energy, Building Technologies Office, 950 L'Enfant
Plaza SW, 6th Floor, Washington, DC 20024. Telephone: (202) 287-1445.
If possible, please submit all items on a CD, in which case it is not
necessary to include printed copies.
No telefacsimiles (``faxes'') will be accepted. For detailed
instructions on submitting comments and additional information on this
process, see section V of this document (Public Participation).
Docket: The docket, which includes Federal Register notices, public
meeting/webinar 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, some documents listed in the index,
such as those containing information that is exempt from public
disclosure, may not be publicly available.
The docket web page can be found at <a href="http://www.regulations.gov/docket?D=EERE-2017-BT-TP-0029">www.regulations.gov/docket?D=EERE-2017-BT-TP-0029</a>. The docket web page contains
instructions on how to access all documents, including public comments,
in the docket. See section V (Public Participation) for information on
how to submit comments through <a href="http://www.regulations.gov">www.regulations.gov</a>.

FOR FURTHER INFORMATION CONTACT:
Ms. Catherine Rivest, 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:
(202) 586-7335. Email: <a href="/cdn-cgi/l/email-protection#aceddcdcc0c5cdc2cfc9ffd8cdc2c8cddec8dffdd9c9dfd8c5c3c2dfecc9c982c8c3c982cbc3da">[email&#160;protected]</a>.
Mr. Eric Stas, U.S. Department of Energy, Office of the General
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121.
Telephone: (202) 586-5827. Email: <a href="/cdn-cgi/l/email-protection#cd88bfa4aee39eb9acbe8da5bce3a9a2a8e3aaa2bb">[email&#160;protected]</a>.
For further information on how to submit a comment, review other
public comments and the docket, or participate in the public meeting
webinar, contact the Appliance and Equipment Standards Program staff at
(202) 287-1445 or by email: <a href="/cdn-cgi/l/email-protection#531223233f3a323d30360027323d373221372002263620273a3c3d201336367d373c367d343c25">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: DOE proposes to incorporate by reference
already-approved industry standards, an update to one of those
standards, and a standard not previously-approved.
ANSI/ASHRAE Standard 37-2009, ``Methods of Testing for Rating
Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment,''
including errata sheet issued March 27, 2019, ASHRAE approved June 24,
2009.
Copies of the American Society of Heating, Refrigerating, and Air-
Conditioning Engineers (``ASHRAE'') ANSI/ASHRAE Standard 37-2009 are
available from the American National Standards Institute (``ANSI''), 25
W. 43rd Street, 4th Floor, New York, NY 10036, (212) 642-4900, or
online at: <a href="https://webstore.ansi.org/">https://webstore.ansi.org/</a>.
ASHRAE errata sheet to ANSI/ASHRAE Standard 37-2009--Methods of
Testing for Rating Electrically Driven Unitary Air-Conditioning and
Heat Pump Equipment, ANSI/ASHRAE Approved March 27, 2019.
Copies of ASHRAE errata sheet to ANSI/ASHRAE Standard 37-2009 are
available from ASHRAE, 180 Technology Parkway NW, Peachtree Corners, GA
30092, (404)-636-8400, or online at <a href="https://ashrae.org/">https://ashrae.org/</a>.
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 approved 1998.
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="https://webstore.ansi.org/">https://webstore.ansi.org/</a>.
AHRI Standard 340/360-2022 (I-P), ``2022 Standard for Performance
Rating of Commercial and Industrial Unitary Air-conditioning and Heat
Pump Equipment,'' AHRI-approved January 26, 2022.
Copies of AHRI Standard 340/360-2022 (I-P) can be obtained from the
Air-Conditioning, Heating, and Refrigeration Institute (``AHRI''), 2311
Wilson Blvd., Suite 400, Arlington, VA 22201, (703) 524-8800, or online
at: <a href="http://www.ahrinet.org/search-standards.aspx">www.ahrinet.org/search-standards.aspx</a>.
See section IV.M of this document for further discussion of these
standards.

Table of Contents

I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Notice of Proposed Rulemaking
III. Discussion
A. Scope of Applicability

[[Page 53303]]

B. Definition
C. Proposed Organization of the WSHP Test Procedure
D. Industry Standards
1. Applicable Industry Test Procedures
a. ISO Standard 13256-1
b. AHRI 340/360-2022 and ASHRAE 37-2009
c. AHRI 600
2. Comments Received on Industry Standards and DOE Responses
3. Proposal for DOE Test Procedure
E. Efficiency Metrics
1. IEER
a. General Discussion
b. Determination of IEER Via Interpolation and Extrapolation
2. COP
a. General Discussion
b. Determination of COP Via Interpolation
3. Entering Air Conditions
4. Operating Modes Other Than Mechanical Cooling and Heating
5. Dynamic Load-Based Test Procedure
F. Test Method
1. Airflow and External Static Pressure
a. Fan Power Adjustment and Required Air External Static
Pressure
b. Setting Airflow and ESP
i. Ducted Units With Discrete-Step Fans
ii. Non-Ducted Units
2. Capacity Measurement
a. Primary and Secondary Methods
b. Compressor Heat
3. Cyclic Degradation
4. Pump Power Adjustment and Liquid External Static Pressure
5. Test Liquid and Specific Heat Capacity
6. Liquid Flow Rate
a. Full-Load Cooling Tests
b. Part-Load Cooling Tests
c. Heating Tests
d. Condition Tolerance
7. Refrigerant Line Losses
8. Airflow Measurement
9. Air Condition Measurements
10. Duct Losses
11. Refrigerant Charging
12. Voltage
G. Configuration of Unit Under Test
1. Specific Components
2. Non-Standard Indoor Fan Motors
H. Represented Values and Enforcement
1. Multiple Refrigerants
2. Cooling Capacity
3. Enforcement of IEER
I. Test Procedure Costs and Impact
J. Compliance Date
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Orders 12866 and 13563
B. Review Under the Regulatory Flexibility Act
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. Description of Materials Incorporated by Reference
V. Public Participation
A. Participation in the Public Meeting Webinar
B. Procedure for Submitting Prepared General Statements for
Distribution
C. Conduct of the Public Meeting Webinar
D. Submission of Comments
E. Issues on Which DOE Seeks Comment
VI. 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)) DOE's energy
conservation standards and test procedures for WSHPs are currently
prescribed in title 10 of the Code of Federal Regulations (``CFR'') at
10 CFR 431.97 and 10 CFR 431.96, respectively. The following sections
discuss DOE's authority to establish and amend test procedures for
WSHPs, as well as relevant background information regarding DOE's
consideration of test procedures 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, as amended (``EPCA''),\2\
Public Law 94-163 (42 U.S.C. 6291-6317, as codified), among other
things, authorizes DOE to regulate the energy efficiency of a number of
consumer products and certain industrial equipment. Title III, Part C
\3\ of EPCA, 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 small, large, and very large
commercial package air-conditioning and heating equipment, including
WSHPs. (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 reflects 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 specifically include definitions (42 U.S.C. 6311),
energy conservation standards (42 U.S.C. 6313), test procedures (42
U.S.C. 6314), labeling provisions (42 U.S.C. 6315), 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 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 (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 covered equipment during a representative
average use cycle and requires that test procedures not be unduly
burdensome to conduct. (42 U.S.C. 6314(a)(2))

[[Page 53304]]

With respect to WSHPs, EPCA requires that the test procedures shall
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 Standard 90.1, ``Energy Standard for Buildings
Except Low-Rise Residential Buildings'' (``ASHRAE Standard 90.1''). (42
U.S.C. 6314(a)(4)(A)) Further, if such an industry test procedure is
amended, DOE must amend 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 the amended test procedure would not produce test
results that reflect the energy efficiency, energy use, and estimated
operating costs of that equipment during a representative average use
cycle or would be unduly burdensome to conduct. (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, DOE 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 comments 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))
In this notice of proposed rulemaking (``NOPR''), DOE is proposing
amendments to the test procedures for WSHPs in satisfaction of the 7-
year-lookback obligations under EPCA. (42 U.S.C. 6314(a)(1))

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'').
This is the test procedure specified by ASHRAE Standard 90.1 for water-
source heat pumps.
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 set-up at
10 CFR 431.96(e), which provide specifications for addressing key
information typically found in the installation and operation manuals.
Id at 77 FR 28991.
On June 22, 2018, DOE published a request for information (``RFI'')
in the Federal Register to collect information and data to consider
amendments to DOE's test procedures for WSHPs. 83 FR 29048 (``June 2018
RFI'').\4\ As part of the June 2018 RFI, DOE identified and requested
comment on several issues associated with the currently applicable
Federal test procedures, in particular concerning methods that are
adopted through incorporation by reference of the applicable industry
standard; efficiency metrics and calculations; additional
specifications for the test methods; and any additional topics that may
inform DOE's decisions in a future test procedure rulemaking, including
methods to reduce regulatory burden while ensuring the test procedure's
accuracy. Id.
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\4\ An extension of the comment period for the June 2018 RFI was
published in the Federal Register on July 9, 2018. 83 FR 31704.
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DOE received comments in response to the June 2018 RFI from the
interested parties listed in Table I-1.

Table I-1--List of Commenters With Written Submissions in Response to
the June 2018 RFI
------------------------------------------------------------------------
Reference in this
Commenter(s) NOPR Commenter type
------------------------------------------------------------------------
Air-Conditioning, Heating, and AHRI............. IR.
Refrigeration Institute.
Appliance Standards Awareness Joint Advocates.. EA.
Project, American Council for
an Energy-Efficient Economy,
Natural Resources Defense
Council.
Northwest Energy Efficiency NEEA............. EA.
Alliance.
Pacific Gas and Electric CA IOUs.......... U.
Company, San Diego Gas and
Electric, and Southern
California Edison;
collectively referred to as
the California Investor-Owned
Utilities.
Trane Technologies............ Trane............ M.
WaterFurnace International.... WaterFurnace..... M.
------------------------------------------------------------------------
EA: Efficiency/Environmental Advocate; IR: Industry Representative; M:
Manufacturer; U: Utility.

A parenthetical reference at the end of a comment quotation or
paraphrase provides the location of the item in the public record.\5\
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\5\ The parenthetical reference provides a reference for
information located in the docket of DOE's rulemaking to develop
test procedures 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''). ISO 13256-1:2021 is discussed further
in section III.D of this NOPR.

II. Synopsis of the Notice of Proposed Rulemaking

In this NOPR, DOE is proposing to amend the Federal test procedures
for WSHPs as follows: (1) expand the scope of the test procedure to
include WSHPs

[[Page 53305]]

with capacities between 135,000 and 760,000 British thermal units per
hour (``Btu/h''); (2) 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'') as the applicable test procedures
for WSHPs, instead of the currently referenced industry test procedure
ISO 13256-1:1998; (3) establish provisions for a new cooling efficiency
metric, integrated energy efficiency ratio (``IEER''), for WSHPs and
provide an alternative method of calculating IEER using interpolation
from test conditions commonly used for WSHPs; (4) modify the test
conditions for measuring the heating coefficient of performance
(``COP'') and provide an alternative method of calculating COP using
interpolation from test conditions commonly used for WSHPs; (5) include
additional specification of setting airflow and external static
pressure (``ESP'') for non-ducted units and ducted units with discrete-
step fans; (6) specify liquid ESP requirements for units with integral
pumps and include a method to account for total pumping effect for
units without integral pumps; (7) specify components that must be
present for testing; and (8) amend certain provisions related to
representations and enforcement in 10 CFR part 429.
DOE proposes to implement these changes by adding new appendices C
and C1 to subpart F of part 431, with both to be titled ``Uniform Test
Method for Measuring the Energy Consumption of Water-Source Heat
Pumps,'' (``appendix C'' and ``appendix C1,'' respectively). 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. As discussed elsewhere in
this NOPR, DOE has tentatively concluded, supported by clear and
convincing evidence, that the proposed amended test procedure in
appendix C1 (relying on AHRI 340/360-2022 and ASHRAE 37-2009) would
provide more representative results and more fully comply with the
requirements of 42 U.S.C. 6314(a)(2) than testing with the current
Federal test procedure (relying on ISO 13256-1:1998). However, use of
proposed appendix C1 would not be required until such time as
compliance is required with amended energy conservation standards for
WSHPs based on IEER, should DOE adopt such standards, although a
manufacturer would need to make any voluntary early representations of
IEER in accordance with appendix C1.
DOE's proposed actions are summarized in Table II-1 and addressed
in detail in section III of this document.

Table II-1--Summary of Changes in the Proposed Test Procedure Relative
to the Current Test Procedure for WSHPs
------------------------------------------------------------------------
Proposed test
Current DOE test procedure procedure in Appendix Attribution
C1
------------------------------------------------------------------------
Scope is limited to units with Expands the scope of Harmonize with
cooling capacity less than the test procedure to scope of test
135,000 Btu/h. additionally include procedure for
units with cooling water-cooled
capacity greater than commercial
or equal to 135,000 unitary air
Btu/h and less than conditioners.
760,000 Btu/h.
Incorporates by reference ISO Incorporates by Improve
13256-1:1998. reference AHRI 340/ representativen
360-2022 and ANSI/ ess of test
ASHRAE 37-2009. procedure.
Includes provisions for Includes provisions Improve
determining EER metric. for determining IEER, representativen
and specifies an ess of test
alternative method of procedure.
calculating IEER
using interpolation
and extrapolation
from results of
testing at ISO 13256-
1:1998 temperatures.
Specifies test condition of 68 Changes the test Improve
[deg]F for measuring COP. condition for COP to representativen
55 [deg]F and ess of test
provides an procedure.
alternative method of
calculating COP using
interpolation from
results of testing at
ISO 13256-1:1998
temperatures.
Does not include specification Includes additional Improve
of setting airflow and ESP specification of representativen
for non-ducted units or setting airflow and ess of test
ducted units with discrete- ESP for non-ducted procedure.
step fans. units and for ducted
units with discrete-
step fans.
Allows for testing at any Specifies liquid ESP Improve
liquid ESP with an adjustment requirements for representativen
to include the pump power to units with integral ess of test
overcome liquid internal pumps, and includes a procedure.
static pressure. method for accounting
for the total pumping
effect for units
without integral
pumps.
Does not include WSHP-specific Includes provisions in Establish WSHP-
provisions for determination 10 CFR 429.43 specific
of represented values in 10 specific to WSHPs to provisions for
CFR 429.43. prevent cooling determination
capacity over-rating of represented
and to determine values.
represented values
for models with
specific components.
Does not include WSHP-specific Adopts product- Establish
enforcement provisions in 10 specific enforcement provisions for
CFR 429.134. provisions for WSHPs DOE testing of
regarding WSHPs.
verification of
cooling capacity,
testing of systems
with specific
components, and DOE
IEER testing.
------------------------------------------------------------------------

DOE has tentatively determined that the proposed amendments
described in section III of this NOPR regarding the establishment of
appendix C would not alter the measured efficiency of WSHPs or require
retesting solely as a result of DOE's adoption of the proposed
amendments to the test procedure, if made final. DOE has tentatively
determined that the proposed test procedure amendments in appendix C1
would, if adopted, alter the measured efficiency of WSHPs. DOE has
tentatively determined that the proposed amendments would increase the
cost of testing relative to the current Federal test procedure. Use of
the proposed appendix C1 and the proposed

[[Page 53306]]

amendments to the representation requirements in 10 CFR 429.43 would
not be required until the compliance date of amended standards
denominated in terms of IEER, although manufacturers would need to use
appendix C1 if they choose to make voluntary representations of IEER
prior to the compliance date. DOE's proposed actions are discussed in
further detail in section III of this NOPR.

III. Discussion

In the following sections, DOE proposes certain amendments to the
Federal test procedure for WSHPs. For each proposed amendment, DOE
provides relevant background information, explains why the amendment
merits consideration, discusses any relevant public comments, and
proposes a potential approach.

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.
The current Federal 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 431.97, Table 3. However, DOE has
identified WSHPs on the market with cooling capacities equal to or
greater than 135,000 Btu/h.\6\ In the June 2018 RFI, DOE sought data
and information on the size of the market for WSHPs with a cooling
capacity over 135,000 Btu/h and any potential limitations to testing
such units. 83 FR 29048, 29050 (June 22, 2018).
---------------------------------------------------------------------------

\6\ For simplicity in this NOPR, DOE refers to cooling capacity
equal to or greater than 135,000 Btu/h as ``over 135,000'' Btu/h.
---------------------------------------------------------------------------

The Joint Advocates encouraged DOE to include WSHPs over 135,000
Btu/h within the scope of the test procedure. (Joint Advocates, No. 10
at p. 1)
AHRI, Trane, and WaterFurnace stated that the market for WSHPs over
135,000 Btu/h is very small--around 0.7 percent of the market--and that
finding a lab to test these units would be difficult for the reasons
that follow. AHRI commented that manufacturers have limitations on the
size of units that can be tested in their own labs, so the proposed
expanded scope of the WSHP test procedure to encompass units with
higher rated capacities would necessitate the use of third-party labs,
resulting in additional costs for testing. AHRI and WaterFurnace
further commented that WSHPs in this capacity range are highly
customized for their application and asserted that testing them would
incur significant costs. Trane added that no independent test labs are
currently certified to test WSHPs over 135,000 Btu/h. (Trane, No. 8 at
p. 2; AHRI, No. 12 at pp. 3-4; WaterFurnace, No. 7 at pp. 2-3)
Furthermore, AHRI and WaterFurnace argued that units with capacity
over 135,000 Btu/h are out of the scope of ISO 13256-1:1998. (AHRI, No.
12 at p. 4; WaterFurnace, No. 7 at p.2) WaterFurnace also commented
that AHRI certification costs would be extreme for such a small market
due to the need to test three larger and more expensive units for
sampling selection of each basic model group, and the likely need to
scrap the units after testing due the significant extent of
customization of larger units. (WaterFurnace, No. 7 at pp. 2-3)
In response, DOE notes that contrary to the assertions of AHRI and
WaterFurnace, no capacity limitation is expressed in ISO 13256-1:1998--
the industry standard currently incorporated by reference--or ISO
13256-1:2021. Once again, DOE has identified numerous model lines of
WSHPs with cooling capacity over 135,000 Btu/h from a wide variety of
manufacturers. The manufacturer literature for all identified model
lines includes efficiency representations that are explicitly based on
ISO 13256-1:1998.
Additionally, DOE is aware of several independent test labs that
have the capability to test WSHPs with cooling capacity over 135,000
Btu/h. DOE conducted investigative testing on multiple WSHP models with
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.
Further, AHRI 340/360-2022 and ANSI/ASHRAE 37-2009 include
provisions for testing units with capacities over 135,000 Btu/h. Both
ASHRAE Standard 90.1 and DOE regulations cover other categories of
commercial air conditioning and heating equipment, including water-
cooled commercial unitary air conditioners (``WCUACs''), with cooling
capacity up to 760,000 Btu/h. DOE has tentatively determined that
testing WSHPs with cooling capacity over 135,000 Btu/h would be of
comparable burden to testing other commercial air conditioning and
heating equipment of similar capacity.
Regarding WaterFurnace's comment that an expansion of test
procedure scope would mean that many large units would need to be
tested, DOE notes that expanding the scope of the test procedure 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 simplify require that if manufacturers choose to
make optional representations of WSHPs with cooling capacity over
135,000 Btu/h, that such optional representations be made in accordance
with the DOE test procedure. Further, 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)).
Therefore, an expansion of scope for the DOE test procedure would not
necessitate the testing of many large units.
For these reasons, DOE has tentatively concluded that testing units
with cooling capacity over 135,000 Btu/h is feasible. Moreover, 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, DOE has tentatively determined that such testing
would not be unduly burdensome. Additionally, expanding the scope of
DOE's test procedure for WSHPs to include equipment with 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

[[Page 53307]]

capacity range are appropriately representative. Therefore, DOE
proposes in this NOPR 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. Specifically, DOE proposes to update table 1 to 10 CFR
431.96 to include WSHPs with 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 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. For both capacity ranges, the specified test
procedure would be the proposed appendix C, and DOE proposes that any
voluntary representations with respect to the energy use or energy
efficiency must be made in accordance with appendix C starting 360 days
after a test procedure final rule is published in the Federal Register.
DOE also proposes that, starting 360 days after a test procedure final
rule is published in the Federal Register, any voluntary
representations of IEER must be made in accordance with the proposed
appendix C1.
DOE does not currently specify energy conservation standards for
WSHPs with 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
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, although any voluntary EER representations would
need to be based on the test procedure in appendix C, and any voluntary
IEER representations would need to be based on the test procedure in
appendix C1 starting 360 days after the publication of a test procedure
final rule. Additionally, if DOE were to adopt standards for WSHPs in
terms of IEER, after the compliance date for those standards, any
representations for WSHPs would be required to be made according to
appendix C1.
Issue 1: DOE requests comments on the proposed expansion of the
scope of applicability of the Federal test procedure to include WSHPs
with cooling capacity between 135,000 and 760,000 Btu/h.

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). 10 CFR 431.92. To
provide consistency with other definitions of specific categories of
commercial package air-conditioning and heating equipment, DOE proposes
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. This proposed clarification to the
``water-source heat pump'' definition would not change the scope of
equipment covered by the definition.
In addition, DOE is proposing to amend the WSHP definition to
clarify that an indoor fan is not an included component for coil-only
WSHPs. The current definition lists the main components of a WSHP, and
it includes ``indoor fan'' on that list. However, DOE has identified
coil-only WSHPs on the market that rely on a separately installed
furnace or modular blower for indoor air movement. To clarify that
coil-only WSHPs are indeed covered under the WSHP definition, DOE is
proposing 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 WSHP definition.
In summary, DOE proposes to amend the definition of WSHP 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 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.''
Issue 2: DOE requests comments 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.

C. Proposed Organization of the WSHP Test Procedure

DOE is proposing to relocate and centralize the current test
procedure for WSHPs to a new appendix C to subpart F of part 431. As
proposed, appendix C would maintain the substance of the current test
procedure. The test procedure as proposed in newly proposed appendix C
would continue to reference ISO 13256-1:1998 and provide for
determining energy efficiency ratio (``EER'') and COP. The proposed
appendix C would centralize the additional test provisions currently
applicable under 10 CFR 431.96, i.e., additional provisions for
equipment set-up (10 CFR 431.96(e)). As proposed, WSHPs would be
required to be tested according to appendix C until such time as
compliance is required with an amended energy conservation standard
that relies on the IEER metric, should DOE adopt such a standard.
DOE is also proposing to establish a test procedure for WSHPs in a
new appendix C1 to subpart F of part 431 that would incorporate by
reference AHRI 340/360-2022 and ASHRAE 37-2009 along with additional
provisions, as discussed in greater detail in the following sections.
As proposed, WSHPs would not be required to test according to the test
procedure in proposed appendix C1 until such time as compliance is
required with an amended energy conservation standard that relies on
the IEER metric, should DOE adopt such a standard, although any
voluntary representations of IEER prior to the compliance date must be
based on testing according to appendix C1.

D. Industry Standards

1. Applicable Industry Test Procedures
a. ISO Standard 13256-1
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.
ISO 13256-1:1998 specifies the cooling efficiency metric, EER,\7\
which is the ratio of the net total cooling capacity to the effective
power input at

[[Page 53308]]

a single set of operating conditions. Table 1 of ISO 13256-1:1998
specifies six sets of operating conditions for determining EER values
based on variation in entering water temperature (``EWT'') \8\ and, for
models with capacity control (i.e., multiple compressor stages),
whether the test is a full-load or part-load test. The initial three
sets, referred to as ``standard rating test'' conditions in Table 1 of
ISO 13256-1:1998, are used to determine full-load EER values, which
represent the cooling efficiency for a WSHP operating at its maximum
capacity in the most demanding conditions (i.e., highest EWT) that the
WSHP would regularly encounter. The three standard rating test
conditions in Table 1 of ISO 13256-1:1998 differ in terms of EWT, in
that they represent the highest EWT that would be regularly encountered
in different specific applications (i.e., 86 [deg]F for water-loop, 59
[deg]F for ground-water, and 77 [deg]F for ground-loop heat pumps).\9\
The standard rating test conditions specified for water-loop heat pumps
are used in the current DOE test procedure.
---------------------------------------------------------------------------

\7\ DOE defines ``EER'' at 10 CFR 431.92 as the ratio of the
produced cooling effect of an air conditioner or heat pump to its
net work input, expressed in BTU/watt-hour.
\8\ ``EWT'' is used to describe the entering liquid temperature
for WSHPs, which may be water or a brine solution, depending on the
liquid temperature used for test.
\9\ EWTs are specified in degrees Celsius in ISO 13256-1:1998,
but they are referred to by their equivalent values of degrees
Fahrenheit in this NOPR to ease comparison with other temperatures
discussed elsewhere in this document.
---------------------------------------------------------------------------

The next three sets of operating conditions for determining EER,
referred to as ``part-load rating test'' conditions in Table 1 of ISO
13256-1:1998, are specified to determine EER values at less than full
capacity for models with capacity control. As with the standard rating
test conditions, Table 1 of ISO 13256-1:1998 specifies part-load rating
test conditions for different specific applications (i.e., 86 [deg]F
for water-loop, 59 [deg]F for ground-water, and 68 [deg]F for ground-
loop heat pumps). None of the part-load rating test conditions are used
in the current DOE test procedure. Although Table 1 of ISO 13256-1:1998
specifies conditions for determining EER for multiple applications and
(as applicable) capacity levels, ISO 13256-1:1998 does not include any
seasonal cooling efficiency metrics.
Additionally, unlike the test methods for other categories of
commercial package air conditioners and heat pumps (e.g., AHRI 340/360-
2022 for commercial unitary air conditioners and heat pumps (``CUAC/
HPs''); AHRI Standard 1230-2021, ``2021 Standard for Performance Rating
of Variable Refrigerant Flow (VRF) Multi-Split Air-Conditioning and
Heat Pump Equipment'' (``AHRI 1230-2021''), for variable refrigerant
flow air conditioners (``VRF multi-split systems''); AHRI Standard 390-
2021, ``2021 Standard for Performance Rating of Single Package Vertical
Air-Conditioners and Heat Pumps'' (``AHRI 390-2021''), for single
package vertical units (``SPVUs''); and AHRI Standard 210/240-2023,
``2023 Standard for Performance Rating of Unitary Air-conditioning &
Air-source Heat Pump Equipment'' (``AHRI 210/240-2023''), for central
air conditioners and heat pumps (``CAC/HPs'')), for ducted units ISO
13256-1:1998 does not produce ratings that reflect indoor fan power
needed to overcome ESP from ductwork. Instead, section 4.1.3 of ISO
13256-1:1998 includes a fan power adjustment (which assumes a fan
efficiency of 0.3 for all units) to be applied such that only the fan
power required to overcome the internal static pressure (``ISP'') of
the unit is taken into account. The exclusion of fan power to overcome
ESP from ductwork in ISO 13256-1:1998 ratings results in higher EER
ratings than would be measured if ratings reflected fan power to
overcome ESP, thereby being more representative of field applications.
Similar to the treatment of fan power, ISO 13256-1:1998 does not
produce ratings that 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 ISP of
the unit is taken into account. 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 EER ratings than would be measured if ratings
reflected pump power to overcome ESP, thereby being more representative
of field applications.
An updated version of ISO Standard 13256-1 (i.e., ISO 13256-1:2021)
was published in 2021. While there are numerous changes in ISO 13256-
1:2021 (discussed in detail in subsequent sections of this NOPR), the
2021 version maintains provisions for determining EER, and it does not
include provisions for determining a seasonal metric that incorporates
tests at multiple conditions. ISO 13256-1:2021 also maintains the same
indoor fan power adjustment and pump power adjustment as in the 1998
version (see sections 5.1.3 and 5.1.4 of ISO 13256-1:2021), thus
continuing to produce ratings that do not reflect fan power and pump
power associated with overcoming ESP. As discussed in subsequent
sections of this document, DOE is proposing provisions in its test
procedures for WSHPs to address the identified shortcomings in ISO
13256-1:1998 and ISO 13256-1:2021.
b. AHRI 340/360-2022 and ASHRAE 37-2009
AHRI 340/360-2022 is the industry test procedure used for testing
CUAC/HPs. AHRI 340/360-2022 includes the seasonal cooling metric IEER
(see section 6.2 of AHRI 340/360-2022), which reflects cooling
performance across a range of operating conditions and load levels.
Specifically, IEER is a weighted average of the EER at full-load and
several part-load conditions intended to represent the range of
conditions that a unit would encounter over a full cooling season. The
vast majority of operating hours for commercial air conditioners and
heat pumps (including CUAC/HPs and WSHPs) occur when conditions are
less demanding than full-load conditions. For example, the IEER metric
in section 6.2.2 of AHRI 340/360-2022 specifies that full-load
conditions account for only 2 percent of operation. AHRI 340/360-2022
also includes minimum ESP requirements that are intended to reflect
ESPs in field installations and includes all indoor fan power needed to
overcome the tested ESP in the calculation of IEER (see section 6.1.3.3
of AHRI 340/360-2022). AHRI 340/360-2022 also includes a power adder to
account for the power of cooling tower fan motor(s) and circulating
water pump(s). Similar to other industry test procedures for commercial
package air-conditioning and heating equipment, AHRI 340/360-2022
references ANSI/ASHRAE 37-2009 (see section 5.1.1 of AHRI 340/360-
2022), which provides a method of test applicable to many categories of
air conditioning and heating equipment. In particular, sections 5 and 6
and appendices C, D, E, and I of AHRI 340/360-2022 reference methods of
test in ANSI/ASHRAE 37-2009. As discussed in subsequent sections of
this notice, DOE has tentatively concluded that AHRI 340/360-2022
addresses many of the identified shortcomings in ISO 13256-1:1998 and
ISO 13256-1:2021.
c. AHRI 600
AHRI is in the process of developing a new industry test standard
for WSHPs titled ``AHRI Standard 600 IEER & SCHE Performance Rating of
Water/Brine Source Heat Pumps'' (``AHRI 600''). This was formerly
designated as AHRI Standard 500P (``AHRI 500P''). DOE has

[[Page 53309]]

participated in AHRI committee meetings working to develop AHRI 600
since 2019. Based on its interactions with the AHRI committee, DOE
understands that AHRI 600 would not include any provisions for testing,
but rather would provide a method for calculation of a seasonal cooling
efficiency metric for WSHPs (i.e., IEER) based on testing conducted
according to ISO 13256-1:1998. Specifically, DOE understands that AHRI
600 would provide for the calculation of IEER for WSHPs via
interpolation and extrapolation of test results reflecting the testing
temperatures specified in Table 1 of ISO 13256-1:1998, and the rating
conditions for the IEER calculation would be based on the EWTs and
weighting factors specified in Table 9 and section 6.2 of AHRI 340/360-
2022 for determining IEER for water-cooled CUACs. AHRI 600 is still in
development and has not yet published. As discussed in subsequent
sections of this notice, DOE has tentatively concluded that the general
methodology in AHRI 600 for determining IEER is appropriate, although
DOE has identified several aspects of the methodology that warrant
further modifications.
2. Comments Received on Industry Standards and DOE Responses
In the June 2018 RFI, DOE discussed how the test method used in ISO
13256-1:1998 is similar to ANSI/ASHRAE 37-2009 and that ANSI/ASHRAE 37-
2009 is the method referenced by the 2015 version of AHRI 340/360 (the
most current version at the time; ``AHRI 340/360-2015''). 83 FR 29048,
29052 (June 22, 2018). DOE also discussed how AHRI 340/360-2015 is
referenced by ASHRAE Standard 90.1 for testing WCUACs, and that DOE was
considering whether using the same method of test for WSHPs and WCUACs
would be appropriate, given the similarities in the design of WSHPs and
WCUACs. Id. DOE requested comment on whether a single test method could
be used for both WSHPs and WCUACs. Id. DOE also sought comment on any
aspects of design, installation, and application of WSHPs that would
make the use of ANSI/ASHRAE 37-2009 infeasible for WSHPs. Id.
In response to the June 2018 RFI, AHRI and Trane stated that
because ASHRAE Standard 90.1 reaffirmed the ISO 13256-1:1998 standard
on October 26, 2018, the statutory trigger provisions of 42 U.S.C.
6314(a)(4)(B) do not provide a basis for DOE to review its WSHP test
procedure at that time. (AHRI, No. 12 at p. 1, Trane, No. 8 at p. 1)
In response, DOE notes that in addition to the statutory trigger
provisions of 42 U.S.C. 6314(a)(4)(B), the Department is statutorily
required to review its test procedures every seven years per the 7-
year-lookback requirements at 42 U.S.C. 6314(a)(1), as outlined in
section I.A of this NOPR.
AHRI, WaterFurnace, and Trane recommended that DOE wait for the ISO
revision process to be completed and adopt the revised version of ISO
13256-1:1998 following a second RFI. (AHRI, No. 12 at p. 6;
WaterFurnace, No. 7 at p. 2; Trane, No. 8 at p. 3) AHRI and
WaterFurnace further commented that the next version of ISO 13256-1 was
expected to publish in early 2019, and these commenters recommended
that DOE should support the development of the next version of ISO
13256-1:1998. (AHRI, No. 12 at pp. 3, 12-13; WaterFurnace, No. 7 at pp.
2, 10) AHRI and WaterFurnace also stated that many key authors of ANSI/
ASHRAE 37-2009 are on the ISO working group, and that the working group
was planning to add clarity to the test method with the next revision
of ISO 13256-1:1998. The commenters also stated that minimum ESPs were
being considered for inclusion in the revised version of ISO 13256-
1:1998. Id.
AHRI and WaterFurnace further stated that for international
standards, each nation requires slight deviations from the written ISO
standard and that the AHRI WSHP/Geothermal Operations Manual \10\
provides the U.S. national deviations from ISO 13256-1:1998. (AHRI, No.
12 at p. 2; WaterFurnace, No. 7 at p. 2) They further stated that the
AHRI WSHP/Geothermal Operations Manual addresses multiple issues raised
by DOE in the June 2018 RFI. Id.
---------------------------------------------------------------------------

\10\ DOE notes that the AHRI geothermal operations manual is
available at: <a href="https://www.ahrinet.org/App_Content/ahri/files/Certification/OM%20pdfs/WSHP_OM.pdf">https://www.ahrinet.org/App_Content/ahri/files/Certification/OM%20pdfs/WSHP_OM.pdf</a> (Last accessed July 29, 2022).
---------------------------------------------------------------------------

In response, DOE notes that ISO 13256-1:2021 also lacks a seasonal
cooling efficiency metric and does not produce ratings that reflect fan
power and pump power associated with overcoming ESP. As discussed, a
seasonal cooling efficiency metric would account for the range of
conditions that a unit would encounter over a full cooling season. In
addition, the inclusion of fan and pump power associated with
overcoming ESP would provide ratings that would be more representative
of the power consumption in field applications needed to overcome
pressure from ductwork and water piping. Section III.D.3 of this
document provides further discussion of these considerations and DOE's
preliminary conclusion that alternate test methods that address these
key issues would provide a more representative measure of a WSHP's
overall energy efficiency.
While an updated version of ISO Standard 13256-1 has published
(i.e., ISO 13256-1:2021), DOE is not aware of a deviation process being
initiated for the U.S. (i.e., development of the version designated
with ``AHRI/ASHRAE'' that is intended for use for testing in the U.S.).
DOE understands that the national deviation process will be initiated
by a WSHP industry committee, but DOE does not know when that will
begin or how long the national deviation process will take. DOE notes
that in the past, the WSHP industry committees have taken years longer
than expected to develop the revised version of ISO 13256-1, as well as
AHRI 600. Specifically, in their RFI comments, AHRI and WaterFurnace
stated that they expected the revised ISO 13256-1 to publish in ``early
2019'' and AHRI 600 to publish in 2019, whereas in reality, the revised
ISO 13256-1 published in 2021 and AHRI 600 remains as yet unpublished.
Therefore, DOE expects that the national deviation process will not be
completed for several years, and the Department cannot speculate as to
the substantive output of those efforts or a final completion date.
Given EPCA's statutory requirement to review the appropriate test
procedures for WSHPs every seven years, DOE has tentatively concluded
that it would be neither appropriate nor permissible to delay the
current rulemaking for the WSHP test procedure until after the
completion of the national deviation process (which the Department
understands has not yet even begun).
DOE further notes that the AHRI WSHP/Geothermal Operations Manual
is not incorporated by reference into the DOE test procedure, nor is it
referenced in ASHRAE Standard 90.1. Therefore, the deviations from the
ISO standard included in the AHRI WSHP/Geothermal Operations Manual are
not reflected in the current DOE test procedure. However, DOE has
nonetheless reviewed the AHRI WSHP/Geothermal Operations Manual as part
of its consideration of potential amended test procedure provisions in
this NOPR.
With regards to use of a part-load efficiency metric, Trane, AHRI,
and WaterFurnace commented that industry is currently developing an
IEER metric for WSHPs. (Trane, No. 8 at p. 4; AHRI, No. 12 at p. 11;
WaterFurnace, No. 7 at p. 9) AHRI and WaterFurnace commented further
that the IEER metric

[[Page 53310]]

is included in the draft of AHRI 500P \11\ and is calculated using
performance data from ISO 13256-1:1998. In addition, AHRI and
WaterFurnace stated that WSHPs in water-loop applications (i.e.,
installed with cooling towers) operate with similar water-loop
conditions to WCUACs. Therefore, the commenters argued that the
provisions used for determining IEER for WSHPs in the draft of AHRI
500P are similar to those included in AHRI 340/360 and AHRI 1230;
specifically, the commenters included a table showing that the IEER EWT
conditions in the draft of AHRI 500P align with those specified in AHRI
340/360. Both AHRI and WaterFurnace commented that they anticipated
AHRI 500P to be completed in 2019. (AHRI, No. 12 at pp. 11-12;
WaterFurnace, No. 7 at p. 9)
---------------------------------------------------------------------------

\11\ As discussed, after DOE received comments in response to
the June 2018 RFI, the draft AHRI Standard 500P was redesignated as
the draft AHRI Standard 600.
---------------------------------------------------------------------------

Once again, DOE notes that AHRI 600 \12\ has not yet published, and
the Department is unaware as to when that document will be completed.
Accordingly, for this NOPR, in addition to proposing a method to
determine IEER by testing at the IEER test points specified in Table 9
of AHRI 340/360-2022, DOE is proposing an alternate method of
calculating IEER (based on interpolation and extrapolation from results
of testing to EWTs specified in Table 1 of ISO 13256-1:1998, rather
than testing directly at the EWTs specified for the IEER metric in
Table 9 of AHRI 340/360-2022) that DOE understands to be consistent
with the approach in the current draft version of AHRI 600. Section
III.E.1.b of this NOPR includes further details on the proposed
optional approach for calculation of IEER based on interpolation and
extrapolation.
---------------------------------------------------------------------------

\12\ As discussed, after DOE received comments in response to
the June 2018 RFI, the draft AHRI Standard 500P was redesignated as
the draft AHRI Standard 600.
---------------------------------------------------------------------------

DOE also received comments from AHRI, Trane, and WaterFurnace that
cautioned against using a different test standard, such as AHRI 340/
360, for testing WSHPs instead of ISO 13256-1 as currently specified.
(Trane, No. 8 at p. 4; AHRI, No. 12 at p. 12; WaterFurnace, No. 7 at p.
10) AHRI, Trane, and WaterFurnace argued that AHRI 340/360 does not
include several important features that are included in ISO 13256-
1:1998 such as: provisions for heating performance, performance mapping
\13\ across a wide temperature range, part-load ratings, application
ratings for well water and geothermal, and provisions for testing units
with variable-speed compressors. (Trane, No. 8 at p. 4; AHRI, No. 12 at
p. 12; WaterFurnace, No. 7 at p. 10) Trane stated that AHRI 340/360
covers only cooling-mode operation of water-cooled units, and that
WSHPs require a test procedure that includes both cooling and heating
cycle operation. (Trane, No. 8 at p. 4) AHRI and WaterFurnace
additionally stated that certain aspects of ISO 13256-1:1998, such as
standard rating conditions, are not included in ANSI/ASHRAE 37-2009
because ANSI/ASHRAE 37-2009 is a method of test rather than a test
standard. (AHRI, No. 12 at pp. 12-13; WaterFurnace, No. 7 at pp. 10-11)
AHRI, Trane, and WaterFurnace further commented that that many aspects
of ANSI/ASHRAE 37-2009 are accounted for in ISO 13256-1:1998. (AHRI,
No. 12 at p. 13; Trane, No. 8 at p. 4; WaterFurnace, No. 7 at p. 10)
AHRI and WaterFurnace also stated that several Environmental Protection
Agency (``EPA''), State, utility, and building code requirements
reference ISO 13256-1:1998, and they asserted that removing reference
to it would have a significant negative impact on the industry and
consumers who use efficiency programs and tax credits when selecting
equipment. (AHRI, No. 12 at p. 12; WaterFurnace, No. 7 at p. 10)
---------------------------------------------------------------------------

\13\ DOE understands use of the term ``performance mapping'' as
referring to making representations of performance across a range of
temperature conditions, typically achieved by interpolating or
extrapolating from test results obtained at specifically defined
test conditions.
---------------------------------------------------------------------------

The following paragraphs provide DOE's responses to concerns
expressed by commenters that AHRI 340/360 and ANSI/ASHRAE 37-2009 lack
certain provisions that are present in ISO 13256-1 and that are needed
for testing WSHPs.
Regarding provisions for heating tests, DOE acknowledges that AHRI
340/360-2022 does not include certain provisions needed for heating-
mode testing of WSHPs because WCUACs, the water-cooled units for which
AHRI 340/360-2022 is intended to apply, are not heat pumps.
Specifically, AHRI 340/360-2022 does not specify the following
provisions for a heating test: an EWT test condition, provisions for
setting liquid flow rate, or how pump effects are accounted for.
Therefore, DOE is proposing additional provisions that would address
these aspects of heating-mode tests of WSHPs, as discussed further in
sections III.E.2, III.F.4, III.F.5, and III.F.6 of this document. DOE
notes that AHRI 340/360-2022 does include provisions appropriate for
air-side measurements in heating tests because AHRI 340/360-2022 covers
air-cooled commercial unitary heat pumps. Furthermore, ANSI/ASHRAE 37-
2009 provides appropriate provisions for a method of test for WSHPs.
DOE has tentatively concluded that its proposals for heating provisions
for WSHPs would, when combined with the provisions in AHRI 340/360-
2022, produce test results representative of an average use cycle.
Regarding performance mapping across a wide temperature range,
part-load ratings, and ratings for ground-water and geothermal
applications, DOE acknowledges that AHRI 340/360-2022 does not include
EWTs specific to multiple applications of WSHPs. By contrast, Table 1
of ISO 13256-1:1998 provides separate EWTs for water-loop, ground-
water, and ground-loop WSHP applications (see discussion in section
III.D.1.a of this NOPR). AHRI 340/360-2022 includes full-load and part-
load cooling EWTs for only water-loop applications of WCUACs, but the
EWT for water-loop applications in Table 1 of ISO 13256-1:1998 is the
only EWT test condition used in the current DOE test procedure. As
discussed in sections III.D.3 and III.E.1 of this NOPR, DOE has
tentatively concluded that the seasonal integrated cooling metric IEER
specified in section 6.2 of AHRI 340/360-2022 would be more
representative of field applications and provide consumers with a
better understanding of year-round performance of WSHPs than the EER
metric measured at a single temperature and load level. However, DOE
recognizes the potential benefits to consumers of allowing
manufacturers to continue to provide performance ratings at the
temperatures and load levels specified in Table 1 of ISO 13256-1:1998,
in addition to providing the proposed IEER ratings which are more
representative of year-round performance. Therefore, as discussed in
section III.E.1.a of this NOPR, DOE is proposing in section 5.2 of
proposed appendix C1 to provide for optional representations of EER at
the EWTs and load levels specified in Table 1 of ISO 13256-1:1998.
Consequently, DOE has tentatively concluded that the proposals in this
NOPR would continue to provide manufacturers the flexibility to offer
full-load and part-load EER ratings at multiple temperatures that can
be used for performance mapping, representations of part-load
performance, and representations of performance for ground-water and
geothermal applications.
Regarding variable-speed compressors, section 6.2 of AHRI 340/360-
2022 includes appropriate provisions for testing and determining IEER
for units with all compressor

[[Page 53311]]

types, including variable-speed compressors. Specifically, Section
6.2.6 of AHRI 340/360-2022 includes provisions addressing
``proportionally capacity controlled units,'' which is defined in
section 3.22 of AHRI 340/360-2022 to include units incorporating one or
more variable-capacity compressors where the compressor capacity can be
modulated continuously or in steps not more than 5 percent of the full-
load cooling capacity. Section 6.2.6 of AHRI 340/360-2022 includes
steps for setting capacity of these units for each IEER test point.
With regards to EPA, State, utility, and building code requirements
that reference ISO 13256-1:1998, DOE does not expect that an update to
the DOE test procedure for WSHPs would create any particular challenges
for any other agency or organization that references the performance
ratings as measured by the DOE test procedure. EPCA directs DOE to
establish and amend test procedures to be reasonably designed to
produce test results which reflect energy efficiency, energy use, and
estimated operating costs of covered equipment during a representative
average use cycle (as determined by the Secretary), and not be unduly
burdensome to conduct. (42 U.S.C. 6314(a)(2)) DOE test procedures are
updated regularly, across many products and equipment types, and other
agencies and organizations have historically updated their requirements
as needed in response to those changes. With regard to EPA
specifically, DOE has responsibility for developing and revising the
test procedures that provide the basis for ratings under EPA's ENERGY
STAR program. DOE and EPA work closely together to update ENERGY STAR
specifications in response to any changes to the relevant DOE test
procedure. Furthermore, DOE is proposing that the amended test
procedure would not be required for use until the effective date of any
future energy conservation standards based on the IEER metric, thereby
providing sufficient advance notice for any agency or organization to
adapt program requirements accordingly.
3. Proposal for DOE Test Procedure
As discussed, EPCA requires that test procedures for covered
equipment, including WSHPs, be reasonably designed to produce test
results which reflect energy efficiency, energy use, and estimated
operating costs of a type of industrial equipment (or class thereof)
during a representative average use cycle (as determined by the
Secretary), and shall not be unduly burdensome to conduct. (42 U.S.C.
6314(a)(2))
For the reasons presented in the remainder of this section, DOE has
tentatively determined that the test procedure for WSHPs as proposed
would improve the representativeness of the current Federal test
procedure for WSHPs and would not be unduly burdensome. Specifically,
DOE has tentatively concluded, supported by clear and convincing
evidence as discussed in the following paragraphs, that testing WSHPs
in accordance with the industry test standards AHRI 340/360-2022 and
ASHRAE 37-2009 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. Therefore, DOE is proposing to amend the test procedure for
WSHPs so as to incorporate by reference in the proposed new appendix C1
the test provisions in AHRI 340/360-2022 and ASHRAE 37-2009, along with
certain additional provisions.
Throughout the remainder of the discussion in section III of this
NOPR, DOE presents the details and justifications for the proposed test
procedure and deviation from the currently referenced industry test
procedure, ISO 13256-1:1998 (i.e., the industry test standard
referenced in ASHRAE Standard 90.1). The following paragraphs summarize
the key areas in which DOE has tentatively concluded, supported by
clear and convincing evidence, that the proposal would improve the
representativeness of the test procedure:
(1) Cooling efficiency metric: As discussed, the cooling metric
specified in the current DOE test procedure (which references ISO
13256-1:1998) is EER, which reflects full-load performance only at a
single operating condition. In contrast, IEER, the metric specified in
section 6.2 of AHRI 340/360-2022, is a seasonal metric that is a
weighted average of the full- and part-load performance at different
outdoor conditions intended to represent average efficiency over a full
cooling season. For the vast majority of operating hours for WSHPs and
other commercial air conditioners and heat pumps installed in the
field, loads are at less than full-load capacity. This is because units
are sized to be able to provide sufficient air conditioning capacity at
the hottest time on the hottest day of the year, but the vast majority
of annual cooling hours are at significantly lower outdoor temperatures
(and thus lower EWTs), with correspondingly lower cooling loads. This
is demonstrated in the IEER metric specified in section 6.2.2 of AHRI
340/360-2022, which specifies a weighting factor for full-load
conditions of only 2 percent of the hours included in the IEER metric,
with the remaining 98 percent of hours assigned to lower load levels
and lower outdoor temperatures. As discussed, from RFI comments and
DOE's participation in AHRI 600 committee meetings, DOE understands
that the AHRI 340/360-2022 IEER weighting factors are also included in
the draft AHRI 600. Therefore, DOE has tentatively concluded that IEER
would be more representative of an average use cycle than the EER
metric. This topic is discussed further in section III.E.1 of this
NOPR.
(2) Fan power and indoor air external static pressure: As
discussed, for ducted units, ISO 13256-1:1998 does not produce ratings
that reflect the fan power needed to overcome ESP. Further, that ISO
standard does not specify ESP requirements for ducted units and instead
uses a fan power adjustment, such that ratings reflect only the fan
power needed to overcome internal static pressure within the unit and
not the ESP from the ductwork that would be installed in the field. In
contrast, Table 7 of AHRI 340/360-2022 specifies minimum ESP
requirements at which performance is measured. Because ducted WSHPs are
manufactured to be installed in the field with ductwork, DOE has
tentatively concluded that a WSHP rating that reflects the indoor fan
power needed to overcome ESP representative of typical installations
(i.e., the approach taken by AHRI 340/360-2022) would produce test
results that are more representative of an average use cycle than
testing in accordance with ISO 13256-1:1998, the standard currently
incorporated by reference.
(3) Pump power and liquid external static pressure: ISO 13256-
1:1998 does not produce ratings that reflect the pump power needed to
overcome liquid ESP. Further, for units with integral pumps, ISO 13256-
1:1998 does not specify ESP requirements and uses a pump power
adjustment such that ratings reflect only the pump power needed to
overcome internal static pressure within the unit. For units with
integral pumps, DOE has tentatively concluded that ratings would be
more representative if based on testing at a liquid ESP that is
representative of the ESP from water piping in typical installations.
For units without integral pumps, DOE has tentatively concluded that
ratings would be more

[[Page 53312]]

representative if a pump power adder is included in the rating that
reflects pump power needed to overcome a field-representative liquid
ESP. More discussion on this topic is provided in section III.F.4 of
this document.
DOE is proposing to adopt in its WSHP test procedure the following
specific sections of AHRI 340/360-2022:

(1) Section 3: Definitions, excluding sections 3.2, 3.4, 3.5,
3.7, 3.8, 3.12, 3.14, 3.15, 3.17, 3.23, 3.26, 3.27, 3.29, 3.30, and
3.36;
(2) Section 5: Test Requirements;
(3) Section 6: Rating Requirements, excluding sections 6.1.1.7,
6.1.2.1, 6.1.3.4.5, 6.1.3.5.4, 6.1.3.5.5, 6.5, 6.6, and 6.7;
(4) Appendix A. References--Normative;
(5) Appendix C. Indoor and Outdoor Air Condition Measurement--
Normative;
(6) Appendix E. Method of Testing Unitary Air Conditioning
Products--Normative;

The key substantive changes that would result from DOE's proposal
to adopt AHRI 340/360-2022 for testing WSHPs include the following:

(1) A new energy efficiency descriptor, IEER, which incorporates
part-load cooling performance (see section 6.2 of AHRI 340/360-
2022);
(2) Minimum ESP requirements, instructions for setting airflow
and ESP, and tolerances for airflow and ESP (see sections 6.1.3.3,
6.1.3.4, and Table 6 of AHRI 340/360-2022);
(3) Fixed inlet and outlet water temperature conditions (see
Table 5 of AHRI 340/360-2022);
(4) Operating tolerance for voltage (see Table 10 of AHRI 340/
360-2022);
(5) Different indoor air conditions used for testing (see Table
5 of AHRI 340/360-2022);
(6) Refrigerant charging instructions for cases where they are
not provided by the manufacturer (see section 5.8 of AHRI 340/360-
2022), and
(7) 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 (see section E6 of Appendix E to AHRI 340/360-2022).

Appendix E of AHRI 340/360-2022 specifies the method of test,
including the use of specified provisions of ANSI/ASHRAE 37-2009.
Consistent with AHRI 340/360-2022, DOE is proposing to incorporate by
reference ANSI/ASHRAE 37-2009 in its test procedure for WSHPs.
Specifically, in section 1 of the proposed test procedure for WSHPs in
the proposed appendix C1, DOE is proposing to adopt all sections except
sections 1, 2, and 4 of ANSI/ASHRAE 37-2009. The key substantive
changes that would result from DOE's proposal to adopt ANSI/ASHRAE 37-
2009 for testing WSHPs include the following:

(1) Provisions for split systems, such as accounting for
compressor heat and refrigerant line losses (see sections 7.3.3.4,
7.3.4.4, and 7.6.1.2 of ASHRAE 37-2009);
(2) Measurement of duct losses for ducted units (see section
7.3.3.3 of ASHRAE 37-2009);
(3) Standardized heat capacity of water and brine (see section
12.2 of ASHRAE 37-2009), and
(4) A calculation for discharge coefficients (see section 6.3.2
of ASHRAE 37-2009).

Throughout the remainder of this NOPR, DOE discusses substantive
differences between the proposed test procedure (including references
to AHRI 340/360-2022 and ASHRAE 37-2009) and the current DOE test
procedure (which incorporates by reference ISO 13256-1:1998). DOE also
identified and considered provisions in the updated industry test
procedure ISO 13256-1:2021 that substantively differ from ISO 13256-
1:1998.

E. Efficiency Metrics

1. IEER
a. General Discussion
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
for CUACs specified in section 6.2 of AHRI 340/360-2022. 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 entering water temperature 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
entering water temperature, not operation across a range of
temperatures and compressor speeds. Neither ISO 13256-1:1998 nor ISO
13256-1:2021 include seasonal metrics.
In the June 2018 RFI, DOE requested comment on whether a seasonal
metric that accounts for part-load performance would be appropriate for
WSHPs, and the Department sought information on the specific details of
a seasonal metric that would best represent average cooling efficiency
for WSHPs. 83 FR 29048, 29051 (June 22, 2018).
NEEA encouraged DOE to consider adopting IEER for WSHPs and to
improve the metric so as to make it more representative of an average
use cycle by including changes to more accurately represent fan energy
use in field applications, accounting for all modes of operation, and
including ventilating and economizing. (NEEA, No. 11 at p. 2)
The Joint Advocates recommended that DOE should consider seasonal
efficiency metrics for WSHPs to better reflect field energy
consumption, including part-load operation. The Joint Advocates stated
that it was their understanding that WSHPs operate most of the time at
part-load, and that, therefore, full-load efficiency ratings do not
provide sufficient information to consumers. The Joint Advocates also
stated that the current metrics do not demonstrate the potential
savings associated with technologies that improve part-load efficiency,
such as variable-speed compressors. (Joint Advocates, No. 10 at p. 2)
The CA IOUs stated that while the IEER metric provides a valuable
measure of annual efficiency, the EER metric is important for achieving
reductions in peak loads. These commenters remarked that because the
IEER metric uses a low weighting (i.e., 2 percent) for the full-load
condition, a standard based only on the IEER metric would incentivize
manufacturers to optimize equipment at the part-load conditions and
could potentially result in equipment that is designed with lower full-
load EERs than the current standards for this equipment. To prevent
poor equipment performance at full-load conditions, the CA IOUs
supported using the IEER metric that measures part-load efficiencies in
conjunction with the currently regulated full-load EER metric. (CA
IOUs, No. 9 at pp. 1-2) The CA IOUs further commented that the
prevalence of economizers in buildings with WSHPs

[[Page 53313]]

should be investigated and that modifications to the IEER metric should
be informed by the outcome of such research before the IEER metric is
implemented as the efficiency metric for WSHPs. (CA IOUs, No. 9 at p.
1)
Trane, AHRI, and WaterFurnace commented that industry is currently
developing an IEER metric for WSHPs (Trane, No. 8 at p. 4; AHRI, No. 12
at p. 11; WaterFurnace, No. 7 at p. 9). AHRI and WaterFurnace explained
further that the IEER metric is included in the draft version of AHRI
500P,\14\ and as drafted, IEER is calculated using performance data
from ISO 13256-1:1998. AHRI and WaterFurnace commented that the
provisions used for determining IEER for WSHPs in the draft version of
AHRI 500P are similar to those included in AHRI 340/360 and AHRI 1230.
Both AHRI and WaterFurnace commented that they anticipated AHRI 500P to
be completed in 2019. (AHRI, No. 12 at p. 11; WaterFurnace, No. 7 at p.
9)
---------------------------------------------------------------------------

\14\ As discussed, after DOE received comments in response to
the June 2018 RFI, the draft AHRI Standard 500P was redesignated as
the draft AHRI Standard 600.
---------------------------------------------------------------------------

As explained previously, DOE notes that the EER metric in DOE's
current test procedure for WSHPs measures only full-load performance,
and the revised industry test procedure ISO 13256-1:2021 does not
include a seasonal metric. For the vast majority of operating hours of
WSHPs installed in the field, loads are less than full-load capacity,
thus causing single-stage WSHPs to cycle and multi-stage WSHPs to
operate at part-load (i.e., less than designed full capacity). Because
a seasonal metric reflects operation at a range of conditions
experienced over the period of a cooling season, DOE has tentatively
concluded that a cooling metric that accounts for part-load performance
across a range of temperatures (such as IEER specified in section 6.2
of AHRI 340/360-2022) would be more representative of an average use
cycle than the full-load EER metric, which reflects operation at a
single condition. Further, a seasonal metric that reflects varying load
levels representative of a full cooling season would better incentivize
use of modulating components (e.g., multi-stage and variable-speed
compressors) that can reduce annual energy consumption in field
installations.
DOE has been participating in AHRI committee meetings to develop
AHRI 600 with the goal of specifying an IEER metric for WSHPs. It is
DOE's understanding that the committee's work is ongoing, and its
completion date is uncertain. However, based on comments received on
the June 2018 RFI, manufacturer feedback obtained via DOE's
participation in AHRI 600 committee meetings, and DOE's own research,
the Department has tentatively concluded that the EWTs and weighting
factors specified in Table 9 and equation 3 of AHRI 340/360-2022 for
water-cooled CUACs would be representative for WSHPs. DOE's
understanding based on a review of market literature and available
studies is that in the past, WSHP installations were more typically
controlled such that water-loop temperatures were maintained at
temperatures above 60 [deg]F through heat provided by a system boiler.
From manufacturer feedback provided in AHRI 600 committee meetings, DOE
understands that in current practice, WSHP installations are typically
controlled to allow water-loop temperatures to drop to temperatures
closer to 50 [deg]F. Manufacturers indicated that this change in how
WSHP system loops are typically controlled in the field is because of
multiple factors. One factor provided by manufacturers is that because
commercial buildings with WSHP installations are typically cooling-
dominated (i.e., most WSHPs spend more time in cooling mode than
heating mode), building engineers have increasingly optimized overall
WSHP system performance by using the cooling tower to decrease EWTs
below 60 [deg]F even when some WSHPs in the loop are in heating mode,
thereby improving efficiency for the WSHPs in cooling mode at the
expense of reducing efficiency for the fewer WSHPs in heating mode.
Additionally, manufacturers indicated that the market penetration of
WSHPs with water-side economizers has significantly increased in recent
years, largely related to requirements in ASHRAE Standard 90.1
regarding presence of economizers in HVAC systems. Water-side
economizers provide compressor-free cooling when supplied with water of
sufficiently low temperature; therefore, manufacturers have indicated
that building engineers are increasingly maintaining WSHP loop
temperatures below 60 [deg]F to take advantage of water-side economizer
cooling.\15\ Given this feedback provided by manufacturers on the WSHP
loop water temperatures typically used in the field, DOE has
tentatively concluded that the IEER EWTs 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)
are representative of current installations of WSHPs. Section III.E.4
of this NOPR includes discussion on other operating modes other than
mechanical cooling and heating, such as ventilation and economizing.
---------------------------------------------------------------------------

\15\ In WSHPs with water-side economizers, if the EWT is
sufficiently low in cooling mode, some or all of the entering water
that would otherwise enter the water-to-refrigerant condenser coil
instead enters the economizer coil, in which the cool water is used
to directly cool indoor air, reducing the need for mechanical
cooling from the compressor.
---------------------------------------------------------------------------

Based on the discussion in the preceding paragraphs, DOE has
tentatively determined that use of a seasonal efficiency metric,
specifically IEER based on AHRI 340/360-2022, would be more
representative of the average use cycle of a unit as compared to the
current EER metric. Once again, DOE notes that while it may have been
expected that AHRI 600 was to publish in 2019, the draft standard has
not yet been finalized. Accordingly, DOE is moving forward and
proposing 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.
DOE is proposing to specify the relevant test procedure requirements
for WSHPs for measuring IEER in section 5.1 of proposed appendix C1.
As discussed, the proposed IEER test procedure for WSHPs would not
be required until such a time as DOE adopts energy conservation
standards for WSHPs denominated in terms of IEER, should DOE adopt such
standards. If DOE were to adopt such standards, such shift to the IEER
metric for WSHPs would require all WSHPs to be re-rated in terms of the
IEER metric. Further, beginning 360 days after final rule publication,
manufacturers would be required to use the proposed test procedure in
appendix C1 to make optional representations of IEER for WSHPs. The
cost and impacts to manufacturers of the proposed test procedure are
discussed further in section III.I of this document. Additionally,
adopting the IEER metric for WSHPs would increase the number of
required cooling-mode tests from one to four. However, as discussed,
DOE understands that AHRI 600 would provide for calculating IEER from
test results measured at the EWTs specified in Table 1 of ISO 13256-
1:1998. Consistent with this approach and as discussed in the following
section, DOE is proposing to allow determination of IEER via
interpolation and extrapolation from testing at the full-load and part-
load EWT conditions specified in Table 1 of ISO 13256-1:1998.

[[Page 53314]]

In response to the CA IOUs' suggestion, although EPCA limits the
agency to promulgation of a single performance standard (see 42 U.S.C.
6311(18)), DOE is proposing to provide 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).
Issue 3: DOE requests comment on its proposal to adopt the test
methods specified in AHRI 340/360-2022 for calculating the IEER of
WSHPs. DOE also requests comment on its proposal that all EER tests at
full-load and part-load 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) are
optional.
b. Determination of IEER Via Interpolation and Extrapolation
As discussed, DOE understands that the draft AHRI 600 would provide
a mechanism for calculating IEER from test results measured at the EWTs
specified in Table 1 of ISO 13256-1:1998. Specifically, interpolation
and extrapolation \16\ from ISO 13256-1:1998 test results would be used
to calculate performance at the EWTs specified in Table 9 of AHRI 340/
360-2022 for WCUACs, allowing calculation of IEER for WSHPs using the
weighting factors specified in section 6.2.2 of AHRI 340/360-2022.
Under this approach, AHRI 600 would not include any provisions for
testing, but rather would provide a method for calculation of IEER
based on results of testing under ISO 13256-1:1998. DOE recognizes that
there may be a value for stakeholders in representations of full-load
and part-load EER ratings at the temperatures specified in Table 1 of
ISO 13256-1:1998. Specifically, these EWTs represent different
applications, and manufacturers may prefer to provide representations
of performance specific to different applications.
---------------------------------------------------------------------------

\16\ Per the draft AHRI 600 method, performance at IEER EWTs can
be determined using test results at two different temperature
conditions (specified in ISO 13256-1:1998). Interpolation is used if
the IEER EWT is between the two tested EWTs, and extrapolation is
used if the IEER EWT is outside the range of the two tested results.
---------------------------------------------------------------------------

The ability to determine EER ratings at the ISO 13256-1:1998 EWTs
(in accordance with the proposed test procedure, at section 5.2 of the
proposed appendix C1), and to determine 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.
Consequently, DOE investigated the AHRI 600 method of calculating IEER.
To evaluate the draft AHRI 600 method of calculating IEER, DOE
conducted investigative testing on a sample of WSHPs. DOE presents the
results of testing 15 WSHPs in the following paragraphs. This testing
compared the interpolation and extrapolation method of calculating IEER
at the ISO 13256-1:1998 EWTs to testing at the IEER EWTs specified in
AHRI 340/360-2022. In summary and for the reasons discussed in the
following paragraphs, DOE has tentatively determined that an
interpolation and extrapolation approach, similar to that in draft AHRI
600 with certain modifications, is appropriately representative to
calculate IEER.
To determine if the interpolation and extrapolation method is
appropriate for WSHPs, DOE evaluated whether the components needed to
calculate IEER can be linearly interpolated across EWT. Specifically,
the parameters necessary for the calculation of IEER are EER, capacity,
total power, and all components of power (i.e., compressor power, fan
power, condenser section power, controls power). DOE tested 15 units at
different EWTs to compare physical tested results and interpolated and
extrapolated values. The method evaluated by DOE determines IEER
ratings for WSHPs by interpolation and extrapolation from full-load
tests at liquid inlet temperatures of 86 [deg]F, 77 [deg]F, and 59
[deg]F and, for two-stage and variable-speed units, part-load tests at
86 [deg]F, 68 [deg]F, and 59 [deg]F. DOE first evaluated the accuracy
of interpolating to a different EWT for full-load tests. For each of
the 15 units tested, DOE conducted full-load tests to measure EER at 86
[deg]F, 77 [deg]F, and 59 [deg]F. DOE then used the results from the 86
[deg]F and 59 [deg]F tests to linearly interpolate to performance at 77
[deg]F, and compared these interpolated results to the results of
testing at 77 [deg]F. Table 3 presents a summary of the percentage
differences between the interpolated and measured values. Positive
values in the average, minimum, and maximum columns of Table 3 indicate
that the values interpolated to 77 [deg]F from results measured at 86
[deg]F and 59 [deg]F were higher than the values measured at 77 [deg]F,
and negative values indicate the opposite.

Table 3--Percentage Differences of Interpolated Results From Measured Results for Capacity, Power, and EER
----------------------------------------------------------------------------------------------------------------
Average
Parameter Average Minimum Maximum absolute value
----------------------------------------------------------------------------------------------------------------
Cooling Capacity................................ -0.2 -1.4 2.2 0.9
Total Power..................................... -0.4 -2.6 1.5 0.8
Interpolated EER................................ 2.3 0.3 4.8 2.3
EER calculated from interpolated capacity and 0.2 -1.7 2.9 1.0
power..........................................
----------------------------------------------------------------------------------------------------------------
Note: Positive values in the average, minimum, and maximum columns indicate that the values interpolated to 77
[deg]F from results measured at 86 [deg]F and 59 [deg]F were higher than the values measured at 77 [deg]F.
Negative values in the average, minimum, and maximum columns indicate that the values interpolated to 77
[deg]F from results measured at 86 [deg]F and 59 [deg]F were lower than the values measured at 77 [deg]F.

As shown in Table 3, the interpolated values for cooling capacity
and total power differed from the corresponding tested values by an
average of less than 1 percent. Therefore, DOE has determined that
interpolating capacity and total power results in representative values
of capacity and total power, respectively. However, the interpolated
EER value at 77 [deg]F was higher than the tested EER value at 77
[deg]F for all tested units, with an average difference of 2.3 percent
(ranging from 0.3 percent to 4.8 percent higher). Because of the
consistent bias in the results showing interpolated EER higher than
tested

[[Page 53315]]

EER,\17\ DOE considered an alternate approach of calculating EER based
on interpolated values of cooling capacity and total power rather than
interpolating EER directly. The bottom row of Table 3 shows the results
of calculating EER at 77 [deg]F using the interpolated values of
cooling capacity and total power. As shown in in the bottom row of
Table 3, calculating EER at 77 [deg]F using interpolated values of
cooling capacity and total power resulted in EER values that were on
average 0.2 percent higher than the tested EER value at 77 [deg]F
(ranging from 1.7 percent lower to 2.9 percent higher). Because
determining EER by interpolating cooling capacity and total power
results in closer agreement to tested values than directly
interpolating EER (and does not consistently bias results toward higher
interpolated EER values), DOE used the former approach in the
calculation of IEER values discussed in the following paragraphs.
---------------------------------------------------------------------------

\17\ As presented in Table 3, the results from DOE's testing
show that that linear interpolation across EWT results in close
agreement for cooling capacity and total power. Because EER =
Cooling Capacity/Total Power, if linear equations are used to
represent the relationship between cooling capacity and EWT, as well
as between total power and EWT, the resulting equation for EER has
equations linearly dependent on EWT in the numerator and
denominator. Such an equation simplifies to an inverse function
(i.e., the variable (EWT) is in the denominator), which is concave
up (i.e., the slope of the EER vs EWT curve increases with
increasing EWT), such that between any two points on the curve, the
curve is always below a line drawn between the two points.
Therefore, calculating EER by linearly interpolating EER values
across EWT consistently results in an interpolated EER value that is
higher than the EER value measured by testing or determined by
linearly interpolating cooling capacity and total power.
---------------------------------------------------------------------------

For determining IEER for single-stage units, this interpolation and
extrapolation approach would be used to determine EER at the EWTs for
all 4 IEER points, and the EER results for the part-load points (i.e.,
test points designated as B, C, and D in AHRI 340/360-2022) would also
be adjusted for cyclic degradation (see discussion in section III.F.2.b
of this document).
For two-stage and variable-speed WSHPs, DOE evaluated a method that
tests at the minimum compressor speed at the EWTs specified in Table 1
of ISO 13256-1:1998 for part-load tests (i.e., at 86 [deg]F, 68 [deg]F,
and 59 [deg]F). As with the draft AHRI 600 method, the method evaluated
by DOE then provides for interpolating to the IEER liquid inlet
temperatures from these part-load tests, and IEER is determined using
interpolated results for the IEER EWTs for both full-load and part-load
tests.\18\ To evaluate the accuracy of this methodology for calculating
IEER for staged WSHPs, DOE conducted additional investigative testing
on 10 of the 15 tested WSHPs (6 two-stage WSHPs and 4 variable-speed
WSHPs). Specifically, these 10 units were tested to calculate IEER via
the interpolation and extrapolation method (by conducting full-load and
part-load tests at the EWTs specified in Table 1 of ISO 13256-1:1998
and using interpolation and extrapolation to calculate IEER) and were
tested to determine IEER per section 6.2 of AHRI 340/360-2022 by
testing at the IEER EWTs and target load levels specified in Table 9 of
AHRI 340/360-2022. Consistent with the discussion in the previous
paragraphs, when interpolating to determine performance at a different
EWT for a given compressor stage for staged units, DOE calculated the
EER values by interpolating and extrapolating values of cooling
capacity and total power, rather than directly interpolating and
extrapolating values of EER. Table 4 presents a summary of the results.
Positive values in the average, minimum, and maximum columns of Table 4
indicate that the IEER values determined via the interpolation and
extrapolation method were higher than the IEER values determined
through testing at the EWTs and load levels specified in section 6.2 of
AHRI 340/360-2022, and negative values indicate the opposite.
---------------------------------------------------------------------------

\18\ After interpolating the full-load and part-load
interpolated across EWT, the AHRI 340/360-2022 IEER calculation
methodology is then used. The interpolated results would either need
cyclic degradation (see discussion in section III.F.2.b of this
NOPR) or interpolation across compressor staging to determine the
specific load EER values to be used in the IEER calculation, unless
the EWT interpolation yields a calculated percent load that meets
the 3 percent tolerance for the respective IEER load point.

Table 4--Percentage Differences of Interpolated IEER From Measured IEER for Two-Stage and Variable-Speed Units
----------------------------------------------------------------------------------------------------------------
Average
Capacity control type Average Minimum Maximum absolute value
----------------------------------------------------------------------------------------------------------------
Two-Stage....................................... -0.9 -2.7 -0.0 0.9
Variable-Speed.................................. -6.3 -13.6 0.2 6.4
----------------------------------------------------------------------------------------------------------------
Note: Positive values in the average, minimum, and maximum columns indicate that the IEER values determined via
the interpolation and extrapolation method were higher than the IEER values determined through testing at the
EWTs and load levels specified in section 6.2 of AHRI 340/360-2022. Negative values in the average, minimum,
and maximum columns indicate that the IEER values determined via the interpolation and extrapolation method
were lower than the IEER values determined through testing at the EWTs and load levels specified in section
6.2 of AHRI 340/360-2022.

As shown in Table 4, for the six tested two-stage WSHPs, the IEER
values calculated using the described interpolation and extrapolation
method were on average 0.9 percent lower than the IEER value measured
from testing per AHRI 340/360-2022 (ranging from 0.0 percent to 2.7
percent lower).
For the four variable-speed units, the IEER values calculated using
the described interpolation and extrapolation method were on average
6.3 percent lower than the IEER value measured from testing per AHRI
340/360-2022 (ranging from 0.2 percent higher to 13.6 percent lower).
These results demonstrate a wider discrepancy from AHRI 340/360-2022
results than for single-stage or two-stage WSHPs. This discrepancy is
likely because the interpolation and extrapolation method described
only includes testing at maximum and minimum compressor speed, whereas
the AHRI 340/360-2022 approach includes testing at compressor speeds to
operate at each of the part-load test points (i.e., 75 percent, 50
percent, and 25 percent load). Therefore, for variable-speed WSHPs with
higher EER at intermediate compressor speeds than at maximum or minimum
compressor speeds, the interpolation and extrapolation method described
results in a lower calculated IEER than testing at the IEER conditions
specified in AHRI 340/360-2022, which was the case for three of the
four tested units. While for certain tested variable-speed units
calculating IEER via interpolation and extrapolation resulted in a
lower IEER value, from participation in AHRI 600 committee

[[Page 53316]]

meetings, DOE understands 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.
Based on the investigative testing conducted, DOE has tentatively
concluded that determining IEER via interpolation and extrapolation
from testing at the ISO 13256-1:1998 EWTs (in accordance with DOE's
proposed test procedure), similar to the method in the draft AHRI 600,
provides appropriately representative results that are comparable to
testing at the EWTs (and for staged units, load levels) specified in
Table 9 of AHRI 340/360-2022. Therefore, DOE is proposing in section 5
of the proposed appendix C1 to allow that IEER for WSHPs can be
calculated from either of two methods: (1) ``option 1''--testing in
accordance with AHRI 340/360-2022 (at EWTs of 85 [deg]F, 73.5 [deg]F,
62 [deg]F, and 55 [deg]F); or (2) ``option 2''--interpolation and
extrapolation of cooling capacity and power values based on testing in
accordance with the proposed test procedure at EWTs of 86 [deg]F, 77
[deg]F, and 59 [deg]F for full-load tests and (for staged units) EWTs
of 86 [deg]F, 68 [deg]F, and 59 [deg]F for part-load tests. For single
speed units, option 2 would require three full-load tests at entering
liquid temperatures of 86 [deg]F, 77 [deg]F, and 59 [deg]F. For two-
stage and variable-speed units, three additional tests at the minimum
compressor speed would be required, at entering liquid temperature of
86 [deg]F, 68 [deg]F, and 59 [deg]F.
Specifically for option 2, aside from the EWTs, the tests for
option 2 would be performed using the same test provisions 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. As discussed, DOE has
tentatively determined that results from the interpolation and
extrapolation method have greater agreement with, and, therefore, are
comparably representative to, the tested results by interpolating
values of cooling capacity and total power rather than interpolating
values of EER; therefore, DOE is proposing that the alternative method
specify interpolation using the cooling capacity and total power. The
proposed provisions for option 2 in section 5.1.2 of proposed appendix
C1 are otherwise generally consistent with the draft AHRI 600 method,
except for the cyclic degradation approach, which is discussed in
section III.F.2.b of this NOPR.
DOE notes that representations for WSHPs can be made either based
on testing (in accordance with 10 CFR 429.43(a)(1)) or AEDMs (in
accordance with 10 CFR 429.43(a)(2)). 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.
Issue 4: DOE requests 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. Specifically, DOE seeks 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.
Issue 5: DOE requests comment on whether the proposed methodology
to determine IEER based on interpolation and extrapolation is
appropriate for variable-speed units. DOE 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.
DOE is aware that ISO 13256-1:2021 includes changes from ISO 13256-
1:1998 with respect to the EWTs specified for cooling tests.
Specifically, Table 2 of ISO 13256-1:2021 specifies full-load cooling
temperatures of 86 [deg]F, 68 [deg]F, and 50 [deg]F, and part-load
cooling temperatures of 77 [deg]F, 59 [deg]F, and 41 [deg]F. Consistent
with the draft AHRI 600 method, DOE is proposing to use the
temperatures specified in Table 1 of ISO 13256-1:1998 for option 2
tests; however, it is expected that the results under the proposed
interpolation and extrapolation method would provide comparable results
using the EWTs specified in Table 2 of ISO 13256-1:2021.
Issue 6: DOE seeks feedback on whether the proposed interpolation
and extrapolation method should be based on testing at the ISO 13256-
1:2021 EWTs.
2. COP
a. General Discussion
DOE's current test procedure for WSHPs measures heating-mode
performance in terms of the COP metric, based on testing with a 68
[deg]F EWT. 10 CFR 431.96. For the reasons explained in the following
paragraphs, DOE is proposing in section 6.2 of proposed appendix C1 to
use an EWT of 55 [deg]F for the COP metric because DOE has tentatively
concluded that 55 [deg]F is more representative of field operation than
the current EWT of 68 [deg]F.
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. Because commercial
buildings served by WSHPs in water-loop applications are typically
cooling-dominated, DOE understands that the majority of heating hours
in these applications occur in simultaneous cooling and heating
operation--in which certain WSHPs (e.g., servicing zones around the
perimeter of the building) are in heating mode while other WSHPs (e.g.,
servicing interior zones closer to the center of the building) are in
cooling mode. Because all WSHPs in the system loop are provided water
with the same EWT, at any given time, WSHPs that are in heating mode
operate at the same EWT as WSHPs in cooling mode. As discussed in
section III.E.1.a of this NOPR, from manufacturer feedback provided in
AHRI 600 committee meetings, DOE understands 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. Correspondingly, DOE is
proposing part-load IEER EWTs that align with AHRI 340/360-2022 and the
draft AHRI 600, including 62 [deg]F for the 50-percent load point and
55 [deg]F for the 25-percent load point.
Because DOE understands that WSHP water-loop temperatures are
typically controlled to drop closer to 50 [deg]F (as represented by the
55 [deg]F EWT for the 25-percent load point), the Department
understands that most hours of heating mode operation for WSHPs in
water-loop applications occur with EWTs closer to 50 [deg]F. Therefore,
while the current 68 [deg]F EWT 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
has tentatively determined that the COP EWT should be no higher than
the lowest EWT used in the IEER metric, which is 55 [deg]F (for the 25-
percent load point), because most heating hours occur when outdoor air
temperatures are lower and, thus, cooling loads are

[[Page 53317]]

lower. Therefore, DOE has tentatively concluded that the COP metric
would be more representative of water-loop WSHP applications if based
on an EWT of 55 [deg]F.
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. However, DOE
currently lacks data or evidence indicating that 50 [deg]F would be a
more representative heating EWT than 55 [deg]F for WSHPs. Therefore, in
the absence of any data suggesting a lower EWT would be more
representative of heating operation of WSHPs, DOE is proposing an EWT
of 55 [deg]F, which aligns with the lowest IEER EWT as proposed.
Issue 7: DOE seeks comment and data on the representativeness of 55
[deg]F as the EWT condition for determining COP. Specifically, DOE
requests feedback and data on whether a lower EWT, such as 50 [deg]F,
would be more representative of heating operation of WSHPs. DOE will
further consider any alternate EWT suggested by comments in developing
any final rule.
Additionally, DOE is proposing provisions in section 6.3 of
proposed appendix C1 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).
b. Determination of COP Via Interpolation
As discussed in section III.E.1.b of this NOPR, DOE is proposing to
include an alternate method for determining IEER that allows
manufacturers to perform tests at the EWTs in Table 1 of ISO 13256-
1:1998 and interpolate efficiency metrics to the EWTs specified in
Table 9 of AHRI 340/360-2022. This method would reduce overall testing
burden for manufacturers who choose to make optional EER
representations at the EWTs specified in Table 1 of ISO 13256-1:1998,
by allowing them to avoid additional testing at the IEER EWTs.
In order to provide comparable flexibility for measuring COP, DOE
is proposing a similar alternative test method in section 6.2.2 of
appendix C1 for determining COP by interpolation from results of
testing at the EWTs specified in Table 2 of ISO 13256-1:1998. To
evaluate the interpolation method for COP, DOE conducted investigative
testing on five WSHPs at the three heating EWTs specified in Table 1 of
ISO 13256-1:1998: 68 [deg]F, 50 [deg]F and 32 [deg]F. DOE interpolated
the cooling capacity and total power results from 68 [deg]F and 32
[deg]F to 50 [deg]F, and then calculated COP at 50 [deg]F using the
interpolated values of cooling capacity and total power.\19\ Finally,
DOE compared these interpolated values to the results of testing at 50
[deg]F. Table 5 presents a summary of the percentage differences
between the interpolated and measured values. Positive values in the
average, minimum, and maximum columns of Table 5 indicate that the
values interpolated to 50 [deg]F from results measured at 68 [deg]F and
32 [deg]F were higher than the values measured at 50 [deg]F, and
negative values indicate the opposite.
---------------------------------------------------------------------------

\19\ As discussed in section III.E.1.b of this NOPR, DOE
tentatively determined that interpolation of EER directly results in
a consistent bias, and that more representative results are obtained
by calculating EER using interpolated values of cooling capacity and
total power. Similarly, for COP, DOE is proposing that COP can be
determined using interpolated values of heating capacity and total
power, rather than interpolating COP values directly.

Table 5--Percentage Differences of Interpolated Results From Measured Results for Capacity, Power, and COP
----------------------------------------------------------------------------------------------------------------
Average
Parameter Average Minimum Maximum absolute value
----------------------------------------------------------------------------------------------------------------
Cooling Capacity................................ -0.4 -1.9 0.6 0.9
Total Power..................................... 0.3 -1.2 2.1 0.9
COP calculated from interpolated capacity and -0.7 -3.9 0.9 1.1
power..........................................
----------------------------------------------------------------------------------------------------------------
Note: Positive values in the average, minimum, and maximum columns indicate that the values interpolated to 50
[deg]F from results measured at 68 [deg]F and 32 [deg]F were higher than the values measured at 50 [deg]F.
Negative values in the average, minimum, and maximum columns indicate that the values interpolated to 50
[deg]F from results measured at 68 [deg]F and 32 [deg]F were lower than the values measured at 50 [deg]F.

As shown in Table 4, the COP calculated from interpolated values of
cooling capacity and total power differed from measured COP by an
average of less than 1 percent. Therefore, DOE has tentatively
concluded that determining COP via interpolation in this temperature
range from testing at the ISO 13256-1:1998 EWTs (in accordance with
DOE's proposed test procedure) provides appropriately representative
results that are comparable to testing at 55 [deg]F. Therefore, DOE is
proposing 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. Aside
from the EWTs, the tests for option B would be performed using the same
test provisions 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 A.
Issue 8: DOE requests comment on the proposal to allow
determination of COP using two different methods: (1) testing at 55
[deg]F; or (2) interpolation of heating capacity and power values based
on testing in accordance with the proposed test procedure at EWTs
specified for heating tests in Table 2 of ISO 13256-1:1998 (i.e., 50
[deg]F and 68 [deg]F). Specifically, DOE seeks 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.
3. Entering Air Conditions
The current DOE 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. Table 2 and Table 3 of ISO 13256-1:2021
specify the same entering air conditions as ISO 13256-1:1998. As

[[Page 53318]]

discussed in section III.D.3 of this NOPR, DOE proposes to adopt AHRI
340/360-2022 as the test procedure for WSHPs. Table 6 of AHRI 340/360-
2022 specifies entering indoor air conditions for standard rating
cooling tests to be 80 [deg]F dry-bulb temperature and a maximum of 67
[deg]F wet-bulb temperature and standard rating heating tests to be 70
[deg]F dry-bulb temperature and a maximum of 60 [deg]F wet-bulb
temperature.
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 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. DOE
surmises 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. 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/HPs. 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/HPs. Therefore, DOE has
tentatively determined that the entering air conditions in AHRI 340/
360-2022 are appropriately representative of the average conditions in
which WSHPs operate in the field. DOE is proposing in sections 5 and 6
of proposed appendix C1 to use entering air conditions from Table 6 of
AHRI 340/360-2022 for both cooling (IEER) and heating (COP) tests.
Issue 9: DOE requests comment on its proposal to specify in
proposed appendix C1 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).
4. Operating Modes Other Than Mechanical Cooling and Heating
On April 1, 2015, DOE published in the Federal Register a
notification of its intent to establish a working group under the
Appliance Standards and Rulemaking Federal Advisory Committee
(``ASRAC'') Commercial and Industrial Fans and Blowers Working Group
(``ASRAC Working Group'') to discuss and, if possible, reach consensus
on the scope of the rulemaking, certain key aspects of a proposed test
procedure, and proposed energy conservation standard for fans and
blowers. 80 FR 17359. The ASRAC Working Group term sheet for commercial
and industrial fans and blowers was approved (Docket No. EERE-2013-BT-
STD-0006-0179).\20\ Recommendation #3 of the term sheet addressed
supply and condenser fans that are embedded in certain covered
equipment. (Id. at p. 3) The ASRAC Working Group recommended that DOE
consider revising efficiency metrics that include energy use of supply
fans in order to include the energy consumption during all relevant
operating modes (e.g., auxiliary heating mode, ventilation mode, and
part-load operation) in the next round of test procedure rulemakings.
(Id. at p. 4) The ASRAC Working Group included WSHPs in its list of
regulated equipment for which fan energy use should be considered. (Id.
at p. 16)
---------------------------------------------------------------------------

\20\ Available at: <a href="http://www.regulations.gov/document/EERE-2013-BT-STD-0006-0179">www.regulations.gov/document/EERE-2013-BT-STD-0006-0179</a>.
---------------------------------------------------------------------------

As part of the June 2018 RFI, DOE stated that it was investigating
whether changes to the WSHP test procedure are needed to properly
characterize a representative average use cycle, including changes to
more accurately represent fan energy use in field applications. 83 FR
29048, 29050 (June 22, 2018). DOE requested information as to the
extent that accounting for the energy use of fans in commercial
equipment such as WSHPs would be additive of other existing accountings
of fan energy use. Id.
In the June 2018 RFI, DOE also sought comment on whether accounting
for the energy use of fan operation in WSHPs would alter measured
efficiency, and if so, to what extent. Id. DOE also requested data and
information regarding what forms of auxiliary heating are installed in
WSHPs, how frequently they operate, and whether they operate
independently of the WSHP. Id. Additionally, DOE requested data and
information on how frequently WSHP supply fans are operated when there
is no demand for heating or cooling, such as for fresh air ventilation
or air circulation or filtration. Id.
The Joint Advocates and NEEA commented that DOE should amend the
test procedure to account for fan energy use outside of mechanical
cooling and heating for fans in regulated equipment to more fully
capture fan energy use. (Joint Advocates, No. 10 at p. 1; NEEA, No. 11
at p. 1) The Joint Advocates asserted that by failing to capture fan
operation for economizing, ventilation, and other functions outside of
cooling mode, the test procedure may be significantly underestimating
fan energy consumption. (Joint Advocates, No. 10 at p. 1)
NEEA commented that the commercial prototype building models used
by Pacific Northwest National Laboratory in the analysis in support of
ASHRAE Standard 90.1 include information on the operation of fans in
ventilation mode and economizer mode and could be used to develop
national average fan operating hours outside of heating and cooling.
(NEEA, No. 11 at pp. 3) Furthermore, NEEA stated that the vast majority
of WSHPs are installed in commercial buildings, thereby subjecting them
to ASHRAE Standard 90.1 code requirements such as the requirement of
water side economizers in many U.S. climate zones. Id. NEEA added that
details of requirements for certain control and component features are
provided in ASHRAE Standard 90.1 and should be an indicator of
prevalence of these features in WSHPs on the market. Id.
NEEA further stated that ANSI and the Air Movement Control
Association (``AMCA'') developed ANSI/AMCA 208-18, ``Calculation of the
Fan Energy Index,'' which provides a potential way to measure embedded
fan performance in WSHPs using the fan energy index (``FEI'').
According to NEEA, DOE could develop a revised IEER-type metric that
weighs together cooling performance (using the IEER test) and fan
efficiency (using an FEI-based metric). NEEA argued that accounting for
the energy use of fan operation in WSHPs does not need to alter
measured efficiency, and that to reduce burden on manufacturers, DOE
could combine the FEI and IEER metrics such that manufacturers would
have multiple viable design option pathways to achieve the minimum IEER
efficiency standard without improving the embedded fan efficiency above
the minimum FEI efficiency standard. (NEEA, No. 11 at p. 2)
Trane commented that there are some applications in which a WSHP
would be used for ventilation, but that ventilation is not the main
use, and that using a WSHP for purposes other than heating and cooling
is rare. Trane stated further that typical practice is for ventilation
air to be provided by a dedicated outdoor air system (``DOAS'') using a
separate ductwork system, whereas the WSHP system provides the heating
and cooling. Finally, Trane commented that for installations in which
the DOAS and WSHPs supply to common ductwork, WSHP fans would operate
when

[[Page 53319]]

ventilation is needed, but rarely would this be needed without heating
or cooling. (Trane, No. 8 at pp. 2, 5)
AHRI and WaterFurnace both stated that a high percentage of WSHP
systems offer a continuous fan mode to circulate fresh air but did not
have data on how often. (AHRI, No. 12 at pp. 4-5; WaterFurnace, No. 7
at p. 3) However, both estimated that a typical WSHP would operate in
continuous fan mode (i.e., without cooling or heating) for
approximately 1,300 hours per year. The commenters estimated total
cooling and heating mode operation of 3,300 hours per year. (AHRI, No.
12 at pp. 9; WaterFurnace, No. 7 at p. 9)
Further, AHRI and WaterFurnace commented that fan power is largely
dependent on motor type and typically represents 13 to 18 percent of
total power. (AHRI, No. 12 at pp. 4, 8-9; WaterFurnace, No. 7 at pp. 3,
8-9) AHRI asserted that EPCA imposes a one-metric-per-product
limitation and that efforts to capture the energy use of a fan during a
mode other than cooling (or heating) would result in an impermissible
design requirement. (AHRI, No. 12 at pp. 5, 10)
AHRI stated that DOE has the authority to include certain fans and
blowers, by rule, as ``covered equipment'' if such products meet all
the requirements of EPCA at 42 U.S.C. 6311(2). AHRI asserted that if
DOE developed a standard for stand-alone industrial fans, it would not
be appropriate to apply that standard to fans embedded in regulated
equipment. Furthermore, AHRI argued that the fact that Congress granted
a specific provision of authority to DOE for a consumer furnace
ventilation metric affirms that DOE is without general authority to
create overlapping ventilation requirements for other regulated
products. (AHRI, No. 12 at pp. 10-11)
Trane and WaterFurnace also commented that regulation of WSHP fans
would produce unnecessary overlapping regulations, and that system-
level efficiency metrics allow for optimization of the entire system.
(Trane, No. 8 at p. 4; WaterFurnace, No. 7 at p. 8) AHRI and
WaterFurnace stated that fan energy in cooling and heating are
accounted for in the current test procedure and that fans are optimized
for these modes because they account for the majority of operational
time. (AHRI, No. 12 at p. 8; WaterFurnace, No. 7 at p. 9)
AHRI and WaterFurnace commented that auxiliary heating is not
common in WSHPs and estimated that electric heat is included in less
than one percent of WSHP shipments. AHRI and WaterFurnace further
commented that the primary mode of operation of most WSHPs is cooling
and that heating requirements are limited, such that adequate heating
can be supplied through heat pump operation alone. (AHRI, No. 12 at p.
4; WaterFurnace, No. 7 at p. 3) Trane stated that for their WSHPs,
electric heat is provided only when heat pump operation alone cannot
meet the heating demand. Trane further stated that the compressors are
locked out while back-up electric heating is used for most WSHPs, with
the exception of rooftop WSHP equipment, which allows auxiliary
electric heat to supplement the heating provided by the heat pump.
(Trane, No. 8 at p. 2)
In response, DOE emphasizes that its request for information
regarding fan energy use was in investigation of energy use of WSHPs in
operational modes other than those currently evaluated by the test
procedure (i.e., operational modes other than cooling and heating). DOE
understands that much of the energy use attributable to these other
modes is likely a product of fan operation. Provisions to measure
energy use for ancillary functions (e.g., economizing, ventilation,
filtration, and auxiliary heat) when there is no heating or cooling are
not included in ISO 13256-1:1998 or AHRI 340/360-2022. As discussed in
section III.D.3 of this NOPR, DOE is proposing to adopt AHRI 340/360-
2022 for testing WSHPs. Additionally, provisions addressing other
operational modes have not been included in the updated ISO 13256-
1:2021. In light of the above, at this time, DOE lacks sufficient
information on the number of units capable of operating in these other
modes or the frequency of operation of these modes during field
conditions to determine whether such testing would be appropriate for
WSHPs and/or to develop a test method capable of accounting for energy
use of such auxiliary functions of WSHPs. To the extent that data and
further information are developed regarding operation of WSHPs in modes
other than mechanical cooling and heating, DOE would consider such
developments in a future WSHP test procedure rulemaking.
5. Dynamic Load-Based Test Procedure
In response to the June 2018 RFI, both NEEA and the Joint Advocates
encouraged DOE to investigate a load-based test method that could allow
more sophisticated and inclusive efficiency metrics. Both NEEA and
Joint Advocates commented that the Canadian Standards Association
(``CSA'') group is developing CSA EXP07 (``Load-based and climate-
specific testing and rating procedures for heat pumps and air
conditioners''), which is a dynamic, load-based test procedure expected
to better capture performance in the field, including the capturing of
cycling losses, benefits of variable-speed operation, and importance of
control strategies. (NEEA, No. 11 at p. 2; Joint Advocates, No. 10 at
p. 2)
DOE is aware of the dynamic, load-based test procedure being
developed by CSA. However, at this time, DOE understands that CSA EXP07
has not been validated and finalized. Furthermore, the CSA EXP07 test
procedure is applicable to CAC/HPs, and that test procedure has not yet
been evaluated for WSHPs. Further, DOE is not aware of data showing
that any dynamic, load-based test procedure produces repeatable and
reproducible test results. Therefore, DOE has tentatively concluded
that further consideration of CSA EXP07 would be premature at this
time, and accordingly, the Department is not proposing to adopt any
dynamic, load-based test procedures in this NOPR.

F. Test Method

1. Airflow and External Static Pressure
a. Fan Power Adjustment and Required Air External Static Pressure
As discussed in section III.D.1.a of this NOPR, for ducted units,
sections 4.1.3.1 and 4.1.3.2 of ISO 13256-1:1998 specify 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. While Table 9 of ISO 13256-1:1998
includes an operating tolerance (i.e., maximum variation of individual
reading from rating conditions) and a condition tolerance (i.e.,
maximum variation of arithmetical average values from specified test
conditions) for external resistance to airflow, the test standard does
not specify to which values of ESP these tolerances are intended to
apply.
In the June 2018 RFI, DOE requested comment on whether minimum ESP
requirements should be included for ducted WSHPs, and if so, what
values would be appropriate. 83 FR 29048, 29050 (June 22, 2018). DOE
also requested information on whether field ESP values typically vary
with capacity, and whether fan power used for overcoming ESP should be
included in the efficiency calculation for WSHPs

[[Page 53320]]

intended to be used with ducting. Id. DOE asked for comment and data on
whether the fan/motor efficiency factor used in the calculation of fan
power for WSHPs is representative of units currently on the market and
whether the value accurately represents the efficiency of existing fans
that are not replaced in WSHP installations. Id at 83 FR 29051.
Additionally, DOE requested comment on whether indoor fans are
typically replaced when coil-only WSHPs are installed. Id.
In response to DOE's request for information, the Joint Advocates
encouraged DOE to establish minimum ESP values for ducted equipment and
to include the fan power used for overcoming external resistance in
efficiency calculations for WSHPs. (Joint Advocates, No. 10 at pp. 1-2)
NEEA commented that representative ESPs for WSHPs are higher than zero
ESP, and the commenter recommended that DOE should ensure the WSHP ESP
requirements reflect field installations, stating that otherwise, WSHP
ratings will neither provide an adequate representation of actual
efficiency nor provide good information to consumers. (NEEA, No. 11 at
p. 3) NEEA also reminded that the ASRAC Working Group recommended that
test procedures for regulated equipment, including WSHPs, be revised to
better capture fan energy use. NEEA further commented that adding
minimum ESP values would not increase test burden. Id.
AHRI, Trane, and WaterFurnace stated that the AHRI WSHP
certification program does require minimum ESPs that increase with
rated capacity for ducted units with fans driven by an electronically-
commutated motor (``ECM''), and that these minimum ESPs are being
considered for inclusion in the revised version of ISO 13256-1. (AHRI,
No. 12 at pp. 5-6; Trane, No. 8 at p. 3; WaterFurnace, No. 7 at p. 5)
AHRI and WaterFurnace commented that the field ESP of commercial WSHPs
is largely tied to the ductwork and a single filter, typically
resulting in ESPs less than 0.50 inches water column (``in
H<INF>2</INF>O''), but the commenters noted that some larger systems
(>60,000 Btu/h) may be installed such that ESP values are as much as
1.0 in H<INF>2</INF>O. (AHRI, No. 12 at p. 5; WaterFurnace, No. 7 at p.
4) AHRI also mentioned that commercial WSHPs are not typically
installed with substantial ancillary filters or other high-static
accessories found in larger air handlers. (AHRI, No. 12 at p. 5)
Trane and AHRI commented that fan power for overcoming ESP should
not be included in the efficiency calculation. (AHRI, No. 12 at p. 6;
Trane, No. 8 at pp. 2-3) AHRI further commented that the ISO 13256-
1:1998 approach (of including a fan power adjustment down to zero ESP)
results from the acknowledgment of the variability of ESP in the wide
variety of WSHP applications that range from cooling towers/boilers to
dry coolers to geothermal earth loop systems. (AHRI, No. 12 at p. 5)
Trane and WaterFurnace further commented that excluding the fan power
for overcoming ESP from the efficiency calculation ensures that units
with indoor fans that produce higher static pressure are not penalized
for having a stronger fan motor. (Trane, No. 8 at pp. 2-3;
WaterFurnace, No. 7 at p. 4) WaterFurnace added that because more
powerful fans to overcome higher field ESPs results in lower certified
efficiency, most manufacturers design to the minimum ESP to avoid the
excess fan power, and that in field applications, this results in low
airflow and poor performance. WaterFurnace commented that their typical
WSHP product is tested at higher ESP (greater than 0.4 in
H<INF>2</INF>O) but then corrected to zero ESP. (WaterFurnace, No. 7 at
pp. 1, 4) AHRI stated that fewer than 10 percent of all installed WSHPs
have a cooling capacity greater than 5 tons, and the organization
further noted that the table of ESP requirements in AHRI WSHP/
Geothermal Operations Manual specifies an ESP of 0.20 in H<INF>2</INF>O
for 5-ton models, suggesting that 90 percent of WSHPs would have an ESP
less than 0.2 in H<INF>2</INF>O. (AHRI, No. 12 at p. 8)
AHRI and WaterFurnace commented that the AHRI WSHP/Geothermal
Operations Manual limits the fan power correction to three percent on
the cooling capacity to prevent any application of the correction as a
way to inflate efficiencies. (AHRI, No. 12 at p. 8; WaterFurnace, No. 7
at p. 8) AHRI and WaterFurnace further commented that aligning ESP
requirements for different equipment categories (with different
conditions and applications) is futile and that there will always be
differences in HVAC test standards. (AHRI, No. 12 at p. 8;
WaterFurnace, No. 7 at p. 7) AHRI, Trane, and WaterFurnace stated that
the fan power adjustment factor in ISO 13256-1:1998 is representative
for WSHPs. (AHRI, No. 12 at p. 8; Trane, No. 8 at p. 4; WaterFurnace,
No. 7 at p. 8) AHRI, Trane, and WaterFurnace also stated that the fan
power adjustment factor provides the ability to predict performance at
any ESP level. (AHRI, No. 12 at p. 3; Trane, No. 8 at p. 3;
WaterFurnace, No. 7 at p. 5)
AHRI and WaterFurnace also stated that the fan efficiency factor
noted in the RFI is the same for all current fan motor designs, both
permanent magnet variable speed and induction technologies, and they
have found them to be reasonable. (AHRI, No. 12 at p. 8; WaterFurnace,
No. 7 at p. 7) WaterFurnace further stated that the fan and pump
correction factors were developed in 1998 after high-efficiency
permanent split capacitor (``PSC'') and ECM fan motor technology were
both deployed into the market and that the factor is intended to cover
a number of technologies. (WaterFurnace, No. 7 at p. 7)
Regarding whether indoor fans are typically replaced when coil-only
WSHPs are installed, AHRI and WaterFurnace commented that they are not
aware of any coil-only WSHPs, and, therefore, that test procedure
revisions to address such units are unnecessary. (AHRI, No. 12 at p. 8;
WaterFurnace, No. 7 at p. 8) AHRI and WaterFurnace also stated that all
commercial WSHPs are packaged units and that split systems are not
commercially used. Id.
In response to those comments on the June 2018 RFI, DOE would
clarify that ducted WSHPs installed in the field must overcome ESP from
ductwork. As noted, the method used in ISO 13256-1:1998 and ISO 13256-
1:2021 excludes the power to overcome ESP via the fan power adjustment,
which adjusts the fan power down to reflect zero ESP. In contrast,
testing per AHRI 340/360-2022 requires testing at a minimum ESP
requirement (specified in Table 7 of AHRI 340/360-2022) and does not
include any adjustments to the fan power. In other words, ratings in
accordance with AHRI 340/360-2022 reflect performance at the applicable
minimum ESP requirement. DOE has tentatively concluded that testing
ducted WSHPs in accordance with AHRI 340/360-2022 (i.e., testing at
minimum ESP requirements with no fan power adjustment) would be more
representative of field installations than the method used in ISO
13256-1:1998, for the following three reasons:
(1) Use of the fan power adjustment in ISO 13256-1:1998 results in
ratings that do not reflect the fan power needed to overcome ESP;
(2) The fan power adjustment in ISO 13256-1:1998 assumes a fan
efficiency of 0.3, which underestimates the efficiency of fans in
WSHPs, and, thus, underestimates the fan power that would be needed for
the fan to operate at zero ESP; and
(3) Rated ESP values that manufacturers use when testing to ISO
13256-1:1998 are typically significantly higher than ESPs
representative of water-loop WSHP installations. Because, as stated,
the fan power

[[Page 53321]]

adjustment subtracts fan power to reflect performance at zero ESP,
assuming a low fan efficiency, testing at ESPs higher than
representative values subtracts more fan power than would typically be
needed to overcome that high tested ESP, and, thus, it further results
in efficiency ratings that underestimate fan power needed to operate at
zero ESP.
DOE conducted investigative testing on five WSHPs to determine the
extent to which ISO 13256-1:1998 accounts for fan energy use compared
to testing at representative ESP requirements per AHRI 340/360-2022.
DOE also determined the fan efficiency of these five units. Of the five
tested units, three had constant airflow ECM motors and two had
constant torque ECM motors.

Table 6--Investigative Testing Results Regarding Fan Power and Fan
Efficiency
------------------------------------------------------------------------

------------------------------------------------------------------------
Fan Power at AHRI 340/360 ESP Requirement (W)........... 262.04
Fan Power Determined According to ISO 13256-1:1998 (W).. 139.57
Average Measured Fan Efficiency......................... 0.46
Measured Fan Efficiency Range........................... 0.34-0.71
------------------------------------------------------------------------

DOE determined the relationship between ESP and fan power for the
five WSHPs by conducting several tests with varying ESP at the rated
airflow. As shown in Table 5, DOE determined the fan power for each of
the five units at the applicable ESP requirement in AHRI 340/360-2022.
These data show that the method in ISO 13256-1:1998 accounts for an
average of only 53 percent of the fan power required to overcome the
ESP specified in AHRI 340/360-2022.
DOE also calculated the fan efficiency for each unit based on tests
conducted with varying ESP at the rated airflow. As shown in Table 5,
DOE found that the measured fan efficiency for all five units is higher
than the fan efficiency value assumed in ISO 13256-1:1998 (30 percent).
Specifically, the average measured efficiency (46 percent) is over 50
percent higher than the ISO 13256-1:1998 value, and the highest
measured efficiency is more than double the ISO 13256-1:1998 value. The
consistent underestimation of fan efficiency by the ISO 13256-1:1998
fan power adjustment equation for the five tested units results in a
larger amount of fan power being subtracted from the measured value
when adjusting down to zero ESP than would be representative of the
actual fan's operation. In other words, when adjusting the measured fan
power down to zero ESP, the fan power adjustment's assumption of a fan
efficiency that is lower than is typical in WSHPs results in more power
being subtracted than the fan would actually have needed to overcome
that level of ESP (because lower-efficiency fans consume more power to
provide the same level of output). Therefore, for these five units the
resulting rating determined per ISO 13256-1:1998 underestimates the fan
power needed to operate at zero ESP because too much fan power is
subtracted using the fan power adjustment.
The low fan efficiency value in the ISO 13256-1:1998 fan power
adjustment equation results in an incentive for manufacturers to test
at a higher ESP than would be representative for WSHPs, to take more
advantage of the fan power adjustment by subtracting a larger
calculated adjustment from the measured fan power (when adjusting fan
power down to reflect performance at zero ESP). DOE's examination of
rated ESP values in supplemental test instructions (``STI'') indicates
that WSHPs are being rated based on testing with ESPs higher than would
be representative. Specifically, DOE examined the STI for 15 WSHPs and
found that the average rated ESP was 0.51 in H<INF>2</INF>O. In
contrast, the rated ESPs in the STI exceeded the AHRI 340/360-2022 ESP
requirements (which, as discussed, align with the ESP levels included
in the AHRI WSHP/Geothermal Operations Manual and are very similar to
the ESP levels in included in ISO 13256:1-2021) by more than the +0.05
in H<INF>2</INF>O tolerance for 13 of the 15 units. Given the low fan
efficiency assumed in the ISO 13256-1:1998 fan power adjustment,
testing at ESPs higher than representative for WSHPs results in
efficiency ratings that underestimate fan power needed to operate at
zero ESP.
Regarding comments received about ESP requirements in the revised
version of ISO 13256-1, DOE acknowledges that Table 1 of ISO 13256-
1:2021 does include minimum ESPs for all fan motor types, and that
those minimum ESPs are generally consistent with the values in Table 7
of AHRI 340/360-2022, albeit with slight differences due to rounding.
However, ISO 13256-1:2021 does not include an upper tolerance on ESP
(i.e., tests can still be conducted at any ESP above the minimum) and
maintains the fan power correction to adjust down to zero ESP. Again,
DOE tentatively finds that its proposed approach based on AHRI 340/360-
2022 would produce results more representative of an average WSHP use
cycle, so the Department is not proposing to use ISO 13256-1:2021 in
this context.
Because the fan power adjustment method used in ISO 13256-1:1998
and ISO 13256-1:2021 does not capture the fan power to overcome ESP,
and underestimates the fan power needed to operate at zero ESP for many
units (as determined from DOE's testing and examination of rated ESPs
from STI), DOE has tentatively concluded that ratings based on
performance at a representative ESP requirement (as is the case in AHRI
340/360-2022) are more representative of the total fan power that would
be consumed in field installations.
The minimum ESP requirements specified in Table 7 of AHRI 340/360-
2022 align with the minimum ESP requirements specified in Table B2 of
the AHRI WSHP/Geothermal Operations Manual and are generally consistent
with the minimum ESPs specified in Table 1 of ISO 13256-1:2021, with
slight differences due to rounding. Based on the inclusion of similar
minimum ESP requirements in the AHRI WSHP/Geothermal Operations Manual
and ISO 13256-1:2021, DOE has tentatively concluded that the minimum
ESP requirements specified in AHRI 340/360-2022 are representative of
water-loop WSHP field installations.
To account for the impacts of ESP typically encountered in the
field, DOE is proposing provisions to reflect fan power to overcome a
representative ESP when calculating efficiency. As per the discussion
in this section and in section III.D.2 of this NOPR, DOE has
tentatively determined that to best reflect field operation, 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. Therefore, DOE has tentatively
determined that for WSHPs the method in AHRI 340/360-2022 is more
representative of field energy use than the methods used in ISO 13256-
1:1998 or ISO 13256-1:2021. As such, DOE is proposing 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.
In the following sections (sections III.F.1.b and III.F.1.b.i of this
document), DOE provides further detail on proposed provisions for
setting airflow and ESP for units intended to be installed both with
and without ducts.
Regarding comments received about WSHPs with higher-static fan
motors, DOE is proposing an approach for

[[Page 53322]]

representations and enforcement of units with non-standard indoor fan
motors (i.e., more powerful fan motors intended for operation with ESPs
higher than the ESP requirements in the test procedure). This approach
would allow for an individual model with a non-standard indoor fan
motor to be included in the same basic model as an individual model
with a standard indoor fan motor, with the rating based on performance
with the standard indoor fan motor, as long as the non-standard indoor
fan motor has the same or better relative efficiency performance as
compared to the standard motor. DOE has tentatively concluded that this
proposed approach addresses the concerns raised by commenters that ESP
requirements would penalize units with higher-static indoor fan motors.
Section III.G.3 of this NOPR includes additional discussion on DOE's
proposed approach for non-standard indoor fan motors.
Regarding comments received about the AHRI WSHP/Geothermal
Operations Manual, DOE notes that the Operations Manual is not
incorporated by reference in the DOE test procedure and is not
referenced in ASHRAE Standard 90.1. Therefore, the provisions included
in the AHRI WSHP/Geothermal Operations Manual are not reflected in the
current DOE test procedure. However, DOE has nonetheless reviewed the
AHRI WSHP/Geothermal Operations Manual as part of its consideration of
potential amended test procedure provisions in this NOPR. DOE notes
that Table B2 of the AHRI WSHP/Geothermal Operations Manual does
specify ESP requirements that align with the ESP requirements specified
in Table 7 of AHRI 340/360-2022; however, the ESP requirements in the
AHRI WSHP/Geothermal Operations Manual only apply to ducted units with
ECM fan motors. DOE has tentatively concluded that specification of ESP
requirements would provide for more representative ratings for all
ducted WSHPs, not just units with ECM fan motors. Additionally, DOE
notes that section A5 of the AHRI WSHP/Geothermal Operations Manual
limits the fan power correction to no more than 3 percent of the
measured cooling capacity. However, because the fan power correction is
applied to both the capacity and total power when calculating EER or
COP, the effect of a fan power correction of 3 percent on the
calculated efficiency would be significantly more than 3 percent.
Further, as discussed, DOE has tentatively concluded that ratings based
on minimum ESP requirements would be more representative than ratings
based on zero ESP (developed using the fan power correction). For these
reasons, DOE is not proposing to incorporate by reference or otherwise
adopt the AHRI WSHP/Geothermal Operations Manual as part of the DOE
WSHP test procedure.
Regarding comments received about coil-only units, DOE has
identified at least one coil-only unit that would meet the definition
of a WSHP. In accordance with DOE's proposal to adopt AHRI 340/360-
2022, coil-only WSHPs would be subject to the test provisions for
setting airflow for coil-only units specified in sections 6.1.3.3 and
6.1.3.4 of AHRI 340/360-2022.
Issue 10: DOE requests comment on the proposal to adopt provisions
from AHRI 340/360-2022 such that 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.
b. Setting Airflow and ESP
ISO 13256-1:1998 specifies airflow rates in section 4.1.5 of that
document, including that: (a) non-ducted heat pumps shall be tested at
airflow rates obtained at zero ESP; (b) ducted heat pumps with internal
fans or with designated air movers shall be tested at the airflow rates
obtained at zero ESP or the manufacturer-specified airflow rate,
whichever is lower, and (c) ducted heat pumps without internal fans
shall be tested at the manufacturer-specified airflow rate subject to a
maximum internal pressure drop. Additionally, paragraph (e)(2) of 10
CFR 431.96 requires that the airflow rate used for testing must be
specified by the manufacturer in the installation and operation manuals
being shipped to the commercial customer, and that if a rated air flow
value for testing is not clearly identified, a value of 400 standard
cubic feet per minute per ton shall be used.
ISO 13256-1:1998 does not indicate which speed setting should be
used to achieve specified airflow for a fan with more than one speed
setting. Also, in some cases, the airflow rate and pressure conditions
specified for a given ducted heat pump without an internal fan may not
be achievable simultaneously. ISO 13256-1:1998 does not provide an
approach for simultaneously achieving the specified airflow rate and
pressure conditions in cases where the airflow may not be achievable
below the maximum internal pressure drop. In the June 2018 RFI, DOE
requested comment on whether indoor fans typically have multiple speed
settings for WSHPs, and if so, how manufacturers choose the speed to
use during testing. DOE also requested comment on how specified airflow
is achieved if none of the speed settings produce that airflow at the
specified internal or external static pressure. 83 FR 29048, 29051
(June 22, 2018).
AHRI and WaterFurnace commented that most WSHP fans have at least
three speeds. (AHRI, No. 12 at p. 7; WaterFurnace, No. 7 at p. 7) Trane
commented that their company offers single-speed and multi-speed units.
(Trane, No. 8 at p. 4) AHRI, Trane, and WaterFurnace stated that as
part of AHRI's certification program, the test facility utilizes the
blower speed specified by the manufacturer in literature and submission
data. (AHRI, No. 12 at p. 7; Trane, No. 8 at p. 4; WaterFurnace, No. 7
at p. 7) AHRI and WaterFurnace further stated that manufacturers select
an airflow that is advantageous for the specifications they are trying
to achieve; for example, low airflows are beneficial for humidity
removal. Id. The commenters also indicated that the AHRI WSHP/
Geothermal Operations Manual specifies steps to be taken if the
manufacturer's specified airflow is not met with the initial fan
settings, which include reducing ESP to a minimum value set forth in
the AHRI WSHP/Geothermal Operations Manual. Id.
AHRI acknowledged that in some cases, the airflow rate and pressure
conditions specified by ISO 13256-1:1998 for a given ducted heat pump
without an internal fan may not be achievable simultaneously. As an
example, AHRI described a scenario in which the manufacturer-specified
airflow may not be achievable below the maximum internal pressure drop
specified in section 4.1.5.3 of ISO 13256-1:1998. AHRI stated that ISO
13256-1:1998 does not provide an approach for simultaneously achieving
the specified airflow rate and pressure conditions in such a case.
(AHRI, No. 12 at p. 7) In such cases, AHRI and WaterFurnace stated that
provisions in Appendix B of the AHRI WSHP/Geothermal Operations Manual
are used that permit a tolerance for achieving the specified airflow
within 10 percent of the manufacturers specified flow rate. (AHRI, No.
12 at p. 7; WaterFurnace, No. 7 at p. 6)
On this topic, DOE notes that the provisions of ISO 13256-1:2021
are equivalent to those in ISO 13256-1:1998 for setting airflow of non-
ducted units and ducted units without internal fans. For ducted units
with internal fans, ISO 13256-1:2021 provides additional specifications
beyond those in ISO 13256-1:1998. Table 1 of ISO 13256-1:2021 provides
minimum ESP values and explains that airflow should be set

[[Page 53323]]

as specified by the manufacturer with an ESP greater than or equal to
the minimum ESP value set forth in ISO 13256-1:2021. For units with
non-constant airflow fans and adjustable speed, ISO 13256-1:2021 states
that the speed may be adjusted as needed to the lowest speed that
provides at least the minimum ESP at the specified airflow rate. In
cases where the airflow rate cannot be maintained within tolerance with
an ESP greater than or equal to the minimum ESP, the test must be run
at the airflow achieved with an ESP equal to the minimum ESP.
As noted in section III.F.1.a of this document, DOE is proposing to
adopt the minimum ESP requirements in Table 7 of AHRI 340/360-2022 and
condition tolerances in Table 6 of AHRI 340/360-2022. For the reasons
that follow, DOE has tentatively concluded that AHRI 340/360-2022 is
superior to available alternatives in terms of these objectives. To
start, DOE has tentatively determined that more specification than
provided in ISO 13256-1:1998 is needed to ensure consistent and
repeatable setting of airflow and ESP for testing, thereby ensuring the
representativeness of the results. For example, ISO 13256-1:1998 does
not specify what to do in certain circumstances when instructions
provided are unclear or conflict (e.g., if no fan control setting is
certified and multiple combinations of ESP and fan speed can provide
the manufacturer-specified airflow). Although ISO 13256-1:2021 provides
more specification than ISO 13256-1:1998 for setting airflow in ducted
units with an internal fan, it still does not address situations in
which instructions are missing, are unclear, or conflict. In addition,
neither version of the ISO test procedure specifies an upper tolerance
on ESP for ducted units. As such, further detail than what is provided
in ISO 13256-1:1998 and ISO 13256-1:2021 is warranted. Furthermore, the
AHRI WSHP/Geothermal Operations Manual includes some provisions on fan
settings, but these provisions are likewise insufficient for setting
airflow and ESP with minimum ESPs and condition tolerances, as that
manual relies on communication and agreement between the manufacturer
and AHRI in situations in which both ESP and airflow tolerances cannot
be met. Such approach is inappropriate in a regulatory context.
Therefore, as stated previously in this NOPR, DOE is proposing to
incorporate by reference AHRI 340/360-2022, including adoption of
sections 6.1.3.3 through 6.1.3.5, which specify a 3 percent condition
tolerance for airflow rate, a -0.00/+0.05 in H<INF>2</INF>O condition
tolerance for ESP, and instructions on setting airflow and ESP during
testing. These sections additionally provide guidance on what to do
during testing if one or both of the conditions cannot be met. DOE
preliminarily finds that these provisions would improve test
repeatability, provide test conditions that are more representative of
field operation, and appropriately address the issue where none of the
speed settings produce the specified airflow at the specified internal
or external static pressure.
DOE notes, however, that the relevant provisions in AHRI 340/360-
2022 were generally developed for ducted units with continuously
variable-speed fans. Accordingly, additional provisions specific to
testing ducted units with discrete-step fans and non-ducted units are
necessary. The following sub-sections discuss the proposed additional
provisions for such WSHPs.
Issue 11: DOE requests comment on the proposed adoption of
provisions from AHRI 340/360-2022 for setting airflow and ESP for WSHP
testing.
(i) Ducted Units With Discrete-Step Fans
Many ducted WSHPs have fans with discrete steps in speed. In
situations where both airflow and ESP tolerances cannot be met, the
instructions in section 6.1.3.5 of AHRI 340/360-2022 can result in
ducted units with discrete-step fans operating with ESPs that are
higher than the tolerance on the ESP requirements due to the difference
in fan speed between each step.
Section 6.1.3.5 of AHRI 340/360-2022 specifies that the measured
airflow during test must be within 3 percent of the rated airflow and
that the ESP during test must be within -0.00/+0.05 in H<INF>2</INF>O
of the minimum ESP specified in Table 6. Section 6.1.3.5.2.4 specifies
that for two adjacent fan control settings, if the lower setting is too
low (such that ESP or airflow are lower than the tolerance range) and
the higher setting is too high (such that ESP or airflow are higher
than the tolerance range), then the higher fan control setting should
be used. At this higher fan control setting, section 6.1.3.5.2.4
specifies to maintain airflow within tolerance, which would result in
an ESP higher than the +0.05 in H<INF>2</INF>O tolerance. However,
WSHPs with discrete-step fans may have a limited number of fan control
settings, such that testing at the higher fan speed in this case may
result in testing with an ESP that significantly exceeds the minimum
ESP requirement. For such units, in a case in which operating at the
lower fan control setting with the ESP in tolerance results in an
airflow slightly lower than 97 percent of the rated airflow, it would
be more representative to test at the lower fan control setting with
the airflow slightly below the 97 percent tolerance, rather than test
at the higher fan control setting with an ESP potentially significantly
exceeding the minimum ESP requirement. In such a case, the industry
test procedures for SPVUs (AHRI 390-2021; section 5.7.3.4.1.4) and CAC/
HPs (AHRI 210/240-2023; section 6.1.5.1.6) allow airflow to drop to 90
percent of the rated airflow while maintaining ESP within tolerance.
DOE has tentatively concluded that adopting this approach for WSHPs
would result in testing at conditions more representative of field
applications.
Therefore, for ducted units with discrete-step fans, DOE is
proposing in section 3.2 of proposed appendix C1 instructions for
setting the fan speed in the scenario in which: (1) tolerances for
airflow and ESP cannot 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. These
proposed instructions specify to exclude sections 6.1.3.5.2.4 and
6.1.3.5.3.2.3 of AHRI 340/360-2022, and to allow airflow to drop to 90
percent of the specified airflow rate while maintaining ESP within
tolerance. If ESP cannot be maintained within tolerance at 90 percent
of the specified airflow rate, the proposed instructions specify to use
the next highest fan speed and allow ESP to exceed the tolerance while
maintaining airflow within tolerance.
Issue 12: DOE requests comment on its proposed instructions for
setting airflow and ESP for ducted WSHP units with discrete-step fans.
(ii) Non-Ducted Units
DOE is aware that some WSHPs may be installed without indoor air
distribution ducts in the field. Depending on the type of installation,
the test method specified in ISO 13256-1:1998 differs; section 4.1.2 of
ISO 13256-1:1998 specifies provisions for WSHPs installed without
ducts, and section 4.1.3 of the standard specifies provisions for WSHPs
installed with ducts. ISO 13256-1:1998 does not specify how to
distinguish whether a unit is ducted or non-ducted. The provisions of
ISO 13256-1:2021 are the same as those of ISO 13256-1:1998 in this
regard.
In the June 2018 RFI, DOE requested comment on the physical
characteristics that distinguish ducted and non-ducted WSHPs. DOE also
requested comment

[[Page 53324]]

on whether any WSHP models can be installed either with or without
indoor distribution ducts, and if such models exist, DOE requested
comment on whether manufacturers test these models to the non-ducted
provisions in section 4.1.2 of ISO 13256-1:1998 or the ducted
provisions in section 4.1.3 of ISO 13256-1:1998, or whether these
models are tested using both provisions of section 4.1.2 and 4.1.3. 83
FR 29048, 29050-29051 (June 22, 2018).
In response to DOE's request for information, AHRI and WaterFurnace
commented that WSHPs may be designed for use either with or without
indoor air distribution ducts, and that while the specified test set-
ups are different, the non-ducted test simulates the conditions of the
ducted test using a hood with zero static to accumulate the supply air
for volumetric and enthalpy measurements. (AHRI, No. 12 at pp. 6-7;
WaterFurnace, No. 7 at pp. 5-6)
AHRI and WaterFurnace also commented that the majority of WSHPs are
designed for use with ductwork but that there are some console units
designed to ``free blow'' into the space with no ductwork at zero ESP.
(AHRI, No. 12 at pp. 6-7; WaterFurnace, No. 7 at pp. 5-6) AHRI added
that such non-ducted WSHPs typically include a tangential blower
(similar to packaged terminal air conditioners) meant for low-static
operation and free discharge into the conditioned space. (AHRI, No. 12
at pp. 6-7) Trane commented that motor horsepower and fan size are
designed to deliver zero ESP for non-ducted units and that units that
are required to be ducted will require a different motor horsepower and
fan size. (Trane, No. 8 at p. 4)
Additionally, AHRI and Trane pointed out that WSHPs are certified
to AHRI as either ``ducted'' or ``non-ducted'' and that the equipment
is tested to the appropriate section of ISO 13256-1:1998. AHRI and
WaterFurnace commented that there are no known WSHP models designed for
both ducted and non-ducted application. (AHRI, No. 12 at pp. 6-7;
WaterFurnace, No. 7 at pp. 5-6) In contrast, Trane stated that although
it does not offer any equipment that can be installed as either ducted
or non-ducted, there is a selection of WSHP equipment that is designed
for both ducted and non-ducted applications. (Trane, No. 8 at pp. 3-4)
Consistent with AHRI's, WaterFurnace's, and Trane's comments, DOE
has identified some WSHPs, marketed as ``console units,'' which would
operate without a duct. As noted previously, AHRI 340/360-2022 does not
have any instructions for setting up airflow and ESP for non-ducted
units. (AHRI 340/360-2022 is the industry test procedure for testing
CUACs and there are no non-ducted CUACs.) Section 4.1.5 of ISO 13256-
1:1998 and section 5.1.5 of ISO 13256-1:2021 include provisions for
setting airflow for non-ducted units at zero ESP, but the provisions in
ISO 13256-1:1998 and ISO 13256-1:2021 do not specify the settings to
use or how to address situations in which test procedure instructions
are missing or conflict (also see discussion in section III.F.1.b of
this NOPR). Therefore, DOE has tentatively concluded that specific
provisions for non-ducted WSHPs are warranted.
To address testing of non-ducted WSHPs, DOE proposes separate
provisions for setting airflow and ESP for non-ducted units in section
3.1 of proposed appendix C1. Consistent with ISO 13256-1:1998 and ISO
13256-1:2021, DOE proposes that non-ducted units be tested at zero ESP,
because non-ducted units would not be installed with ductwork in the
field. DOE proposes that these provisions would apply to all units that
are not configured exclusively for delivery of conditioned air to the
indoor space without a duct(s). Units that are configured for delivery
of conditioned air to the indoor space without a duct(s) would be
required to use the provisions for setting airflow and ESP in section
6.1.3 of AHRI 340/360-2022 and section 3.2 of proposed appendix C1, as
applicable.
DOE is proposing in section 3.1 of proposed appendix C1 that WSHP
units that are not configured exclusively for delivery of conditioned
air to the indoor space without a duct(s) would be tested with a target
ESP of 0.00 in H<INF>2</INF>O (consistent with ISO 13256-1:1998 and ISO
13256-1:2021) within a tolerance of -0.00/+0.05 in H<INF>2</INF>O in
place of the ESP specified in Table 7 of AHRI 340/360-2022 (because the
ESP requirements in AHRI 340/360-2022 are intended to reflect the
pressure drop in ductwork for ducted units). The proposed ESP tolerance
for non-ducted units aligns with the tolerance for ducted units in AHRI
340/360-2022. Instead of the instructions for setting airflow and ESP
in section 6.1.3.5 of AHRI 340/360-2022, DOE proposes that if both the
ESP and airflow cannot be simultaneously maintained within tolerance
for any test, to maintain the ESP within the required tolerance and use
an airflow as close to the target value as possible (i.e., prioritize
maintaining ESP in tolerance over maintaining airflow in tolerance).
This is because testing an ESP of more than 0.05 in H<INF>2</INF>O
would not be representative for a non-ducted unit which would not be
installed with ductwork in the field. Finally, DOE proposes that if an
airflow out of tolerance is used for the full-load cooling test, then
the measured full-load cooling airflow is to be used as the target
airflow for all subsequent tests that call for the full-load cooling
airflow within a tolerance of +/-3 percent. These provisions are
similar to those included for testing non-ducted units in other
industry test standards for comparable categories of commercial air
conditioners and heat pumps, such as AHRI 390-2021 for testing SPVUs.
DOE has tentatively determined that these provisions would provide
a representative and repeatable test procedure for non-ducted WSHPs,
and that they would be appropriate for testing WSHPs because they are
the generally accepted industry method used for testing similar
equipment such as SPVUs. This proposed approach remedies some of the
shortcomings identified with the current WSHP test procedure which
incorporates by reference ISO 13256-1:1998.
Issue 13: DOE requests comment on its proposal for setting airflow
and ESP for non-ducted WSHP units.
2. Capacity Measurement
a. Primary and Secondary Methods
The current DOE 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. 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.
In the June 2018 RFI, DOE discussed how ANSI/ASHRAE 37-2009 is
similar to the test method in ISO 13256-1:1998, and that DOE was
considering whether testing to ANSI/ASHRAE 37-2009 would be appropriate
for WSHPs. DOE further discussed how 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

[[Page 53325]]

rather than to be averaged with the primary measurement (see section
10.1 and Table 1 of ANSI/ASHRAE 37-2009). 83 FR 29048, 29052 (June 22,
2018).
In the June 2018 RFI, DOE requested information on whether one of
the two capacity measurements prescribed in ISO 13256-1:1998 gives a
consistently higher or lower result than the other, or whether one of
the methods can be considered more accurate for a range of different
WSHP configurations and models. Id. Additionally, DOE requested comment
on whether the ANSI/ASHRAE 37-2009 approach for determination of rated
capacity (i.e., using the primary method's measurement as the rated
capacity rather than averaging the two capacity measurements) would
result in more representative ratings than the ISO 13256-1:1998
approach. Id.
Trane commented that the capacity value measured by the liquid
enthalpy method is generally higher than the value measured by the
indoor air enthalpy method, stating that air-side measurements have
more opportunity for losses than water-side measurements. (Trane, No. 8
at p. 5) AHRI and WaterFurnace commented that the water side test is
generally simpler to conduct and also more accurate than the air
enthalpy method, because the uncertainties of measurement are much
lower in the water-side calculations. (AHRI, No. 12 at p. 13;
WaterFurnace, No. 7 at p. 11)
AHRI, Trane, and WaterFurnace recommended continuing to use the
average of the air-side and water-side measurements as the basis for
capacity ratings. (AHRI, No. 12 at p. 13; Trane, No. 8 at p. 5;
WaterFurnace, No. 7 at p. 11) AHRI and WaterFurnace stated that the
current approach in ISO 13256-1:1998 represents a compromise that helps
ensure best testing procedures. (AHRI, No. 12 at p. 13; WaterFurnace,
No. 7 at p. 11) AHRI argued that the ANSI/ASHRAE 37-2009 approach does
not yield more representative ratings compared to the ISO 13256-1:1998
method. (AHRI, No. 12 at p. 13) Trane further asserted that the average
of the methods is more accurate than the measurement from either single
method alone. (Trane, No. 8 at p. 5) AHRI and WaterFurnace also stated
that ANSI/ASHRAE 37-2009 does not include the liquid enthalpy method of
test required on the source side for all WSHPs. (AHRI, No. 12 at p. 13;
WaterFurnace, No. 7 at p. 10)
In response, DOE notes first that the capacity measurement
provisions in section 7.1 of ISO 13256-1:2021 differ from those in
section 6.1 of ISO 13256-1:1998 in several ways. Instead of averaging
the two capacity measurements, section 7.1 of ISO 13256-1:2021
specifies that the capacity rating is equal to the value determined
from the air side (referred to as the load side in ISO 13256-1:2021),
consistent with the approach used in section 10.1.2 of ANSI/ASHRAE 37-
2009. ISO 13256-1:2021 also does not allow use of the calorimeter
method in place of the indoor air enthalpy method for measuring
capacity on the load side, but section 7.1 of ISO 13256-1:2021 allows
use of the refrigerant enthalpy method for configurations that cannot
use the indoor air enthalpy method. Section 7.1 of ISO 13256-1:2021
continues to require the liquid enthalpy method for measuring capacity
on the liquid side (referred to as the source side in ISO 13256-
1:2021). Section 7.1 of ISO 13256-1:2021 also continues to require the
two capacity measurements to agree within 5 percent for the test to be
valid.
As discussed in section III.D.2 of this NOPR, DOE proposes 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. 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.
Regarding commenters' claims that ANSI/ASHRAE 37-2009 does not
include the liquid enthalpy method of test required on the source side
for all WSHPs, as discussed, ANSI/ASHRAE 37-2009 does include a liquid
enthalpy method of test. The liquid enthalpy method is referred to as
the outdoor liquid coil method in section 7 of ANSI/ASHRAE 37-2009, and
it provides a measurement of liquid enthalpy that is similar to the
measurement provided by the liquid enthalpy method in normative
appendix C of ISO 13256-1:1998. As discussed, Table 1 of ANSI/ASHRAE
37-2009 specifies three secondary capacity measurement methods (i.e.,
outdoor liquid coil, refrigerant enthalpy, and compressor calibration
methods) that may be used to conduct the secondary measurements that
are required for testing WSHPs with cooling capacity less than 135,000
Btu/h, rather than requiring the outdoor liquid coil for all water-
source units (as is the case in section 6.1 of ISO 13256-1:1998). Table
1 of ANSI/ASHRAE 37-2009 also specifies the applicability of each
secondary capacity method based on the configuration of the unit being
tested. This specification of applicable secondary capacity measurement
methods in ANSI/ASHRAE 37-2009 ensures that the chosen secondary
capacity measurement is accurate because the outdoor liquid coil method
in ANSI/ASHRAE 37-2009 is not applicable for certain unit
configurations in which the compressor heat would not be sufficiently
accounted for. Specifically, section 7.6.1.2 and note g to Table 1 of
ANSI/ASHRAE 37-2009 specify that the outdoor liquid coil method may not
be used if the system has a compressor that is ventilated by outdoor
air or a remote outdoor compressor that is not insulated per section
7.6.1.2 of ANSI/ASHRAE 37-2009. Section III.F.2.b of this NOPR includes
further discussion on this topic.
As part of DOE's proposal generally to adopt the test provisions in
section E6 of AHRI 340/360-2022, DOE is proposing to adopt the
provisions for measuring capacity in AHRI 340/360-2022 instead of those
in section 6.1 of ISO 13256-1:1998. Using the indoor air enthalpy
measurement as the measurement of capacity ensures that actual output
of the WSHP--the cooling or heating of air--is used as the measure of
capacity. The approach used in section 6.1 of ISO 13256-1:1998, in
which the indoor air enthalpy measurement is averaged with the liquid
enthalpy measurement, has the potential to result in capacity values
that are higher than the actual delivered capacity because of heat
transfer to/from the ambient air (either through heat transfer through
the WSHP cabinet walls or air leakage). This potential is consistent
with Trane's comment that the capacity value measured by the liquid
enthalpy method is generally higher than the value measured by the
indoor air enthalpy method. In addition,

[[Page 53326]]

the approach used in section E6 of AHRI 340/360-2022 is consistent with
the approach in section 7.1 of ISO 13256-1:2021, in that the indoor air
enthalpy measurement is used as the capacity measurement in ISO 13256-
1:2021. It is also consistent with the industry test procedures for
other categories of air conditioning and heating equipment (e.g., AHRI
Standard 1230, AHRI Standard 390, and AHRI Standard 210/240).
Therefore, DOE has tentatively concluded that it is more representative
for the capacity rating of WSHPs to be determined with the indoor air
enthalpy method, and for the secondary measurement to serve only as a
verification of the indoor enthalpy measurement, rather than being
averaged with the indoor air enthalpy method result to determine the
capacity rating.
The proposed provisions do not permit use of the calorimeter method
or refrigerant enthalpy method in place of the indoor enthalpy method,
which is allowed in section 6.1 of ISO 13256-1:1998 and section 7.1 of
ISO 13256-1:2021. However, DOE has tentatively concluded that
alternatives to the indoor air enthalpy method are not necessary
because DOE is not aware of any WSHPs that are unable to use the indoor
enthalpy method as specified in ANSI/ASHRAE 37-2009 (with additional
provisions in AHRI 340/360-2022).
The proposed provisions also allow a difference in capacity
measurements of up to 6 percent in section E6.4.2 of AHRI 340/360-2022
instead of the 5 percent allowed in section 6.1 of ISO 13256-1:1998.
DOE has tentatively concluded that this reduces burden while still
ensuring accurate measurements of indoor air enthalpy. Once again, this
proposal is consistent with the industry test procedures for other
categories of air conditioning and heating equipment (e.g., AHRI
Standard 1230, AHRI Standard 390, and AHRI Standard 210/240).
Issue 14: DOE requests comment on its proposed approach to adopt
the provisions in AHRI 340/360-2022 and ANSI/ASHRAE 37-2009 regarding
primary and secondary capacity measurements.
b. Compressor Heat
DOE has identified split-system WSHPs available on the market. For
at least one of these split systems WSHPs, the unit containing the
compressor is intended for either indoor or outdoor installation. The
installed location of the compressor, in relation to the conditioned
space and other system components, impacts the capacity of a WSHP
system and the provisions necessary for accurately measuring system
capacity due to the generation of heat during compressor operation.
As discussed in section III.F.2.a of this NOPR, the current DOE
test procedure, through adoption of ISO 13256-1:1998, requires use of
two methods to measure space-conditioning capacity provided by a WSHP.
One of these methods, the indoor air enthalpy method (see normative
annex B of ISO 13256-1:1998), measures capacity directly by measuring
mass flow and enthalpy change of the indoor air.\21\ The second method,
the liquid enthalpy test method (see normative annex C of ISO 13256-
1:1998), measures heat transferred at the liquid coil. The liquid
enthalpy measurement is adjusted by adding or subtracting the total
unit input power (including the compressor input power) from the
measured liquid side capacity in the heating or cooling mode tests,
respectively, using the equations in sections C3.1 and C3.2 of ISO
13256-1:1998.
---------------------------------------------------------------------------

\21\ The alternative calorimeter room test method (see normative
annex E of ISO 13256-1:1998), allowed to be used instead of the
indoor air enthalpy method for non-ducted WSHPs, also measures
indoor space-conditioning capacity directly.
---------------------------------------------------------------------------

The liquid enthalpy adjustment in sections C3.1 and C3.2 of ISO
13256-1:1998 assumes that all compressor heat is absorbed and
ultimately transferred to the conditioned space, thereby increasing
heating capacity or decreasing cooling capacity. However, this fails to
account for any heat transferred from the compressor or other
components to their surroundings that does not contribute to space
conditioning. For example, in the case of a split-system WSHP with an
uninsulated compressor/liquid coil section installed outdoors, the air
that absorbs compressor heat would not directly affect the conditioned
space. In this case, adding or subtracting the entire compressor input
power to or from the capacity calculated based on liquid temperature
change likely overestimates the impact of compressor power input on the
indoor-side capacity that is calculated using the liquid enthalpy-based
method.
In the June 2018 RFI, DOE requested comment on whether there are
split-system WSHP models on the market for which the unit containing
the compressor is intended only for outdoor installation or only for
indoor installation. DOE further requested comment on manufacturers'
practices for testing split-system WSHPs for which the compressor is
not housed in the section containing the indoor refrigerant-to-air
coil, including which test rooms are used for the compressor section,
and whether any adjustments are made to properly account for the
compressor heat. 83 FR 29048, 29053 (June 22, 2018).
In response to DOE's requests for comment, AHRI, Trane, and
WaterFurnace commented that accounting for compressor heat would not be
a relevant issue because there are very few, if any, split-system WSHPs
in the commercial market. (AHRI, No. 12 at p. 13; Trane, No. 8 at p. 5;
WaterFurnace, No. 7 at pp. 11-12) The CA IOUs commented that, based on
the AHRI directory, 90 percent of WSHPs are single-package units. (CA
IOUs, No. 9 at p. 2)
As stated previously, DOE has identified a number of split-system
WSHPs, several of which are certified in the DOE Compliance
Certification Database, and the Federal test procedure \22\ applies to
any WSHP that meets DOE's definition of a WSHP. Further, because split-
system WSHPs are available on the market, test procedure provisions are
needed for testing them, regardless of their share of the WSHP market.
---------------------------------------------------------------------------

\22\ Currently, the DOE test procedure applies to all WSHPs with
a capacity less than 135,000 Btu/h. However, DOE is proposing in
section III.A of this NOPR to increase the scope of the Federal test
procedure to include all WSHPs with a capacity less than 760,000
Btu/h.
---------------------------------------------------------------------------

Sections D.4 and D.5 of ISO 13256-1:2021 use the same adjustment of
the liquid enthalpy method as sections C3.1 and C3.2 of ISO 13256-
1:1998. Thus, ISO 13256-1:2021 provides no additional methods to
address compressor heat for split systems with the compressor in the
liquid coil section.
As discussed in section III.D.2 of this NOPR, DOE proposes to adopt
specific sections of AHRI 340/360-2022 in its test procedure for WSHPs.
AHRI 340/360-2022 in turn references the test method in ANSI/ASHRAE 37-
2009. Sections 6.1.3 and 6.1.5 of ANSI/ASHRAE 37-2009 contain
provisions for addressing compressor heat in the indoor air enthalpy
method that are similar to the provisions in sections F7.3 and F7.5 of
ISO 13256-1:1998. For secondary capacity measurements, however, ANSI/
ASHRAE 37-2009 has provisions that go beyond the provisions in ISO
13256-1:1998 to ensure that capacity is measured more accurately than
it is by ISO 13256-1:1998, as discussed in the following paragraphs.
Section 7.6 of ANSI/ASHRAE 37-2009 includes a liquid enthalpy
measurement method (referred to as the

[[Page 53327]]

``outdoor liquid coil method'' and applicable to both single-package
units and split systems) that is similar to the method in normative
annex C of ISO 13256-1:1998 in that it adjusts the liquid enthalpy
measurement by the total input power of the WSHP. For split-system
WSHPs, ANSI/ASHRAE 37-2009 includes the outdoor liquid coil method, the
refrigerant enthalpy method, and the compressor calibration method as
options for conducting the secondary measurements that are required for
testing WSHPs with cooling capacity less than 135,000 Btu/h. However,
ANSI/ASHRAE 37-2009 limits use of the outdoor liquid coil method so
that it does not apply for certain unit configurations in which the
compressor heat would not be sufficiently accounted for. Specifically,
Section 7.6.1.2 and note g to Table 1 of ANSI/ASHRAE 37-2009 specify
that the outdoor liquid coil method may not be used if the system has a
compressor that is ventilated by outdoor air or a remote outdoor
compressor that is not insulated per section 7.6.1.2 of ANSI/ASHRAE 37-
2009. These limits on the applicability of the outdoor liquid coil
method in ANSI/ASHRAE 37-2009 minimize discrepancy between measurements
from the indoor air enthalpy method and liquid coil method by ensuring
that either: (1) compressor heat is captured in indoor air enthalpy
measurements, or (2) compressor heat loss to outdoor air is minimal
because the compressor is sufficiently insulated.
For split-system WSHPs for which the outdoor liquid coil method in
ANSI/ASHRAE 37-2009 cannot be used (i.e., the system has a compressor
that is ventilated by outdoor air or a remote outdoor compressor that
is not insulated per section 7.6.1.2 of ANSI/ASHRAE 37-2009), ANSI/
ASHRAE 37-2009 requires the use of either the refrigerant enthalpy
method specified in section 7.5 of ANSI/ASHRAE 37-2009 or the
compressor calibration method specified in section 7.4 of ANSI/ASHRAE
37-2009. For both of these methods, measured capacity is adjusted by
only the input power of the indoor section of the WSHP, and not the
total input power. Therefore, for both methods, the compressor heat
lost to outdoor air from a remote outdoor compressor or compressor
ventilated by outdoor air would appropriately be excluded from capacity
measurements, similar to the indoor air enthalpy method. Therefore, for
WSHPs with those configurations, the refrigerant enthalpy method and
compressor calibration method specified in sections 7.5 and 7.4
(respectively) of ANSI/ASHRAE 37-2009 would provide a more
representative result as compared to the approach used in normative
annex C of ISO 13256-1:1998 (i.e., liquid enthalpy method).
Based on the discussion in the prior paragraphs, DOE tentatively
concludes that the proposed test procedure would provide an accurate
secondary measure of capacity for all equipment configurations and
would provide a more representative secondary measure of capacity than
ISO 13256-1:1998 or ISO 13256-1:2021 for split systems with the
compressor mounted in the outdoor section.
3. Cyclic Degradation
As discussed in section III.D.2 of this NOPR, DOE proposes to adopt
specific sections of AHRI 340/360-2022 in its test procedure for WSHPs,
including section 6.2.3.2 of that industry standard. 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. 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.
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. This means that equation 4
of AHRI 340/360-2022 assumes that the indoor fan continues to operate
when the compressor cycles off. DOE understands that the draft of AHRI
600 has an equation similar to equation 4 of AHRI 340/360-2022, but the
equation in draft of AHRI 600 assumes that the indoor fan stops
operating whenever the compressor cycles off.
As discussed previously in section III.E.4 of this NOPR,
stakeholders provided comment regarding the operation of a WSHP,
including operation of the fan, in modes other than mechanical heating
and cooling. (AHRI, No. 12 at pp. 4-5, 9; WaterFurnace, No. 7 at pp. 3,
9; Trane, No. 8 at pp. 2, 5) These comments on fan operation
specifically referred to operation when there is no heating or cooling,
but they might also be applicable to the issue of fan operation during
compressor cycling under part-load conditions. Certain comments
indicated that it is common for WSHP fans to operate continuously to
provide air circulation or ventilation air. (AHRI, No. 12 at pp. 4-5;
WaterFurnace, No. 7 at p. 3) Continuous operation of WSHP fans
indicates that the fan would continue to run when the compressor cycles
off.
In addition, the cyclic degradation approach used in equation 4 of
AHRI 340/360-2022 is used in the IEER metric for multiple other
categories of commercial HVAC equipment, indicating that it is common
for the indoor fan to continue operating while the compressor cycles
off. AHRI 340/360-2022 is used for testing CUAC/HPs, and equation 4 of
AHRI 340/360-2022 is equivalent to equation 10 of AHRI 1230-2021 (which
is used for testing VRF multi-split systems) and equation 3 of AHRI
390-2021 (which is used for testing SPVUs). These other equipment
categories typically operate in similar environments to WSHPs (i.e.,
commercial buildings with ventilation air requirements). Similar to
these other equipment categories, DOE acknowledges that not all WSHPs
are installed in the same manner, and the Department understands that
fans operate continuously for many, but not all, installed WSHPs.
However, comments received suggest that continuous operation of fans is
representative of operation of many WSHPs, and adopting a cyclic
degradation approach that assumes continuous fan operation is
consistent with the IEER approach used for other equipment categories
that use the IEER metric.
For the foregoing reasons, DOE has tentatively concluded that the
cyclic degradation approach in equation 4 of AHRI 340/360-2022 is
representative of WSHP operation. Therefore, DOE is proposing to adopt
the approach in AHRI 340/360-2022 in proposed appendix C1. DOE is also
proposing in section 5.1.2.5.4 of proposed appendix C1 that the same
approach for cyclic degradation be used when determining IEER through
interpo

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