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Rule2022-22257

Energy Conservation Program: Test Procedure for Central Air Conditioners and Heat Pumps

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Published

October 25, 2022

Effective

November 25, 2022

Issuing agencies

Energy Department

Abstract

The U.S. Department of Energy ("DOE") is amending the test procedures for central air conditioners and heat pumps that will be required for certification of compliance with applicable energy conservation standards starting January 1, 2023, to address a limited number of specific issues, and making minor corrections to the current test procedures that are required for certification of compliance with applicable energy conservation standards prior to January 1, 2023. This rulemaking does not satisfy the 7-year lookback requirement prescribed by the Energy Policy and Conservation Act ("EPCA").

Full Text

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[Federal Register Volume 87, Number 205 (Tuesday, October 25, 2022)]
[Rules and Regulations]
[Pages 64550-64607]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-22257]

[[Page 64549]]

Vol. 87

Tuesday,

No. 205

October 25, 2022

Part II

Department of Energy

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10 CFR Parts 429 and 430

Energy Conservation Program: Test Procedure for Central Air
Conditioners and Heat Pumps; Final Rule

Federal Register / Vol. 87 , No. 205 / Tuesday, October 25, 2022 /
Rules and Regulations

[[Page 64550]]

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DEPARTMENT OF ENERGY

10 CFR Parts 429 and 430

[EERE-2021-BT-TP-0030]
RIN 1904-AF29

Energy Conservation Program: Test Procedure for Central Air
Conditioners and Heat Pumps

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

ACTION: Final rule.

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SUMMARY: The U.S. Department of Energy (``DOE'') is amending the test
procedures for central air conditioners and heat pumps that will be
required for certification of compliance with applicable energy
conservation standards starting January 1, 2023, to address a limited
number of specific issues, and making minor corrections to the current
test procedures that are required for certification of compliance with
applicable energy conservation standards prior to January 1, 2023. This
rulemaking does not satisfy the 7-year lookback requirement prescribed
by the Energy Policy and Conservation Act (``EPCA'').

DATES: The effective date of this rule is November 25, 2022. The final
rule changes will be mandatory for product testing starting April 24,
2023. The incorporation by reference of a certain publication listed in
the rule was approved by the Director of the Federal Register on
February 6, 2017.

ADDRESSES: The docket, which includes Federal Register notices, public
meeting attendee lists and transcripts, comments, and other supporting
documents/materials, is available for review at <a href="http://www.regulations.gov">www.regulations.gov</a>.
All documents in the docket are listed in the <a href="http://www.regulations.gov">www.regulations.gov</a>
index. However, not all documents listed in the index may be publicly
available, such as those containing information that is exempt from
public disclosure.
A link to the docket web page can be found at <a href="http://www.regulations.gov/docket/EERE-2021-BT-TP-0030">www.regulations.gov/docket/EERE-2021-BT-TP-0030</a> The docket web page contains instructions
on how to access all documents, including public comments, in the
docket.
For further information on how to review the docket contact the
Appliance and Equipment Standards Program staff at (202) 287-1445 or by
email: <a href="/cdn-cgi/l/email-protection#59182929353038373a3c0a2d38373d382b3d2a082c3c2a2d3036372a193c3c773d363c773e362f">[email&#160;protected]</a>.

FOR FURTHER INFORMATION CONTACT:
Mr. Lucas Adin, 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) 287-5904. Email: <a href="/cdn-cgi/l/email-protection#064776766a6f6768656355726768626774627557736375726f6968754663632862696328616970">[email&#160;protected]</a>.
Mr. Pete Cochran, U.S. Department of Energy, Office of the General
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121.
Telephone: (202) 586-9496. Email: <a href="/cdn-cgi/l/email-protection#39495c4d5c4b175a565a514b5857795148175d565c175e564f">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION: DOE maintains the following previously
approved incorporation by reference in part 430:
ANSI/ASHRAE Standard 37-2009, Methods of Testing for Rating
Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment,
ANSI approved June 25, 2009;
Copies of ANSI/ASHRAE 37-2009, can be purchased from
<a href="http://www.ashrae.org/resources--publications">www.ashrae.org/resources--publications</a>.
For a further discussion of this standard, see section IV.M of this
document.

Table of Contents

I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Final Rule
III. Discussion
A. Scope of Applicability
B. Requests for Future Test Procedure Revisions
C. Topics Arising From Test Procedure Waivers
1. Fan Power at Reduced Airflows for Coil-Only Systems
2. Variable-Speed Coil-Only Test Procedure
3. Space-constrained Coil-Only CAC Ratings
D. Other Test Procedure Revisions
1. Air Volume Rate Changing With Outdoor Conditions
2. Wet Bulb Temperature for H4 5 [deg]F Heating Tests
3. Hierarchy of Manufacturer Installation Instructions
4. Adjusting Airflow Measurement Apparatus To Achieve Desired
SCFM at Part-Load Conditions
5. Revision of Equations Representing Full-Speed Variable-Speed
Heat Pump Operation at and Above 45 [deg]F Ambient Temperature
6. Calculations for Triple-Capacity Northern Heat Pumps
7. Heating Nominal Air Volume Rate for Variable-Speed Heat Pumps
8. Clarifications for HSPF2 Calculation
9. Distinguishing Central Air Conditioners and Heat Pumps From
Commercial Equipment
10. Additional Test Procedure Revisions
E. Other Revisions Regarding Representations
1. Required Represented Values for Models Certified Compliant
With Regional Standards
F. Test Procedure Costs and Impact
G. Compliance Date and Waivers
H. Requests for Standards Relief
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 Material Incorporated by Reference
N. Congressional Notification
V. Approval of the Office of the Secretary

I. Authority and Background

Central air conditioners (``CACs'') and central air conditioning
heat pumps (``HPs'') (collectively, ``CAC/HPs'') are included in the
list of ``covered products'' for which DOE is authorized to establish
and amend energy conservation standards and test procedures (42 U.S.C.
6292(a)(3)) DOE's energy conservation standards and test procedures for
CAC/HPs are currently prescribed at title 10 of the Code of Federal
Regulations (``CFR''), part 430, Sec. 430.32(c), and 10 CFR part 430,
subpart B, appendices M (``appendix M'') and M1 (``appendix M1''). The
following sections discuss DOE's authority to establish test procedures
for CAC/HPs and relevant background information regarding DOE's
consideration of test procedures for this product.

A. Authority

The Energy Policy and Conservation Act, as amended (``EPCA''),\1\
authorizes DOE to regulate the energy efficiency of a number of
consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317) Title III, Part B \2\ of EPCA established the Energy Conservation
Program for Consumer Products Other Than Automobiles, which sets forth
a variety of provisions designed to improve energy efficiency. These

[[Page 64551]]

products include CAC/HPs,\3\ the subject of this document. (42 U.S.C.
6292(a)(3))
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\1\ 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).
\2\ For editorial reasons, upon codification in the U.S. Code,
Part B was redesignated Part A.
\3\ This rulemaking uses the term ``CAC/HP'' to refer
specifically to central air conditioners (which include heat pumps)
as defined by EPCA. (42 U.S.C. 6291(21))
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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. 6291),
test procedures (42 U.S.C. 6293), labeling provisions (42 U.S.C. 6294),
energy conservation standards (42 U.S.C. 6295), and the authority to
require information and reports from manufacturers (42 U.S.C. 6296).
The Federal testing requirements consist of test procedures that
manufacturers of covered products must use as the basis for: (1)
certifying to DOE that their products comply with the applicable energy
conservation standards adopted pursuant to EPCA (42 U.S.C. 6295(s)),
and (2) making representations about the efficiency of those consumer
products (42 U.S.C. 6293(c)). Similarly, DOE must use these test
procedures to determine whether the products comply with relevant
standards promulgated under EPCA. (42 U.S.C. 6295(s))
Federal energy efficiency requirements for covered products
established under EPCA generally supersede State laws and regulations
concerning energy conservation testing, labeling, and standards. (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. 6297(d))
Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures
DOE must follow when prescribing or amending test procedures for
covered products. EPCA requires that any test procedures prescribed or
amended under this section be reasonably designed to produce test
results which measure energy efficiency, energy use or estimated annual
operating cost of a covered product during a representative average use
cycle or period of use and not be unduly burdensome to conduct. (42
U.S.C. 6293(b)(3))
If the Secretary determines, on her own behalf or in response to a
petition by any interested person, that a test procedure should be
prescribed or amended, the Secretary shall promptly publish in the
Federal Register proposed test procedures and afford interested persons
an opportunity to present oral and written data, views, and arguments
with respect to such procedures. (42 U.S.C. 6293(b)(2)) The comment
period on a proposed rule to amend a test procedure shall be at least
60 days and may not exceed 270 days. Id. In prescribing or amending a
test procedure, the Secretary shall take into account such information
as the Secretary determines relevant to such procedure, including
technological developments relating to energy use or energy efficiency
of the type (or class) of covered products involved. Id.
DOE's regulations at 10 CFR 430.27 provide that any interested
person may seek a waiver from the test procedure requirements if
certain conditions are met. A waiver requires manufacturers to use an
alternate test procedure in situations in which the DOE test procedure
cannot be used to test the product or equipment, or use of the DOE test
procedure would generate unrepresentative results. 10 CFR 430.27(a)(1).
DOE's regulations at 10 CFR 430.27(l) require that as soon as
practicable after the granting of any waiver, DOE will publish in the
Federal Register a notice of proposed rulemaking (``NOPR'') to amend
its regulations so as to eliminate any need for the continuation of
such waiver. As soon thereafter as practicable, DOE will publish in the
Federal Register a final rule. 10 CFR 430.27(l).
DOE is publishing this final rule for the limited purpose of
addressing its obligations under the waiver process regulations at 10
CFR 430.27 and to incorporate additional corrections and improvements.

B. Background

As discussed, DOE's existing test procedures for CAC/HPs appear at
appendices M and M1 (both titled ``Uniform Test Method for Measuring
the Energy Consumption of Central Air Conditioners and Heat Pumps'').
On January 5, 2017, DOE published a final rule regarding the
Federal test procedure (``TP'') for CAC/HPs. 82 FR 1426 (``January 2017
CAC TP Final Rule''). The January 2017 CAC TP Final Rule amended
appendix M and established appendix M1, use of which is required
beginning January 1, 2023, for any representations, including
compliance certifications, made with respect to the energy use or
efficiency of CAC/HPs. Id. Appendix M provides for the measurement of
the cooling and heating performance of CAC/HPs using the seasonal
energy efficiency ratio (``SEER'') metric and heating seasonal
performance factor (``HSPF'') metric, respectively. Appendix M1
specifies a revised SEER metric (i.e., SEER2) and a revised HSPF metric
(``HSPF2'').
Since the publication of the January 2017 CAC TP Final Rule, DOE
has granted various petitions for waiver and interim waiver from
certain provisions of appendix M and/or M1.\4\ Additionally, DOE is
aware of testing conducted per both appendices M (via Compliance,
Certification and Enforcement (``CCE'') testing and other verification
programs) and M1 (via investigative testing to support development of
the 2023 energy efficiency standards). Through these efforts, DOE has
been made aware of several items for which test procedure amendments
are warranted in order to improve clarity or to reduce burden. In each
of these cases, DOE has determined that the amendments would have no or
negligible impact on ratings and thus do not require amendment of the
energy conservation standards per 42 U.S.C. 6293(e). These amendments
are described in section III.D of this final rule. Further, on May 8,
2019, AHRI submitted a comment responding to the notice of proposed
rulemaking to revise and adopt procedures, interpretations, and
policies for consideration of new or revised energy conservation
standards (2020 Process Rule NOPR, 84 FR 3910, Feb. 13, 2019) The
comment included as Exhibit 2 a ``List of Errors Found in both appendix
M and appendix M1'' (``AHRI Exhibit 2,'' EERE-2017-BT-STD-0062-0117 at
pp. 23-24). Many of the errors pointed out by AHRI regard typographical
errors in appendices M and M1. These issues are addressed in various
places of this final rule, including footnotes describing amendments to
correct section references, nomenclature, etc. that did not warrant
standalone discussion sections.
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\4\ Waivers granted to GD Midea Heating and Ventilating
Equipment Co., Ltd. (83 FR 56065), Johnson Controls, Inc. (83 FR
12735 and 84 FR 52489), and TCL Air Conditioner (Zhongshan) Co.,
Ltd. (84 FR 11941), interim waivers granted to National Comfort
Products, Inc. (83 FR 24754), Aerosys Inc. (83 FR 24762), LG
Electronics U.S.A., Inc. (85 FR 40272), and Goodman Manufacturing
Company, L.P. (86 FR 40534).
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On March 24, 2022, DOE published a notice of proposed rulemaking
regarding the Federal test procedure for CAC/HPs. 87 FR 16830 (``March
2022 CAC TP NOPR''). The March 2022 CAC TP NOPR proposed changes to
improve the functionality of appendix M1 to address the issues
identified in test procedure waivers, improve representativeness and
correct typographical issues raised by commenters. Id. DOE held a
public meeting related to the NOPR on April

[[Page 64552]]

18, 2022 (hereafter the ``2022 CAC TP NOPR Public Meeting'').
DOE received comments in response to the March 2022 CAC TP NOPR
from the interested parties listed in Table I-1.

Table I-1--List of Commenters With Written Submissions in Response to the March 2022 CAC TP NOPR
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Reference in this final Comment No. in
Commenter(s) rule the docket Commenter type
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Air-Conditioning, Heating, & AHRI...................... 25 Trade Association.
Refrigeration Institute.
Appliance Standards Awareness Project Joint Advocates........... 18 Efficiency organizations.
(ASAP), American Council for an Energy-
Efficient Economy (ACEEE).
Pacific Gas and Electric Company, San CA IOUs................... 20 Efficiency organization.
Diego Gas and Electric, Southern
California Edison--collectively
California Investor Owned Utilities.
Carrier Global Corporation.............. Carrier................... 15 Manufacturer.
Daikin Comfort Technologies Daikin.................... 24 Manufacturer.
Manufacturing Company, L.P.
Emerson Climate Technologies, Inc....... Emerson................... 14 Manufacturer.
Leaders Building of America............. LBA....................... 3 Trade Association.
Lennox International Inc................ Lennox.................... 19 Manufacturer.
National Comfort Products, Inc.......... NCP....................... 16 Manufacturer.
Northwest Energy Efficiency Alliance.... NEEA...................... 23 Alliance of Efficiency
Organizations.
Nortek Global HVAC (NGH)................ Nortek.................... 13 Manufacturer.
New York State Energy Research and NYSERDA................... 17 Efficiency organization.
Development Authority.
Rheem Sales Company..................... Rheem..................... 21 Manufacturer.
Samsung HVAC............................ Samsung................... 22 Manufacturer.
Trane Technologies...................... Trane..................... 10 Manufacturer.
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A parenthetical reference at the end of a comment quotation or
paraphrase provides the location of the item in the public record.\5\
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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 central air conditioners and heat pumps (Docket
No. EERE-2021-BT-TP-0030, 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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The CA IOUs, Carrier, Daikin, Emerson, Joint Advocates, Lennox,
NEEA, Nortek, NYSERDA, and Rheem commented that they largely supported
DOE's efforts in amending the existing test procedure in appendix M1.
(CA IOUs, No. 20 at p. 3, Carrier, No. 20 at p. 1, Daikin, No. 24 at p.
1, Emerson, No. 14 at p. 1, Joint Advocates, No. 18 at p. 1, Lennox,
No. 19 at p. 1, NEEA, No. 23 at p. 1, Nortek, No. 13 at p. 1, NYSERDA,
No. 17 at p. 1, Rheem, No. 21 at p. 1) Emerson requested that DOE
publish the revised test procedure as soon as reasonably possible, so
that manufacturers will have time to comply with the compliance date of
January 1, 2023. (Emerson, No. 14 at p. 3) Nortek also requested that
DOE publish the final rule soon, so that they can have certainty with
the revised test procedure, in order to serve the CAC/HP market
efficiently. (Nortek, No. 13 at p. 3)

II. Synopsis of the Final Rule

In this final rule, DOE is updating appendix M1 to subpart B of
part 430, ``Uniform Test Method for Measuring the Energy Consumption of
Central Air Conditioners and Heat Pumps.'' DOE has identified certain
provisions of appendix M1 that may benefit from additional detail and/
or instruction. The updates are as follows:
(1) Adjusting the default fan power for two-stage coil-only systems
when testing at low stage with reduced air volume rate to be more
representative of fan input power trends as air volume rate reduces;
(2) Defining ``variable-speed communicating coil-only central air
conditioner or heat pump'' and ``variable-speed non-communicating coil-
only central air conditioner or heat pump'' and establishing procedures
specific for testing such systems;
(3) Allowing the adjustment of the air volume rate as a function of
outdoor air temperature during testing for blower coil systems with
either multiple-speed or variable-speed indoor fans and with a control
system capable of adjusting air volume rate as function of outdoor air
temperature;
(4) Adjusting the maximum wet bulb temperature from 3 [deg]F to 4
[deg]F for the H4 test condition;
(5) Specifying in section 2(B) of appendix M1, that the
instructions presented in the labels attached to the unit take
precedence over the installation manuals printed and shipped with a
product;
(6) Specifying in sections 3.1.4.1.1, 3.1.4.1.2, and 3.1.4.4.3 of
appendix M1 that the airflow measurement apparatus fan must be adjusted
if necessary to maintain the same air volume rate for different test
conditions for systems not including multiple-speed or variable-speed
indoor fans with control system capability to adjust air volume rate as
function of operating conditions such as outdoor air temperature; and
(7) Revising the equations representing full-capacity operation of
variable-speed heat pumps at and above 45 [deg]F ambient temperature to
be consistent with the intent for nominal capacity operation.
Additionally, in this final rule, DOE is updating 10 CFR part 429,
``Certification, Compliance, and Enforcement for Consumer Products and
Commercial and Industrial Equipment.'' DOE has identified certain
provisions of part 429 that may benefit from additional detail and/or
instruction. The proposed updates are as follows:
(1) Clarifying the language for required represented values for
single-stage and two-stage coil-only CACs; and
(2) Providing additional direction regarding the regional standard
requirements in part 429.
The adopted amendments are summarized in Table II-1 compared to the
test procedure provision prior to the amendment, as well as the reason
for the adopted change. Additional proposed incidental changes are
summarized in Table III-4, Table III-5 and Table III-6 in section
III.D.10 of this document.

[[Page 64553]]

Table II-1--Summary of Changes in the Amended Test Procedure
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DOE test procedure prior to amendment Amended test procedure Attribution
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Calculate indoor fan power of two-stage Calculate indoor fan power of two-stage Improve
coil-only CACs and HPs using constant coil-only CACs and HPs for reduced air representativeness.
default fan power values that do not vary volume rate tests using new default fan
with air volume rate (441W/1000 scfm for power values air volume rate (335 W/1000
most two-stage coil-only CACs and HPs and scfm for most two-stage coil-only CACs
406 W/1000 scfm for mobile-home and space- and HPs and 308 W/1000 scfm for mobile-
constrained CACs and HPs). home and space-constrained CACs and HPs).
Use linear interpolation to determine fan
performance at intermediate airflow rates
between 75 percent and 100 percent of
full-load air volume rate.
No test procedure provisions for variable- Test procedures and requirements Incorporate test
speed, coil-only CACs and HPs. established for variable-speed coil-only procedures contained in
systems, include new definitions for test procedure waivers.
``variable-speed communicating coil-only
central air conditioner or heat pump''
and ``variable-speed non-communicating
coil-only central air conditioner or heat
pump,'' for which the newly established
test procedures have more flexibility.
Appendix M1 currently does not explicitly For blower coil systems with multiple- Improve
allow for variation of air volume rate as speed or variable-speed indoor fans and representativeness for
outdoor temperature changes when testing the control system capability to adjust certain models.
blower coil systems. air volume rate as a function of outdoor
air temperature, allow such air volume
rate variation during testing.
Appendix M1 contains provisions for Amend the wet bulb test condition for the Reduce test burden by
conducting an optional H4 heating test at H4 test to be 4 [deg]F maximum instead of reducing the time
a 5 [deg]F outdoor ambient dry-bulb the current condition of 3 [deg]F needed to remove
temperature and, at a maximum, a 3 [deg]F maximum. sufficient moisture to
outdoor wet-bulb temperature. achieve the wet bulb
requirement.
Clarification regarding which form of Add direction to prioritize the Improve
installation instructions to use, if instructions presented in the label representativeness and
multiple forms are provided, only for attached to the unit over the repeatability.
variable refrigerant flow (VRF) installation instructions shipped with
multisplit systems. the unit for all CAC/HP products.
Appendix M1 currently is not clear about Add specific instruction to adjust the Improve
how to achieve the same air volume rate airflow measurement apparatus fan but not representativeness and
for different test conditions. the fan of the unit under test to achieve repeatability.
the same air volume rate for different
tests.
The equations for full-capacity operation Revise the equations for full-capacity Improve
for variable-speed heat pumps at and operation at and above 45 [deg]F to be representativeness.
above 45 [deg]F ambient temperature are more consistent with compressor speed
based on operating in this range with a used in normal operation for this
compressor speed the same as its temperature range, represented by the
operation in 17 [deg]F ambient nominal heating test condition, H1N.
temperature.
10 CFR part 429 provides requirements Reinforce the language explaining regional Improve clarity.
regarding regional CAC/HP efficiency requirements.
standards.
10 CFR 429.16(a)(1) provides requirements Modify the instructions in that section to Improve repeatability.
for represented values of single-stage improve clarity without changing meaning.
and two-stage coil-only CACs that can
lead to different interpretation.
10 CFR 430.2 defines central air Add exclusions for additional commercial Improved
conditioner, excluding two commercial package air-conditioning and heating representativeness.
package air-conditioning and heating categories that justifiably are not
categories--packaged terminal air central air conditioners.
conditioners and packaged terminal heat
pumps.
----------------------------------------------------------------------------------------------------------------

As mentioned previously, DOE is also fixing typographical errors in
appendices M and M1 that were raised by AHRI. (``AHRI Exhibit 2,''
EERE-2017-BT-STD-0062-0117 at pp. 23-24) DOE is addressing these issues
in this rulemaking.
Under 42 U.S.C. 6293(e)(1), DOE is required to determine whether an
amended test procedure will alter the measured energy use of any
covered product. If an amended test procedure does alter measured
energy use, DOE is required to make a corresponding adjustment to the
applicable energy conservation standard to ensure that minimally
compliant covered products remain compliant. (42 U.S.C. 6293(e)(2)) DOE
has determined that the amendments described in section III of this
final rule would not alter the measured efficiency of CAC/HPs that are
rated using the test procedure that is currently required for testing,
i.e., appendix M. The revisions applicable for appendix M simply fix
errors within the current test procedure. With respect to appendix M1,
many of the amendments clarify test procedures rather than making
changes that would affect the measurements. Variable-speed coil-only
systems are not addressed currently in the test procedure, so this
final rule establishes a method of test for those products. For two-
stage coil-only systems, DOE is amending the default fan power
coefficients and default fan heat coefficients to be more
representative, as further described in section III.C.1 of this
document, which DOE believes will slightly improve the measured
efficiency of these combinations as compared to their current
representative values. Given that two-stage combinations are not
representative of minimally compliant combinations, DOE has determined
that this amendment would not require an

[[Page 64554]]

adjustment to the energy conservation standard for central air
conditioners and heat pumps to ensure that minimally compliant central
air conditioners and heat pumps would remain compliant. Additionally,
DOE has determined that the amendments would not increase the cost of
testing. Discussion of DOE's actions are addressed in detail in section
III of this final rule.
The effective date for the amended test procedures adopted in this
final rule is 30 days after publication of this document in the Federal
Register. Representations of energy use or energy efficiency must be
based on testing in accordance with the amended test procedures
beginning 180 days after the publication of this final rule.

III. Discussion

A. Scope of Applicability

DOE is amending the test procedures at appendix M1 for CAC/HP and
implementing a few minor clerical revisions to the test procedures at
appendix M. A ``central air conditioner or central air conditioner heat
pump'' is defined as a product, other than a packaged terminal air
conditioner or packaged terminal heat pump, which is powered by single
phase electric current, air cooled, rated below 65,000 British thermal
units per hour (``Btu/h''), not contained within the same cabinet as a
furnace, the rated capacity of which is above 225,000 Btu/h, and is a
heat pump or a cooling unit only. A central air conditioner or central
air conditioning heat pump may consist of: A single-package unit; an
outdoor unit and one or more indoor units; an indoor unit only; or an
outdoor unit with no match. In the case of an indoor unit only or an
outdoor unit with no match, the unit must be tested and rated as a
system (combination of both an indoor and an outdoor unit). 10 CFR
430.2.
Appendices M and M1 apply to the following CACs/HPs:
<bullet> Split-system air conditioners, including single-split,
multi-head mini-split, multi-split (including VRF), and multi-circuit
systems;
<bullet> Split-system heat pumps, including single-split, multi-
head mini-split, multi-split (including VRF), and multi-circuit
systems;
<bullet> Single-package air conditioners;
<bullet> Single-package heat pumps;
<bullet> Small-duct, high-velocity systems (including VRF);
<bullet> Space-constrained products--air conditioners; and
<bullet> Space-constrained products--heat pumps.
See Section 1.1 of appendices M and M1.
DOE is not proposing to change the scope of CACs/HPs covered by
appendices M and M1.

B. Requests for Future Test Procedure Revisions

DOE has considered whether the current test procedures for
variable-speed systems generally give manufacturers too much
flexibility in specifying fixed settings of the compressor and indoor
fan for testing without requiring the selected settings to be
demonstrated using native control testing. DOE is aware that there is
ongoing work addressing questions about whether the current DOE test
procedure for variable-speed systems is fully representative of native
control operation.\6\ However, DOE has initiated this rulemaking not as
a comprehensive revision that will satisfy the 7-year lookback
requirements (see 42 U.S.C. 6293(b)(1)(A)), but instead as an action
that will address a focused group of known issues, including those that
have been raised through the test procedure waiver process. Thus, DOE
limited its amendments addressing potential concerns about variable-
speed systems to coil-only systems, for which there are clear
differences in system controls architecture that impact the performance
of these systems in the field, particularly when using non-
communicating controls. However, DOE may more comprehensively address
these issues for all variable-speed systems in a future rulemaking.
---------------------------------------------------------------------------

\6\ E.g., The German energy regulatory body, Bunderstalt
f[uuml]r Materialforschung und-Pr[uuml]fung (``BAM''), has developed
a dynamic load compensation method, to be used as an alternative to
EN 14825:2016 ``Air conditioners, liquid chilling packages and heat
pumps, with electrically driven compressors, for space heating and
cooling. Testing and rating at part load conditions and calculation
of seasonal performance''. Additionally, the Canadian Standards
Association (``CSA'') has published the first draft edition of
CSA:EXP07:19 ``Load-based and climate-specific testing and rating
procedures for heat pumps and air conditioners'' (``EXP07'').
---------------------------------------------------------------------------

The CA IOUs, Joint Advocates, NEEA, and NYSERDA all encouraged DOE
to review ways to improve the representativeness of the test procedures
for CAC/HP in a future rulemaking under DOE's 7-year lookback
authority. Specifically, the CA IOUs, Joint Advocates, and NEEA all
requested that DOE explore approaches that would capture the
performance of variable-speed and multi-stage systems operating under
native controls rather than under fixed compressor and fan speed
controls. (CA IOUs, No.20 at pp.2-3; Joint Advocates, No.18 at p.1;
NEEA, No.23 at p.1)
The CA IOUs contended that the current test procedure does not
fully reflect energy use during the shoulder-season hours when outdoor
temperatures are typically between 55 [deg]F and 64 [deg]F and the
equipment is likely in fan-only mode (i.e., the compressor is not
running). (CA IOUs, No.20 at pp.2-3) DOE acknowledges the CA IOUs'
comment that shoulder-season fan energy consumption is not captured by
either the SEER/SEER2 or HSPF/HSPF2 metrics, which are constructed to
represent the cooling season efficiency and heating season efficiency,
respectively. However, as previously mentioned, DOE is only planning to
address a focused group of known issues in this rulemaking and will
evaluate and addresses a broader set of changes in a future rulemaking.
The CA IOUs acknowledged this point in their comment, by suggesting
that DOE consider fan-only energy use during the shoulder-season in a
subsequent review of the CAC/HP test procedure. Id. Therefore, DOE will
not adopt any amendments in this rulemaking related to shoulder-season
energy consumption, as suggested by the CA IOUs.
The CA IOUs also suggested that DOE consider approaches in a future
rulemaking to incorporate the power consumption of auxiliary components
like fans and crankcase heaters operating when the compressor is off.
(CA IOUs, No.20 at pp.2-3) DOE notes that there are already test
procedures and energy conservation standards governing the allowable
off-mode power consumption for CACs and HPs, which encapsulates the
off-mode and standby power consumed by auxiliary components such as
crankcase heaters as suggested by the CA IOUs. These test procedures
are enumerated in section 4.3 of appendices M and M1, and standards are
enumerated at 10 CFR 430.32(c)(4).
The CA IOUs further requested that DOE amend the definition of
``variable-speed compressor systems'' to incorporate CAC/HPs with at
least three compressor capacity stages that do not meet the definitions
of VRF or triple-capacity northern heat pumps. Specifically, the CA
IOUs suggested the following definition (additions in italics):
Variable-speed compressor system means ``a central air conditioner
or heat pump that has a compressor that uses a variable-speed drive to
vary the compressor speed to achieve variable capacities or a
compressor with at least three compressor capacity stages not including
triple-capacity northern heat pumps.'' (CA IOUs, No.20 at p.2)
Section 1.2 of appendix M1 defines ``variable-speed compressor
systems'' as those CAC/HPs that have ``a compressor

[[Page 64555]]

that uses a variable-speed drive to vary the compressor speed to
achieve variable capacities.'' The definition for ``variable
refrigerant flow (VRF) systems'' includes the language ``multi-split
system with at least three compressor capacity stages, distributing
refrigerant through a piping network to multiple indoor blower coil
units.'' The definition for ``triple-capacity, northern heat pump'' in
appendix M1 includes ``a heat pump that provides two stages of cooling
and three stages of heating.'' DOE agrees with the CA IOUs' assertion
that as currently structured, the definitions in appendix M1 do not
explicitly clarify coverage for the specific case of CAC/HP systems
having three or more stages (but without a variable-speed drive), do
not include multiple indoor units (which would meet the definition for
VRF), and are not heat pumps that include two cooling stages and three
heating stages (which would meet the definition for triple-capacity
northern heat pump). However, DOE is not aware of, nor did the CA IOUs
identify, the existence of such systems. Also, as previously mentioned,
DOE is only planning to address a focused group of known issues in this
rulemaking and will evaluate and addresses a broader set of changes in
future rulemaking. Therefore, DOE will not adopt the revised definition
of ``variable-speed compressor systems,'' as suggested by the CA IOUs
in this rulemaking. DOE may consider changes to the definition of
``variable-speed compressor system'' in a future rulemaking, if
provided additional evidence of systems existing that meet the criteria
of the hypothetical system described by the CA IOUs.
NEEA and the Joint Advocates recommended that DOE adopt a test
procedure that evaluates performance under loads that respond to the
heat pump's internal firmware. (NEEA, No.23 at p.1; Joint Advocates,
No.18 at pp. 3-4) NEEA provided data to support their claim that
seasonal efficiency performance is highly dependent on the installed
firmware of the system. Id. at pp.3-4. NEEA compiled this information
in a report \7\ that was also cited by the Joint Advocates in their
comment. (Joint Advocates, No.18 at p.4)
---------------------------------------------------------------------------

\7\ NEEA report ``Heat Pump and Air Conditioner Efficiency
Ratings: Why Metrics Matter'' available online at: <a href="https://neea.org/resources/heat-pump-and-air-conditioner-efficiency-ratings-why-metrics-matter">https://neea.org/resources/heat-pump-and-air-conditioner-efficiency-ratings-why-metrics-matter</a>.
---------------------------------------------------------------------------

NEEA also requested that DOE adopt a load-based test procedure with
the tested system operating under native controls. (NEEA, No.23 at p.2)
NEEA again provided data concerning the representativeness of the
existing DOE test procedure as compared to field data. NEEA cited
several ongoing projects related to evaluation of load-based testing of
CAC/HP and recommended that DOE leverage this work as a part of the
next CAC/HP test procedure rulemaking. Id. at pp.5-7. NEEA additionally
requested that DOE consider increasing the amount of data reported for
heat pumps operating at pert-load heating conditions, specifically
advocating for required reporting of COP for low-compressor-stage tests
at 67 [deg]F and 47 [deg]F. Id. at p.7.
NYSERDA encouraged DOE to start immediately on foundational work
needed to improve the standard and test procedure to better account for
equipment performance in cold climates. NYSERDA requested that DOE make
the H4, H4<INF>2</INF>, or H4<INF>3</INF> heating tests mandatory in
order to produce more representative ratings that account for system
performance at 5 [deg]F. NYSERDA also requested that DOE explore how to
test and report relative capacity maintenance at temperatures lower
than the heating mode test temperatures that are used to determine
nominal capacity and suggested that DOE prescribe performance
requirements of low-temperature capacity maintenance for products
advertised as cold-climate heat pumps.\8\ Further, NYSERDA requested
that DOE evaluate how a variety of sizing approaches could be
incorporated into the test procedure. NYSERDA highlighted that DOE has
previously established that the sizing assumptions inherent in the DOE
test procedure are based on cooling capacity and provided an example of
a sizing and selection guide that emphasizes heating function.\9\
NYSERDA ultimately acknowledged that DOE is addressing a more limited
set of issues in this rulemaking and suggested that if their comments
could not be considered now, they should be considered applicable for
the next test procedure update for CACs or other HVAC equipment, as
appropriate. (NYSERDA, No.17 at pp.2-3)
---------------------------------------------------------------------------

\8\ NYSERDA cited the EPA's Energy Star Version 6.1 CAC/HP
specification, which prescribes a heating capacity maintenance of
70% at 5 [deg]F relative to 47 [deg]F for cold-climate heat pumps.
The Energy Star specification can be found online at: <a href="https://www.energystar.gov/sites/default/files/ENERGY%20STAR%20Central%20Air%20Conditioner%20and%20Heat%20Pump%20Version%206.1%20Final%20Specification.pdf">https://www.energystar.gov/sites/default/files/ENERGY%20STAR%20Central%20Air%20Conditioner%20and%20Heat%20Pump%20Version%206.1%20Final%20Specification.pdf</a>.
\9\ NYSERDA identified NEEP's ASHP sizing and selection guide,
available online at: <a href="https://neep.org/sites/default/files/resources/ASHP%20Sizing%20%26%20Selecting%20-%208x11_edits.pdf">https://neep.org/sites/default/files/resources/ASHP%20Sizing%20%26%20Selecting%20-%208x11_edits.pdf</a>.
---------------------------------------------------------------------------

In summary, DOE received a variety of comments that requested
changes to the CAC test procedure beyond the limited scope of proposals
in the March 2022 CAC TP NOPR. DOE received comments recommending
consideration of load-based testing methods, controls validation
(particularly for variable-speed systems), amended metrics, amended
definitions, and expansion of test methods to capture low-temperature
heating performance for heat pumps. As stated, DOE will consider these
comments when conducting the next rulemaking that includes a full
review of the CAC test procedure.

C. Topics Arising From Test Procedure Waivers

1. Fan Power at Reduced Airflows for Coil-Only Systems
a. Background
Coil-only air conditioners are matched split-systems consisting of
a condensing unit and indoor coil that are distributed in commerce
without an indoor blower or separate designated air mover. Such systems
installed in the field rely on a separately installed furnace or a
modular blower for indoor air movement. Because coil-only CAC/HPs do
not include their own indoor fan to circulate air, the DOE test
procedures prescribe equations that are used to calculate the assumed
(i.e., ``default'') power input and heat output of an average furnace
fan with which the test procedure assumes the indoor coil is pared in a
field installation. In each equation, the measured airflow rate (in
cubic feet per minute of standard air (``scfm'')) is multiplied by a
defined coefficient (expressed in Watts (``W'') per 1,000 scfm (``W/
1000 scfm'') for fan power, and British Thermal Units (``Btu'') per
hour (``Btu/h'') per 1000 scfm (``Btu/h/1000 scfm'') for fan heat),
hereafter referred to as the ``default fan power coefficient'' and
``default fan heat coefficient.'' The resulting fan power input value
is added to the electrical power consumption measured during testing.
The resulting fan heat output value is subtracted from the measured
cooling capacity of the CAC/HP for cooling mode tests and added to the
measured heating capacity for heating mode tests.
In appendix M1, separate fan power and fan heat equations are
provided for different types of coil-only systems (i.e., the equations
for mobile home or space-constrained are different than for
``conventional'' non-mobile home and non-space-constrained).\10\ 10 CFR
part

[[Page 64556]]

430, subpart B, appendix M1, see, e.g., section 3.3. For coil-only
units installed in mobile-homes and for space-constrained systems,
appendix M1 defines a default fan power coefficient of 406 W/1000scfm
and a default fan heat coefficient of 1,385 Btu/h/1000 scfm. See, e.g.,
appendix M1, section 3.3.d. For coil-only units installed in
conventional (i.e., non-mobile-home and non-space-constrained) systems,
appendix M1 defines a default fan power coefficient of 441 W/1000 scfm
and a default fan heat coefficient of 1,505 Btu/h/1000 scfm. See, e.g.,
appendix M1, section 3.3.e. In appendix M1, for both the default fan
power coefficient and default fan heat coefficient, the same
coefficient is used for both the full-load and part-load tests.
---------------------------------------------------------------------------

\10\ The different default fan power and default fan heat
coefficients for mobile-home and space-constrained systems as
compared to conventional systems reflect the lower duct pressure
drop expected for such systems in field operation--the lower values
are consistent with the lower external static pressure levels
required in testing of blower-coil systems intended for mobile home
and spaced-constrained applications (see Table 4 of appendix M1).
---------------------------------------------------------------------------

In the March 2022 CAC TP NOPR, DOE discussed a petition for waiver
and interim waiver filed by Nortek on September 7, 2021, that requested
an alternate test procedure that would define lower default fan power
and fan heat coefficients for the part-load tests, instead of applying
the same coefficients to both the full-load and part-load tests, as is
done in appendix M1. 87 FR 16830, 16834-16835; see Nortek, EERE-2021-
BT-WAV-0025, No. 1 at pp. 4-9. In response, DOE published a notice that
announced its receipt of the petition for waiver and denial of Nortek's
petition for an interim waiver. Id. See 86 FR 63357 (``Notification of
Petition for Waiver''). In the Notification of Petition for Waiver, DOE
noted that applying the modified default fan power coefficients and
default fan heat coefficients in appendix M1 to products such as those
that are the subject of Nortek's petition was determined to be
representative of the systems' performance and reflected the adoption
of the recommendations of a working group formed to negotiate a notice
of proposed rulemaking for energy conservation standards for CAC/HPs;
and that the modified coefficients were subject to public comment
during the 2016 test procedure rulemaking for CAC/HPs (``2016 CAC TP
Rulemaking''). Id. See 82 FR 1426, 1452. DOE also noted that Nortek
commented in support of the modified coefficients during the 2016 CAC
TP Rulemaking. Id.
In response to the issue raised by Nortek, DOE re-examined the
furnace fan electrical power consumption data collected for the furnace
fans rulemaking (see 79 FR 506, Jan. 3, 2014) that was used to develop
the default fan power coefficients and default fan heat coefficients
for coil-only products in appendix M1. DOE extended the prior analysis
to examine both full-load and part-load air volume rates.\11\ DOE
correlated the predicted power consumption with the predicted air
volume rate for each furnace fan to determine adjusted values of the
default fan power coefficients that may result in a more representative
estimate of fan power and fan heat at reduced airflow conditions,
compared to the coefficients currently defined in appendix M1. DOE's
analysis indicated that at a reduced air volume rate of 75 percent, the
average indoor fan power coefficient would be 360 W/1000 scfm for coil-
only CAC/HPs in a conventional (i.e., non-mobile-home and non-space-
constrained) installation. For mobile-home and space-constrained
systems, the average indoor fan power coefficient would be 331 W/1000
scfm.\12\ DOE also calculated the fan heat coefficients associated with
these power input levels. The average indoor fan heat coefficients
would be 1,228 Btu/hr/1000 scfm and 1,130 Btu/h/1000 scfm for
conventional (i.e., non-mobile-home and non-space-constrained) and
mobile-home/space-constrained installations, respectively. 78 FR 16830,
16834-16835.
---------------------------------------------------------------------------

\11\ To ensure consistency across analyses, DOE aggregated the
data by applying market weightings to each type and brand of furnace
model, using the same market shares that were used in the previous
analysis for the 2016 CAC TP Rulemaking.
\12\ For example, under DOE's proposed changes to appendix M1,
for a two-stage coil-only system in a conventional application that
has a cooling full-load air volume rate of 1640 scfm and a cooling
minimum (i.e., part-load) air volume rate of 1,230, the default fan
power at full load would be calculated as (441 W/1000scfm x 1640
scfm = 723 W); and default fan power at part-load would be
calculated as (360 W/1000scfm x 1230 scfm = 443 W).
---------------------------------------------------------------------------

The analysis conducted by DOE for the March 2022 CAC TP NOPR
resulted in higher default fan power coefficients and default fan heat
coefficients at the reduced 75 percent air volume rate than the values
presented in the Nortek waiver petition. DOE tentatively concluded that
its analysis is a more appropriate representation of average furnace
fan power consumption than the results presented by Nortek because (1)
DOE's analysis relied on empirical test results while Nortek's analysis
was theoretical, (2) DOE's analysis applied the same weighting factors
\13\ from the 2016 CAC TP Rulemaking to ensure consistency, and (3)
DOE's analysis considered constant-torque brushless-permanent-magnet
``X13'' motors while Nortek's analysis did not. DOE proposed to amend
the default fan power coefficients and default fan heat coefficients
for coil-only fan power when operating at reduced air volume rates to
reflect the results of its analysis. Id.
---------------------------------------------------------------------------

\13\ DOE's analysis included weighting based on market share by
brand, installations per cooling capacity range, and projected
shares in 2021 for different furnace fan motor types.
---------------------------------------------------------------------------

AHRI, Carrier, Emerson, the Joint Advocates, Lennox, Nortek, and
Rheem all supported DOE's proposal to reduce the default fan power and
fan heat coefficients for low-stage operation of coil-only
conventional, mobile-home and space-constrained CACs. (AHRI, No.25 at
p.3; Carrier, No.15 at p.2; Emerson, No.14 at p.1; Joint Advocates,
No.18 at p.1; Lennox, No.19 at p.2; Nortek, No.13 at p.1; Rheem, No.21
at p.1) Carrier, the Joint Advocates, and Lennox all stated that DOE's
proposal to include a lower default fan power coefficient at part-load
airflows would improve the representativeness of testing for two-stage
coil-only systems over the current approach in appendix M1. (Carrier,
No.15 at p.1; Joint Advocates, No.18 at p.1; Lennox, No.19 at p.2) Even
though there was general support for DOE's proposals, several comments
were received on the specific proposed values and the assumptions made
in order to calculate them. The following sections detail these
specific comments.
b. BPM Market Penetration
Despite supporting DOE's proposal to establish a second default fan
power coefficient representing low-stage operation, AHRI argued that
DOE's proposed part-load default fan power and heat coefficients were
still higher than they should be. (AHRI, No.25 at pp. 2-3) Carrier,
Daikin, Emerson, Lennox, Nortek, and Rheem all agreed with the AHRI
comment that the part-load default fan power and heat coefficients
should be lower than the proposed values. (Carrier, No.15 at p.2;
Daikin, No.24 at p.1; Emerson, No.14 at p.1; Lennox, No.19 at p.2;
Nortek, No.13 at pp.1-2; Rheem, No.21 at pp.1-2)
A key factor in AHRI's argument was that the actual market
saturation rate of furnace fans installed with higher-efficiency
brushless permanent magnet ``BPM'' \14\ fan motors is higher than
assumed in the analyses presented by DOE. (AHRI, No.25 at pp.2-3) DOE
first

[[Page 64557]]

presented its assumptions regarding relative prevalence of BPM motors
for furnace fans in a December 5, 2016, Technical Support Document
(``TSD'') used for the concurrent energy conservation standards
(``ECS'') rulemaking. EERE-2014-BT-STD-0048-0098 (``December 2016 CAC
ECS TSD''). In that document, DOE described its findings that in
2021,\15\ the estimated mix of blower types in existing furnaces would
be 77 percent permanent split capacitor (``PSC''), 15 percent constant-
speed BPM, and 9% constant-torque BPM. (EERE-2014-BT-STD-0048-0098,
page 7-16) DOE assumed the same proportion of furnace fan motor types
in its analysis for the March 2022 CAC TP NOPR.
---------------------------------------------------------------------------

\14\ In their comment, AHRI used the term ``electronically
commutated motor'' (ECM) to describe higher-efficiency motors
available in the furnace fans market. However, all instances in this
final rule have been changed to ``brushless permanent magnet'' (BPM)
which better describes the motor construction.
\15\ At the time the 2016 CAC ECS TSD was drafted, the proposed
compliance date for amended standards was Jan. 1, 2021--therefore
DOE forecasted the fan motor proportions in the anticipated year
that standards would come into effect. In the January 2017 direct
final rule regarding energy conservation standards (82 FR 1786,
January 6, 2017) (``January 2017 CAC ECS Direct Final Rule''),
however, the compliance date was delayed by two years to January 1,
2023. DOE did not provide estimates of assumed furnace fan motor
composition in the year 2023.
---------------------------------------------------------------------------

In order to support its claim that the market saturation rate of
BPM furnace fan motors was higher than the rate estimated by DOE, AHRI
cited the 2019 compliance date for efficiency standards for furnace
fans and stated that nearly all new furnaces shipped since 2019 have
exclusively used BPMs. (AHRI, No.25 at pp.2-3) AHRI also claimed that
the pending refrigerant change in the U.S. will require replacement of
R-410A systems in both indoor and outdoor units for CAC systems,
starting in 2025. AHRI asserted that due to these regulations,
consumers with older furnaces would be more likely to simultaneously
replace their furnaces at the same time as a whole-system CAC
replacement, leading to a wave of newly installed furnace fans using
BPM fan motors. Id. AHRI then forecasted the number of installed
furnaces and percent share of furnaces with BPM furnace fans using
DOE's estimates for equipment retirement Weibull curves, AHRI
historical shipments data,\16\ and 2015 Residential Energy Consumption
Survey (RECS) microdata.\17\ Ultimately, AHRI forecasted the
penetration of BPM furnace fan motors to reach 50 percent by 2025. Id.
NCP and Nortek both supported AHRI's analysis regarding the relative
prevalence of furnace fans having BPM motors, stating that the Fan
Energy Rating (FER) standards effectively obsoleted PSC motors in new
furnace fans in favors of BPM motors. (NCP, No.16 at pp.8-9; Nortek,
No.13 at p.2) NCP reiterated AHRI's claim that future refrigerant
regulations could increase the pace of furnace replacements and thus
accelerate the adoption of furnace fans with BPM motors. (NCP, No.16 at
p.8)
---------------------------------------------------------------------------

\16\ AHRI historical shipments estimates available online at:
<a href="https://ahrinet.org/resources/statistics/historical-data/furnaces-historical-data">https://ahrinet.org/resources/statistics/historical-data/furnaces-historical-data</a>.
\17\ Residential Energy Consumption Survey data available online
at: <a href="https://www.eia.gov/consumption/residential/data/2015/">https://www.eia.gov/consumption/residential/data/2015/</a>.
---------------------------------------------------------------------------

To evaluate AHRI's claims about furnace fan BPM penetration rates,
DOE reconstructed AHRI's analysis using RECS microdata and engineering
assumptions about typical furnace lifetime and historical prevalence of
BPM fan motors in furnace fans. DOE estimated the annual inflows and
outflows (i.e., new sales and decommissioning at end-of-life) of BPM
furnace fan motors, using the assumption that all new furnace fan
motors would be BPM in years 2019 and onwards. Because AHRI did not
explicitly describe how hypothetical refrigerant regulations would
translate into accelerated uptake in furnace fans having BPM motors,
DOE did not account for an increased rate of ``whole-system'' CAC
replacements (and therefore furnace fan replacements) when evaluating
furnace fan BPM penetration forecasts. Using these assumptions, DOE
estimates that the percentage of installed BPM furnace fan motors in
2021 to be 29 percent (as compared to 24 percent \18\ estimated in the
December 2016 CAC ECS TSD). Further, DOE's estimates support AHRI's
claim that the installed base of BPM furnace fans is likely to grow to
40 percent by 2023 and 50 percent by the year 2025. Therefore, DOE has
used these values of BPM market penetration to re-evaluate the NOPR
analysis to calculate default low-stage fan power coefficients and fan
heat coefficients in the next section.
---------------------------------------------------------------------------

\18\ BPM estimate from 2016 CAC ECS TSD reflects the sum of CT-
BPM (9%) and CA-BPM (15%).
---------------------------------------------------------------------------

c. Determining Low-Stage Coefficients
In consideration of DOE's proposals regarding default fan power
coefficients, AHRI also asserted that DOE's analysis included incorrect
assumptions about the relationship between electrical power consumption
and delivered airflow, which they claimed should be a cubic
relationship based on fan affinity laws. AHRI provided aggregated data
from a selection of 78 furnace fans to support their assertions. Id. at
pp.3-4. Lennox and Rheem reiterated AHRI's comment, stating that the
application of the same default coefficient at part-load airflows is
not representative of the performance of the two-stage equipment
operation, as the fan efficiency improves as airflow is reduced thus
increasing overall system efficiency. (Lennox, No.19 at p.2, Rheem,
No.21 at pp.1-2) Lennox and Rheem also elaborated that fan affinity
laws show that fan speed and power have a cubic relationship, not the
constant relationship \19\ currently used in the test procedure. Id.
AHRI further claimed that of the 78 collected furnace fans in their
data set, there was not a statistically significant difference in full-
load performance (measured in Watts per cfm) between models having
furnace fans with PSC motors and models having furnace fans with PBM
motors. As a result, AHRI did not argue that the full-load default fan
power and heat coefficients should be changed but did suggest lower
default fan power and fan heat coefficients low-stage operation. AHRI
proposed default low-stage fan power coefficients of 322 W/1000 scfm
for conventional systems and 296 W/1000 scfm for mobile-home/space-
constrained systems.\20\ (AHRI, No.25 at pp.3-4) As indicated, Carrier,
Daikin, Emerson, Lennox, Nortek, and Rheem all referenced the AHRI
analysis in their comments and supported the alternate default fan
power coefficients proposed by AHRI. (Carrier, No.15 at p.2; Daikin,
No.24 at p.1; Emerson, No.14 at p.1; Lennox, No.19 at p.2; Nortek,
No.13 at pp.1-2; Rheem, No.21 at pp.1-2)
---------------------------------------------------------------------------

\19\ The DOE test procedure does not prescribe a constant
default fan power, but rather a constant default fan power
coefficient, so that the calculated fan power varies linearly with
air volume rate. See appendix M1, sections 3.3, 3.5.1, 3.7, and
3.9.1.
\20\ AHRI also provided corresponding default fan heat
coefficients of 1099 Btu/h/1000scfm and 1010 Btu/h/1000scfm for
conventional and mobile-home/space-constrained coil-only CACs,
respectively.
---------------------------------------------------------------------------

DOE understands the theoretical basis of fan laws which describe a
cubic relationship between fan shaft power and delivered air volume
rate for an idealized fan. However, real fan shaft power does not
always consistently follow the fan laws \21\ and motor efficiency
generally decreases as shaft power decreases from rated load,\22\ which
would cause motor input power to deviate from the cubic relationship
even if the shaft power followed it. The AHRI comment does not provide
a more

[[Page 64558]]

detailed breakdown of analytical results allowing confirmation of
general consistency of the two analytical approaches. As noted, DOE has
re-evaluated the NOPR analysis to calculate default low-stage fan power
coefficients and fan heat coefficients, using the assumption that BPM
furnace fan penetration is 40 percent in the year 2023 (the compliance
date of CAC energy conservation standards in terms of appendix M1
metrics). 10 CFR 430.32(c)(5). DOE re-analyzed the same dataset used in
the furnace fans rulemaking and applied a proportion of 40 percent BPM
and 60 percent PSC motors, while keeping all other elements of the
analysis unchanged (see 79 FR 506, Jan. 3, 2014). For the reasons
described in section III.C.1.e of this document, DOE did not consider
separate default fan power coefficients for space-constrained coil-only
CACs and is instead continuing to treat mobile-home and space-
constrained systems jointly. This evaluation results in default low-
stage fan power and heat coefficients that are lower than the values
proposed in the March 2022 CAC TP NOPR, and DOE is adopting these lower
values in this final rule. The fan motor re-weighting had negligible
impact on the full-load airflow values for default fan power and
default fan heat coefficients, therefore, DOE is not amending the full-
load values in this final rule, consistent with comments received from
AHRI. (AHRI, No.25 at p.3) The results of DOE's analysis are summarized
in Table III-1.
---------------------------------------------------------------------------

\21\ This catalog of several indoor air handling units
demonstrates on the 6th page examples of fan performance curves,
where the fan efficiency does not always follow a simple quadratic
curve: <a href="https://content.greenheck.com/public/DAMProd/Original/10002/IAH_catalog.pdf">https://content.greenheck.com/public/DAMProd/Original/10002/IAH_catalog.pdf</a>.
\22\ As per ANSI/AMCA Standard 241-21 (Test Procedure for
Calculating Fan Energy Index (FEI) for Commercial and Industrial
Fans and Blowers), the motor efficiency for variable-speed motors is
not always directly proportional to the load, as demonstrated in
Figure F.3. Source: <a href="https://www.amca.org/assets/resources/public/pdf/Publications/AMCA-214-21.pdf">https://www.amca.org/assets/resources/public/pdf/Publications/AMCA-214-21.pdf</a>.

Table III-1--Default Fan Power and Fan Heat Coefficients for Coil-Only CACs and HPs
----------------------------------------------------------------------------------------------------------------
Default fan
Air volume power Default fan heat
System type rate (%) coefficient (W/ coefficient (Btu/h/
1000scfm) 1000scfm)
----------------------------------------------------------------------------------------------------------------
Conventional Coil-Only...................................... 100 441 1505
75 335 1143
Mobile-Home and Space-Constrained Coil-Only................. 100 406 1385
75 308 1051
----------------------------------------------------------------------------------------------------------------

d. Interpolated Coefficients Between 75 and 100 Percent Air Volume Rate
In the March 2022 CAC TP NOPR, DOE also stated that the reduced air
volume rate used for low-stage operation of two-stage coil-only systems
may be higher than 75 percent of the full-load air volume rate, if the
manufacturer's instructions specify a higher part-load air volume rate.
DOE proposed that in such cases, (i.e., in any case where the reduced
air volume rate is greater than 75 percent of the full-load air volume
rate) the default fan power values associated with full-load air volume
rate be used. However, DOE hypothesized that in these scenarios, the
appropriate default fan power coefficient and default fan heat
coefficient may be values between the reduced values discussed above
and the values used for full-load air volume rate. DOE set out two
alternative options to its proposed approach: (1) allowing the reduced
value up to a threshold value, e.g., 80 percent of full-load air volume
rate, above which the full-load value would be required, and (2)
requiring a linear interpolation of the default fan power coefficient
between the reduced value at 75 percent of full-load air volume rate to
the full-load value at 100 percent.\23\ 78 FR 16830, 16835.
---------------------------------------------------------------------------

\23\ For example, for non-mobile-home and non-space-constrained
systems, if a linear interpolation of the default fan power
coefficient is required, it would be equal to 360 + (441-
360)*(%FLAVR-75%)/(100%-75%), where %FLAVR is the reduced air volume
rate used for the test expressed as a percentage of the full load
air volume rate.
---------------------------------------------------------------------------

AHRI, Carrier, Daikin, Emerson, Lennox, and Nortek all supported
the second alternative option set forth by DOE, i.e., requiring a
linear interpolation of the default fan power coefficient based on
percentage full-load air volume rate. (AHRI, No.25 at p.6; Carrier,
No.15 at p.2; Daikin, No.24 at p.1; Emerson, No.14 at pp.1-2; Lennox,
No.19 at p.2; Nortek, No.13 at p.1) AHRI provided a table of power
consumption rate as a function of airflow percentage and stated that a
third-order equation would be most accurate, however intermediate
values for default fan power coefficient would be most easily
calculated using linear interpolation. (AHRI, No.25 at pp.4-6)
Based on the comments, DOE is finalizing the approach of requiring
linear interpolation of default fan power and default fan heat
coefficients for all tests where the specified airflow is between 75
percent and 100 percent of the full load air volume rate.
e. Considerations for Space-Constrained Systems
As previously mentioned in section III.C.1.b, NCP supported AHRI's
claims that due to the FER furnace fan standards coming into effect in
2019, and due to anticipated refrigerant regulations, the relative
penetration rate of furnace fans with BPM motors is higher than the
proportion estimated by DOE in the January 2017 CAC TP Final Rule.
(NCP, No.16 at pp.8-9) NCP also remarked that DOE's proposal for
default fan power coefficients implies that space-constrained coil-only
units are similar to those of mobile homes, and implies that both
should use a default fan power and capacity adjustment that is
representative of operation at a minimum external static pressure (ESP)
of 0.30 inches w.c.\24\ NCP asserted that data based on mobile homes is
not an appropriate basis for space-constrained condensing units used in
multi-family housing applications. NCP claimed that although the size
of the indoor units is similarly restricted in mobile-home and space-
constrained applications, mobile-home applications do not limit the
size of the outdoor unit in the same way as space-constrained
installations, which require a smaller footprint for the condensing
unit. NCP elaborated that this discrepancy allows for mobile-home
systems to have a relatively larger condenser coil surface area
(providing improved performance) and that their models of space-
constrained outdoor units do not have sufficient space to increase the
condenser coil size. NCP thus asserted that the default fan power
coefficients proposed by DOE in the March 2022 CAC TP NOPR remains
unrealistic for NCP's space-constrained CAC systems and would prohibit
NCP from meeting the minimum energy efficiency standard. NCP requested
that if the Department does not continue to waive requirements for
coil-only testing of space-constrained condensing units, DOE should
amend the default fan

[[Page 64559]]

power and fan heat coefficients to reflect real world conditions. (NCP,
No.16 at pp. 7-8) NCP provided confidential information regarding the
performance of their ``Through-the-Wall'' (TTW) space-constrained
condensing units when paired with various indoor unit air handlers,
including different NCP-branded air handlers and with other brands of
furnaces (indicative of a coil-only installation). NCP then
incorporated its findings along with the data provided by AHRI and
proposed a default fan power coefficient of 321 Watts per 1000 scfm for
space-constrained coil-only CAC systems operating at low-stage airflow.
Id. at p.9.
---------------------------------------------------------------------------

\24\ Appendix M1 requires that both ducted space-constrained and
ducted mobile-home CACs be tested at a minimum ESP of 0.30 inches
w.c. 87 FR 16834 (Mar. 24, 2022) (citing 82 FR 1426, 1453 (Jan. 5,
2017)).
---------------------------------------------------------------------------

In response to NCP's assertion that separate test procedure
considerations should be given for default fan power coefficients for
space-constrained CAC systems vs those for mobile-home CAC systems, DOE
notes that this topic was previously discussed in the January 2017 CAC
TP Final Rule. In that rule DOE determined, with stakeholder support,
appropriate default fan power and default fan heat coefficients for
mobile home coil-only systems required to be tested at a minimum
external static pressure of 0.30 in. w.c. 82 FR 1426, 1451-1452. DOE
also noted in that final rule that recommendation #2 of the January
2016 Appliance Standards and Rulemaking Federal Advisory Committee
(ASRAC) CAC/HP Working Group Term Sheet (2016 CAC Term Sheet)
recommended 0.30 inches w.c. as the minimum external static pressure
requirement for testing space-constrained CACs Id. DOE is maintaining
the determination from the January 2017 CAC TP Final Rule and the
current test procedure approach, which uses the same default fan power
coefficient and default fan heat coefficient for space-constrained and
mobile home CAC.
2. Variable-Speed Coil-Only Test Procedure
a. Background
As discussed, appendices M and M1 contain provisions for testing
split-system CAC/HPs equipped with ``coil only'' indoor units that, in
a field installation, are paired with an existing furnace or other air
handler that includes the fan required to circulate conditioned air
through ductwork. These provisions apply to single-stage and two-stage
systems and address only two levels of air volume rate, for full-load
and minimum operation.\25\ Appendices M and M1 do not include
provisions for testing variable-speed systems equipped with coil-only
indoor units (``VSCO'' CACs). In the March 2022 CAC TP NOPR, DOE
discussed waiver requests that it had received from multiple
manufacturers regarding the test provisions for VSCO CACs. 82 FR 16830,
16836-16837. The various waiver requests are summarized in this final
rule in Table III-2.
---------------------------------------------------------------------------

\25\ Section 3.1.4.1.1.c (cooling full-load air volume rate),
section 3.1.4.2.c (cooling minimum air volume rate), section
3.1.4.4.2.c (heating full-load air volume rate), and section
3.1.4.5.2.d (heating minimum air volume rate) of appendix M1.
---------------------------------------------------------------------------

With the exception of the Goodman Manufacturing Company, L.P.
(``Goodman'') petition for waiver (86 FR 40534 (July 28, 2021)), all
petitioners submitted petitions for waiver for products that use ``non-
communicative'' conventional controls, i.e., controls that use low-
voltage on-off signals from the thermostat to indicate the need for
conditioning in the conditioned space. As required under the specified
alternate test procedures for these ``non-communicative variable-speed
coil-only systems,'' they must be tested according to the appendix M
provisions applicable to variable-speed systems (e.g., three different
compressor speeds in the cooling mode), except that the subject systems
must be tested using the full-load cooling air volume rate at all test
conditions. (GD Midea, EERE-2017-BT-WAV-0060, No. 1, pp. 1-3; TCL,
EERE-2018-BT-WAV-0013, No. 1, pp. 2-4; LG, EERE-2019-BT-WAV-0023, No.
1, pp 3-4) DOE noted that the waivers for non-communicative systems
indicated only that ``compressor speed varies based only on controls
located on the outdoor unit.'' (GD Midea, EERE-2017-BT-WAV-0060, No. 1,
p. 6; TCL, EERE-2018-BT-WAV-0013, No. 1, p. 4; LG, EERE-2019-BT-WAV-
0023, No. 1, pp 2) An interim test procedure waiver was also granted to
Goodman for their ``communicative'' variable-speed, coil-only CAC/HPs.
Goodman's petition claimed that for their systems, both the outdoor
unit and indoor coil communicate with each other to control the
variable-speed compressor, along with the multi-speed indoor fan. 86 FR
40534, 40539. The Goodman interim waiver test procedure specifies use
of the cooling full-load air volume rate for the full-load cooling and
full-load heating tests; and the cooling minimum air volume rate for
the cooling minimum, heating minimum, cooling intermediate, and heating
intermediate tests. Id.

Table III-2--Status and Details of Variable-Speed, Coil Only (VSCO) Waiver Requests
----------------------------------------------------------------------------------------------------------------
Manufacturer Petition description Docket Status
----------------------------------------------------------------------------------------------------------------
GD Midea Heating & Ventilating Non-communicating VSCO. EERE-2017-BT-WAV-0060.............. Interim and
Equipment Co., Ltd. (GD Midea). Full load air volume Waiver Granted.
rate used for
intermediate and
minimum.
TCL air conditioner (zhongshan) Non-communicating VSCO. EERE-2018-BT-WAV-0013.............. Interim and
Co. Ltd. (``TCL AC''). Full load air volume Waiver Granted.
rate used for
intermediate and
minimum.
LG Electronics U.S.A., Inc. Non-communicating VSCO. EERE-2019-BT-WAV-0023.............. Interim Granted.
(LGE). Full load air volume
rate used for
intermediate and
minimum.
Goodman........................ Communicating VSCO. EERE-2021-BT-WAV-0001.............. Interim Granted.
Minimum air volume
rate used for
intermediate and
minimum.
----------------------------------------------------------------------------------------------------------------

In the March 2022 CAC TP NOPR, DOE explained that it was
reconsidering its approach to the waivers for the non-communicative
VSCO systems. First, DOE explained that the waiver petitions had not
provided information regarding, nor had DOE evaluated, the compressor
speed selections used for different test conditions specified in
appendix M or M1. 87 FR 16830, 16836. DOE elaborated that it had also
not compared these speed selections with those used by blower-coil
variable speed systems for the same test conditions. Id. DOE determined
that based on the

[[Page 64560]]

information received and evaluated, it could not conclude that the
alternate test procedures specified in the waivers are representative
of average use cycles of CAC/HPs. Id. DOE proposed provisions as
generally prescribed in the relevant waivers, except that, for all
variable-speed coil-only systems, regardless of communicative
capability, use of a reduced-air volume rate would be allowed for part-
load operation, i.e., using the cooling minimum air volume rate for the
cooling minimum, heating minimum, cooling intermediate, and heating
intermediate tests. 87 FR 16830, 16837-16838. The proposed test
procedure also incorporated the reduced default fan power and default
fan heat coefficients at reduced air volume rates discussed in section
III.C.1 of this document.
Regarding indoor airflow rate for VSCO systems, DOE pointed out
that the test procedure for two-stage coil-only systems is premised on
the system using a two-stage thermostat and associated wiring that
responds to indoor temperature measurements and sends voltage signals
that enable two-stage control of both the compressor speed and the
indoor fan speed. 87 FR 16830, 16836-16837. DOE similarly assumed the
presence of necessary wiring for the installation of variable-speed
systems. Id. DOE elaborated that if the system does not include the
capability to control an existing furnace fan at two air volume rates,
the manufacturer would have the option of specifying minimum/
intermediate air volume rates equal to the full-load air volume rate.
Id.
Regarding compressor speed control for VSCO systems, DOE proposed
to define ``communicating control'' in the context of variable-speed,
coil-only CAC/HPs in order to differentiate between the test procedure
provisions that would be applicable to communicating systems from those
applicable to non-communicating systems. 87 FR 16830, 16837-16838. See
section III.C.2.b. DOE further proposed provisions for setting
compressor speed reflecting the attributes of the controls.
Specifically, DOE proposed to require that non-communicative variable-
speed coil-only systems be tested using an on-off control signal
consistent with the control characteristics and also eliminating the
E<INF>V</INF> test for cooling and H2<INF>V</INF> for heating as well
as including H2<INF>2</INF>, H2<INF>1</INF>, and H3<INF>1</INF> for
heating. In contrast, DOE proposed that systems that meet the newly
proposed criteria for ``communicating'' control would use compressor
speeds and tests consistent with the existing variable-speed test
procedure for blower-coil systems. Id.
With respect to DOE's proposal to add testing provisions for VSCO
CACs in appendix M1, Carrier, Joint Advocates, Lennox, Nortek, and
Rheem commented that they supported DOE's proposals to add testing
provisions for variable-speed coil-only CAC/HPs. (Carrier, No.15 at
p.1, Joint Advocates, No.18 at p.2, Lennox, No.19 at p.3, Nortek, No.13
at p.2, Rheem, No.21 at p.2) Carrier stated that they agreed that a
communicating and non-communicating procedure should be created, and
supported DOE's proposed test procedure for each type of system.
(Carrier, No.15 at p.1) The Joint advocates added that they supported
incorporating provisions for testing variable-speed coil-only units to
ensure that the test procedure reflects differences in system controls
architecture between communicating and non-communicating systems.
(Joint Advocates, No.18 at p.2) They further commented that DOE's
hybrid approach for aligning minimum air volume requirements between
two-capacity and variable-speed coil-only units (for both communicating
and non-communicating systems) was logical, as non-communicating
systems have characteristics of both variable-speed and two-stage
systems due to limitations of the less sophisticated control systems.
Id. Lennox stated that DOE's proposal provides a consistent test method
according to defined system capabilities while allowing for expanded
opportunity for variable speed equipment to be installed in replacement
applications with existing furnace or modular blowers. (Lennox, No.19
at p.3) Nortek explicitly stated that they were in favor of adopting
the test procedures that were contained in the waivers, giving the
Goodman waiver (86 FR 40534 (July 28, 2021)), as an example. AHRI
commented that they agreed that systems meeting the criteria for
variable-speed communicating coil-only CAC or HP definition should
follow the existing variable-speed test procedure, although AHRI
proposed an alternate definition for communicating control as described
in section III.C.2.b of this document. (AHRI, No.25 at p.6)
b. Test Differences Based on Communicating Capability
As previously stated, the test procedure for two-stage coil-only
systems is premised on the system using a two-stage thermostat and
associated wiring that responds to indoor temperature measurements and
sends voltage signals that enable two-stage control of both the
compressor speed and the indoor fan speed. A more sophisticated control
approach is required to enable a variable speed system to modulate
compressor speed control (e.g., proprietary thermostat, serial
communication wiring, and/or electronic sensors at the indoor coil). In
the March 2022 CAC TP NOPR, DOE proposed to define ``variable-speed
communicating oil-only central air conditioner or heat pump'' in
section 1.2 of appendix M1, to distinguish variable-speed coil-only
systems with such controls, as a variable-speed compressor system
having a coil-only indoor unit that is installed with a control system
that (1) communicates the difference in space temperature and space
setpoint temperature (not a setpoint value inferred from on/off
thermostat signals) to the control that sets compressor speed; (2)
provides a signal to the indoor fan to set fan speed appropriate for
compressor staging and air volume rate; and (3) has installation
instructions indicating that the required control system meeting both
(1) and (2) must be installed. 87 FR 16830, 16837.
DOE also proposed to define variable-speed systems that do not have
this communicating feature as a variable-speed compressor system having
a coil-only indoor unit that does not meet the definition of variable-
speed communicating coil-only central air conditioner or heat pump. Id.
DOE elaborated that variable-speed coil-only systems that meet the
``communicating'' definition would be tested like any other variable-
speed system, except that the heating full-load air volume rate would
be equal to the cooling full-load air volume rate, and the intermediate
and minimum cooling and heating air volume rates would all be the
higher of (1) the rate specified by the installation instructions
included with the unit by the manufacturer and (2) 75 percent of the
full-load cooling air volume rate. Id.
DOE further proposed that those variable-speed coil-only systems
that are not ``communicating'' as defined above would be tested with
additional limitations as if they have some variable-speed system
characteristics and some two-stage coil-only system characteristics.
Specifically, (a) the outdoor unit and/or the indoor unit would be
provided with a control signal indicating operation at high or low
stage, rather than testing with compressor speed fixed at specified
speeds, and (b) air volume rates would be determined consistent with
the requirement for two-stage coil-only systems. Id. A key implication
of (a) is that there would be no intermediate compressor speed
operation. Under DOE's proposed test procedure, many of

[[Page 64561]]

the requirements associated with variable-speed operation would,
however, be retained. For example, such systems would be allowed to
have ``minimum speed-limiting'' control for heat pump mode (see the
alternative calculations representing minimum-speed operation in
appendix M1, section 4.2.4.b). The test method for non-communicating
variable-speed coil-only systems would include requiring tests for
minimum-speed operation for both the 35 [deg]F and 17 [deg]F heating
test conditions so that the HSPF2 calculations utilize test results for
appropriate compressor speeds. Also, the full compressor speed during
heating mode operation would be allowed to vary with outdoor
temperature, there would be an H1<INF>N</INF> test to represent the
nominal capacity, and the same provisions for calculation of full-speed
capacity and power applied to conventional variable-speed systems would
be used (see, e.g., the calculations in appendix M1, sections 3.6.4,
4.2.4.c and 4.2.4.d). If a manufacturer chooses to run the optional
H1<INF>2</INF> test (i.e., if compressor speed for the H1<INF>N</INF>
test is different than compressor speed for the H3<INF>2</INF> test,
and the manufacturer chooses to run the H1<INF>2</INF> test rather than
use the standardized slope factors described in appendix M1, section
3.6.4.b), then the test would be run with over-ride of compressor speed
using the same speed as used for the H3<INF>2</INF> test. This is the
only test for which such over-ride would be allowed.
To ensure consistency of testing, it may be necessary for
manufacturers to certify whether a variable-speed coil-only rating is
based on non-communicating or communicating control. However, this
change was not proposed in the March 2022 CAC TP NOPR and may be
considered in a separate rulemaking.
In the March 2022 CAC TP NOPR, DOE acknowledged that there may be
variable-speed control technology that cannot be tested according to
the proposed test approach described previously for non-communicating
variable-speed coil-only systems. 87 FR 16830, 16838. Specifically, the
test approach may not result in tests that meet the stability
requirements for testing (i.e., the measurements might not meet the
tolerance requirements in Table 2 of ANSI/ASHRAE 37-2009, ``Methods of
Testing for Rating Electrically Driven Unitary Air-Conditioning and
Heat Pump Equipment'' (``ASHRAE 37-2009''), which is incorporated by
reference by the DOE test procedure). Or the proposed test procedure
might evaluate such a basic model in a manner so unrepresentative of
its true energy consumption characteristics as to provide materially
inaccurate comparative data. Id. DOE stated that in this case, the
manufacturer would be able to petition DOE for a waiver and include a
suggested alternate test procedure as provided in 10 CFR 430.27. DOE
elaborated that as part of its review of such a waiver and alternate
test procedure, DOE would consider the correlation between results of a
suggested alternate test procedure and results of testing when using
the two-stage two-wire controls expected to be available in a general
coil-only system installation, recognizing that the latter testing may
involve dynamics that exceed the measurement tolerances discussed
above. DOE would also consider the control hardware involved in
achieving appropriate control for indoor and outdoor conditions and
some understanding of how the control works. Id.
With respect to DOE's proposal to define variable speed
communicating coil-only CACs and HPs, Emerson supported the
differentiation of communicating and non-communicating variable speed
CACs that maintains the ability to set compressor speed and optimize
airflow relative to the compressor speed. (Emerson, No.14 at p.3) The
Joint Advocates supported DOE's proposed definition but encouraged DOE
to revise the definition to clarify that the installation instructions
refer to those of the indoor unit (not of the control system). (Joint
Advocates, No.18 at pp.2-3) AHRI commented that they supported the
concept of the definition but recommended modifications to be more
inclusive of other approaches. AHRI proposed an alternate definition as
follows:
Variable-Speed Communicating Coil-Only Central Air Conditioner or
Heat Pump means a variable-speed compressor system having a coil-only
indoor unit that is installed with communicative controls to change the
compressor speed by 3 or more speeds and indoor air flow by 2 or more
speeds and controls the system by monitoring the change in system
control parameter/s and automatically sets the compressor speed, indoor
air flow and other system components as required to maintain the indoor
room temperature. (AHRI, No.25 at p.6)
Carrier, Daikin, Nortek, and Samsung incorporated AHRI's proposed
definition in their comments. (Carrier, No.25 at pp.2-3; Daikin, No.24
at p.2; Nortek, No.13 at p.2; Samsung, No.22 at p.2) AHRI, Carrier,
Daikin, Nortek, and Samsung all agreed that DOE's proposed definition
is too restrictive and should be modified to allow for potential
alternate control strategies that could be used to properly control
compressor speed and coordinate with indoor fan speed. Id. AHRI,
Daikin, and Samsung stated that communication of set point and indoor
temperature is not the only parameter that can be used to set fan and
compressor speeds, suggesting that it is not necessary to achieve
proper compressor control, and provided hypothetical examples of other
control parameters that could be used to set compressor speeds, such as
outside air conditions, indoor humidity levels, or refrigerant
pressures and temperatures. (AHRI, No. 25 at p.6; Daikin, No.24 at p.2;
Samsung, No.22 at pp.1-2) Daikin elaborated that the DOE definition
should be modified to allow for technology advancements in control
technology and recommended a definition similar to the definition for
``demand defrost control systems'', which requires that the control
scheme ``monitor one or more parameters that always vary.'' (Daikin,
No.24 at p.2) Samsung elaborated that DOE's proposal would require a
communicating thermostat, which they claimed to be unnecessary for
achieving appropriate compressor and fan control and stated would add
unnecessary cost to the consumer. (Samsung, No.22 at pp.1-2)
While DOE acknowledges that there may be other control approaches
to set compressor speed other than approaches that communicate the
difference in space temperature and space setpoint temperature, DOE
notes that minimizing this difference between a controlled parameter
and its setpoint is the key function of the control system, and use of
this parameter to set conditioning system operation is a fundamental
feature of most modern control systems. In its proposal, DOE
distinguished between communicating and non-communicating based on
whether the system includes this fundamental aspect of control systems.
DOE premised its proposals on the understanding that non-communicating
systems would likely encounter greater issues regarding the
representativeness of field-versus-tested performance, as compared to
communicating systems.
As mentioned, DOE acknowledges that other control approaches may
provide control represented adequately by the fixed-speed testing that
is currently prescribed in its test procedures for CAC/HP system but
given the fundamental difference in the control approach, i.e., not
using information about the space temperature deviation from setpoint,
DOE does not believe there has been sufficient

[[Page 64562]]

information provided confirming this adequacy. As DOE considers more
comprehensive test procedure changes in a future rulemaking, it will
further evaluate this issue and is open to revising the definition
accordingly. Also, the proposed definition does not restrict other
control parameters in addition to the space temperature offset from
setpoint being used by the control system to set system operation.
Hence, DOE is adopting the definition for communicating and non-
communicating variable-speed coil-only system as proposed.
As previously introduced, DOE also considered that it may be
necessary for manufacturers to certify whether a variable speed coil-
only rating is based on non-communicating or communicating control but
did not propose any certification requirements in the March 2022 CAC TP
NOPR and instead stated that these changes may be considered in a
separate rulemaking. 87 FR 16830, 16838.
In response, the Joint Advocates supported the concept that DOE
require certification of VSCO units as communicating or non-
communicating and encouraged DOE to finalize all pertinent
certification provisions as soon as possible. (Joint Advocates, No. 18
at p. 2) As indicated, DOE may consider certification requirements in a
separate rulemaking.
c. Applicability to Variable Speed Blower Coil Systems
In the March 2022 CAC TP NOPR, DOE further discussed that
installations using non-communicating controls may not be limited only
to variable-speed coil-only systems but could also occur with variable-
speed blower-coil systems. 87 FR 16830, 16838. DOE noted that the
proposed test procedure distinguishes between the testing approach used
for coil-only configurations and the testing approach used for blower-
coil configurations. Id. DOE argued that as coil-only installations are
much more likely than blower-coil installations to involve use of both
the existing furnace fan and existing controls, the non-communicating
test procedure should be reflective of coil-only installations because
they are more representative than blower coil installations. Id.
With respect to the applicability of the proposed VSCO testing
provisions to variable speed blower-coil CACs and HPs, Emerson
commented that the ability to set compressor speed and optimize airflow
rate relative to compressor speed may be even more important in blower-
coil systems than in coil-only systems and requested that DOE address
this point. (Emerson, No. 14 at p. 3) Trane similarly asserted that it
is important that DOE addresses non-communicating, blower-coil variable
speed systems in addition to the proposed provisions for coil-only
systems. (Trane, No. 10 at p. 2) Trane stated that such blower-coil
systems have the same issue of misrepresenting the applied performance
(i.e., the performance measured in a field installation) by allowing
them to use the communicating, variable speed procedures. Id. Trane
elaborated that the wiring and control of such systems is obvious from
the installation instructions, and they operate in a similar fashion to
the furnace-coil (i.e., coil-only) combinations with one or two-stage
fan operation. Id. Trane provided an example \26\ of such a product
where a variable-speed CAC outdoor unit is certified with an indoor
blower-coil unit only capable of one stage of airflow operation, and
the connections are non-communicating 24V signals between equipment and
thermostat. Id.
---------------------------------------------------------------------------

\26\ Trane provided an example of a Bosch system with AHRI
reference number 206395973 and provided a link to the installation
instructions: <a href="https://www.bosch-thermotechnology.us/us/media/country_pool/documents/bosch_ids_bva15_iom_10.2020.pdf">https://www.bosch-thermotechnology.us/us/media/country_pool/documents/bosch_ids_bva15_iom_10.2020.pdf</a>.
---------------------------------------------------------------------------

DOE acknowledges the concerns expressed by Trane and Emerson that
questions remain regarding use of non-communicating controls for
blower-coil systems and whether the compressor and/or fan speeds used
for testing such systems are representative of field operation.
However, DOE initiated this rulemaking to address a focused group of
known issues, including those that have been raised through the test
procedure waiver process. As noted in the March 2022 CAC TP NOPR, DOE
limited its proposals addressing potential concerns about variable-
speed systems to coil-only systems and may more comprehensively address
these issues for all variable-speed systems in a future rulemaking that
will satisfy the 7-year lookback requirements (see 42 U.S.C.
6293(b)(1)(A)). 87 FR 16830, 16838.
d. Represented Values and Testing Requirements
Coil-only testing approaches for variable-speed systems address the
installation of variable-speed technology in which the newly installed
system uses existing components, for example an existing furnace fan.
For single-capacity and two-capacity split-system air-conditioners,
certification requirements anticipate this likely installation scenario
by requiring that such models include performance representations with
a coil-only combination representative of the least-efficient
combination in which the outdoor unit is sold (see 10 CFR
429.16(a)(1)). For variable speed split-system air conditioners,
represented values are required for every individual combination
distributed in commerce, including all coil-only and blower-coil
combinations (see 10 CFR 429.16(a)(1)). However, there is no
requirement that each model of outdoor unit include at least one
representation based on the least-efficient coil-only combination
distributed in commerce. In the March 2022 CAC TP NOPR, DOE considered
whether such a requirement may be appropriate for variable-speed
systems. 87 FR 16830, 16838-16839.
Through a review of product datasheets and installation
instructions, DOE found that there is a wide range of instruction
regarding whether variable-speed CAC systems must be paired with
specific models of indoor units and/or air movers (e.g., furnaces) in
order to achieve the represented performance. Id. DOE identified that
some literature is very clear that achieving the rated performance for
a given outdoor unit is contingent on installation with specific
components (e.g., communicating controls and indoor fans capable of
variable-speed operation), while other literature does not mention the
need for such components. Id. DOE identified that this latter group is
not limited to brands that have been granted test procedure waivers or
interim waivers for testing variable-speed coil-only systems,
indicating that the issue is more broadly applicable to variable-speed
CAC installations and it is possible that variable-speed systems are
being installed in coil-only applications for which representations of
performance are not representative of actual performance (because the
represented values are based on blower-coil pairing while the
installation scenario is coil-only). Id. However, because less than 5
percent of variable speed system installations are coil-only \27\ and
the number of certified combinations of VSCO systems is a small
percentage \28\ of overall variable

[[Page 64563]]

speed system certifications, DOE concluded that VSCO installations are
not likely representative of variable speed system operation as a
whole. Id.
---------------------------------------------------------------------------

\27\ Based on information DOE has from the previous energy
conservation standards rulemaking pertaining to central air
conditioners and heat pumps. See 82 FR 1786.
\28\ For example, there are roughly 27,000 combinations listed
in the AHRI Database for which a non-zero intermediate indoor air
volume rate is listed, indicating that the combination is a
variable-speed model. DOE reviewed the current certifications in the
certification compliance management system and found that there are
approximately 400 variable-speed coil-only combinations,
representing roughly 1.5 percent of the total variable speed
combinations certified to the Department.
---------------------------------------------------------------------------

In the March 2022 CAC TP NOPR, in order to improve
representativeness of the representations of VSCO installations DOE
proposed tested-combination requirements pertaining to variable speed
systems, summarized here in Table III-3. 87 FR 16830, 16839.

Table III-3--Proposed Tested Combination Requirements for Variable Speed
Split-System CACs
------------------------------------------------------------------------
Required tested
Scenario combination
------------------------------------------------------------------------
Outdoor unit is distributed in commerce with any Variable Speed Non-
non-communicating coil-only combination(s). Communicating Coil-
Only.
Outdoor unit is distributed in commerce with any Variable Speed
communicating coil-only combination(s), but no Communicating Coil-
non-communicating coil-only combination. Only.
Outdoor unit is only distributed in commerce Variable Speed Blower-
with blower-coil combinations. Coil.
------------------------------------------------------------------------

In the March 2022 CAC TP NOPR, DOE noted that the variable-speed
coil-only waiver petitions addressed both air-conditioners and heat
pumps. 87 FR 16380, 16389. Thus, DOE considered whether the coil-only
tested combination requirement should apply to variable speed heat
pumps and/or to single-stage and/or two-stage heat pumps. Id. DOE noted
that coil-only heat pumps allow the heating system to provide heat
either using the furnace or the heat pump. Id. There has been greater
interest in such systems in recent years, since they provide heating
with a furnace in extreme cold conditions for which a heat pump may
have limited capacity and/or reduced efficiency.\29\ DOE proposed to
require coil-only tested combinations for variable-speed heat pumps,
but not for single- and two-stage heat pumps, because DOE expects that
the representativeness of blower-coil tests would deviate more from
coil-only tests for variable-speed systems, due to the use of a
variable-speed indoor fan and use of an intermediate air volume rate
used for intermediate-speed testing for variable-speed systems. Id. DOE
argued that the test procedures for single-stage and two-stage heat
pumps are more restrictive with regard to allowed air volume rates and
thus performance differences between blower-coil and coil-only
operation would be less. Id.
---------------------------------------------------------------------------

\29\ <a href="https://www.trane.com/residential/en/resources/glossary/dual-fuel-heat-pump/">https://www.trane.com/residential/en/resources/glossary/dual-fuel-heat-pump/</a> (last accessed 2/4/2022).
---------------------------------------------------------------------------

Regarding variable-speed coil-only systems using indoor units
manufactured by independent coil manufacturers (``ICMs''), in the March
2022 CAC TP NOPR, DOE noted that the regulations require certification
of the performance of every individual combination distributed in
commerce, including both blower-coil and coil-only (see 10 CFR
429.16(a)(1)). Id. However, a tested combination for an ICM indoor unit
must include the least-efficient outdoor unit with which the indoor
unit is distributed in commerce (see 10 CFR 429.6(b)(2)(i)). Id. DOE
stated in the NOPR that it does not believe any changes are needed with
respect to ICM certifications as the current regulations already
encompass representing all combinations distributed in commerce,
including noncommunicating and communicating variable-speed coil only
systems. Id. Further, DOE noted that the least-efficient outdoor unit
with which the indoor unit is distributed in commerce is not likely to
be a variable-speed system, and thus the question of communicating or
non-communicating coil-only status does not apply. Id.
DOE received comments from multiple stakeholders regarding its
proposals for represented values and testing requirements for VSCO CACs
and HPs.
Lennox agreed with DOE's proposal not to require that all variable-
speed CACs and HPs have a coil-only representation, as is required for
single- and two-stage split air-conditioning systems. (Lennox, No. 19
at p. 3)
Rheem disagreed with DOE's proposal to implement differing test
methods for communicating and non-communicating VSCO systems. (Rheem,
No. 21 at p. 2) Rheem elaborated that even though they support the DOE
proposal to expand the federal test procedure to account for coil-only
variable speed systems, the exclusive distinction between communicating
and non-communicating classifications for coil-only variable speed
systems creates additional complexity and has the potential to add more
test burden while reducing market flexibility. Id. Rheem stated that
ideally there would only be one test procedure for coil-only variable
speed systems, and preferably the one test would be the non-
communicating method, as this would likely represent the least
efficient system that may be installed the field. Id. Rheem recommended
that DOE reconsider the merits of implementing differing test methods
and suggested further study by DOE to quantify the difference in
efficiency representation between the test methods for communicating
versus non-communicating prior to incorporating this into the final
rule. Id.
DOE is working to better understand the differences in performance
between communicating and non-communicating systems but believes that
the fundamental differences in the control architecture of the two
approaches will lead to performance differences. For example, DOE
expects that non-communicating VSCO systems, when subjected to an
applied load, will likely demonstrate ``hunting'' for compressor speed,
fan speeds, and valve positions, which would reduce the measured
efficiency and potentially invalidate test results. For communicating
VSCO systems, however, DOE expects that these systems will be more
likely to include the requisite hardware and controls architecture to
accurately and repeatably set position of modulating components during
testing.
Trane commented that although DOE's recommendations for variable-
speed coil-only test procedures were a good start at addressing 24V
coil-only ratings with variable speed outdoor units, it needs to be
expanded. (Trane, No. 10 at pp. 1-2) Trane specified that in situations
where two-stage thermostats are paired with a two-stage airflow capable
furnace, the proposed procedure is a reasonable rating approach, but
that in the converse case with a single-stage thermostat or a single-
stage airflow furnace, the proposed procedure will inflate the unit
efficiency. Id. Trane recommended that two-different `coil-only
ratings' should be listed for such systems. Id. Trane elaborated that
an accessory note would indicate the applicable installation (1-stage
or 2-stage). Id. The rating

[[Page 64564]]

procedure for the 1-stage case would essentially follow the single
capacity system rating procedures, whereas the 2-stage case would
follow the procedure proposed by DOE in the March 2022 CAC TP NOPR. Id.
Trane also provided two connection diagrams \30\ as examples. Id. Both
diagrams showed connection with either a 1-stage thermostat and indoor
unit or a 2-stage thermostat and indoor unit. Id.
---------------------------------------------------------------------------

\30\ Trane provided examples of two Bosch systems with AHRI
reference numbers 206395973 and 206395967 and provided a link to the
installation instructions: <a href="https://www.bosch-thermotechnology.us/us/media/country_pool/documents/bosch_ids_bovb18_iom_10.2020.pdf">https://www.bosch-thermotechnology.us/us/media/country_pool/documents/bosch_ids_bovb18_iom_10.2020.pdf</a>.
---------------------------------------------------------------------------

DOE notes that representations of performance for both single-stage
and two-stage installations are not required for two-stage coil-only
systems. The two-stage coil only test provisions in the current DOE
test procedure are premised on the installation location having two-
stage thermostat wiring (Final Rule Technical Supporting Document,
EERE-2014-BT-STD-0048, No. 98, p. 8-25). DOE similarly assumes the
presence of the necessary wiring for the installation of variable-speed
coil-only systems in two-stage configuration.
Daikin commented that due to the nature of variable-speed CAC and
HP, having a coil-only representation requirement for ICMs may be
appropriate. (Daikin, No. 24 at p. 2) DOE notes that the current
requirements in 10 CFR 429.16 already require a representation for
every combination distributed in commerce, and hence any coil-only
product distributed in commerce by an ICM would already be required to
have a coil-only representation for variable-speed combinations with
which it is distributed in commerce. The further clarification of non-
communicating VSCO combinations in this rule extends that requirement
such that there must at least be a representation based on the non-
communicating VSCO test procedure if non-communicating combinations are
distributed in commerce.
Daikin and Rheem disagreed with the proposal to require the tested
combination to be coil-only for variable-speed systems that are
distributed in commerce in some cases with coil-only combinations.
(Daikin, No. 24 at p. 2; Rheem, No. 21 at p. 2) Daikin claimed that a
mandatory coil-only tested combination requirement for variable speed
systems would burden manufacturers of such systems with additional
testing requirements and would force lower represented values not
indicative of variable speed performance in typical installations.
(Daikin, No. 24 at p. 2) Daikin stated that manufacturers would still
test a blower-coil combination if the regulations require them to test
a coil-only combination, because of the vast majority of full-system
installations for VS systems. Id. Although Daikin did not explain why a
manufacturer couldn't test a coil-only combination and use an
alternative efficiency determination method (``AEDM'') to determine the
representative value for blower-coil systems with which the same
outdoor unit is paired, DOE acknowledges that the wider range of air
volume rates allowed with blower-coil testing as compared with coil-
only testing \31\ could make the use of testing (as opposed to an AEDM)
more important in determination of an accurate representation for
blower-coil systems than for coil-only systems. In addition, the
Emerson comments described in the following paragraph suggest that many
variable-speed outdoor models with blower-coil representations may be
distributed in commerce for a small percentage of installations in
coil-only combinations (see Emerson, No. 14 at p. 2). Although not
explicitly mentioned in comments addressing this topic, DOE realizes
that manufacturers may have already completed testing for many models
in advance of the January 1, 2023, date on which appendix M1 will be
required--requiring a coil-only representation at this late stage may
require additional testing. Thus, DOE is partially retracting the
proposed requirement for a coil-only tested combination for VS systems
distributed in commerce in coil-only combinations. Specifically, DOE is
maintaining this requirement only for non-communicating coil-only
combinations. As already discussed, the control approach for non-
communicating systems is fundamentally different than the control
approach for communicating systems. Hence, DOE is not convinced that a
test using the provisions for communicating VS systems (either blower-
coil or coil-only) would provide sufficient indication of non-
communicating performance to allow accurate prediction of non-
communicating performance using an AEDM based on the communicating
system test. Thus, DOE will not require at this time that the tested
combination be coil-only in cases where only communicating VSCO
combinations (and no non-communicating VSCO combinations) are
distributed in commerce with a given outdoor unit. However, DOE may
reconsider these decisions in a later rulemaking.
---------------------------------------------------------------------------

\31\ As described in section III.C.2.c, VSCO systems will use at
most two air volume rates, while blower-coil VS systems may have
multiple air volume rates. First, there is an intermediate air
volume rate explicitly anticipated for such systems (see appendix
M1, section 3.1.4.3). Also, as discussed in section III.D.1, DOE is
clarifying that air volume rate may change with outdoor air
temperature.
---------------------------------------------------------------------------

Emerson commented that it agreed with DOE's assessment that less
than 5 percent of variable speed systems are installed as coil-only
configurations today. (Emerson, No. 14 at pp. 1-2) However, Emerson
commented that it believes that two-stage CACs currently have a
similarly small portion of installations in a coil-only configuration,
and elaborated that they believe that energy specifications and test
procedures should be technology-neutral and advocated that all
modulating technology (i.e., two or more stages) should be treated in
the same manner regarding coil-only representation requirements. Id.
Emerson asserted that because of the ability to install VSCO CACs with
a non-communicating thermostat, and because coil-only installation
percentages are similar between variable speed and two-stage CACs, the
coil-only representation requirement should either apply for both
technologies or for neither technology. Id. Emerson provided examples
of variable speed CAC product literature indicating that even for
outdoor units with communicating capability, there are instructions for
installation in a non-communicating setup using a conventional 24V non-
communicating thermostat control.\32\ Id. Emerson also highlighted that
in some cases, the product literature provides instructions for a non-
communicating coil-only installation but shows represented values that
are unclear whether they are derived from a blower-coil pairing or from
the non-communicating coil-only installation.\33\ Id. Emerson
elaborated that this creates the possibility that variable speed
systems are currently being installed in coil-only applications

[[Page 64565]]

for which the system representations may not be representative of
actual performance. Id.
---------------------------------------------------------------------------

\32\ Emerson identified the Bosch BOVB 18 split system heat pump
with ratings as low as 15 SEER (link: <a href="https://issuu.com/boschthermotechnology/docs/bosch_ids_family?fr=sYmYyNDIwODA0Mzg">https://issuu.com/boschthermotechnology/docs/bosch_ids_family?fr=sYmYyNDIwODA0Mzg</a>) and
the Daikin FTQ series heating and cooling systems, with SEER ratings
from 14.8-16 SEER (link: <a href="https://backend.daikincomfort.com/docs/default-source/product-documents/light-commercial/brochures/cb-ftqducted.pdf?sfvrsn=608a2626_20&_ga=2.261207556.887080242.1653602507-1260064005.1653602507&_gl=1*1cbcmhc*_ga*MTI2MDA2NDAwNS4xNjUzNjAyNTA3*_ga_MXJ05EZJZT*MTY1MzYwMjUwNi4xLjEuMTY1MzYwMjU5OS4w">https://backend.daikincomfort.com/docs/default-source/product-documents/light-commercial/brochures/cb-ftqducted.pdf?sfvrsn=608a2626_20&_ga=2.261207556.887080242.1653602507-1260064005.1653602507&_gl=1*1cbcmhc*_ga*MTI2MDA2NDAwNS4xNjUzNjAyNTA3*_ga_MXJ05EZJZT*MTY1MzYwMjUwNi4xLjEuMTY1MzYwMjU5OS4w</a>).
\33\ Emerson identified the Lennox Elite Series EL18XCV Units
(link: <a href="https://tech.lennoxintl.com/C03e7o14l/VIu12Ch2uV/507955-01a.pdf">https://tech.lennoxintl.com/C03e7o14l/VIu12Ch2uV/507955-01a.pdf</a>) and the Carrier 24VNA0 Infinity Variable Speed Air
Conditioners with Greenspeed Intelligence (link: <a href="https://esmithair.com/wp-content/uploads/2020/02/Air-Conditioners_24VNA0.pdf">https://esmithair.com/wp-content/uploads/2020/02/Air-Conditioners_24VNA0.pdf</a>).
---------------------------------------------------------------------------

In response to Emerson's comments about installation instructions
allowing for installation of non-communicating coil-only installations
for VS systems that presumably are tested on the basis of blower-coil
configurations, DOE notes that 10 CFR 429.16 already requires that
representations be provided for all combinations distributed in
commerce. Hence, representations are required for coil-only
combinations for any VS outdoor unit that is distributed in commerce in
such combinations. The changes in this final rule stipulate that any
such coil-only representation be based on whether the control system
with which it is installed is communicating or non-communicating.
In response to Emerson's comments that coil-only installations are
rare also for two-stage systems, DOE notes that the comments received
on the topic of the default fan power values for low-stage operation
when testing two-stage coil-only systems (see section III.C.1) suggests
otherwise. None of the comments addressed the possibility that a coil-
only configuration may not be representative of two-stage system
installations. Further, the discussion emphasized the trends in motor
technology of furnaces that have shipped in recent years (see, e.g.,
AHRI, No. 25 at p. 3), suggesting that the representative air movers
for two-stage systems will in many cases be existing furnaces rather
than the fans of blower-coils systems. Hence, in this final rule DOE
has not removed the coil-only representation requirement for two-stage
systems or added such a requirement for variable-speed systems.
In summary, manufacturers will be required to represent variable-
speed ACs based on how they distribute them in commerce, which includes
whether they are coil-only communicating, coil-only noncommunicating,
or blower coil, as applicable to a given model of outdoor unit.
3. Space-Constrained Coil-Only CAC Ratings
a. Background
In the March 2022 CAC TP NOPR, DOE discussed the current
requirements for determining represented values of energy efficiency
and capacity for CACs and HPs at Sec. 429.16(a). 87 FR 16830, 16839-
16841. This section specifies that for each model of outdoor unit of a
split-system CAC with single-stage or two-stage compressors,
manufacturers are required to provide represented values based on at
least one coil-only combination that is representative of the least
efficient combination distributed in commerce with that model of
outdoor unit. The requirement to provide coil-only ratings for each
basic model also applies to single split CACs designed for space-
constrained applications (``SC-CAC''). Additional blower-coil ratings
are allowed (i.e., optional) for any applicable individual
combinations, if distributed in commerce. 10 CFR 429.16(a).
DOE also discussed the related waiver requests received from
manufacturers of space-constrained split-system CACs following the
January 2017 CAC TP Final Rule. 87 FR 16830, 16839-16841. DOE received
petitions for test procedure waivers from National Comfort Products
(``NCP''), AeroSys, and First Company related to the represented value
requirements for space-constrained split-system CACs. Id. Each
petitioner claimed that specified basic models of SC-CAC outdoor units
listed in their respective petitions are designed and intended to be
sold only with proprietary blower-coil indoor units equipped with high-
efficiency electronically commutated (``ECM'') fan motors, and not as a
coil-only combination, and therefore requested exemption from the
requirements at 10 CFR 429.16(a)(1) to provide represented values as a
coil-only combination. (NCP, EERE-2017-BT-WAV-0030, No. 1 at p. 1;
AeroSys, EERE-2017-BT-WAV-0042; No. 1 at p. 1; First Co., EERE-2018-BT-
WAV-0012, No. 2 at p. 1) As described in the March 2022 CAC TP NOPR,
DOE denied First Co.'s petition, Aerosys filed for bankruptcy following
DOE's granting them an interim waiver, and DOE granted an interim
waiver applicable for appendix M to NCP on May 15, 2018. 87 FR 16830,
16841.
In the March 2022 CAC TP NOPR, DOE proposed several revisions
related to representation requirements for space-constrained split-
system CACs. 87 FR 16830, 16840-16841. Specifically, DOE proposed to
amend the language in the table found in 10 CFR 429.16(a)(1) to clarify
the rating requirements pertaining to single-split CACs with single-
stage or two-stage compressors.\34\ Id. DOE also tentatively concluded
that measuring the performance of space-constrained systems exclusively
with high-efficiency blower-coil combinations, as requested in waiver
petitions from NCP, AeroSys, and First Co., is not generally
representative of field operation. Id. DOE also noted that because
NCP's waiver petition and the prescribed alternate test procedure are
specific to appendix M, the interim waiver will terminate on the date
on which testing is required under appendix M1 (i.e., January 1, 2023).
Id. DOE therefore did not propose amendments to appendix M1 to
incorporate the interim test procedure waiver granted to NCP, and
requested comment on these proposals. Id.
---------------------------------------------------------------------------

\34\ DOE's proposed clarifications would require every single-
stage and two-stage outdoor unit of single-split CAC to have a
compliant rating with a coil-only combination that is distributed in
commerce and representative of the least efficient combination
distributed in commerce for that particular model of outdoor unit.
---------------------------------------------------------------------------

The Joint Advocates and Lennox supported DOE's proposal to require
coil-only representations for all single- and two-stage single-split
system CACs, including space-constrained systems. (Joint Advocates, No.
18 at p. 3; Lennox, No. 19 at p. 3) Lennox elaborated on their support
by stating that consistency in requirements across similar product
types provides consumers with more information to properly compare
product choices and promotes market fairness.
In contrast with the Joint Advocates and Lennox, AHRI and NCP did
not support DOE's proposal. (AHRI, No. 25 at pp. 2-3; NCP, No. 16 at
pp. 2-10) AHRI and NCP criticized several aspects of DOE's proposal to
require coil-only ratings for space-constrained CACs. Id. In general,
AHRI and NCP critiqued the factual basis underlying DOE's assumptions
that a coil-only rating would be most representative of real-world
performance for space-constrained systems, and asserted that DOE must
amend the test procedure in appendix M1 to incorporate the interim
waiver granted to NCP. (AHRI, No. 25 at p. 3; NCP, No. 16 at p. 2) NCP
also claimed that they would face undue burden from DOE's proposal,
related to sunk design and testing costs and potential redesign costs
they claim would be required to generate a compliant coil-only rating.
(NCP, No. 16 at p. 2) AHRI elaborated by claiming that DOE did not
provide persuasive data to justify not amending appendix M1 to specify
testing of space-constrained split-system CACs in a manner consistent
with NCP's waiver and that the test procedure outlined in the waiver
produces results that more accurately reflect the performance of space-
constrained CAC systems, as opposed to a coil-only rating. (AHRI, No.
25 at p. 3)
b. Applicability of Coil-Only Requirement
In the March 2022 CAC TP NOPR, DOE briefly discussed some of the
reasoning from past documents used to

[[Page 64566]]

support the coil-only representation requirement for spilt-system air
conditioners generally. 87 FR 16830, 16847. DOE also discussed the
applicability of the coil-only requirement for space-constrained CACs,
specifically. 87 FR 16830, 16841. This section provides a more
extensive discussion of the historical context to further support DOE's
position on this matter, in light of comments on this rulemaking as
well as historical assertions from manufacturers of space-constrained
products that the coil-only provisions should not apply to these
products (e.g., see First Co. comments at EERE-2016-BT-TP-0029, No. 21
at p. 2).
The historical application of the coil-only representation
requirement to SC-CACs involves several changes in regulatory
provisions for this type of product, including the provisions for
``Through-the-Wall'' (TTW) product classes of CACs and HPs. In their
waiver petition, and in comments in response to the March 2022 CAC TP
NOPR, NCP refers to their models of space-constrained CACs as ``TTW''
products. However, while the models that were the subjects of the NCP
waiver are physically installed through the exterior wall, the specific
term ``through-the-wall'' no longer has regulatory meaning as a defined
class of products. As explained in the following paragraphs, the TTW
product class expired from DOE definitions in 2010 and is no longer
applicable.
In a May 2002 final rule for energy conservation standards for CACs
and HPs, (``May 2002 CAC ECS Final Rule''), DOE established separate
product classes of SC and TTW product classes. 67 FR 36368, 36406 (May
23, 2002). DOE defined TTW CACs and HPs based on physical
characteristics of the unit (i.e., limitations on cooling capacity and
heat exchanger area), and the installation scenario (i.e., designed to
be installed within a fixed-size opening in an external wall). 10 CFR
430.2. The definition for TTW CACs was also limited to products
manufactured prior to January 23, 2010. Id. In an August 2004
rulemaking for energy conservation standards for CACs and HPs (``August
2004 CAC ECS Final Rule''), DOE elaborated that after January 23, 2010,
the standards for space-constrained products would apply to TTW CACs
and HPs. 69 FR 50997, 50998 (August 17, 2004). In a June 2011 direct
final rule (DFR) regarding energy conservation standards for
residential furnaces and CACs/HPs (``June 2011 Furnaces & CAC ECS
DFR'') DOE discussed the recent expiration of the through-the-wall
product class for CACs. 76 FR 37408, 37446 (June 27, 2011). DOE noted
that the TTW product class expired on January 23, 2010, and
reclassified all TTW products into corresponding classes of space-
constrained CACs. Id. To further illuminate this point, DOE added a
footnote to the energy conservation standards tables at Sec.
430.32(c)(2) to clarify the treatment of TTW product classes. 76 FR
37408, 37546.
The existence of the TTW product class (and subsequent expiration
in 2010) interacts with the coil-only representation requirements
described by DOE in other documents. In an October 2007 test procedure
final rule for CACs (``October 2007 CAC TP Final Rule''), DOE discussed
the required indoor unit combinations for determination of represented
values for CACs and HPs. 72 FR 59906, 59913-59914 (October 10, 2007).
DOE clarified in this rule that for most classes of single-stage,
single-split CACs the highest sales volume indoor unit would be a coil-
only indoor unit, and thus DOE's regulations required that represented
values for these systems be determined based on a coil-only pairing.
Id. DOE included exemptions to the coil-only representation requirement
for certain kinds of single-stage, single-split CACs that would likely
be distributed in commerce only with blower-coil indoor units. Id.
These exempted product classes included mini-splits, multi-splits, and
TTW units. Id. For each of these classes, DOE clarified in the October
2007 CAC TP Final Rule that representations could be based on blower-
coil combinations. Id.
In subsequent documents, DOE re-iterated the coil-only
representation requirement and clarified the applicability to space-
constrained CACs. In a draft guidance document published August 19,
2014 (``2014 CAC Guidance''), DOE stated that split-system CACs with
more than one compressor stage may be tested and rated as a blower-coil
combination only if the condensing unit is sold exclusively with
blower-coil indoor units. EERE-2014-BT-GUID-0033-0001, p. 1. The 2014
CAC Guidance stated that per existing regulations in the CFR, no
provisions existed permitting use of a blower-coil for testing and
rating a split-system central air conditioner where the condenser unit
is also offered for sale with a coil-only indoor unit and that,
furthermore, there was no provision in the CFR permitting the use of a
blower-coil for testing and rating a condensing unit with a single-
speed compressor. Id. Soon thereafter, DOE published a test procedure
final rule pertaining to CACs and HPs (``June 2016 CAC TP Final
Rule''). 81 FR 36992 (June 8, 2016). DOE adopted language that
explicitly required a coil-only representation requirement for single-
split single- and two-stage CACs into its provisions at 10 CFR
429.16(a)(1), which became effective 180 days following the publication
of the final rule (i.e., December 5, 2016). DOE also adopted these
provisions for space-constrained split-system CACs given that they are
subject to the same test procedures and sampling plans as non-space-
constrained single-split air conditioners. 81 FR 36992, 37002. DOE also
adopted provisions at Sec. 429.16(b)(2) requiring that such systems be
tested with ``the model of coil-only indoor unit that is likely to have
the largest volume of retail sales with the particular model of indoor
unit.'' 81 FR 36992, 37050.
In the January 2017 CAC TP Final Rule, DOE kept the same approach
from the June 2016 CAC TP Final Rule requiring that represented values
for one- and two-stage single-split CACs (including space-constrained)
must be determined based on a coil-only value representative of the
least-efficient combination distributed in commerce with that
particular model of outdoor unit. DOE amended the tested combination
requirements to prevent possible conflict between the representation
requirements and the tested combination requirements. Instead of
requiring the ``highest sales volume'' indoor unit in the tested
combination, the January 2017 CAC TP Final Rule required, simply, ``A
model of coil-only indoor unit''. 82 FR 1426, 1470. This clarification
made clear that in all instances, one- and two-stage single-split CACs
(including space-constrained) were required to test and determine
represented values based on a coil-only indoor unit, regardless of
prevalence of retail sales.
In the January 2017 CAC TP Final Rule, DOE also fielded comments
from manufacturers of space-constrained CACs regarding the interplay of
the TTW and space-constrained product classes with the coil-only
representation and testing requirements. 82 FR 1426, 1461-1462. DOE
reiterated that an exclusion for coil-only testing of space-constrained
products was never established, and that manufacturers of space-
constrained products had always been subject to the coil-only rating
requirement, as clarified in the June 2016 CAC TP Final Rule. Id. DOE
also alluded to the expiration of the TTW product class, describing
that the coil-only exclusion for TTW CACs, previously present in 10 CFR
429.16(a)(2)(ii), would not encompass

[[Page 64567]]

the circumstances described by the commenters. Id. DOE reiterated that
while the language being adopted in the January 2017 CAC TP Final Rule
explicitly removed the exclusion from a coil-only testing requirement
for TTW units sold and installed with blower-coil units--it would have
no effect on the ratings procedures for space-constrained units (due
the 2010 expiration of the TTW product class), which are subject to the
same coil-only provisions as for other split system CACs. Id.
In summary, single-split single-stage CACs, including space-
constrained CACs, have historically always been subject to a coil-only
representation requirement, via application of the highest-sales-
volume-combination (HSVC) concept. DOE has, at multiple points, made
this requirement more explicit in the regulatory text but has
consistently held that space-constrained CACs were never excluded from
this requirement. For space-constrained CACs meeting the historical
definition of through-the-wall (TTW) products, DOE has similarly
explained in multiple documents that this product class expired in
January 2010 at which point TTW products were subsumed by the space-
constrained product class, which DOE explained explicitly in the
January 2017 CAC TP Final Rule (82 FR 1426, 1462). Through these facts
it is evident that through-the-wall space-constrained CACs, such as
those identified in NCP's waiver petition, have been subject to the
coil-only rating requirement at least since 2010, and the January 2017
CAC TP Final Rule did not represent the first instance of this
practice.
c. Other Considerations
i. Prevalence of Coil-Only Installations for Space-Constrained CACs
In response to the March 2022 CAC TP NOPR, NCP commented that it
does not manufacture a coil-only indoor unit that may be matched with
the condensing units specified in their waiver, nor do they identify or
offer any other coil-only matched system for distribution in commerce.
(NCP, No. 16 at p.10) Additionally, AHRI and NCP questioned the
representativeness of a coil-only rating for space-constrained
products. Specifically, they both challenged DOE's assumption that the
relative division of coil-only installations applies equally between
typical CAC and space-constrained CAC. (AHRI, No. 25 at p. 2; NCP, No.
16 at pp. 3-5) AHRI asserted that space-constrained CAC systems are
typically installed in multi-family buildings (as opposed to single-
family homes) and claimed that coil-only installations for space-
constrained systems are significantly less common than coil-only
installations for conventional split CACs. (AHRI, No. 25 at p. 2) AHRI
cited DOE's determination that, in 2021, 39% of split-system CAC
installations would be blower-coil indoor units and the remaining 61
percent would be coil-only installations.\35\ Id. AHRI contrasted this
with 2015 RECS microdata showing that for multi-family buildings, only
45 percent of buildings use natural gas or other fuel source for
heating while 55 percent of buildings use electric resistance heating.
Id. DOE interprets AHRI`s comment to imply that space-constrained CACs
are most typically installed in multi-family housing, and multi-family
buildings are predominated by electric heating (which would be
indicative of a blower-coil CAC using electric resistance heating
elements) rather than combustion heating (which would be indicative of
a coil-only CAC paired with a furnace). Therefore, AHRI's comment
implies that space-constrained CACs would be represented more
accurately by a blower-coil combination instead of a coil-only
combination. NCP reiterated the data presented by AHRI and commented
that coil-only installations for space-constrained systems are
uncommon. (NCP, No. 16 at pp. 3-5)
---------------------------------------------------------------------------

\35\ As introduced in section III.D.1.b of this rulemaking, DOE
first discussed its assumptions regarding market penetration rates
for various types of furnace fan motors in the December 2016 CAC ECS
TSD (EERE-2014-BT-STD-0048-0098, page 7-16). These same proportions
were carried through in the analysis proposed in the March 2022 CAC
TP NOPR.
---------------------------------------------------------------------------

DOE notes that although AHRI provided summary data regarding the
heating source for multi-family buildings, neither AHRI nor NCP
provided concrete data showing the relative proportion of coil-only
installations for space-constrained CACs vs coil-only installations for
conventional CACs. DOE finds that AHRI's inference that a higher
proportion of electric heating in multi-family homes does not
constitute sufficient evidence to conclude that the proportion of coil-
only installations for space-constrained systems is lower than the
proportion for conventional systems. With respect to NCP's comment that
they do not manufacture or specify coil-only indoor units to be paired
with their TTW condensing units, DOE notes that the coil-only
representation requirement is equally applicable for all single- and
two-stage split-system CACs. This requirement accounts for the
likelihood that CAC outdoor units may be installed as a coil-only
configuration, even if not specified as such by the outdoor unit
manufacturer. In this manner, the coil-only requirement provides a
conservative estimate of performance that captures the range of likely
installation scenarios for these products. Therefore, DOE concludes
that an approach consistent with the January 2017 CAC TP Final Rule
(i.e., requiring coil-only representations for all single- and two-
stage split system CACs, including space-constrained) provides more
representative measurement of space-constrained system performance. DOE
also acknowledges Lennox's comment stating that by continuing to
require a coil-only representation for all types of split-system CACs,
consumers would have better ability to compare products on the basis of
cost-efficiency tradeoffs. (Lennox, No. 19 at p. 3)
ii. Systems Distributed in Commerce
In the March 2022 CAC TP NOPR, DOE highlighted instances for which
outdoor units designed for space-constrained applications are being
distributed in commerce without a corresponding blower-coil indoor
unit, indicating the potential for pairing a replacement outdoor unit
with an existing indoor unit using a legacy fan that would not likely
be comparable to the ECM fan of the blower-coil indoor unit on which
the system rating is based. 87 FR 16830, 16841. DOE noted that the
cited example is for sale of an NCP outdoor unit, which indicates that
it is impossible to ensure its installation with a blower-coil indoor
unit, as suggested by NCP's waiver petition. Id.
AHRI and NCP challenged DOE's conclusion that NCP's space-
constrained CAC models are distributed in commerce with a coil-only
indoor unit pairing. (AHRI, No. 25 at p. 2; NCP, No. 16 at p. 10) NCP
stated that they do not manufacture a coil-only indoor unit that may be
matched with their space-constrained condensers, nor do they identify
or offer any other coil-only matched system for distribution in
commerce. (NCP, No. 16 at p. 10) NCP also noted that in the case
identified by DOE of an online distributor selling NCP's space-
constrained outdoor units in an unmatched pairing, this was in error
and that NCP quickly took actions to rectify the situation. Id. NCP
demonstrated steps they undertake to ensure that its space-constrained
condenser units are properly sold and marketed as matching pairs with
blower-coil indoor units and offered to provide enhanced documentation
including a product label. Id. NCP concluded by stating that as a small
company, it does not have the appropriate resources to police the

[[Page 64568]]

actions of distributors or installers. (NCP, No. 16 at p. 7) AHRI
offered similar commentary, claiming that DOE made a logical leap by
attributing the actions of a single distributor to actions taken by
NCP, and asserted that the distributor did not follow manufacturer
sales guidelines. (AHRI, No. 25 at p. 2)
Regarding NCP's claim that the example provided by DOE was an
aberration and not representative of their normal distribution
practices, DOE has found additional evidence beyond what was presented
in the NOPR demonstrating that NCP condensers may be distributed in
commerce as unspecified pairings. DOE has found additional listings
from two other distributors advertising NCP condensing units (in fact,
the same units identified in NCP's interim waiver) being sold without a
matched blower-coil indoor unit.\36\ Further, while DOE acknowledges
NCP's status as a small business entity, and the potential difficulties
with policing the activity of distributors, DOE notes that the coil-
only representation requirement for split-system one and two-stage CACs
is designed to capture the range of installations scenarios in which
these systems are likely to be installed. Correspondingly, the coil-
only representation requirement offers a conservative method that
ensures that consumers would be purchasing systems that are compliant
with national standards, even if installed in a coil-only
configuration.
---------------------------------------------------------------------------

\36\ DOE identified the NCPE-418-5010 condensing unit sold as a
standalone unit at both SkipTheWarehouse and on Johnstone Supply,
available online at: <a href="https://skipthewarehouse.com/ncpe4185010-15-ton-thru-the-wall-split-system-condensing-unit">https://skipthewarehouse.com/ncpe4185010-15-ton-thru-the-wall-split-system-condensing-unit</a> and <a href="https://www.johnstonesupply.com/product-view?pID=B61-354">https://www.johnstonesupply.com/product-view?pID=B61-354</a>, respectively.
---------------------------------------------------------------------------

iii. Interaction With Energy Conservation Standards
Notwithstanding their concerns about the representativeness of
coil-only representations for space-constrained CACs, NCP stated that
they have begun the process of designing and testing modifications to
their space-constrained outdoor units that could allow certifications
with coil-only representations (such as incorporating high-efficiency
DC fan motors, microchannel heat exchangers and/or proprietary
compressor developments), but that these design changes would come at a
considerable cost increase.\37\ (NCP, No. 16 at pp. 5-7) NCP claimed
that they utilize the most efficient components available that are
economically justifiable and asserted that the technical constraints
preventing the certification of its space-constrained condenser units
as a coil-only combination have not changed since they submitted their
original waiver petition. Id. Particularly, NCP highlighted that they
are limited in what they can do to improve the efficiency of the units
due to the dimensional restrictions of the space-constrained
configuration. Id. NCP also provided data showing that even if DOE were
to introduce a lower default fan power coefficient for coil-only CACs
at low-stage operation (as discussed in section III.C.1 of this final
rule), it would still be difficult to meet DOE standards. Id.
---------------------------------------------------------------------------

\37\ On August 11, 2022, NCP submitted an enclosure to their
earlier comment that contained new test data and design information.
NCP claimed that they had not yet identified a combination of
components that would allow its TTW condensing units tested with
coil-only indoor units to reach the applicable energy conservation
standards and capacity requirements. NCP reiterated their opinion
that the unacceptable test results were caused by the physical
constraints placed on space-constrained TTW condensing units. (NCP,
No. 26 at p.2) Available online at: <a href="https://www.regulations.gov/document/EERE-2021-BT-TP-0030-0026">https://www.regulations.gov/document/EERE-2021-BT-TP-0030-0026</a>.
---------------------------------------------------------------------------

AHRI and NCP also claimed that DOE's decision at this stage in the
process to terminate and discontinue the test procedure waiver for
appendix M by not incorporating it into the M1 procedure would place
undue burden on NCP, a small manufacturer. (AHRI, No. 25 at p. 2; NCP,
No. 16 at pp. 9-10) AHRI stated that manufacturers have substantially
completed testing according to appendix M1 and that NCP was in the
process of finalizing M1 product designs and preparing for 2023
implementation. (AHRI, No. 25 at p. 2) NCP stated that its space-
constrained condensing units are designed and intended to be paired
with specified air handlers. (NCP, No. 16 at pp. 9-10) NCP elaborated
that due to the new M1 testing procedures they have designed,
prototyped, tested, and begun manufacture of a new air handler, which
they asserted was an arduous, costly undertaking for a small business.
Id. NCP also highlighted the challenges of simultaneously addressing
the pending refrigerant change in 2025, which they asserted would
require replacement of R-410a refrigerants in its outdoor units. Id.
NCP concluded by stating that if DOE continues with the proposed
approach of requiring coil-only representations for space-constrained
systems tested according to appendix M1, it will require redesign of
their space-constrained products (as previously described) and would
substantially increase the burden and cost of testing as well as
resource allocation for NCP. Id.
With respect to NCP and AHRI's arguments regarding the potential
difficulties meeting standards, DOE notes that the stringency of
standards for such TTW products have not changed since Jan 23, 2010
(the date when the TTW product class was subsumed by the space-
constrained product class) and they have been required to meet a 12
SEER standard ever since. The stringency will also not be increasing
for these products in the upcoming 2023 standards, where DOE has
established equivalent-stringency SEER2 standards. Lennox concurred
with DOE's finding that extending the current test procedure waivers
for space-constrained systems is unnecessary, because adequate
standards relief was already provided when DOE maintained the existing
standard levels with no increase in stringency during the previous
energy conservation standards rulemaking. (Lennox, No. 19 at pp. 3-4)
Because DOE did not increase the stringency of standards for space-
constrained systems in the previous ECS rulemaking, manufacturers of
space-constrained systems who were already producing space-constrained
products compliant with standards in terms of SEER and following the
existing representation requirements (i.e., based on a coil-only
rating) \38\ would not incur any costs in order to comply with SEER2
standards based on coil-only ratings. DOE also notes that in their
comment, NCP identified several combinations of coil-only indoor units
that were technologically capable of meeting SEER2 standard levels.
Additionally, the topic of cost/efficiency tradeoffs for space-
constrained systems was discussed in the previous ECS rulemaking, and
are not subject to reevaluation in the context of this rulemaking,
which is limited to the test procedure.
---------------------------------------------------------------------------

\38\ See October 2016 CAC ECS notification of data availability
NODA, where DOE described its provisional translations between SEER
and SEER2 for space-constrained products. DOE conducted a crosswalk
for SC-CACs to account for the increased minimum external static
pressure requirement in appendix M1 which would increase the indoor
fan power consumption. DOE's crosswalk analysis assumed a coil-only
rating as the starting point (i.e., for appendix M measurements),
and a coil-only rating as the end point (i.e., for appendix M1
measurements). 81 FR 74727, 74729-74730.
---------------------------------------------------------------------------

d. Conclusions
As described in preceding sections, DOE has made the following
determinations regarding representation requirements for space-
constrained CACs:
1. Single-split, single-stage CACs, including space-constrained
CACs, have historically always been subject to a

[[Page 64569]]

coil-only representation requirement. DOE has clarified this
requirement at multiple points in the regulatory text, but has
consistently held that space-constrained CACs were never excluded from
this requirement.
2. For space-constrained CACs meeting the historical definition of
through-the-wall (TTW) products, DOE has similarly explained in
multiple documents that this product class expired in January 2010 at
which point TTW products were subsumed by the space-constrained product
class and became subject to the coil-only representation requirement.
3. Based on the best available data, the coil-only representation
requirement for split-system space-constrained CACs is representative
of real-world installations. This determination is supported by the
finding that, despite manufacturer efforts, space-constrained outdoor
units are still being distributed in commerce in a manner consistent
with coil-only installations.
4. Space-constrained systems have been subject to a coil-only
requirement since January 2010, and standards have remained at
equivalent stringency since that time. Manufacturers of space-
constrained systems that have been producing compliant products would
not incur any costs in order to comply with SEER2 standards.
Further, DOE notes that the interim waiver granted to NCP was only
applicable for appendix M, and NCP did not submit any waiver request
applicable to appendix M1. As previously discussed, DOE proposed in the
NOPR not to incorporate into appendix M1 the waiver method granted to
NCP for appendix M. In summary, consistent with its proposals in the
March 2022 CAC TP NOPR DOE is maintaining the requirement that space-
constrained CACs follow the existing representation requirements at 10
CFR 429.16, including the requirement for all one- and two-stage split-
system CACs to develop represented values based on testing with a coil-
only indoor unit representative of the least efficient coil-only indoor
unit distributed in commerce for that basic model.

D. Other Test Procedure Revisions

1. Air Volume Rate Changing With Outdoor Conditions
In the NOPR, DOE explained that requirements for setting air volume
rate in section 3.1.4 of appendix M1 may be in conflict with
instructions to use air volume rates that represent a ``normal
installation'' in section 3.2, particularly for modern blower-coil
systems with multiple-speed or variable-speed indoor fans and control
systems, which may change air volume rate in response to operating
conditions such as outdoor air temperature. 87 FR 16830, 16841. To
address this issue, DOE proposed in the March 2022 CAC TP NOPR to
explicitly state in Step 7 of sections 3.1.4.1.1.a, 3.1.4.2.a, and
3.1.4.3.a that, for blower-coil systems in which the indoor blower
capacity modulation correlates with outdoor dry bulb temperature or
sensible-to-total cooling capacity ratio, use an air volume rate that
represents a normal operation. 87 FR 16830, 16841-16842. Also, DOE
indicated that to ensure consistency of testing, it may be necessary
for manufacturers to certify whether the system varies blower speeds
with outdoor air conditions. However, certification is not being
addressed in this rulemaking and may be addressed in a separate
rulemaking. Id.
In response, Lennox, Rheem and Trane commented that they support
DOE's proposal to add clarifying language to allow fan speed and air
volume adjustments for varying outdoor conditions that are
representative of normal field operation, for blower-coil systems with
multiple-speed or variable-speed indoor fans. (Lennox, No. 19 at p. 4,
Rheem, No. 21 at p. 2, Trane, No. 10 at p. 3) Rheem further commented
that they also support the control system capability to adjust air
volume rate as a function of outdoor air temperature, allowing such air
volume rate variation during testing. (Rheem, No. 21 at pp. 2-3) In
order to make the procedure more representative of field conditions,
Rheem suggested that external static pressure should change in relation
to full stage air flow by using the fan affinity laws, similar to
external static adjustments for multi-stage equipment. Id.
Additionally, Rheem suggested that DOE's proposal to add clarifying
language for blower speed variation should apply to section
3.1.4.4.3.a, instead of section 3.1.4.3.a. Id. Trane pointed out that
they have products that vary the fan speed based on various conditions
such as outdoor ambient and stated that the proposed change is needed
to clear up the discrepancy in procedures. (Trane, No. 10 at p. 3) They
stated that there are several reasons why airflow may be varied from a
nominal setting at different conditions; for example, to optimize
sensible heat ratio and comfort, to maintain consistent heating supply
air temperatures, and to maximize system efficiency. Id.
In response to Rheem's comment about external static adjustments,
DOE believes that the proposed regulatory language already addresses
this factor, in particular the language: ``and calculate the target
minimum external static pressure as described in section 3.1.4.2 of
this appendix,'' which is included in Step 7 where the proposed
revisions were made. The adjustment of external static pressure
described in section 3.1.4.2 specifies that pressure varies as the
square of the air flow, consistent with the fan affinity laws mentioned
by Rheem. Hence, DOE is finalizing the revision without additional
changes in regard to instructions regarding external static pressure.
Also, in response to Rheem, DOE acknowledges that the NOPR preamble
incorrectly cited section 3.1.4.3.a instead of 3.1.4.4.3.a.--the change
was proposed and is finalized in section 3.1.4.4.3.a.
NEEA pointed out that DOE's proposal does not require certification
of the fan speeds that represent ``normal'' operation for the different
test points, and expressed concern that this approach will allow
products to be tested more favorably without confirmation that the
testing represents how products operate in the field. (NEEA, No. 23 at
p. 2) NEEA recommended that DOE verify blower speed variation with a
load-based test procedure using native controls of the system. Id.
As previously stated, certification corresponding to the test
procedure changes are not being addressed in this final rule but may be
considered in a separate rulemaking. Regarding NEEA's recommendation
for a test procedure requiring native controls, DOE notes that this
test procedure rulemaking was initiated as a quick fix of a limited set
of known issues, and that more comprehensive revisions to address
native controls may be considered in a future rulemaking that would
satisfy the 7-year lookback requirements. See further discussion in
section III.B of this document.
Based on the comments received, DOE is finalizing the provisions
regarding variation of indoor air volume rate by adopting the
clarifying language to Step 7 of sections 3.1.4.1.1.a, 3.1.4.2.a, and
3.1.4.4.3.a, as proposed.
2. Wet Bulb Temperature for H4 5 [deg]F Heating Tests
Appendix M1 specifies required and optional heating mode test
conditions for heat pumps, designated as ``H'' conditions. See Tables
11 through 15 of appendix M1. Appendix M1 provides for conducting
optional ``H4'' heating tests at a 5 [deg]F outdoor ambient dry-bulb
temperature and, at a maximum, a 3 [deg]F

[[Page 64570]]

outdoor wet-bulb temperature.\39\ The 3 [deg]F wet bulb condition
represents an extremely dry air condition, which may be difficult to
attain and maintain due to issues with infiltration and ground moisture
passing through the floor in some laboratory setups. Consequently, in
the March 2022 CAC TP NOPR, DOE proposed to amend the wet bulb test
condition for all H4 tests to be 4 [deg]F maximum instead of the
current condition of 3 [deg]F maximum. 87 FR 16830, 16842.
---------------------------------------------------------------------------

\39\ The tests at this condition are optional for heat pumps,
except for Triple-Capacity Northern heat pumps.
---------------------------------------------------------------------------

In response, Carrier, Daikin, Lennox, Nortek, NYSERDA, and Rheem
commented that they all support DOE's proposal to increase the wet bulb
test condition to 4 [deg]F maximum from the 3 [deg]F maximum for H4
tests. (Carrier, No. 15 at p. 1, Daikin, No. 24 at p. 2, Lennox, No. 19
at p. 4, Nortek, No. 13 at p. 3, NYSERDA, No. 17 at p. 2, Rheem, No. 21
at p. 3) Carrier stated that increasing the wet bulb test condition in
the H4 test will reduce the test burden, and Lennox further asserted
that conducting the H4 tests previously in various manufacturer
laboratories has proven to be overly burdensome for the variety of
reasons DOE cites in the CAC TP NOPR at 87 FR 16842. (Carrier, No. 15
at p. 1, Lennox, No. 19 at p. 4) Carrier and Lennox commented that
increasing the maximum wet bulb temperature for the H4 test will
significantly reduce manufacturer test burden. Id. Lennox commented
that this will also help avoid additional capital investments in lab
facilities for specialized equipment to attain the wet bulb requirement
of 3 [deg]F and this relief will allow more test facilities to be
capable of validating performance at low ambient conditions while
maintaining sufficiently low humidity conditions to provide reasonable
test results. (Lennox, No. 19 at p. 4) Nortek also commented that
increasing the wet bulb temperature on the H4 test from 3 [deg]F to 4
[deg]F will reduce their test burden by reducing the time required to
remove moisture in achieving the wet bulb temperature test point.
(Nortek, No. 13 at p. 3) NYSERDA commented that the proposed amendment
of the wet bulb temperature conditions for the H4, H4<INF>2,</INF> or
H4<INF>3</INF> heating tests to a 4 [deg]F maximum temperature will
make the current optional cold temperature test easier to reliably
replicate and should improve understanding of system performance at
cold temperatures for more basic models being distributed in commerce.
(NYSERDA, No. 17 at p. 2)
Based on the discussion presented in the March 2022 CAC TP NOPR and
given the general support of the proposals by commenters, DOE is
finalizing its amendment and increasing the wet bulb test condition to
a maximum of 4 [deg]F for H4 tests.
3. Hierarchy of Manufacturer Installation Instructions
Instructions for installation of CAC/HP products can take multiple
forms, including documents shipped with the product, labels affixed to
the outdoor unit and/or indoor unit, and online documents.
Section 2(A) of appendix M1 provides requirements regarding the
installation instructions to be used and their order of precedence
(i.e., installation instruction hierarchy) for variable refrigerant
flow (``VRF'') multi-split systems. Section 2(A) specifies that
installation instructions that appear in the labels applied to the unit
take precedence over installation instructions that are shipped with
the unit. Further, Section 2(A) specifies that the term
``manufacturer's installation instructions'' does not include online
manuals. Appendix M1 does not specify installation instruction
hierarchy for any other types of CAC/HP products.
Throughout appendix M1, references to manufacturer's installation
instructions are made regarding refrigerant charging requirements
(section 2.2.5), installation of an air supply plenum adapter accessory
for testing small-duct, high-velocity systems (section 2.4.1.c), and
control circuit connections between the furnace and the outdoor unit
for coil-only systems (section 3.13.1.a).
DOE notes that it initially proposed in a supplemental NOPR
published November 9, 2015 (``November 2015 SNOPR'') that the hierarchy
of installation instructions be located in proposed section 2.2.5.1 of
appendix M1, which pertains to refrigerant charging requirements. See
80 FR 69278, 69350.\40\ However, as finalized in the June 2016 CAC TP
Final Rule, the installation instruction hierarchy provision was
located within section 2(A) of appendix M1, and therefore applies only
to testing of VRF multi-split systems. 81 FR 36992, 37060. The June
2016 CAC TP Final Rule did not provide a discussion of this change.
---------------------------------------------------------------------------

\40\ DOE also notes that as initially proposed, installation
instructions that are shipped with the unit were to take precedence
over installation instructions that appear in the labels applied to
the unit, but this hierarchy was reversed in the final rule. 81 FR
36992, 37060.
---------------------------------------------------------------------------

The requirements regarding installation instruction would be
equally applicable to classes of CAC/HP other than VRF multi-split
systems. As noted, manufacturer's installation instructions are
referenced in a number of provisions in appendix M1. Therefore, in the
March 2022 CAC TP NOPR, DOE proposed to add in section 2(B) of appendix
M1, ``Testing Overview and Conditions for Systems Other than VRF,'' the
same requirements associated with installation instructions that are in
section 2(A), i.e., what instructions can be used and what instructions
take precedence. 87 FR 16830, 16842. Doe noted that this proposal would
align the approach for all classes of CAC/HP with the current approach
for VRF CAC. Id.
Lennox and Rheem commented that they support DOE's proposal for
aligning the approach regarding installation instruction precedence for
all classes of CAC/HP with the current approach of VRF AC. (Lennox, No.
19 at p. 4, Rheem, No. 21 at p. 3) Rheem further suggested that for
clarity in the final rule, DOE should clearly specify whether a sticker
on the unit takes precedence over installation instructions,
particularly where use of the installation instructions is referenced
in the appendix M1 test procedure (Rheem, No. 21 at p. 3).
Additionally, Rheem stated that DOE also specifies a Section 2(B) will
be added to appendix M1 to 10 CFR part 430. Rheem points out that
Section 2(B) already exists in the test procedure, and therefore DOE
should add a section 2(C) to capture these changes.\41\ Id.
---------------------------------------------------------------------------

\41\ In the May 2022 CAC TP NOPR, DOE had stated that they will
add instructions to the already existing Section 2(B), and not that
a new section is needed. Hence, DOE will not add a Section 2(C), as
suggested by Rheem.
---------------------------------------------------------------------------

In response to Rheem's comment regarding addition of section 2(B)
of appendix M1, DOE notes that it indicated that the additional
requirements regarding installation instructions would be inserted ``in
section 2(B),'' not that a new section 2(B) would be added. In response
to the comment about clarifying whether a sticker on the unit takes
precedence over installation instructions, DOE believes that the
language proposed for section 2(B), ``Installation instructions that
appear in the labels applied to the unit shall take precedence over
installation instructions that come packaged with the unit,''
sufficiently clarifies this point. Specifically, ``installation
instructions'' does extend to installation instructions that appear on
the labels applied to the unit, and that such installation instructions
take precedence over installation instructions that are not applied to
the unit.

[[Page 64571]]

Trane commented that even though they agreed with hierarchy
proposed by DOE, they raised a concern that that some combinations of
indoor units require unique charging instructions, as opposed to the
typical instructions, i.e., subcooling target, listed on outdoor unit
labels. (Trane, No. 10 at p. 3) They cited the variations of indoor
internal coil volume with various matched pairs as the reason for this.
Hence, Trane suggested that outdoor nameplates should have a footnote
referring the installer to the indoor product instructions for any
exception, unless otherwise noted. Id.
In response to Trane's comment, DOE agrees that there may be
circumstances in which the very different design details of multiple
indoor units paired with the same outdoor unit could affect the optimum
installation approach. In such cases, the manufacturer has the
discretion to indicate in the outdoor unit installation instructions
that specific instructions provided with indoor units be followed. Such
an approach would not be contrary to the established precedence of the
outdoor unit's installation instructions and would not be contrary to
the proposed appendix M1 requirements, as long as the instructions used
are not online instructions. DOE does not believe that appendix M1
should be modified to specifically explain this possibility.
Hence, DOE is adding the installation instruction hierarchy to
appendix M1 section 2(B) as proposed.
4. Adjusting Airflow Measurement Apparatus To Achieve Desired SCFM at
Part-Load Conditions
Sections 3.1.4.1.1, 3.1.4.2, and 3.1.4.4.3 of appendix M1 each
specify seven steps for achieving the correct air volume rate to be
used for testing (cooling full-load air volume rate, cooling minimum
air volume rate, and heating full-load air volume rate, respectively).
Each of these sections indicates that the measured air volume rate when
adjustments are complete should be used for all tests that call for the
same nominal air volume rate, i.e., cooling full-load, cooling minimum,
or heating full-load air volume rate, using the final fan speed or
control settings. However, when operating at different test conditions,
differences in air density and/or loading of condensate on the indoor
coil may lead to different measured air volume rates.\42\ None of the
section 3.1.4.1.1, 3.1.4.2, or 3.1.4.4.3 of appendix M1 indicate what
adjustments are allowed or required to obtain the same air volume rate
for different operating conditions. In order to clarify how to achieve
the same air volume rates for different operating conditions, DOE
proposed to explicitly require that the airflow measurement apparatus
fan be adjusted if needed to maintain a constant air volume rate for
all tests using the same nominal air volume rate. Similarly, the
section would explicitly state that the speed and settings of the fan
of the unit under test are not to be adjusted. 87 FR 16830, 16843
(March 24, 2022).
---------------------------------------------------------------------------

\42\ When operating in cooling mode, water vapor in the return
air may condense and collect and flow down the coil into the indoor
unit's drain pan. This removal of water vapor is called
dehumidification--it occurs only in cooling mode and its magnitude
depends on the test conditions.
---------------------------------------------------------------------------

In response, Lennox commented that they support DOE's proposals to
add more specific direction to step 7 of sections 3.1.4.1.1, 3.1.4.2,
and 3.1.4.4.3, as proposed. (Lennox, No.19 at p.4) Rheem commented that
although they agree that the proposed changes may assist in the
repeatability of certification tests, they disagree that DOE's
proposals would be more representative than the current test procedure.
(Rheem, No. 21 at p. 3) Rheem stated that once a ducted CAC/HP is
installed in a consumer's home, the airflow and external static
pressure will change with conditions, as reflected in the current test
procedure. Id. Rheem noted that in the discussion under III.C.1 of the
NOPR, DOE proposed to allow the air volume rate to change if the native
controls of the system modulate indoor blower capacity. Rheem
recommended that DOE add language to clarify that this allowance to
adjust the airflow measurement apparatus only applies to systems that
do not modulate indoor blower capacity. Id.
DOE does not agree with Rheem's comment suggesting that the current
test procedure does not allow adjustment of the airflow measurement
apparatus fan. Specifically, the words, ``use the final speed or
control settings'' is not clear regarding whether this applies to the
unit under test, the code tester, or both. DOE notes that by not
specifically precluding adjustment of the code tester fan, the current
Federal test procedure does not fully specify the allowable fan
adjustments, leaving open the possibility for clarification.
In response to Rheem's comment regarding clarifying language, DOE
notes that the proposed additions indicate that the final indoor fan
speed or control settings of the unit under test must be used for all
tests that use the same nominal air volume rate (e.g., cooling full-
load air volume rate), and that the fan of the airflow measurement
apparatus should be adjusted if needed to obtain the same air volume
rate (in scfm), unless the system modulates the indoor blower speed for
different outdoor conditions or to adjust the sensible to total heat
ratio. DOE considers this text is sufficiently clear that the
instructions apply to systems that do not modulate indoor blower
capacity. Further, DOE points out that adjustment of the airflow
measurement apparatus would very likely be required for systems that do
modulate the indoor blower capacity, to maintain the relationship
between air volume rate and external static pressure, as required by
section 3.1.4.2 of appendix M1.
Hence, DOE is finalizing the changes to step 7 of the requirements
for setting air volume rate as proposed.
5. Revision of Equations Representing Full-Speed Variable-Speed Heat
Pump Operation at and Above 45 [deg]F Ambient Temperature
In a variable speed system, the compressor's actual speed at its
full-load condition may change as the outdoor temperature changes.
While the compressor speed at full speed may differ at different
outdoor temperatures, accuracy of predictions using the test results
from two temperature conditions to calculate the performance for a
third temperature condition is maximized when the same compressor speed
is used for the tests at the two different ambient temperature
conditions (see, e.g., 81 FR 58164, 58178 (August 24, 2016)).
For calculation of full-speed compressor heating mode performance
in the temperature ranges less than 17 [deg]F and greater than or equal
to 45 [deg]F, the test procedure determines performance based on the
H3<INF>2</INF> and H1<INF>2</INF> tests, which are conducted at 17
[deg]F and 47 [deg]F, respectively (see appendix M1, sections 4.2.4.c,
which refers to equations 4.2.2-3 and 4.2.2-4 in Section 4.2.2). As
indicated in appendix M1 in the Table 14 footnotes, the H1<INF>2</INF>
test is run with the compressor speed that represents normal operation
at 17 [deg]F conditions. However, for many variable-speed heat pumps,
this is a higher compressor speed than would be normal for operation at
47 [deg]F conditions.
The H1<INF>N</INF> test represents normal 47 [deg]F operation, as
indicated in the Table 14 footnotes. For heat pumps with different
normal speeds for 17 [deg]F and 47 [deg]F conditions, the full-speed
compressor performance equation is not appropriately representative for
temperatures greater than or equal to 45 [deg]F. For example, at 47
[deg]F, the equation would indicate that the capacity is equal to the
H1<INF>2</INF> capacity, even though the H1<INF>N</INF> test is
specifically intended to represent capacity at 47 [deg]F. To rectify

[[Page 64572]]

this issue, DOE proposed in the March 2022 CAC TP NOPR to amend the
portion of the equations representing performance in conditions warmer
than 45 [deg]F. 87 FR 16830, 16843. Specifically, DOE proposed that the
capacity equation for this temperature range would be multiplied by the
ratio of the capacities of the H1<INF>N</INF> and H1<INF>2</INF> tests.
Id. Similarly, DOE proposed that the power input equation for this
range would be multiplied by the ratio of the power inputs measured in
the H1<INF>N</INF> and H1<INF>2</INF> tests. Id. DOE noted that this
would change the calculated capacity and power input for the range of
temperature above 45 [deg]F to be consistent with the compressor speed
of the H1<INF>N</INF> test (which is intended to represent performance
in this range), rather than with the compressor speed of the
H3<INF>2</INF> test, which is conducted in a 17 [deg]F ambient
temperature. Id.
In response, Lennox supported DOE's proposed change to the full-
capacity performance equations for variable speed heat pumps in the
ambient temperature range above 45 [deg]F. (Lennox, No. 19 at p. 5)
Rheem recommended that DOE does not make the proposed changes. (Rheem,
No. 21 at p. 4) Rheem contended that the proposal to modify the
capacity and power equations above 45 [deg]F would not have significant
effect on heat pump HSPF2 calculations, since variable speed
applications would likely operate in low stage during low building load
conditions. Rheem questioned the value of adding complexity to variable
speed HSPF2 calculations if the change will not have meaningful effect
on the results and recommends that DOE not change the current
calculation method for HSPF2 of variable speed heat pumps. (Rheem, No.
21 at pp. 3-4) DOE considers that the proposed calculation changes
(i.e., applying a simple ratio coefficient) does not represent any
significant increase in complexity compared to the overall scale of
test procedure calculations and that it is important to provide for a
more accurate calculation of HSPF2, even if the impact on the
calculated HSPF2 value is minimal. Therefore, DOE is finalizing its
proposed approach in this final rule.
6. Calculations for Triple-Capacity Northern Heat Pumps
Section 4.2.6 of appendix M1 includes additional steps for
calculating HSPF2 of a heat pump having a triple-capacity compressor.
Heat pumps with triple-capacity compressors respond to building heating
load by operating at low (k=1), high (k=2), or booster (k=3) capacity
or by cycling on and off at one or more of those stages. Section
4.2.6.5 covers the scenario where the heat pump alternates between high
(k=2) and booster (k=3) compressor capacity to satisfy the building
load. In this scenario, the total electrical power consumption is
determined by calculating the fraction of time the system spends
operating in the high and booster stage, respectively, and then
weighting the steady-state power consumption at each operating state
accordingly. Section 4.2.6.5 gives equations for calculating the
fraction of load addressed by the high compressor stage, denoted as
``X\k=2\(T<INF>j</INF>)'', as well as the fraction of load addressed by
the booster compressor stage ``X\k=3\(T<INF>j</INF>)''. These
proportions should, by definition, be complementary because the system
is either operating in high compressor stage or boost compressor stage.
However, the equation for the booster capacity load factor
``X\k=3\(T<INF>j</INF>)'' is erroneously set equal to the high-capacity
load factor ``X\k=2\(T<INF>j</INF>)'' as opposed to the complementary
value ``1 X\k=2\(T<INF>j</INF>).'' Therefore, DOE proposed to correct
the booster capacity load factor equation to be defined as
X\k=3\(T<INF>j</INF>) = 1-X\k=2\(T<INF>j</INF>). DOE did not receive
any comments in response to its proposal, and is therefore finalizing
its proposed approach in this final rule.
7. Heating Nominal Air Volume Rate for Variable-Speed Heat Pumps
Appendix M1 includes procedures for calculating the heating
capacity and power input for variable-speed heat pumps at various test
conditions. The H1<INF>N</INF> test is used to calculate the nominal
heating capacity of the system at 47 [deg]F ambient temperature,
whereas the H1<INF>2</INF> test is used to calculate maximum heating
capacity at 47 [deg]F and the H1<INF>1</INF> test is used to calculate
minimum heating capacity at 47 [deg]F. Section 3.1.4.7 of appendix M1
requires that manufacturers must specify a heating nominal air volume
rate for each variable-speed heat pump system and must provide
instructions for setting the fan speed or controls. The heating full-
load air volume rate is defined in section 3.1.4.4 of appendix M1,
which ties the heating full-load air volume rate to the cooling full-
load air volume rate and denotes static pressure requirements. However,
in Table 14 to appendix M1 (which specifies heating mode test
conditions for units having a variable-speed compressor), the
H1<INF>N</INF> test (used for calculating nominal heating capacity at
47 [deg]F) is erroneously specified as using the ``Heating Full-load''
air volume rate instead of the heating nominal air volume rate. Because
the H1<INF>N</INF> test is intended to represent nominal heating
capacity, DOE is amending Table 14 to specify the ``heating nominal air
volume rate'' as defined in section 3.1.4.7 of appendix M1 as opposed
to the ``heating full-load air volume rate''. As discussed in section
III.C.2 of this final rule, DOE is also amending the test provisions
for variable-speed compressor systems with coil-only indoor units. The
amendments mentioned in this section only apply to variable-speed
systems equipped with blower-coil indoor units, while variable-speed
coil-only systems would be required to test using the heating full-load
air volume rate at the H1<INF>N</INF> test condition.
DOE did not receive any comments in response to this issue in the
March 2022 CAC TP NOPR and is finalizing its proposal to specify
heating nominal air volume rate as the air volume rate to be used for
the H1<INF>N</INF> heating test for variable-speed heat pumps.
8. Clarifications for HSPF2 Calculation
Section 4.2 of appendix M1 contains methodologies for calculating
HSPF2 for all heat pumps. DOE has identified an instance where
additional instruction may be warranted to make clear the calculation
procedures across different types of heat pump systems. In the March
2022 CAC TP NOPR, DOE proposed to clarify the appropriate slope
adjustment factor to be used in the calculation for building heating
load (Equation 4.2-2). 87 FR 16830, 16844.
As written, Equation 4.2-2 refers to the heating load line slope
adjustment factor ``C'', which varies by climate region according to
Table 20. However, Table 20 includes both the ``C'' factor as well as a
factor denoted ``C<INF>VS</INF>''--the variable-speed slope factor,
which includes different coefficients that impact calculation of HSPF2.
C<INF>VS</INF> is not explicitly referenced in the definitions
surrounding Equation 4.2-2, therefore DOE proposed to amend the
language of that paragraph to indicate that the slope adjustment factor
``C'' should be used when calculating building heating load except for
variable-speed compressor systems, where the variable-speed slope
adjustment factor ``C<INF>VS</INF>'' should be used instead. Id.
DOE did not receive any comments regarding this proposal and is
thus adopting its proposal to clarify the calculation process for
heating load line slope factor as it pertains to variable-speed heat
pumps.
9. Distinguishing Central Air Conditioners and Heat Pumps From
Commercial Equipment
EPCA defines ``industrial equipment'' as equipment of a type which,
among other requirements, is not a covered product under section
6291(a)(2), i.e.,

[[Page 64573]]

not a covered consumer product. (42 U.S.C.6311(2)(A)) Small, large, and
very large commercial package air conditioning and heating equipment
are included as types of covered industrial equipment. (42
U.S.C.6311(1)(B,C,D))
EPCA defines ``central air conditioner'' as a product, other than a
packaged terminal air conditioner, which is powered by single phase
electric current, is air-cooled, is rated below 65,000 Btu per hour, is
not contained within the same cabinet as a furnace the rated capacity
of which is above 225,000 Btu per hour and is a heat pump or a cooling
only unit. (42 U.S.C. 6291(21)) DOE understands that there are basic
models on the market that meet the central air conditioner definition
but are exclusively distributed in commerce for commercial and
industrial applications. In DOE's view, there are certain types of
equipment that meet the EPCA definition of CAC but that EPCA did not
intend for DOE to regulate as consumer products. To clarify that any
such model is not a central air conditioner, DOE proposed in the March
2022 CAC TP NOPR to revise the central air conditioner definition so
that it explicitly excludes these equipment categories, similar to the
way the original EPCA definition excludes packaged terminal air
conditioners and packaged terminal heat pumps. The exclusion for
single-package vertical air-conditioners and heat pumps would refer
specifically to those models that could be confused with central air
conditioners, i.e., those that are single-phase with capacity less than
65,000 Btu/h, for which the test procedure notice of proposed
rulemaking for single-package vertical air conditioners and heat pumps
has proposed new definitions. 87 FR 2490, 2518 (January 14, 2022).
DOE emphasizes that the exclusion from the central air conditioner
definition for a given model depends on whether it meets the definition
for one of the excluded categories. For example, a model must meet the
packaged terminal air conditioner definition in 10 CFR 431.92 to be
considered to be a packaged terminal air conditioner. If such a model
had both characteristics listed in the central air conditioner
definition and similarities to packaged terminal air conditioners, but
was not ``intended for mounting through the wall,'' it would be missing
a key characteristic of the packaged terminal air conditioner
definition. Unless it met the definition for one of the other
categories proposed to be excluded, it would be considered a central
air conditioner and covered under the applicable standards and test
procedures in part 430 irrespective of whether it gets installed in a
consumer or commercial building.
DOE did not receive any comments in response to its proposed
clarification of the definition of central air conditioners and heat
pumps at 10 CFR 430.2 to exclude other similar product categories for
consideration of coverage. Therefore, DOE is finalizing its proposals
from the NOPR without amendment in this final rule.
10. Additional Test Procedure Revisions
On May 8, 2019, AHRI submitted a comment responding to the notice
of proposed rulemaking to revise and adopt procedures, interpretations,
and policies for consideration of new or revised energy conservation
standards (2020 Process Rule NOPR, 84 FR 3910, Feb. 13, 2019). The
comment included as Exhibit 2 a ``List of Errors Found in appendix M
and appendix M1'' (``AHRI Exhibit 2''). (EERE-2017-BT-STD-0062-0117 at
pp. 23-24) Many of the errors pointed out by AHRI regard typographical
errors in appendices M and M1. DOE published a correcting amendment to
appendices M and M1 on December 2, 2021 (``December 2021 Correcting
Amendment''). 86 FR 68389. The December 2021 Correcting Amendment
addressed some of the ``Errors'' identified in AHRI Exhibit 2, but not
all of them. In the March 2022 CAC TP NOPR, DOE proposed to address
additional ``Errors'' identified in AHRI Exhibit 2, discussed in the
following sections to improve accuracy and representativeness of the
test procedures. 87 FR 16830, 16845.
a. Revisions Specific to Appendix M
AHRI's comment identified three areas of appendix M where they
requested changes. (AHRI Exhibit 2, EERE-2017-BT-STD-0062-0117 at pp.
23-24) These are detailed in Table III-4. Additionally, DOE identified
one transcription error in the December 2021 Correcting Amendment
related to changes made in section 3.6.4 of appendix M. DOE is making
corresponding revisions in this final rule to correct that
transcription error.

Table III-4--AHRI-Identified Errors to Appendix M
----------------------------------------------------------------------------------------------------------------
Original appendix M Proposed change in the
Section language AHRI comment summary March 2022 CAC TP NOPR
----------------------------------------------------------------------------------------------------------------
1.2.............................. Nominal cooling capacity The H1N test is required Remove the ``Optional
is approximate to the in section 3.6.4, and H1N test'' and replace
air conditioner cooling section 3.6.4 the ``H12'' with
capacity tested at A or designates the H1N ``H1N''
A2 condition. Nominal test--not the H12 test.
heating capacity is
approximate to the heat
pump heating capacity
tested in H12 test (or
the optional H1N test).
4.1.4.2.......................... A = EER \k=1\(T) - B * T - The EER\k=1\(Tj) should Revise the formula to
C * T2\2\. be EER\k=2\(Tj) because implement this change
the coefficient ``A'' to EER\k=2\(Tj).
only utilizes the
maximum speed
temperature, T2.
4.2.c............................ For a variable-speed heat 2017 and later versions Accurately implement the
pump, Qh\k\(47) = of appendix M use change intended by the
Qh\k=N\(47), the space H\k=2\calc for all December 2021
heating capacity conditions, as Correcting Amendment.
determined from the H1N explained in 3.6.4.
test. This should not be an
exception for the rest
of the calculations.
----------------------------------------------------------------------------------------------------------------

The following sections discuss changes to the language of appendix
M that DOE believes will improve clarity regarding how tests and
calculations are to be conducted to determine capacity levels and
efficiency metrics to address the topics identified in AHRI's comment.
i. Definition of Nominal Capacity
AHRI commented that the description of nominal heating capacity
within the definition for ``nominal capacity'' in

[[Page 64574]]

section 1.2 of appendix M incorrectly references the H1<INF>N</INF>
test as ``optional.'' AHRI claimed that, on the contrary, the
H1<INF>N</INF> test is required for heat pumps. (AHRI Exhibit 2, EERE-
2017-BT-STD-0062-0117 at pp. 23-24) DOE agrees with the AHRI comment,
since section 3.6.4, ``Tests for a Heat Pump Having a Variable-Speed
Compressor,'' requires the H1<INF>N</INF> test. Therefore, DOE proposed
in the March 2022 CAC TP NOPR to revise the definition of ``nominal
capacity'' to remove the references to the H1<INF>2</INF> test in its
entirety to avoid confusion. 87 FR 16830, 16845.
In response to the NOPR proposal, the CA IOUs commented that by
making this reference to the H1<INF>N</INF> test, DOE is making the
definition inapplicable to systems with single-speed and two-capacity
compressors. (CA IOUs, No. 20 at pp.1-2) The CA IOUs proposed the
following definition, so that it may be applicable to single-stage and
two-stage heat pumps (additions in italics, deletions in [brackets]):
Nominal capacity means ``the capacity that is claimed by the
manufacturer on the product name plate. Nominal cooling capacity is
approximate to the air conditioner cooling capacity tested at A or
A<INF>2</INF> condition. Nominal heating capacity is approximate to the
heat pump heating capacity tested in the H1 or H1<INF>2</INF> test for
units that have a single-speed compressor, the H12 test for units that
have a two-capacity compressor or are a triple-capacity northern heat
pump,\43\ or [(or the optional H1<INF>N</INF> test).] the H1N test for
units that have a variable-speed compressor.'' Id.
---------------------------------------------------------------------------

\43\ Appendix M1, section 1.2, defines ``triple-capacity,
northern heat pump'' as a heat pump that provides two stages of
cooling and three stages of heating. The two common stages for both
the cooling and heating modes are the low-capacity stage and the
high-capacity stage. The additional heating mode stage is the
booster capacity stage, which offers the highest heating capacity
output for a given set of ambient operating conditions.
---------------------------------------------------------------------------

DOE notes that the term nominal heating capacity is only used to
specify the heating capacity for the H1<INF>N</INF> test for variable-
speed systems. Additionally, the term nominal capacity is not required
for certification of CAC/HPs. Hence, DOE is not revising the definition
as suggested by the CA IOUs and DOE is instead finalizing the
definition as proposed in the March 2022 CAC TP NOPR.
ii. Revising Energy Efficiency Ratio Equation at Intermediate
Compressor Speed
In section 4.1.4.2 of appendix M, there are a series of equations
used to calculate EERk=i(T<INF>j</INF>), the steady-state
energy efficiency ratio of the test unit when operating at an
intermediate compressor speed (k=i) for outdoor temperature
T<INF>j</INF>. This value is calculated using a quadratic equation:
EERk=i(T<INF>j</INF>) = A + B*T<INF>j</INF> +
C*T<INF>j</INF>\2\. These coefficients (A, B and C) are calculated by
their own respective formulae.
AHRI commented that the formula for the ``A'' coefficient has an
error. Specifically, EERk=1(T<INF>2</INF>) in the equation
should be EERk=2(T<INF>2</INF>) because the coefficient
``A'' only utilizes maximum-speed temperature T<INF>2</INF>. (AHRI
Exhibit 2, EERE-2017-BT-STD-0062-0117 at pp. 23-24) In the March 2022
CAC TP NOPR, DOE proposed to revise this calculation such that it uses
the intended ``k=2''. 87 FR 16830, 16845. The use of ``k=2'' is
supported both by its appearance in ASHRAE 116-2010, ``Methods for
Testing for Rating Seasonal Efficiency of Unitary Air Conditioners and
Heat Pumps'' (see page 25), and also in the DOE test procedure final
rule that first established test methods for variable-speed systems. 49
FR 8304, 8316 (March 14, 1987).
DOE did not receive any comments in response to this proposed
correction and is therefore finalizing its proposed approach in this
final rule.
iii. Clarification of Compressor Speed Limits in Heating Tests for Heat
Pumps Having a Variable-Speed Compressor
In the December 2021 Correcting Amendment, DOE discussed
corrections to the compressor speed limitations for the H1<INF>N</INF>
heating mode test for both appendices M and M1. 86 FR 68389, 68390.
However, when setting out the correcting language in the amendatory
instruction for appendix M, the instructions erroneously directed to
revise the fifth sentence of paragraph a. to section 3.6.4, when the
instructions were intended to revise the seventh sentence of the same
paragraph. As currently printed, the text in paragraph a. of section
3.6.4 to appendix M includes two sentences starting with ``for a
cooling/heating heat pump . . .'' that give conflicting instructions.
Accordingly, DOE proposed in the March 2022 CAC TP NOPR to revise this
paragraph to reflect the intent of the December 2021 Correcting
Amendment and, by extension, the January 2017 CAC TP Final Rule. 87 FR
16830, 16845. DOE did not receive any comments and is therefore
finalizing as proposed.
b. Revisions Specific to Appendix M1
AHRI's comment identified one area of appendix M1 where they
requested a change. (``AHRI Exhibit 2,'' EERE-2017-BT-STD-0062-0117 at
p. 23) This requested change is detailed in Table III-5.

Table III-5--AHRI-Identified Errors to Appendix M1
----------------------------------------------------------------------------------------------------------------
Proposed change in the March
Section Original appendix M1 language AHRI comment summary 2022 CAC TP NOPR
----------------------------------------------------------------------------------------------------------------
4.2............... Qh(47 [deg]F): the heating For variable speed heat Revise the language to be
capacity at 47 [deg]F pumps, the language should clearer about what capacity
determined from the H2 H12or be clarified to H\k=2\calc. to use for different types
H1N test, Btu/h. of heating-only heat pumps.
----------------------------------------------------------------------------------------------------------------

The following sections discuss amendments to the language of
appendix M1 that DOE believes will improve clarity regarding how tests
and calculations are to be conducted to determine capacity levels and
efficiency metrics to address the topic identified in AHRI's comment,
additional topics in comments from interested parties, and other areas
for improvement identified by DOE.
i. Detailed Descriptions of Capacity for Different Subcategories
AHRI commented that in Section 4.2 of appendix M1, which describes
the calculation for HSPF2 for different subcategories of heat pumps,
there is a lack of clarity in the term for heating capacity measured at
47 [deg]F, ``Q<INF>h</INF>(47 [deg]F),'' in Equation 2-2, the building
load, ``BL(T<INF>j</INF>),'' equation. (``AHRI Exhibit 2,'' EERE-2017-
BT-STD-0062-0117 at p. 23) Currently, the description of
Q<INF>h</INF>(47 [deg]F) says that it is ``determined from the H,
H1<INF>2</INF> or H1<INF>N</INF> test.'' Additionally, the first ``H''
is missing an additional character to specify the appropriate test
point. DOE agrees with

[[Page 64575]]

AHRI's assessment of this description, and DOE proposed in the March
2022 CAC TP NOPR to revise this description to include specific
instructions for which test point is appropriate for different heat
pump subcategories. DOE proposed to specify that the H1 test is for a
heat pump with a single-speed compressor, the H1<INF>2</INF> test is
for a heat pump with a two-speed compressor, and the H1<INF>N</INF>
test is for a heat pump with a variable-

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