84188 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

DEPARTMENT OF ENERGY 

10 CFR Parts 429 and 431 

[EERE–2017–BT–TP–0029] 

RIN 1904–AE05 

Energy Conservation Program: Test 

Procedure for Water-Source Heat 

Pumps 

AGENCY: Office of Energy Efficiency and 

Renewable Energy, Department of 

Energy. 

ACTION: Final rule. 

SUMMARY: The U.S. Department of 

Energy (‘‘DOE’’) is amending its test 

procedure for water-source heat pumps 

to expand the scope of applicability of 

the test procedure, incorporate by 

reference a new industry consensus test 

standard for water-source heat pumps, 

adopt a seasonal cooling efficiency 

metric, and specify more representative 

test conditions used for measuring 

heating performance. DOE has 

determined that the amended test 

procedure will produce results that are 

more representative of an average use 

cycle and be more consistent with 

current industry practice without being 

unduly burdensome to conduct. 

Additionally, DOE is adopting 

provisions governing public 

representations of efficiency for this 

equipment. 

DATES: The effective date of this rule is 

January 3, 2024. The amendments will 

be mandatory for product testing 

starting November 29, 2024. 

The incorporation by reference of 

certain material listed in the rule is 

approved by the Director of the Federal 

Register on January 3, 2024. 

ADDRESSES: The docket, which includes 

Federal Register notices, public meeting 

attendee lists and transcripts, 

comments, and other supporting 

documents/materials, is available for 

review at www.regulations.gov. All 

documents in the docket are listed in 

the www.regulations.gov 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 www.regulations.gov/docket/ 

EERE-2017-BT-TP-0029. 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: 

ApplianceStandardsQuestions@

ee.doe.gov. 

FOR FURTHER INFORMATION CONTACT: 

Mr. Troy Watson, U.S. Department of 

Energy, Office of Energy Efficiency and 

Renewable Energy, Building 

Technologies Office, EE–5B, 1000 

Independence Avenue SW, Washington, 

DC 20585–0121. Telephone: (240) 449– 

9387. Email: 

ApplianceStandardsQuestions@

ee.doe.gov. 

Ms. Kristin Koernig, U.S. Department 

of Energy, Office of the General Counsel, 

GC–33, 1000 Independence Avenue SW, 

Washington, DC 20585–0121. 

Telephone: (202) 586–3593. Email: 

Kristin.Koernig@hq.doe.gov. 

SUPPLEMENTARY INFORMATION: DOE 

incorporates by reference the following 

material into 10 CFR parts 429 and 431: 

AHRI Standard 600–2023 (I–P), 2023 

Standard for Performance Rating of 

Water/Brine to Air Heat Pump 

Equipment, approved September 

11, 2023 (‘‘AHRI 600–2023’’). 

ANSI/ASHRAE Standard 37–2009, 

Methods of Testing for Rating 

Electrically Driven Unitary AirConditioning and Heat Pump 

Equipment, ASHRAE-approved 

June 24, 2009 (‘‘ANSI/ASHRAE 37– 

2009’’). 

Errata sheet for ANSI/ASHRAE 

Standard 37–2009, Methods of 

Testing for Rating Electrically 

Driven Unitary Air-Conditioning 

and Heat Pump Equipment, March 

27, 2019. 

ISO Standard 13256–1:1998, Watersource heat pumps—Testing and 

rating for performance—Part 1: 

Water-to-air and brine-to-air heat 

pumps, approved 1998 (‘‘ISO 

13256–1:1998’’). 

Properties of Secondary Working Fluids 

for Indirect Systems, including 

Section 2.3 Errata Sheet, Melinder, 

published 2010 (‘‘Melinder 2010’’). 

Copies of AHRI 600–2023 are 

available from the Air-Conditioning, 

Heating, and Refrigeration Institute 

(‘‘AHRI’’), 2311 Wilson Blvd., Suite 400, 

Arlington, VA 22201, (703) 524–8800, or 

by going to www.ahrinet.org. 

Copies of ANSI/ASHRAE 37–2009 

and Errata sheet for ANSI/ASHRAE 

Standard 37–2009 are available from the 

American Society of Heating, 

Refrigerating, and Air-Conditioning 

Engineers (‘‘ASHRAE’’), 180 Technology 

Parkway NW, Peachtree Corners, GA 

30092, (404) 636–8400, or by going to 

www.ashrae.org. (ASHRAE standards 

are co-published with American 

National Standards Institute (‘‘ANSI’’)). 

Copies of ISO Standard 13256–1:1998 

can be obtained from the International 

Organization for Standardization 

(‘‘ISO’’), Chemin de Blandonnet 8 CP 

401, 1214 Vernier, Geneva, Switzerland, 

+41 22 749 01 11, or online at: 

www.iso.org/store.html. 

Copies of Melinder 2010 are available 

from the International Institute of 

Refrigeration (‘‘IIR’’), 177 Boulevard 

Malesherbes 75017 Paris, France; +33 

(0)1 42 27 32 35; www.iifiir.org. 

See section IV.N of this document for 

further discussion of these standards. 

Table of Contents 

I. Authority and Background 

A. Authority 

B. Background 

II. Synopsis of the Final Rule 

III. Discussion 

A. Scope of Applicability 

1. WSHPs With Cooling Capacity Greater 

Than or Equal to 135,000 Btu/h 

2. Representations for Residential 

Applications 

B. Definition 

C. Organization of the Amended DOE Test 

Procedures 

D. Updates to Industry Standards 

1. Comments Regarding DOE’s Authority 

2. Comments Regarding DOE’s Test 

Procedure Development Process 

3. Comments Supporting the Adoption of 

AHRI 340/360–2022 

4. Comments Opposing the Adoption of 

AHRI 340/360–2022 

5. Comments Encouraging the Adoption of 

AHRI 600 

6. Finalized DOE Test Procedure 

E. Efficiency Metrics 

1. IEER 

2. ACOP 

3. Optional Representations 

4. Entering Air Conditions 

F. Test Method 

1. Airflow and External Static Pressure 

2. Capacity Measurement 

3. Pump Power Adjustment and Liquid 

External Static Pressure 

4. Test Liquid and Specific Heat Capacity 

5. Liquid Flow Rate 

6. Refrigerant Line Losses 

7. Airflow Measurement 

8. Air Condition Measurement 

9. Duct Losses 

10. Refrigerant Charging 

11. Voltage 

12. Non-Standard Low-Static Indoor Fan 

Motors 

G. Configuration of Unit Under Test 

1. Background and Summary 

2. General Comments Received 

3. Approach for Exclusion of Certain 

Components 

H. Represented Values and Enforcement 

1. Cooling Capacity 

2. Enforcement of IEER 

I. Test Procedure Costs 

J. Effective and Compliance Dates 

IV. Procedural Issues and Regulatory Review 

A. Review Under Executive Orders 12866, 

13563, and 14094 

B. Review Under the Regulatory Flexibility 

Act 

1. Description and Estimate of Small 

Entities Regulated 

2. Description and Estimate of Compliance 

Requirements 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84189 

1The Energy Policy and Conservation Act, as 

amended (‘‘EPCA’’) defines ‘‘commercial package 

air conditioning and heating equipment’’ as aircooled, water-cooled, evaporatively-cooled, or 

water-source (not including ground-water-source) 

electrically operated unitary central air conditioners 

and central air conditioning heat pumps for 

commercial application. (42 U.S.C. 6311(8)(A)) 

EPCA further defines ‘‘small commercial package 

air conditioning and heating equipment’’ as 

commercial package air conditioning and heating 

equipment that is rated below 135,000 Btu per hour 

(cooling capacity); ‘‘large commercial package air 

conditioning and heating equipment’’ as 

commercial package air conditioning and heating 

equipment that is rated at or above 135,000 Btu per 

hour and below 240,000 Btu per hour (cooling 

capacity); and ‘‘very large commercial package air 

conditioning and heating equipment’’ as 

commercial package air conditioning and heating 

equipment that is rated at or above 240,000 Btu per 

hour and below 760,000 Btu per hour (cooling 

capacity). (42 U.S.C. 6311(8)(B)–(D)) 

2All references to EPCA in this document refer 

to the statute as amended through the Energy Act 

of 2020, Public Law 116–260 (Dec. 27, 2020), which 

reflect the last statutory amendments that impact 

Parts A and A–1 of EPCA. 

3For editorial reasons, upon codification in the 

U.S. Code, Part C was redesignated Part A–1. 

3. Certification Statement 

C. Review Under the Paperwork Reduction 

Act of 1995 

D. Review Under the National 

Environmental Policy Act of 1969 

E. Review Under Executive Order 13132 

F. Review Under Executive Order 12988 

G. Review Under the Unfunded Mandates 

Reform Act of 1995 

H. Review Under the Treasury and General 

Government Appropriations Act, 1999 

I. Review Under Executive Order 12630 

J. Review Under Treasury and General 

Government Appropriations Act, 2001 

K. Review Under Executive Order 13211 

L. Review Under Section 32 of the Federal 

Energy Administration Act of 1974 

M. Congressional Notification 

N. Description of Materials Incorporated by 

Reference 

V. Approval of the Office of the Secretary 

I. Authority and Background 

Water-source heat pumps (‘‘WSHPs’’) 

are a category of small, large, and very 

large commercial package airconditioning and heating equipment,1

which are included in the list of 

‘‘covered equipment’’ for which DOE is 

authorized to establish and amend 

energy conservation standards and test 

procedures. (42 U.S.C. 6311(1)(B)–(D); 

6313(a)(1)(G)–(I)) DOE’s test procedure 

for WSHPs is currently prescribed at 

title 10 of the Code of Federal 

Regulations (‘‘CFR’’) part 431.96. The 

following sections discuss DOE’s 

authority to establish and amend a test 

procedure for WSHPs and relevant 

background information regarding 

DOE’s consideration of a test procedure 

for this equipment. 

A. Authority 

The Energy Policy and Conservation 

Act, Public Law 94–163, as amended 

(‘‘EPCA’’),2 authorizes DOE to regulate 

the energy efficiency of a number of 

consumer products and certain 

industrial equipment. (42 U.S.C. 6291– 

6317) Title III, Part C of EPCA,3 added 

by Public Law 95–619, Title IV, section 

441(a), established the Energy 

Conservation Program for Certain 

Industrial Equipment, which sets forth a 

variety of provisions designed to 

improve energy efficiency. This 

equipment includes WSHPs, the subject 

of this document. (42 U.S.C. 6311(1)(B)– 

(D)) 

The energy conservation program 

under EPCA consists essentially of four 

parts: (1) testing, (2) labeling, (3) Federal 

energy conservation standards, and (4) 

certification and enforcement 

procedures. Relevant provisions of 

EPCA include definitions (42 U.S.C. 

6311), test procedures (42 U.S.C. 6314), 

labeling provisions (42 U.S.C. 6315), 

energy conservation standards (42 

U.S.C. 6313), and the authority to 

require information and reports from 

manufacturers (42 U.S.C. 6316; 42 

U.S.C. 6296). 

The Federal testing requirements 

consist of test procedures that 

manufacturers of covered equipment 

must use as the basis for: (1) certifying 

to DOE that their equipment complies 

with the applicable energy conservation 

standards adopted pursuant to EPCA (42 

U.S.C. 6316(b); 42 U.S.C. 6296), and (2) 

making other representations about the 

efficiency of that equipment (42 U.S.C. 

6314(d)). Similarly, DOE uses these test 

procedures to determine whether the 

equipment complies with relevant 

standards promulgated under EPCA. 

Federal energy efficiency 

requirements for covered equipment 

established under EPCA generally 

supersede State laws and regulations 

concerning energy conservation testing, 

labeling, and standards. (42 U.S.C. 

6316(a) and 42 U.S.C. 6316(b); 42 U.S.C. 

6297) DOE may, however, grant waivers 

of Federal preemption for particular 

State laws or regulations, in accordance 

with the procedures and other 

provisions of EPCA. (42 U.S.C. 

6316(b)(2)(D)) 

Under 42 U.S.C. 6314, EPCA sets forth 

the criteria and procedures DOE must 

follow when prescribing or amending 

test procedures for covered equipment. 

EPCA requires that any test procedures 

prescribed or amended under this 

section must be reasonably designed to 

produce test results which reflect energy 

efficiency, energy use or estimated 

annual operating cost of a given type of 

covered equipment during a 

representative average use cycle (as 

determined by the Secretary) and 

requires that test procedures not be 

unduly burdensome to conduct. (42 

U.S.C. 6314(a)(2)) 

EPCA requires that the test 

procedures for commercial package air 

conditioning and heating equipment be 

those generally accepted industry 

testing procedures or rating procedures 

developed or recognized by the AirConditioning, Heating, and Refrigeration 

Institute (‘‘AHRI’’) or by the American 

Society of Heating, Refrigerating and 

Air-Conditioning Engineers 

(‘‘ASHRAE’’), as referenced in ASHRAE 

90.1, ‘‘Energy Standard for Buildings 

Except Low-Rise Residential Buildings’’ 

(‘‘ASHRAE 90.1’’). (42 U.S.C. 

6314(a)(4)(A)) Further, if such an 

industry test procedure is amended, 

DOE must update its test procedure to 

be consistent with the amended 

industry test procedure, unless DOE 

determines, by rule published in the 

Federal Register and supported by clear 

and convincing evidence, that such test 

procedure would not meet the 

requirements in 42 U.S.C. 6314(a)(2) 

and (3), related to representative use 

and test burden. (42 U.S.C. 

6314(a)(4)(B)) 

EPCA also requires that, at least once 

every 7 years, DOE evaluate test 

procedures for each type of covered 

equipment, including WSHPs, to 

determine whether amended test 

procedures would more accurately or 

fully comply with the requirements for 

the test procedures to not be unduly 

burdensome to conduct and be 

reasonably designed to produce test 

results that reflect energy efficiency, 

energy use, and estimated operating 

costs during a representative average 

use cycle. (42 U.S.C. 6314(a)(1) 

In addition, if the Secretary 

determines that a test procedure 

amendment is warranted, the Secretary 

must publish proposed test procedures 

in the Federal Register and afford 

interested persons an opportunity (of 

not less than 45 days’ duration) to 

present oral and written data, views, 

and arguments on the proposed test 

procedures. (42 U.S.C. 6314(b)) If DOE 

determines that test procedure revisions 

are not appropriate, DOE must publish 

in the Federal Register its 

determination not to amend the test 

procedures. (42 U.S.C. 6314(a)(1)(A)(ii)) 

DOE undertook this rulemaking in 

satisfaction of the 7-year-lookback 

obligations under EPCA. (42 U.S.C. 

6314(a)(1)). As discussed previously in 

this document, WSHPs are a category of 

commercial package air conditioning 

and heating equipment. EPCA requires 

the DOE test procedures for commercial 

package air conditioning and heating 


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84190 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

4An extension of the comment period for the 

June 2018 RFI was published July 9, 2018. 83 FR 

31704. 

5The parenthetical reference provides a reference 

for information located in the docket of DOE’s 

rulemaking to develop an amended test procedure 

for WSHPs. (Docket No. EERE–2017–BT–TP–0029, 

which is maintained at www.regulations.gov). The 

references are arranged as follows: (commenter 

name, comment docket ID number, page of that 

document). 

equipment to be the generally accepted 

industry testing procedure developed or 

recognized by AHRI or by ASHRAE, as 

referenced in ASHRAE 90.1. (42 U.S.C. 

6314(a)(4)(A)) EPCA further requires 

that each time the referenced industry 

test procedure is amended in ASHRAE 

90.1, DOE must amend its test 

procedure to be consistent with the 

industry update, unless DOE determines 

in a rulemaking that there is clear and 

convincing evidence that the updated 

update industry test procedure would 

not be representative of an average use 

cycle or would be unduly burdensome 

to conduct. (42 U.S.C. 6314(a)(4)(B)(C)) 

However, under the 7-year-lookback 

obligations, there is no ‘‘clear and 

convincing evidence’’ required in EPCA. 

Rather, EPCA only requires that DOE 

determine whether the amended test 

procedure would more accurately or 

fully comply with the requirements for 

the test procedure to not be unduly 

burdensome to conduct and be 

reasonably designed to produce test 

results that reflect energy efficiency, 

energy use, and estimated operating 

costs during a representative average 

use cycle. (42 U.S.C. 6314(a)(1)) 

DOE is publishing this final rule in 

satisfaction of its statutory obligations 

under EPCA. (42 U.S.C. 6314(a)(1)(A)) 

B. Background 

DOE’s existing test procedure for 

WSHPs is specified at 10 CFR 431.96 

(‘‘Uniform test method for the 

measurement of energy efficiency of 

commercial air conditioners and heat 

pumps’’). The Federal test procedure 

currently incorporates by reference 

International Organization for 

Standardization (‘‘ISO’’) Standard 

13256–1 (1998), ‘‘Water-source heat 

pumps—Testing and rating for 

performance—Part 1: Water-to-air and 

brine-to-air heat pumps,’’ (‘‘ISO 13256– 

1:1998’’). 

DOE initially incorporated ISO 

13256–1:1998 as the referenced test 

procedure for WSHPs on October 21, 

2004 (69 FR 61962), and DOE last 

reviewed the test procedure for WSHPs 

as part of a final rule for commercial 

package air conditioners and heat 

pumps published in the Federal 

Register on May 16, 2012 (‘‘May 2012 

Final Rule’’; 77 FR 28928). In the May 

2012 Final Rule, DOE retained the 

reference to ISO 13256–1:1998 but 

adopted additional provisions for 

equipment setup at 10 CFR 431.96(e), 

which provide specifications for 

addressing key information typically 

found in the installation and operation 

manuals. 77 FR 28928, 28991. 

On June 22, 2018, DOE published a 

request for information (‘‘RFI’’) to 

collect information and data to consider 

amendments to DOE’s test procedure for 

WSHPs (‘‘June 2018 RFI’’). 83 FR 

29048.4 Subsequently, on August 30, 

2022, DOE published a notice of 

proposed rulemaking (‘‘NOPR’’) in 

which DOE responded to stakeholders’ 

comments on the June 2018 RFI and 

proposed amendments to its test 

procedure for WSHPs (‘‘August 2022 

NOPR’’) 87 FR 53302. In the August 

2022 NOPR, DOE proposed to amend 

the test procedures for WSHPs to 

incorporate by reference AHRI Standard 

340/360–2022 (I–P), ‘‘2022 Standard for 

Performance Rating of Commercial and 

Industrial Unitary Air-conditioning and 

Heat Pump Equipment’’ (‘‘AHRI 340/ 

360–2022’’) and ANSI/ASHRAE 

Standard 37–2009, ‘‘Methods of Testing 

for Rating Electrically Driven Unitary 

Air-Conditioning and Heat Pump 

Equipment’’ (‘‘ANSI/ASHRAE 37– 

2009’’). Id. at 87 FR 53348. Specifically, 

DOE proposed to implement these 

changes by adding new appendices C 

and C1 to subpart F of part 431, both 

titled ‘‘Uniform Test Method for 

Measuring the Energy Consumption of 

Water-Source Heat Pumps.’’ (‘‘appendix 

C’’ and ‘‘appendix C1,’’ respectively). Id. 

at 87 FR 53351–52252. The current DOE 

test procedure for WSHPs would be 

relocated to appendix C without change, 

and the new test procedure adopting 

AHRI 340/360–2022 and ANSI/ 

ASHRAE 37–2009 and any other 

amendments would be set forth in 

proposed appendix C1 for determining 

IEER. Id. at 87 FR 53352–53353. DOE 

held a public meeting on September 14, 

2022 (‘‘NOPR public meeting’’) to 

present the key proposals from the 

August 2022 NOPR. 

DOE received comments in response 

to the August 2022 NOPR from the 

interested parties listed in Table I.1. 

TABLE I.1—LIST OF COMMENTERS WITH WRITTEN SUBMISSIONS IN RESPONSE TO THE AUGUST 2022 NOPR 

Commenter(s) Reference in this final rule Comment No. 

in the docket Commenter type 

Air-Conditioning, Heating and Refrigeration Institute ............ AHRI ...................................... 24 Trade Association. 

Appliance Standards Awareness Project, American Council 

for an Energy-Efficient Economy.

Joint Commenters ................. 27 Efficiency Organizations. 

Northwest Energy Efficiency Alliance .................................... NEEA ..................................... 25 Efficiency Organization. 

New York State Energy Research and Development Authority.NYSERDA ............................. 21 State Agency. 

ClimateMaster, Inc ................................................................. ClimateMaster ....................... 22 Manufacturer. 

WaterFurnace International ................................................... WaterFurnace ........................ 20 Manufacturer. 

Enertech Global, LLC ............................................................ Enertech ................................ 19 Manufacturer. 

Florida Heat Pump Manufacturing ........................................ FHP ....................................... 26 Manufacturer. 

The Geothermal Exchange Organization .............................. GeoExchange ........................ 29 Trade Association. 

Madison Indoor Air Quality .................................................... MIAQ ..................................... 23 Manufacturer. 

Trane Technologies ............................................................... Trane ..................................... 28 Manufacturer. 

A parenthetical reference at the end of 

a comment quotation or paraphrase 

provides the location of the item in the 

public record.5 In addition to the 

comments listed in Table I.1, DOE also 

received 2 comments from anonymous 

individuals, which were considered in 

the development of this final rule, but 

not cited individually. To the extent 

that interested parties have provided 

written comments that are substantively 

consistent with any oral comments 

provided during the NOPR public 

meeting, DOE cites the written 

comments throughout this final rule. 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84191 

6ASHRAE 90.1–2022 lists ANSI/AHRI/ASHRAE 

13256–1: 1998 (2021) as the test procedure for 

WSHPs. However, DOE believes ASHRAE intended 

to include ‘‘2012’’ in the parentheses as that was the 

most recent year in which the 1998 version of 

13256–1 was redesignated. 

Any oral comments provided during the 

webinar that are not substantively 

addressed by written comments are 

summarized and cited separately 

throughout this final rule. 

In May 2021, ISO published an 

updated version of Standard 13256–1, 

ISO Standard 13256–1 (2021), ‘‘Watersource heat pumps—Testing and rating 

for performance—Part 1: Water-to-air 

and brine-to-air heat pumps,’’ (‘‘ISO 

13256–1:2021’’). In January 2023, 

ASHRAE published ASHRAE 90.1– 

2022. ASHRAE 90.1–2022 did not 

update the referenced test procedure for 

WSHPs.6

On September 11, 2023, AHRI 

published a new industry test standard 

for WSHPs, titled AHRI Standard 600, 

‘‘Standard for Performance Rating of 

Water/Brine to Air Heat Pump 

Equipment’’ (‘‘AHRI 600–2023’’). DOE 

worked with stakeholders (including 

WSHP manufacturers and efficiency 

advocates) as part of the AHRI 

Geothermal and WSHP standards 

technical committee (‘‘STC’’) to develop 

AHRI 600–2023, which addresses many 

of the issues in the current WSHP test 

procedure that DOE raised in the August 

2022 NOPR. The intent of the 

Geothermal and WSHP STC was for 

AHRI 600–2023 to be used for testing 

WSHPs instead of any versions of ISO 

Standards 13256–1. 

II. Synopsis of the Final Rule 

In this final rule DOE is establishing 

new appendices C and C1 to subpart F 

of part 431. The current DOE test 

procedure for WSHPs is relocated to 

appendix C without change. The 

amended test procedure for WSHPs is 

established in a new appendix C1, 

which includes the following amended 

test procedure requirements for WSHPs 

for measuring the updated efficiency 

metrics: (1) integrated energy efficiency 

ratio (‘‘IEER’’) for WSHPs using AHRI 

600–2023; and (2) applied coefficient of 

performance (‘‘ACOP’’) using AHRI 

600–2023. Use of the amended test 

procedure in appendix C1 will not be 

required until such time as compliance 

is required with amended energy 

conservation standards for WSHPs 

denominated in terms of IEER, should 

DOE adopt such standards. 

Additionally, DOE is expanding the 

scope of the test procedure to include 

WSHPs with capacities between 135,000 

and 760,000 British thermal units per 

hour (‘‘Btu/h’’), as well as specifying the 

components that must be present for 

testing and amending certain provisions 

related to representations and 

enforcement in 10 CFR part 429. 

As discussed in this final rule, DOE 

has concluded that the amended test 

procedure in appendix C1 

(incorporating by reference the most 

recent industry consensus test standard 

for WSHPs, AHRI 600–2023) provides 

more representative results and more 

fully complies with the requirements of 

42 U.S.C. 6314(a)(2) than testing with 

the current Federal test procedure 

(based on ISO 13256–1:1998). 

The adopted amendments are 

summarized in Table II.1 and compared 

to the test procedure provisions in place 

prior to the amendment, as well as the 

reason for the adopted change. 

TABLE II.1—SUMMARY OF CHANGES IN THE AMENDED TEST PROCEDURE

Current DOE test procedure Amended test procedure Attribution 

Located in 10 CFR 431.96 .......................................... Current test procedure moved to appendix C to 10 

CFR 431.96 and amended test procedure established in appendix C1 to 10 CFR 431.96.

Readability of test procedure. 

Scope is limited to units with a cooling capacity less 

than 135,000 Btu/h.

Expands the scope of the test procedure to additionally include units with a cooling capacity greater than or equal to 135,000 Btu/h and less than 

760,000 Btu/h in 10 CFR 431.96.

Harmonize with scope of test procedure for water-cooled commercial unitary air conditioners. 

Incorporates by reference ISO 13256–1:1998 ........... Incorporates by reference AHRI 600–2023 into appendix C1.Improve representativeness of test 

procedure. 

Includes provisions for determining EER metric ......... Includes provisions for determining IEER by incorporating by reference AHRI 600–2023 into appendix C1.Improve representativeness of test 

procedure. 

Specifies test condition of 68 °F for measuring coefficient of performance (‘‘COP’’).Changes the test condition for ACOP to 50 °F, by 

incorporating by reference AHRI 600–2023 into 

appendix C1.

Improve representativeness of test 

procedure. 

Does not include WSHP-specific provisions for determination of represented values in 10 CFR 429.43.Includes provisions in 10 CFR 429.43 specific to 

WSHPs for determining represented values.

Establish WSHP-specific provisions for determination of represented values. 

Does not include WSHP-specific enforcement provisions in 10 CFR 429.134.Adopts product-specific enforcement provisions for 

WSHPs regarding verification of cooling capacity, 

testing of systems with specific components, and 

IEER testing conducted by DOE.

Establish enforcement provisions 

for DOE testing of WSHPs. 

DOE has determined that the test 

procedure in appendix C, as described 

in section III of this final rule regarding 

the establishment of appendix C, does 

not alter the measured efficiency of 

WSHPs or require retesting solely as a 

result of the establishment of appendix 

C. Additionally, DOE has determined 

that the establishment of appendix C 

will not increase the cost of testing. 

DOE has determined that the 

amended test procedure adopted in 

appendix C1 does alter the measured 

efficiency of WSHPs and would increase 

the cost of testing relative to the current 

Federal test procedure, as discussed 

further in section III.I of this document. 

However, as stated, use of appendix C1 

will not be required until the 

compliance date of any amended 

standards denominated in terms of 

IEER, should DOE adopt such standards. 

DOE has also determined that the 

amended test procedure will not be 

unduly burdensome to conduct. 

For units with cooling capacity 

greater than or equal to 135,000 Btu/h 

and less than 760,000 Btu/h newly 

added within scope of the WSHP test 

procedure, testing according to the 

established test procedure for purposes 

of certifications of compliance will not 


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84192 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

be required until the compliance date of 

any energy conservation standards for 

such equipment, should DOE adopt 

such standards. However, if a 

manufacturer chooses to make 

representations of the energy efficiency 

or energy use of such equipment, 

beginning 360 days after publication of 

the final rule in the Federal Register, 

the manufacturer will be required to 

base such representations on the DOE 

test procedure. (42 U.S.C. 6314(d)(1)) 

The effective date for the amended 

test procedure adopted in this final rule 

is 30 days after publication of this 

document in the Federal Register. 

Discussion of DOE’s actions are 

addressed in detail in section III of this 

document. 

III. Discussion 

A. Scope of Applicability 

This rulemaking applies to WSHPs, 

which are a category of small, large, and 

very large commercial package airconditioning and heating equipment. 

(See 42 U.S.C. 6311(1)(B)–(D)) In its 

regulations, DOE defines WSHP as ‘‘a 

single-phase or three-phase reversecycle heat pump that uses a circulating 

water loop as the heat source for heating 

and as the heat sink for cooling. The 

main components are a compressor, 

refrigerant-to-water heat exchanger, 

refrigerant-to-air heat exchanger, 

refrigerant expansion devices, 

refrigerant reversing valve, and indoor 

fan. Such equipment includes, but is not 

limited to, water-to-air water-loop heat 

pumps.’’ 10 CFR 431.92. 

1. WSHPs With a Cooling Capacity 

Greater Than or Equal to 135,000 

Btu/h 

The current Federal WSHP test 

procedure and energy conservation 

standards apply to WSHPs with a rated 

cooling capacity below 135,000 Btu/h. 

10 CFR 431.96, Table 1 and 10 CFR 

431.97, Table 3. In the August 2022 

NOPR, DOE proposed to expand the 

scope of applicability of the test 

procedure to include WSHPs with a 

cooling capacity between 135,000 and 

760,000 Btu/h. 87 FR 53302, 53307. 

Specifically, DOE proposed to update 

Table 1 to 10 CFR 431.96 to include 

WSHPs with a cooling capacity greater 

than or equal to 135,000 Btu/h and less 

than 240,000 Btu/h under Large 

Commercial Package Air-Conditioning 

and Heating Equipment; and to include 

WSHPs with a cooling capacity greater 

than or equal to 240,000 Btu/h and less 

than 760,000 Btu/h under Very Large 

Commercial Package Air-Conditioning 

and Heating Equipment. Id. In the 

August 2022 NOPR, DOE tentatively 

determined that, based on the presence 

on the market of units over 135,000 Btu/ 

h with efficiency ratings and the 

identification of laboratories capable of 

testing such units, such testing would 

not be unduly burdensome. Id. at 87 FR 

53306. Additionally, DOE stated that 

expanding the scope of DOE’s test 

procedure for WSHPs to include 

equipment with a cooling capacity 

between 135,000 Btu/h and 760,000 

Btu/h would ensure that representations 

for all WSHPs are made using the same 

test procedure and that ratings for 

equipment in this cooling capacity 

range are appropriately representative. 

Id. at 87 FR 53306–53307. DOE 

requested comments on the proposed 

expansion of the scope of applicability 

of the Federal test procedure to include 

WSHPs with a cooling capacity between 

135,000 and 760,000 Btu/h. Id. at 87 FR 

53307. 

In response to the June 2022 NOPR, 

some commenters expressed concern 

with the proposal to expand the scope 

of the test procedure. AHRI commented 

that it is concerned with DOE’s proposal 

to expand testing coverage and update 

test procedures without taking steps to 

measure the impact on manufacturers 

and third-party test labs. (AHRI, No. 24 

at pp. 2–3) AHRI asserted that the 

August 2022 NOPR does not show 

evidence of DOE’s participation in the 

critical consensus process required for 

developing test procedures and 

improving efficiency for ASHRAE 90.1, 

which involves conversations regarding 

lab capabilities, product availability, 

and product efficiencies. (Id.) 

AHRI further commented that the 

impact on manufacturers of DOE’s 

proposed test coverage expansion has 

not been quantified. (Id. at p. 3) AHRI 

stated that it expects third-party test 

labs will not be able to accommodate 

the expanded scope to include 

equipment up to 760,000 Btu/h, as such 

an expansion of scope would require 

test labs to increase their testing 

capacity from 3 gallons per minute 

(‘‘GPM’’) per ton (‘‘GPM/ton’’) at 50 °F to 

nearly 200 GPM. (Id.) AHRI commented 

that the additional constraints placed on 

test labs would cause delays in testing 

other equipment as well as WSHPs. (Id.) 

Similarly, ClimateMaster opposed 

DOE’s proposal to include WSHP 

equipment with capacities greater than 

135,000 Btu/h within the scope of the 

test procedure due to the cost burden 

that ClimateMaster asserted would be 

imposed on manufacturers and 

consumers. (ClimateMaster, No. 22 at p. 

2) ClimateMaster stated that these larger 

model sizes account for only 0.4 percent 

of its overall market volume from 2019 

to 2021. (Id.) ClimateMaster presented 

data showing that adding the highercapacity models to the scope of the test 

procedure would increase the 

certification cost by $184,000 per year to 

accommodate testing and equipment 

costs. (Id.) ClimateMaster further 

commented that third-party compliance 

labs are unable to test equipment above 

420,000 Btu/h, which would render 

DOE’s proposal to test WSHPs that 

reach 760,000 Btu/h impossible. (Id.) 

ClimateMaster noted that the increased 

cost burden needed to accommodate 

such a small percentage of affected 

equipment would negatively affect 

consumers as well as manufacturers. 

(Id.) ClimateMaster recommended that 

DOE maintain the scope of applicability 

of the Federal test procedure to only 

include WSHPs with cooling capacity 

below 135,000 Btu/h. (Id. at p. 3) 

FHP commented that its main concern 

regarding DOE’s proposal to expand the 

scope of applicability is lab availability. 

(FHP, No. 26 at p. 2) FHP stated that it 

has found only a limited supply of 

WSHP testing facilities, none of which 

have a capacity to test equipment over 

480,000 Btu/h. (Id.) FHP recommended 

that DOE provide a list of testing 

facilities for WSHPs with a cooling 

capacity greater than 135,000 Btu/h, 

stating that multiple testing facilities 

must be available to ensure that an 

increased demand for large unit testing 

does not also cause spikes in testing 

costs due to supply and demand 

pressures. (Id.) FHP further commented 

that WSHPs with capacities above 

135,000 Btu/h account for less than 1 

percent of the market share. (Id.) 

MIAQ commented that it is concerned 

DOE has not quantified the impact on 

manufacturers and third-party labs of 

expanding the scope of coverage to 

larger equipment. (MIAQ, No. 23 at p. 

3) MIAQ stated that conversations 

regarding lab capabilities and product 

availability and efficiency occur during 

the consensus process required for 

developing test procedures in ASHRAE 

90.1. (Id.) MIAQ stated that the water 

volume required for testing larger 

capacities up to 760,000 Btu/h may 

limit testing. (Id.) More specifically, 

MIAQ stated that testing a 760,000 Btu/ 

h WSHP would require approximately 

200 GPM of 50 °F water, which MIAQ 

stated would require large chillers to 

maintain the water at the correct 

temperature. (Id.) MIAQ also noted that 

due to the increased need for larger 

spaces capable of testing such 

equipment, there could be bottlenecks at 

third-party test labs, which also test 

other categories of commercial package 

air conditioning and heating equipment. 

(Id.) 


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WaterFurnace stated that there are no 

known WSHP products with a cooling 

capacity above approximately 360,000 

Btu/h nor any test facilities capable of 

testing such WSHPs at the required 

conditions for IEER. (WaterFurnace, No. 

20 at p. 6) WaterFurnace commented 

that DOE did not justify regulating this 

larger equipment and that doing so 

would be a burden on the industry and 

testing facilities. (Id.) 

Other commenters supported the 

proposal to expand the scope of the 

WSHP test procedure. The Joint 

Commenters, NEEA, and NYSERDA 

supported DOE’s proposal to include 

WSHPs with cooling capacities between 

135,000 and 760,000 Btu/h in the scope 

of the test procedure. (Joint 

Commenters, No. 27 at p. 1; NEEA, No. 

25 at p. 2; NYSERDA, No. 21 at p. 2) 

The Joint Commenters stated that they 

believe it is important that equipment in 

this capacity range be testing using a 

standardized test procedure and that 

expanding the scope of the test 

procedure would bring it into alignment 

with test procedures for other 

commercial package air-conditioning 

and heating equipment. (Joint 

Commenters, No. 27 at p. 1) 

NEEA commented that, while this 

size range may account for relatively 

few annual sales, expanding the test 

procedure to larger capacity equipment 

would ensure that large equipment is 

fairly rated and regulated and held to 

the same standards as smaller 

equipment of the same type. (NEEA, No. 

25 at p. 2) 

NYSERDA asserted that expanding 

the scope is a feasible and necessary 

change to ensure that WSHPs of varying 

sizes are consistently tested according to 

industry standards, which will 

demonstrate to customers that WSHPs— 

especially geothermal WSHPs—are 

reliable and thus enable WSHP market 

growth. (NYSERDA, No. 21 at p. 2) 

As discussed in the August 2022 

NOPR, DOE has identified numerous 

model lines of WSHPs with a cooling 

capacity over 135,000 Btu/h from a wide 

variety of manufacturers. 87 FR 53302, 

53306. The manufacturer literature for 

all identified model lines includes 

efficiency representations that are 

explicitly based on ISO 13256–1:1998, 

the current industry standard, 

indicating efficiency representations can 

be made for these models using an 

industry consensus test procedure for 

WSHPs. Id. 

In response to comments from AHRI, 

Climate Master, and WaterFurnace, as 

discussed in the August 2022 NOPR, 

DOE is aware of several independent 

test labs that have the capability to test 

WSHPs with a cooling capacity over 

135,000 Btu/h. Id. DOE conducted 

investigative testing on multiple WSHP 

models with a cooling capacity over 

135,000 Btu/h at one such independent 

test lab and did not encounter any 

difficulties specific to units in this 

capacity range. Id. Regarding comments 

by ClimateMaster and FHP stating that 

test labs cannot test units greater than 

420,000 Btu/h and 480,000 Btu/h, 

respectively, comments submitted by 

WaterFurnace indicate that the largest 

models currently available on the 

market are 360,000 Btu/h, which DOE 

research corroborates. As such, any 

capacity limitations for testing as 

asserted by ClimateMaster and FHP 

would not impact any models currently 

on the market. 

Further, DOE notes that AHRI 600– 

2023 includes provisions for testing 

units with capacities over 135,000 Btu/ 

h. Both ASHRAE 90.1 and DOE 

regulations cover other categories of 

commercial air conditioning and 

heating equipment, including watercooled commercial unitary air 

conditioners (‘‘WCUACs’’), with a 

cooling capacity up to 760,000 Btu/h. 

As discussed in the August 2022 NOPR, 

DOE has determined that testing WSHPs 

with a cooling capacity over 135,000 

Btu/h would be of comparable burden to 

testing other commercial air 

conditioning and heating equipment of 

similar capacity, such as WCUACs. Id. 

Regarding comments on the potential 

burden of testing such units, EPCA does 

not require DOE to consider only 

burden-reducing options, but rather 

requires only that the test procedure 

must not be unduly burdensome to 

conduct. Expanding the scope of the test 

procedure to include larger equipment 

would not necessitate certification 

unless DOE were to establish standards 

for such equipment. Until such a time, 

an expansion of scope for the test 

procedure would require only that if 

manufacturers choose to make optional 

representations of efficiency for WSHPs 

with a cooling capacity over 135,000 

Btu/h, that such optional 

representations be made in accordance 

with the DOE test procedure. Further, 

DOE notes that representations for 

WSHPs can be made either based on 

testing (in accordance with 10 CFR 

429.43(a)(1)) or based on alternative 

efficiency determination methods 

(‘‘AEDMs’’) (in accordance with 10 CFR 

429.43(a)(2)). An AEDM is a computer 

modeling or mathematical tool that 

predicts the performance of non-tested 

basic models. These computer modeling 

and mathematical tools, when properly 

developed, can provide a means to 

predict the energy usage or efficiency 

characteristics of a basic model of a 

given covered product or equipment 

and reduce the burden and cost 

associated with testing. Whereas DOE 

requires at least two units to be tested 

per basic model when represented 

values are determined through testing, 

DOE requires each AEDM to be 

validated by tests of only two WSHP 

basic models of any capacity (in 

accordance with 10 CFR 429.70(c)(2)). 

Based on DOE’s observation of the 

prevalence of use of AEDMs for WSHP 

and similar equipment for which energy 

conservation standards currently apply 

(i.e., for equipment with a cooling 

capacity no greater than 135,000 Btu/h), 

DOE expects that representations of 

efficiency could be determined through 

the use of AEDMs for the majority of 

models with a cooling capacity over 

135,000 Btu/h. As such, DOE expects an 

expansion of scope for the DOE test 

procedure to include equipment with a 

cooling capacity over 135,000 Btu/h 

would not necessitate the testing of 

many such larger units. Therefore, 

testing would not be as burdensome as 

noted by commenters. 

Based on the presence on the market 

of units over 135,000 Btu/h, the 

identification of laboratories capable of 

testing such units, DOE’s observation 

that representations of efficiency for 

such equipment are currently being 

made, and the inclusion of units over 

135,000 Btu/h within the scope of the 

most recent industry consensus test 

standard for WSHPs (AHRI 600–2023), 

DOE has determined that testing units 

with a cooling capacity over 135,000 

Btu/h is feasible and would not be 

unduly burdensome. As discussed, 

expanding the scope of DOE’s test 

procedure for WSHPs to include 

equipment with a cooling capacity 

between 135,000 Btu/h and 760,000 

Btu/h would ensure that representations 

for all WSHPs are made using the same 

test procedure and that ratings for 

equipment in this cooling capacity 

range are appropriately representative. 

For the reasons discussed in the 

proceeding paragraphs and in the 

August 2022 NOPR, DOE is expanding 

the scope of applicability of the WSHP 

test procedure to include WSHPs with 

a cooling capacity between 135,000 and 

760,000 Btu/h consistent with the scope 

of AHRI 600–2023. Specifically, DOE is 

updating Table 1 to 10 CFR 431.96 to 

include WSHPs with a cooling capacity 

greater than or equal to 135,000 Btu/h 

and less than 240,000 Btu/h under Large 

Commercial Package Air-Conditioning 

and Heating Equipment and to include 

WSHPs with a cooling capacity greater 

than or equal to 240,000 Btu/h and less 

than 760,000 Btu/h under Very Large 


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84194 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

Commercial Package Air-Conditioning 

and Heating Equipment. 

As previously discussed, DOE does 

not currently specify energy 

conservation standards for WSHPs with 

a cooling capacity over 135,000 Btu/h. 

DOE would consider any future 

standards applicable to WSHPs over 

135,000 Btu/h in a separate energy 

conservation standards rulemaking. 

Manufacturers of WSHPs with a cooling 

capacity over 135,000 Btu/h would not 

be required to test WSHPs with a 

cooling capacity over 135,000 Btu/h 

until such time as compliance with 

standards for this equipment were 

required, should DOE adopt such 

standards. DOE notes, however, that 

beginning 360 days after this final rule 

publishes in the Federal Register, any 

voluntary representations with respect 

to energy use or efficiency must be 

based on the test procedure in appendix 

C, and any voluntary representations of 

IEER or ACOP must be based on the test 

procedure in appendix C1. 

2. Representations for Residential 

Applications 

Sections 6.5 and 6.6 of AHRI 600– 

2023 state that provisions for 

determination of residential cooling 

capacity and efficiency are to be added 

in a future revision. In the August 2022 

NOPR, DOE proposed to allow optional 

energy efficiency ratio (‘‘EER’’) and COP 

representations at the full-load and partload EWT conditions specified in Table 

1 of ISO 13256–1:1998 per the DOE test 

procedure proposed in appendix C1. 87 

FR 53302, 53313. DOE notes that the 

residential representations discussed in 

AHRI 600–2023 are separate from the 

proposed optional representations from 

the August 2022 NOPR, as test 

provisions in AHRI 600–2023 specify 

separate air and liquid external static 

pressures to be used during testing to 

develop ratings for residential 

applications. However, the residential 

representations have not yet been fully 

developed for WSHPs, as indicated in 

sections 6.5 and 6.6 of AHRI 600–2023. 

Therefore, DOE is not adding any 

provisions regarding residential 

representations in this final rule but will 

continue to work with the AHRI 600 

committee to develop such provisions. 

B. Definition 

As discussed, WSHPs are a category 

of commercial package air-conditioning 

and heating equipment. The current 

definition for ‘‘water-source heat pump’’ 

does not explicitly state that it is 

‘‘commercial package air-conditioning 

and heating equipment.’’ This is 

inconsistent with the definitions of most 

other categories of commercial package 

air-conditioning and heating equipment 

(e.g., computer room air conditioner, 

single package vertical air conditioner, 

variable refrigerant flow multi-split air 

conditioner). See 10 CFR 431.92. 

To provide consistency with other 

definitions of specific categories of 

commercial package air-conditioning 

and heating equipment, DOE proposed 

in the August 2022 NOPR to amend the 

definition of ‘‘water-source heat pump’’ 

to explicitly indicate that WSHPs are a 

category of commercial package airconditioning and heating equipment. 87 

FR 53302, 53307. This proposed 

clarification to the ‘‘water-source heat 

pump’’ definition would not change the 

scope of equipment covered by the 

definition. 

In addition, the current definition for 

WSHPs lists the main components of a 

WSHP and it includes ‘‘indoor fan’’ on 

that list. See 10 CFR 431.92. DOE 

discussed in the August 2022 NOPR that 

it has identified coil-only WSHPs on the 

market that rely on a separately 

installed furnace or modular blower for 

indoor air movement. 87 FR 53302, 

53307. To clarify that coil-only WSHPs 

are covered under the WSHP definition, 

DOE proposed to amend the WSHP 

definition to make clear that an indoor 

fan is not an included component for 

coil-only WSHPs. Id. Specifically, DOE 

proposed to include the parenthesized 

statement ‘‘except that coil-only units 

do not include an indoor fan’’ in the 

sentence listing the main components in 

the proposed WSHP definition. Id. 

DOE requested comment on the 

proposed change to the definition of 

WSHP to explicitly indicate that WSHP 

is a category of commercial package airconditioning and heating equipment 

and to clarify that the presence of an 

indoor fan does not apply to coil-only 

units. Id. 

ClimateMaster generally agreed with 

DOE’s proposed definition of WSHP, 

but requested clarity on what 

constitutes a commercial system. 

(ClimateMaster, No. 22 at p. 3) 

ClimateMaster commented that other 

industry test programs clearly 

demarcate the difference between 

systems through listed capacity. (Id.) 

ClimateMaster noted that the current 

definition includes only packaged 

systems but that DOE’s proposed 

amendments in the August 2022 NOPR 

specified procedures for testing split 

systems. (Id.) ClimateMaster stated that 

it is not able to determine with the 

current definition what exact products 

would fall under the certification 

program and how DOE would enforce 

which products are covered by the 

applicable standards. (Id.) 

ClimateMaster also stated that there 

were non-reversible WSHP products 

that operate as either cooling only units 

or utilize a hydronic coil that are not 

covered by the current definition. 

ClimateMaster stated that provisions 

should be made for this equipment type. 

(Id.) 

WaterFurnace questioned whether it 

would be necessary to change the 

definition of WSHP if DOE were to 

maintain the method of test based on 

ISO 13256 and AHRI 600. 

(WaterFurnace, No. 20 at p. 6) 

WaterFurnace recommended using the 

term ‘‘heat pump’’ in lieu of ‘‘air 

conditioner and heating equipment,’’ 

which WaterFurnace asserted is 

technically inaccurate. (Id.) 

Regarding ClimateMaster’s request for 

clarity regarding the definition, DOE 

notes that all products that meet the 

WSHP definition, with sizes less than 

760,000 Btu/h cooling capacity (see 

discussion in section III.A of this final 

rule), would be considered a WSHP, 

regardless of whether the models are 

marketed and distributed in commerce 

for commercial or residential 

applications. The definition of WSHPs 

includes both single-package and splitsystem equipment. 

Regarding WaterFurnace’s comment 

on whether it would be necessary to 

change the definition of WSHP if DOE 

were to maintain the method of test 

based on ISO 13256 and AHRI 600, the 

DOE definition of WSHP serves to 

specify models that are within the scope 

of coverage of DOE’s regulations and is 

independent of the test procedure being 

used for WSHPs. DOE also notes in 

response to WaterFurnace’s comment 

that the definition of WSHP already 

uses the term ‘‘heat pump’’ to define 

WSHP and that the term ‘‘commercial 

package air-conditioning and heating 

equipment’’ is being added to the 

definition only to indicate the larger 

type of equipment, as defined in the 

EPCA, of which WSHPs are a category. 

Regarding ClimateMaster’s comment 

that the current definition does not 

cover units that are not reversible, DOE 

considers water-source heat pumps to 

include only models with reverse-cycle 

heating; therefore, DOE is not removing 

the ‘‘reverse-cycle’’ provision from the 

WSHP definition. 

For the reasons discussed, DOE is 

adopting an amended definition of 

WSHP that is identical to the definition 

proposed in the August 2022 NOPR, as 

follows: 

Water-source heat pump means 

commercial package air-conditioning 

and heating equipment that is a singlephase or three-phase reverse-cycle heat 

pump that uses a circulating water loop 

as the heat source for heating and as the 


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heat sink for cooling. The main 

components are a compressor, 

refrigerant-to-water heat exchanger, 

refrigerant-to-air heat exchanger, 

refrigerant expansion devices, 

refrigerant reversing valve, and indoor 

fan (except that coil-only units do not 

include an indoor fan). Such equipment 

includes, but is not limited to, water-toair water-loop heat pumps. 

C. Organization of the Amended DOE 

Test Procedures 

In this final rule, DOE is relocating 

and centralizing the current test 

procedure for WSHPs to a new 

appendix C to subpart F of part 431 and 

establishing an amended test procedure 

for WSHPs in a new appendix C1 to 

subpart F of part 431. Appendix C 

maintains the substance of the current 

test procedure and continues to 

reference ISO 13256–1:1998 and 

provide for determining EER and COP. 

Appendix C also includes the additional 

test provisions for equipment set-up 

currently codified at 10 CFR 431.96(e). 

As discussed, WSHPs are required to be 

tested according to appendix C until 

such time as compliance is required 

with an amended energy conservation 

standard based on the amended test 

procedure in appendix C1, should DOE 

adopt such a standard. 

DOE is also establishing an amended 

test procedure for WSHPs in a new 

appendix C1 to subpart F of part 431 

that includes provisions for determining 

IEER and ACOP by incorporating by 

reference AHRI 600–2023, as discussed 

further throughout this document. 

WSHPs are not required to be tested 

according to appendix C1 until such 

time as compliance is required with an 

amended energy conservation standard 

denominated in terms of the IEER 

metric, should DOE adopt such a 

standard; although, any voluntary 

representations of IEER prior to the 

compliance date of any such standard 

must be based on testing according to 

appendix C1. 

D. Updates to Industry Standards 

As noted in section I.B. of this 

document, the DOE test procedure 

currently incorporates by reference ISO 

13256–1:1998 and includes additional 

provisions for equipment set-up at 10 

CFR 431.96(e), which provide 

specifications for addressing key 

information typically found in the 

installation and operation manuals. In 

the August 2022 NOPR, DOE proposed 

to adopt an amended test procedure for 

WSHPs in a new appendix C1 that 

would incorporate by reference AHRI 

340/360–2022 for measuring efficiency 

using IEER. 87 FR 53302, 53311. 

Because AHRI 340/360–2022 references 

ANSI/ASHRAE 37–2009 for test 

provisions, DOE also proposed to 

incorporate by reference relevant 

sections of ANSI/ASHRAE 37–2009 in 

its amended test procedure for WSHPs. 

Id. at 87 FR 53312. Compared to the 

current test procedure, the key 

substantive changes that would result 

from DOE adopting the proposed test 

procedure included the following: 

(1) A new energy efficiency 

descriptor, IEER, which incorporates 

part-load cooling performance; 

(2) Modified test conditions for 

determining COP; 

(3) Minimum external static pressure 

(‘‘ESP’’) requirements, instructions for 

setting airflow and ESP, and tolerances 

for airflow and ESP, and 

(4) Specified liquid ESP requirements 

for units with integral pumps and a 

method to account for total pumping 

effect for units without integral pumps. 

Id. at 87 FR 53305. 

In response to this proposal, DOE 

received multiple comments 

(summarized in the following subsections) urging DOE not to incorporate 

by reference AHRI 340/360–2022 as the 

test procedure for WSHPs, to continue 

to collaborate with industry on 

finalizing AHRI 600, and to instead 

adopt the revised industry test standard 

resulting from work on AHRI 600. As 

previously noted, after publication of 

the August 2022 NOPR, DOE worked 

with the AHRI Geothermal and WSHP 

STC to develop a revised version of 

AHRI 600 (AHRI 600–2023) to address 

the issues DOE raised in the August 

2022 NOPR. As discussed further 

throughout this section, AHRI 600–2023 

includes a method to determine IEER for 

WSHPs similar to that proposed in the 

August 2022 NOPR and addresses many 

of the concerns expressed by 

commenters in response to the August 

2022 NOPR. As discussed, AHRI 600– 

2023 is intended to serve as the primary 

industry test procedure for WSHPs 

going forward and it does not reference 

any versions of ISO Standard 13256–1. 

Instead, AHRI 600–2023 references 

ANSI/ASHRAE 37–2009 and includes 

sufficient provisions for testing WSHPs 

that references to test provisions in ISO 

Standard 13256–1 or AHRI 340/360– 

2022 are not needed. 

As discussed further throughout this 

section, in this final rule, DOE is 

adopting an amended test procedure 

that incorporates by reference AHRI 

600–2023, with minor differences as 

explained further throughout the 

following sections of this document. 

In the following sections, DOE 

summarizes comments received in 

response to the August 2022 NOPR with 

regard to industry standards. 

1. Comments Regarding DOE’s 

Authority 

As discussed previously in this 

document, with respect to small, large, 

and very large commercial package air 

conditioning and heating equipment (of 

which WSHPs are a category), EPCA 

directs that when the generally accepted 

industry testing procedures or rating 

procedures developed or recognized by 

AHRI or by ASHRAE, as referenced in 

ASHRAE 90.1, are amended, the 

Secretary shall amend the DOE test 

procedure consistent with the amended 

industry test procedure or rating 

procedure unless the Secretary 

determines, by clear and convincing 

evidence, that to do so would not meet 

the requirements for test procedures to 

produce results representative of an 

average use cycle and is not unduly 

burdensome to conduct. (42 U.S.C. 

6314(a)(4)(A)–(B)) 

In response to the August 2022 NOPR, 

AHRI, MIAQ, and WaterFurnace 

expressed concern with DOE’s proposal 

to adopt a test procedure different from 

the industry standard (i.e., ISO 13256– 

1:1998 and the not yet published AHRI 

600 standard), and the procedure cited 

in ASHRAE 90.1. (AHRI, No. 24 at pp. 

1–2; MIAQ, No. 23 at pp. 1–2; 

WaterFurnace, No. 20 at p. 1) AHRI, 

MIAQ, and WaterFurnace noted that 

EPCA explicitly directs DOE to adopt 

the industry consensus test procedure 

cited in ASHRAE 90.1 and asserted that 

EPCA precludes DOE from adopting as 

a national standard a wholly different 

test procedure from that cited in 

ASHRAE 90.1. (Id.) These commenters 

urged DOE to adopt a revised test 

method only after it has been published 

by AHRI and adopted by ASHRAE in 

ASHRAE 90.1. (Id.) 

MIAQ asserted further that EPCA 

requires DOE to justify by clear and 

convincing evidence each amendment 

or difference between AHRI 340/360– 

2022 and ISO 13256–1:1998. (MIAQ, 

No. 23 at p. 2) MIAQ commented that 

DOE has determined in past 

rulemakings that ISO 13256–1 is cost 

effective and representative of energy 

use. (Id.) MIAQ stated that any 

deviation from ASHRAE 90.1 requires 

quantification of the burden and that 

only modifications that reduce testing 

burden on manufacturers can be 

considered. (Id. at p. 3) 

AHRI and MIAQ commented that 

DOE and outside stakeholders have 

been developing a consensus-based 

revision to the test procedure for 

commercial packaged air conditioners 

and heat pumps (‘‘CUAC/HPs’’). (AHRI, 


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No. 24 at p. 2; MIAQ, No. 23 at p. 2) 

AHRI and MIAQ further stated that after 

AHRI 600 has been finalized and 

adopted, AHRI will introduce the new 

test procedure to ASHRAE 90.1 to begin 

the procedural process for updates. 

(AHRI, No. 24 at p. 3; MIAQ, No. 23 at 

p. 2) AHRI and MIAQ commented that 

waiting to harmonize standards would 

establish consistent energy efficiency 

levels and design requirements between 

industry and Federal requirements, as 

well as comparable metrics and scope. 

(AHRI, No. 24 at p. 3; MIAQ, No. 23 at 

pp. 2–3) AHRI and MIAQ recommended 

that DOE continue to work with AHRI 

and other stakeholders to finalize AHRI 

600 and support a proposed amendment 

to ASHRAE 90.1, which DOE could 

adopt as the national test procedure 

during the next rulemaking. (AHRI, No. 

24 at p. 4; MIAQ, No. 23 at pp. 3, 9) 

ClimateMaster commented that DOE 

has not followed a cooperative approach 

to improve the test methods as proposed 

in the August 2022 NOPR. 

(ClimateMaster, No. 22 at p. 1) 

ClimateMaster asserted that this seems 

to violate EPCA, which requires DOE to 

adopt the test procedure cited in 

ASHRAE 90.1. (Id.) 

With regard to comments asserting 

that DOE does not have the authority to 

adopt a test procedure prior to its 

inclusion in ASHRAE 90.1, EPCA 

provides DOE with authority to adopt 

an amended test procedure in 

satisfaction of EPCA’s 7-year-lookback 

review requirement for test procedures. 

(42 U.S.C. 6314(a)(1)(A)). Under its 7- 

year-lookback review, DOE must ensure 

that test procedures established are 

reasonably designed to produce test 

results which reflect energy efficiency, 

energy use, and estimated operating 

costs during a representative average 

use cycle and are not unduly 

burdensome to conduct. (42 U.S.C. 

6314(a)(2)) During its 7-year lookback 

review, DOE is directed by EPCA to 

evaluate whether an amended test 

procedure would more accurately or 

fully comply with those requirements, 

and if DOE determines an amended test 

procedure would do so, then DOE is 

required to prescribe such test 

procedures for the equipment class. (42 

U.S.C. 6314(a)(1)(A)) It is important to 

note that under the 7-year lookback DOE 

does not need clear and convincing 

evidence that an amended test 

procedure would more accurately or 

fully comply with EPCA’s requirements. 

(Id.) Rather, DOE must show that the 

amended test procedure is reasonably 

designed to produce test results which 

reflect energy efficiency, energy use, 

and estimated operating costs during a 

representative average use cycle and are 

not unduly burdensome to conduct. (42 

U.S.C. 6314(a)(2)) For example, a test 

procedure referenced by ASHRAE 90.1 

may not be reasonably representative 

because more representative test 

procedures are available. And a test 

procedure that was reasonably 

representative in the past may become 

unreasonably representative when 

newly available test procedures allow 

for better, more complete 

measurements. DOE’s 7-year-lookback 

review under EPCA ensures that DOE is 

not bound to an industry test procedure 

that has not been updated and is no 

longer representative of current 

equipment. 

DOE notes that submitted comments 

from AHRI, WaterFurnace, 

ClimateMaster, and MIAQ do not 

mention DOE’s 7-year-lookback review 

and therefore only engaged with the 

review process under 42 U.S.C. 

6314(a)(4)(A). AHRI stated in its written 

comment that DOE is mandated to adopt 

an industry test procedure only after 

that test procedure is adopted in 

ASHRAE 90.1 but identified no such 

mandate within the statute itself. It is 

important to note that the 7-yearlookback review language at issue here 

was added to EPCA in EISA 2007, well 

after the relevant ASHRAE 90.1 test 

procedure language was added in 1992. 

(Compare Sec. 302 of EISA 2007, Pub. 

L. 110–140, 121 STAT. 1552 (Dec. 19, 

2007) with Sec. 121 of the Energy Policy 

Act of 1992, Pub. L. 106–486, 106 

STAT. 2808 (Oct. 24, 1992)). Therefore, 

the most natural reading of the two 

provisions together is that Congress 

intended to add the 7-year-lookback 

review to those triggers for review of test 

procedures that already existed. The 

language of the 7-year-lookback review 

applies generally to all covered 

equipment. Rather than restrict DOE to 

an outdated test procedure in the 

manner the industry commenters 

suggest, EPCA instead compels DOE to 

use due diligence to review the totality 

of relevant and available information 

before settling on appropriate energy 

conservation standards and test 

procedures. 

As a result, it is appropriate for DOE 

to consider in its 7-year-lookback 

whether amendments to the test 

procedure would more accurately 

produce test results which reflect energy 

efficiency, energy use, and estimated 

operating costs during a representative 

average use cycle and would not be 

unduly burdensome to conduct even 

without an update to AHSRAE 90–1. 

DOE finds here that the test procedure 

provided in the updated industry 

consensus test standard for WSHPs 

(AHRI 600–2023), and therefore the test 

procedure specified in the regulatory 

text of this final rule, is more 

representative without incurring undue 

burden, as discussed below, thereby 

satisfying EPCA’s requirements. 

DOE acknowledges that DOE has 

previously stated that it will only 

consider an update to ASHRAE 90.1 

that modifies the referenced industry 

test procedure to be a trigger under that 

provision of the statute, as opposed to 

an update of just the industry test 

procedure itself. (See e.g., 86 FR 35668, 

35676 (July 7, 2021)). DOE stands by 

that position regarding what constitutes 

a triggering event in the context of 

ASHRAE equipment and does not 

consider the provisions in 42 U.S.C. 

6314(a)(4) to have been triggered. 

However, that does not preclude DOE 

from considering an amended test 

procedure when reviewing DOE’s test 

procedures under EPCA’s 7-yearlookback provision. Not only does DOE 

have discretion to do so, but it has a 

statutory duty to do so, to ensure that 

its test procedures produce results that 

are representative of an average use 

cycle and are not unduly burdensome to 

conduct. 

DOE has determined that the test 

procedure adopted in this final rule for 

WSHPs would improve the 

representativeness of the current 

Federal test procedure for WSHPs and 

would not be unduly burdensome. 

Specifically, DOE has concluded that 

testing WSHPs in accordance with AHRI 

600–2023 would provide more 

representative results and more fully 

comply with the requirements of 

paragraph (2) of 42 U.S.C. 6314(a) than 

testing in accordance with the currently 

referenced standard ISO 13256–1:1998, 

as discussed in more detail in section 

III.D.6 of this final rule. And while clear 

and convincing evidence is not needed 

when amending a test procedure under 

the 7-year-lookback, DOE finds that the 

test procedure amendments adopted 

here are supported by clear and 

convincing evidence as outlined in this 

final rule. DOE discusses the specific 

test procedure updates included in 

appendix C1, resulting from the 

incorporation by reference of AHRI 600– 

2023, in sections III.E and III.F of this 

final rule. Therefore, DOE is adopting an 

amended test procedure for WSHPs that 

incorporates by reference AHRI 600– 

2023, with minor deviations. With 

regard to the assertion by AHRI and 

MIAQ that any deviation from ASHRAE 

90.1 requires quantification of the 

burden, and MIAQ’s assertion that only 

modifications that reduce testing burden 

on manufacturers can be considered, 

DOE does not agree that EPCA requires 

DOE to consider only deviations that 


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would reduce burden. Rather, EPCA 

requires only that DOE ensure that test 

procedures established are not unduly 

burdensome to conduct. (42 U.S.C. 

6314(a)(2)) 

With regard to the assertion by AHRI 

and MIAQ that EPCA requires DOE to 

justify by clear and convincing evidence 

each amendment or difference from the 

industry test procedure referenced by 

ASHRAE 90.1, DOE does not agree that 

EPCA requires such a line-by-line 

assessment of an amended test 

procedure. First, as stated previously, 

there is no requirement for clear and 

convincing evidence in EPCA for a test 

procedure amendment under the 7-yearlookback. Additionally, if DOE were 

amending a test procedure pursuant to 

the ASHRAE trigger, EPCA requires 

only that DOE shall amend the test 

procedure for the product as necessary 

to be consistent with the amended 

industry test procedure or rating 

procedure unless it determines, 

supported by clear and convincing 

evidence, that to do so would not meet 

the requirements of EPCA (42 U.S.C. 

6314 (a)(4)(B)). If DOE makes such a 

determination, DOE may establish an 

amended test procedure, but there is no 

requirement for DOE to show, by clear 

and convincing evidence, that DOE’s 

amended test procedure is reasonably 

designed to produce test results which 

reflect energy efficiency, energy use, 

and estimated operating costs during a 

representative average use cycle and are 

not unduly burdensome to conduct. 

(See 42 U.S.C. 6314(a)(2)). Additionally, 

if DOE does not make such a 

determination, there is no requirement 

that DOE show, by clear and convincing 

evidence, that an amended test 

procedure, which is consistent with the 

industry test procedure, is reasonably 

designed to produce test results which 

reflect energy efficiency, energy use, 

and estimated operating costs during a 

representative average use cycle and are 

not unduly burdensome to conduct. 

2. Comments Regarding DOE’s Test 

Procedure Development Process 

In response to the June 2022 NOPR, 

DOE received comments regarding its 

rulemaking development process. AHRI 

recommended that DOE follow a 

transparent, cooperative, or consensusbased regulatory development process. 

(AHRI, No. 24 at p. 4) AHRI commented 

that, in the past, DOE has had difficulty 

duplicating test results without the help 

and guidance of manufacturers and 

AHRI testing facilities and that the 

complex controls and operational 

characteristics of WSHP equipment 

require manufacturer and testing facility 

experience to test properly. (Id.) AHRI 

acknowledged that DOE has tested 15 

units from the WSHP industry but 

stated that DOE did not release the data 

and results of the testing. (Id.) AHRI 

expressed further concern that the 

testing cited in the August 2022 NOPR 

was not shared with the relevant AHRI 

committee and requested that DOE 

share the results of its findings with 

stakeholders in order to allow for 

validation and review. (Id. at pp. 2, 4) 

AHRI recommended that DOE work 

with industry on finalizing AHRI 600, 

conduct any necessary testing or 

calculations to develop a document 

agreed upon by DOE and relevant 

stakeholders, and follow the proper 

procedures to introduce the finalized 

test procedure and updated efficiency 

standards in ASHRAE 90.1. (Id.) AHRI 

commented that it will support the 

necessary updates to the Federal 

procedure and metrics after DOE takes 

the aforementioned steps. (Id.) 

ClimateMaster commented that DOE 

did not follow a cooperative process to 

improve the test methods for WSHPs 

and that neither AHRI nor the WSHP 

industry was consulted in a working 

group setting with other stakeholders, 

which was inconsistent with past and 

current industry approaches. 

(ClimateMaster, No. 22 at p. 1) 

WaterFurnace commented that it 

believed a more transparent and 

consensus-based development process 

is warranted before DOE implements 

new WSHP test procedures and that 

DOE should seek industry and AHRI 

input in order to validate and review the 

testing results. (WaterFurnace, No. 20 p. 

2) WaterFurnace recommended that 

DOE implement an Appliance 

Standards and Rulemaking Federal 

Advisory Committee (‘‘ASRAC’’) 

Working Group for all future 

undertakings to propose substantial 

changes in regulatory policy so as to 

work out complex issues in a common 

forum with industry and AHRI. (Id.) 

With respect to the comments from 

AHRI, ClimateMaster, and 

WaterFurnace, DOE notes that it may 

establish a negotiated rulemaking 

working group under ASRAC in 

accordance with the Federal Advisory 

Committee Act (‘‘FACA’’) and the 

Negotiated Rulemaking Act (‘‘NRA’’) (5 

U.S.C. 561–570, Pub. L. 104–320) to 

negotiate proposed test procedures and 

amended energy conservation standards 

if DOE determines that the use of the 

negotiated rulemaking process is in the 

public interest according to the 

requirements of FACA and in a manner 

consistent with the requirements of the 

NRA. However, in this rulemaking, DOE 

is following the traditional rulemaking 

notice-and-comment process. 

DOE recognizes the benefits of 

developing test procedures through a 

consensus-based process and notes that 

DOE has participated in the AHRI 

process and has worked with the AHRI 

Geothermal and WSHP STC in 

developing AHRI 600–2023, which is 

incorporated by reference in this final 

rule. As noted in the August 2022 

NOPR, DOE has participated in AHRI 

committee meetings working to develop 

AHRI 600 since 2019. See 87 FR 53302, 

53308–53309. In particular, DOE 

brought up many of the concerns raised 

in August 2022 NOPR in ISO 13256–1 

and AHRI 600 meetings for several years 

prior to the publication of the August 

2022 NOPR, but the committees 

declined to address these issues in the 

draft industry test procedures at that 

time. At the time of drafting of the 

August 2022 NOPR, AHRI 600 was still 

in development and had not yet 

published. In the August 2022 NOPR, 

DOE outlined its understanding that the 

intent of AHRI 600 would be to provide 

a method for calculation of IEER for 

WSHPs based on testing conducted 

according to ISO 13256–1:1998. Id. at 87 

FR 53309. In the August 2022 NOPR, 

DOE tentatively concluded that the 

general methodology in AHRI 600 for 

determining IEER is appropriate. Id. 

However, DOE identified several aspects 

of the methodology that warrant further 

modifications. Id. In the August 2022 

NOPR, DOE noted that it could not 

speculate as to the substantive outputs 

of the ISO 13256–1 National deviation 

and the AHRI 600 committee’s efforts. 

Id. Consistent with DOE’s procedure for 

notice-and-comment rulemakings, DOE 

also conducted the NOPR public 

meeting that provided opportunity for 

stakeholders to provide feedback on 

DOE’s proposals. The feedback DOE 

received in both NOPR public meeting 

comments and written comments was 

considered in subsequent AHRI 600 

committee meetings and drafting of this 

final rule. 

Since the publication of the August 

2022 NOPR, DOE continued to work 

with industry in AHRI 600 committee, 

as recommended by commenters, to 

address the test procedure concerns 

DOE raised in the August 2022 NOPR 

with the intent that a revised industry 

test procedure specific to WSHPs could 

be adopted in a final rule. Rather than 

continue to simultaneously modify and 

maintain ISO 13256–1 and AHRI–600, 

the committee members voted to merge 

them into a comprehensive unified test 

procedure, AHRI 600. More specifically, 

the methodology specified in ISO 

13256–1 has been incorporated into 


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AHRI 600–2023. Therefore, AHRI 600– 

2023 does not reference ISO 13256–1. 

Regarding AHRI’s comment about 

sharing data, DOE presented the results 

of its testing in the August 2022 NOPR. 

Id. at 87 FR 53314–53317. Based on 

participation in AHRI 600 committee 

meetings following the August 2022 

NOPR, additional data from DOE’s 

investigative testing was not needed for 

the committee to reach resolution on the 

content of AHRI 600–2023. 

On September 11, 2023, AHRI 600– 

2023 was published. DOE notes that the 

statutory deadline for publishing a test 

procedure final rule for WSHPs was 

May 16, 2019. (42 U.S.C. 6314(a)(1)) 

Given EPCA’s statutory requirement to 

review the appropriate test procedures 

for WSHPs every seven years, DOE has 

concluded that it would be neither 

appropriate nor permissible to delay the 

current rulemaking for the WSHP test 

procedure until after ASHRAE 90.1 

adopts AHRI 600–2023 as the test 

procedure for WSHPs. To avoid any 

further delay, DOE is adopting a test 

procedure for WSHPs that incorporates 

by reference AHRI 600–2023, with 

minor deviations. 

3. Comments Supporting the Adoption 

of AHRI 340/360–2022 

In response to the June 2022 NOPR, 

some commenters supported adopting 

AHRI 340/360–2022 in the WSHP test 

procedure. NEEA generally supported 

DOE’s efforts to align the WSHP test 

procedure with other water-cooled 

unitary systems, including by 

integrating fan energy into the test 

procedure for ducted WSHPs. (NEEA, 

No. 25 at p. 1) In particular, NEEA 

supported DOE’s proposal to align the 

WSHP test procedure with AHRI 340/ 

360–2022 and ANSI/ASHRAE 37–2009. 

(Id. at p. 2) NEEA stated that aligning 

the testing of WSHPs with ANSI/ 

ASHRAE 37–2009 would ensure that 

WSHP ratings will be consistent with 

other water-cooled and direct expansion 

cooling systems. (Id.) NEEA also 

supported the introduction of an IEER 

metric rather than rating only with EER. 

(Id.) NEEA stated that the proposed test 

procedure would impact the current 

modeling approach for WSHP standard 

reference systems used to determine 

total system performance ratio in the 

2018 Washington State Energy Code, but 

NEEA acknowledged that potential 

advancements to the test procedure and 

ratings metric would provide an 

important improvement in 

representativeness for this equipment. 

(Id. at p. 1) 

NYSERDA generally supported DOE’s 

proposed amendments for the WSHP 

test procedure and concurred with 

DOE’s tentative determination that the 

changes would improve the 

representativeness of the WSHP test 

procedure. (NYSERDA, No. 21 at pp. 1– 

2) NYSERDA asserted that this would 

spur growth in the market for WSHPs, 

including geothermal heat pumps. (Id. 

at p.2) 

As discussed previously, in this final 

rule, DOE is incorporating by reference 

AHRI 600–2023 into appendix C1 in 

lieu of incorporating by reference AHRI 

340/360–2022 as proposed in the 

August 2022 NOPR. DOE notes, 

however, that the majority of the 

technical content from the proposed test 

procedure in the August 2022 NOPR 

remains consistent in the test procedure 

finalized in this final rule. Any changes 

to technical provisions from the August 

2022 NOPR proposal were due to 

industry consensus culminating in the 

AHRI 600–2023 standard. Throughout 

this final rule, DOE discusses in detail 

the technical differences between the 

test procedure proposed in the August 

2022 NOPR and the version finalized in 

this final rule. 

4. Comments Opposing the Adoption of 

AHRI 340/360–2022 

Other commenters opposed the 

proposal in the August 2022 NOPR to 

adopt AHRI 340/360–2022 in the WSHP 

test procedure. AHRI and MIAQ 

expressed concern that the impact on 

manufacturers of DOE’s proposal to 

update the WSHP test procedure has not 

been quantified. (AHRI, No. 24 at p. 2; 

MIAQ, No. 23 at p. 3) AHRI and MIAQ 

stated that the capability of testing 

WSHPs to AHRI 340/360–2022 has not 

been assessed by third-part test labs. 

(Id.) 

AHRI and MIAQ noted that an 

ASRAC Working Group has been 

formed in an effort to negotiate test 

procedures and energy efficiency 

standards for CUAC/HPs, the scope of 

which stands to result in significant 

modifications to AHRI 340/360–2022 

and the efficiency measures for such 

equipment. (AHRI, No. 24, at p. 2; 

MIAQ, No. 23 at p. 2) AHRI and MIAQ 

further noted, however, that WSHPs are 

outside the scope of these efforts, 

potentially leaving a significant gap in 

ratings (i.e., were WSHPs to be rated 

using AHRI 340/360). (Id.) 

WaterFurnace expressed concern 

regarding DOE’s sampling and testing 

procedure for modifying AHRI 340/360, 

especially considering the complexity of 

the product’s controls and operational 

characteristics and taking into account 

past instances in which DOE has 

struggled to duplicate test results 

without manufacturer and AHRI testing 

support. (WaterFurnace, No. 20 at p. 2) 

WaterFurnace agreed with AHRI’s 

concerns that the impact on 

manufacturers of DOE’s proposal to 

update test procedures has not been 

adequately quantified, nor was it clear 

whether third-party test labs have the 

capability to accommodate the proposed 

changes. (Id. at p. 2) 

WaterFurnace, ClimateMaster, 

Enertech, and FHP all expressed 

concern that DOE’s proposal to test 

WSHPs using AHRI 340/360–2022 

would require manufacturers to test 

WSHPs to two different test standards 

because geothermal applications for 

WSHPs would still require testing to 

ISO 13256–1. (WaterFurnace, No. 20 at 

p. 3; ClimateMaster, No. 22 at p. 1; 

Enertech, No. 19 at p. 1; FHP, No. 26 at 

p. 3) WaterFurnace noted that ISO 

13256–1 is already referenced in several 

Federal, State, and local codes. 

(WaterFurnace, No. 20 at p. 3) 

WaterFurnace and ClimateMaster stated 

that implementing a dual certification 

process would be burdensome for 

manufacturers. (WaterFurnace, No. 20 at 

p. 3; ClimateMaster, No. 22 p. 1) 

Enertech also noted that Federal and 

State tax credits specifically reference 

ISO/AHRI 13256–1:1998 for efficiency 

ratings and that the ENERGY STAR 

specifications directly reference the ISO 

13256–1:1998 standard for the ENERGY 

STAR Tier 3 efficiency requirements. 

(Enertech, No. 19 at p. 1) 

WaterFurnace asserted that DOE 

underestimated the significance and the 

burden that the proposed changes to the 

WSHP test procedure would impose 

upon manufacturers and industry 

players. (WaterFurnace, No. 20 at p. 3) 

WaterFurnace identified the following 

assumptions and shortcomings in AHRI 

340/360–2022 that it stated were not 

appropriately addressed in the August 

2022 NOPR: 

(1) While the August 2022 NOPR 

stated that IEER can be calculated and 

an interpolation can be performed using 

existing data from ISO 13256–1, 

WaterFurnace determined that the 

entering air, water flow, external static 

and airflow conditions differ from AHRI 

340/360–2022, which will therefore 

require additional testing by the 

manufacturer and the implementation of 

a new certification program; 

(2) Currently, performance mapping 

capability is available across a wide 

range of entering water temperatures 

(‘‘EWT’’) used in modeling software 

such as EQuest and DOE’s EnergyPlus, 

and all of this detail would be lost with 

the implementation of AHRI 340/360– 

2022 because it only presents a single 

IEER cooling metric and a single heating 

point; 


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(3) Provisions should be added under 

AHRI 340/360–2022 for hybrid heat 

pumps, which are unique in their 

capability for refrigerant cooling with 

other non-refrigerant heating capability; 

(4) Provisions should be added under 

AHRI 340/360–2022 for split 

configurations, which are offered for 

smaller WSHPs; 

(5) Provisions should be added under 

AHRI 340/360–2022 for small WSHPs 

with non-ducted applications (e.g., 

console units), along with language that 

takes into account the fact that many of 

these units are installed into residential 

buildings with substantial heating that 

would not fit the AHRI 340/360–2022 

conditions; 

(6) While DOE proposed to adopt 

heating test conditions for WSHPs that 

are not specified in AHRI 340/360– 

2022, this overlooks other testing 

requirements and language that would 

need to be addressed (e.g., minimum 

and maximum operating conditions) in 

order to adequately add heating tests to 

a cooling-only standard; 

(7) Provisions should be added under 

AHRI 340/360–2022 for antifreeze 

blends and their fluid characteristics 

(i.e., alcohols, salts, and glycols); 

(8) Test procedures would need to be 

modified to account for smaller WSHP 

units, as AHRI 340/360–2022 requires 

an airflow tolerance of less than 3 

percent and is thus designed around 

larger product designs with drives and 

adjustable sheaves that accommodate 

this airflow capability; 

(9) Although AHRI 340/360–2022 is 

primarily an air-source standard that 

utilizes air and refrigerant enthalpy test 

methods, water-source equipment is 

more consistently and accurately tested 

with a liquid enthalpy test method and 

would need to use air or refrigerant 

enthalpy only as secondary methods— 

and, furthermore, this process would be 

inconsistent with part load 

measurements under AHRI 340/360– 

2022; 

(10) Manufacturer-specified liquid 

flow rate is preferred over the AHRI 

340/360–2022 method of setting liquid 

flow rate using a 10 °F temperature rise 

to establish flow rates; 

(11) Continuous 24/7 fan operation is 

an outdated idea according to ASHRAE 

90.1; and 

(12) Issues addressed by Working 

Groups under ASRAC will likely result 

in massive changes to AHRI 340/360 

regarding air-side measurements and 

will take focus away from necessary 

modifications to provisions for watercooled units and, thus, changes for 

water-cooled units to AHRI 340/360 will 

likely be of secondary importance to the 

ASRAC committee. (Id. at pp. 3–4) 

WaterFurnace also commented that 

because AHRI 340/360–2022 is 

primarily an air-source standard, AHRI 

340/360–2022’s comparatively small 

water-cooled section is used to certify 

approximately 1,000 units per year in 

contrast to the 200,000 unit sales per 

year under the AHRI/ISO 13256 

certification programs. (Id. at p. 5) 

Therefore, WaterFurnace noted that 

moving testing of WSHPs (with much 

higher shipments) to the smaller watercooled section of AHRI 340/360–2022 

would not be logical considering the 

noted changes required. (Id.) 

WaterFurnace commented that 

changing to a different AHRI 340/360– 

2022 standard and separating out 

geothermal applications to ISO 13256 

would be disruptive to both the watersource and geothermal industries at a 

time when the use of heat pumps is 

being encouraged by national, state, and 

local regulations as a carbon-reduction 

solution. (Id.) WaterFurnace stated that 

tax credits and rebates based upon 

AHRI/ISO 13256 performance have been 

legislatively codified and will be 

difficult to change, and further noted 

that the Inflation Reduction Act 

references ASHRAE 90.1 and AHRI/ISO 

13256 as a measurement of 

performance. (Id. at p. 6) WaterFurnace 

stated that other governmental programs 

such as ENERGY STAR have 

specifications and benefits based on 

AHRI/ISO 13256 performance 

certification and that decarbonization 

policy programs by utilities, cities, and 

states rely on such certification as well. 

(Id.) 

ClimateMaster commented that DOE 

would need to address the following 

issues with AHRI 340/360–2022: 

(1) AHRI 340/360–2022 needs to be 

updated to include the appendix C1 

additions, a process that will likely be 

delayed by a current ASRAC working 

group undertaking to amend the current 

AHRI 340/360–2022 test procedures 

with a focus on air-source equipment; 

(2) AHRI 340/360–2022 does not 

include test requirements for watersource heating; 

(3) AHRI 340/360–2022 does not 

include test provisions for non-ducted 

equipment; 

(4) The airflow setting and tolerance 

specified by AHRI 340/360–2022 does 

not cover or is incompatible with 

current WSHP equipment; 

(5) AHRI 340/360–2022 does not 

include a pump power adder for all 

equipment sizes, nor is DOE’s proposal 

to utilize the pump power adder in 

AHRI 920 representative of installed 

WSHP systems; 

(6) AHRI 340/360–2022 does not 

include glycols or antifreeze solutions 

in the method of test, and the 

recommended solution is not 

representative of the fluids used for 

WSHPs in the field or test laboratories 

currently used in the development, 

qualification, and compliance processes; 

and 

(7) The refrigerant charging 

requirements included in AHRI 340/ 

360–2022 are not applicable, accurate, 

or relevant to WSHP systems. 

(ClimateMaster, No. 22 at pp. 1–2) 

Enertech commented that AHRI 340/ 

360–2022 lacks testing parameters for 

water source heating, testing parameters 

for non-ducted equipment, testing 

methods utilizing antifreeze blends, and 

parameters for pump power adder for 

small equipment. (Enertech, No. 19 at p. 

1) Enertech noted that AHRI 340/360– 

2022 requires a ±3 percent airflow 

tolerance during testing, which Enertech 

asserted is unrealistic for small-capacity 

equipment. (Id.) For these reasons, 

Enertech disagreed that new efficiency 

ratings could be interpolated from 

conditions common to the WSHP 

industry and asserted that new testing 

would be required for all products 

offered by any manufacturer. (Id.) 

Enertech stated that adopting AHRI 340/ 

360–2022 as the DOE test procedure for 

WSHPs would result in long-term 

disruptions to the geothermal and 

WSHP industries. (Id. at p. 2) 

FHP commented that adopting test 

methods per AHRI 340/360–2022 would 

require additional testing effort, time, 

and resources, and would result in 

additional costs to the industry. (FHP, 

No. 26 at p. 3) FHP commented further 

that AHRI 340/360–2022 contains 

differences in standard test conditions 

that would require additional testing as 

well as changes to (1) the design of the 

units to ensure 10 °F temperature rise on 

the water side and (2) the fan/motor 

selections and programs to maintain the 

proper air flow at defined static 

pressures and airflow tolerances. (Id.) 

FHP stated that the use of two standards 

may split the current WSHP product 

designs, thereby adding permanent 

design burden to current product 

offerings. (Id.) 

FHP stated that the proposed changes 

to the WSHP test procedure could be the 

most impactful regulatory issue for the 

WSHP industry and that the industry’s 

resources are completely dedicated to 

the development of equipment that uses 

low-global warming potential 

refrigerants through January 1, 2025. 

(FHP, No. 26 at p. 5) FHP expressed 

concern about the impact of moving to 

an entirely new test procedure that 

would require re-testing, re-designing, 

and potentially re-certifying most of its 

basic model groups. (Id.) FHP also 


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expressed concerns about the additional 

resources and maintenance potentially 

required by having two separate product 

designs and validations for WSHPs. (Id.) 

FHP also stated that current AEDMs 

are based on the leading industry 

standard for these types of equipment. 

(Id. at p. 2) More specifically, FHP 

stated that its current AEDM is based on 

the ISO 13256–1:1998 test standard and 

that DOE’s proposal to reference AHRI 

340/360–2022 as the test procedure for 

WSHPs would require additional testing 

and new AEDMs. (Id.) FHP commented 

that even reduced testing to validate 

AEDMs would be unduly burdensome 

for such a small market. (Id.) 

During the public meeting, AAON 

commented that the amount of testing in 

the proposed test procedure was rather 

extreme and asked DOE to share the 

testing burden assessment. (Public 

Meeting Transcript, No. 17 at p. 60) 

GeoExchange commented that 

manufacturers of geothermal heat 

pumps have significant concerns with 

the August 2022 NOPR as written and 

believe it will subject WSHPs and 

geothermal heat pumps to competing 

and inconsistent certification standards. 

(GeoExchange, No. 29 at p. 1) 

GeoExchange commented that these 

issues will complicate production of 

these products and increase costs for 

consumers. (Id.) GeoExchange stated 

that the timing of the August 2022 

NOPR coincides with efforts by the 

industry to complete work on its 

development of a standard that 

recognizes the overlap between different 

applications of heat pump technology 

and minimizes unnecessary disruptions 

for manufacturers. (Id.) 

DOE appreciates these comments 

regarding the proposal to adopt AHRI 

340/360–2022 in the WSHP test 

procedure. As discussed, in this final 

rule, DOE is no longer adopting AHRI 

340–360–2022 and is adopting instead 

an amended test procedure for WSHPs 

that incorporates by reference AHRI 

600–2023. Because AHRI 600–2023 was 

developed through an industry 

consensus process subsequent to the 

timing of the August 2022 NOPR 

comment period, DOE surmises that the 

testing approach specified in AHRI 600– 

2023 represents the prevailing industry 

consensus regarding the most 

appropriate method of testing WSHPs 

and addresses the issues raised by 

commenters regarding DOE’s proposal 

to adopt AHRI 340/360–2022 as the test 

procedure for WSHPs. See sections III.E 

and III.F of this final rule for discussion 

of specific test procedure topics raised 

by interested parties in response to the 

August 2022 NOPR. 

Further, in response to the test burden 

comments, DOE did quantify per-test 

burden of the proposed test procedure 

in the August 2022 NOPR and found 

that the proposed test procedure was 

not unduly burdensome to conduct. 87 

FR 53302, 53340. A similar analysis is 

presented in this final rule (see section 

III.I of this document for details), and 

the same conclusion is reached. 

Additionally, as discussed in this 

document, DOE is adopting a test 

procedure incorporating by reference 

the industry consensus test standard, 

AHRI 600–2023. Therefore, DOE has 

determined that the amended test 

procedure will not increase burden as 

compared to the latest draft industry 

consensus test standard. 

5. Comments Encouraging the Adoption 

of AHRI 600 

Numerous commenters encouraged 

DOE to adopt AHRI 600 in an amended 

WSHP test procedure in response to the 

August 2022 NOPR. AHRI 

recommended that DOE refrain from 

adopting AHRI 340/360–2022 for 

WSHPs in favor of continuing to 

collaborate with industry on finalizing 

AHRI 600. (AHRI, No. 24 at p. 4) AHRI 

commented that AHRI 600 has been 

under development for several years 

and that, despite some delays, is 

steadily progressing. (Id.) AHRI 

commented that during the discussions 

for the development of AHRI 600, the 

committee considered applying AHRI 

340/360–2022 to calculate IEER. (Id.) 

AHRI commented that it continues to 

improve AHRI 600 test procedures (e.g., 

by resolving issues to fan power, 

external static pressure, water 

temperature, and subsequent efficiency 

levels) and that AHRI will continue 

committing to frequent meetings to 

satisfactorily resolve the issues raised in 

August 2022 NOPR. (Id.) 

WaterFurnace stated that AHRI 600 

draft standard was released in October 

2022 and achieves the objectives of the 

August 2022 NOPR without industry 

distractions. (WaterFurnace, No. 20 p. 5) 

WaterFurnace commented that AHRI 

600 standard is on track for committee 

review by October 31, 2023. (Id.) 

WaterFurnace stated that the quickest 

way to implement appropriate changes 

to WSHP test procedures would be to 

adopt versions of AHRI 600 and ISO 

13256–1, as modifying test procedures 

to comply with AHRI 340/360–2022 

would entail substantial changes that 

will delay the implementation process. 

(Id. at p. 4) 

WaterFurnace commented that it 

supports development of AHRI 600 test 

procedure and recommended that the 

DOE test procedure reference it directly 

instead of AHRI 340/360–2022. (Id. at p. 

5) WaterFurnace stated that the AHRI 

600 standard can resolve most of the 

issues DOE identified in the August 

2022 NOPR regarding the current WSHP 

test procedure. (Id.) WaterFurnace 

recommended that DOE re-evaluate the 

August 2022 NOPR proposal and 

support WaterFurnace’s proposal to 

quickly adopt AHRI 600 and the 

national deviation updates to AHRI/ISO 

13256. (Id. at p. 11) WaterFurnace 

commented that doing so will help 

industry achieve DOE’s desired goals 

faster and with less disruption. (Id.) 

WaterFurnace commented that it 

supports implementation of an updated 

AHRI/ISO 13256:1998 with a targeted 

national deviation and revised annexes. 

(Id. at p. 5) WaterFurnace commented 

that an updated AHRI/ISO 13256:1998 

with a targeted national deviation can 

solve specific issues mentioned in the 

August 2022 NOPR regarding AHRI/ISO 

13256 with changes that would not be 

substantial, stating that the method of 

testing WaterFurnace follows aligns 

with the August 2022 NOPR. (Id.) 

WaterFurnace commented that many of 

the issues raised by DOE center on 

specific issues and test methods 

currently in use that can be documented 

and solved with a national deviation 

from AHRI/ISO 13256. (Id.) 

WaterFurnace stated that it has 

developed a draft of this national 

deviation that will address the noted 

shortcomings and can be completed in 

a similar time frame as AHRI 600 

approval. (Id.) 

ClimateMaster commented that DOE’s 

proposal to move WSHPs to AHRI 340/ 

360–2022 would create too significant a 

change in the industry and instead 

recommended considering AHRI 600, 

which uses existing ISO/AHRI 13256–1 

certified data to mathematically 

calculate the system IEER. 

(ClimateMaster, No. 22 at p. 1) 

ClimateMaster further commented that 

DOE should consider updating the ISO/ 

AHRI 13256–1:1998 standard to include 

national deviations to address specific 

issues such as: (1) modifying refrigerant 

charging and airflow/ESP requirements; 

and (2) the need to include a reference 

to ASHRAE 37 and provisions for air 

sampling for air-side capacity 

measurements. (Id. at p. 2) 

Enertech suggested adopting AHRI 

600 for calculating IEER rather than the 

AHRI 340/360–2022 method. (Enertech, 

No. 19 at p. 2) 

MIAQ recommended that DOE work 

with industry to finalize AHRI Standard 

600, conduct any necessary testing/ 

calculations to develop a crosswalk, and 

follow proper procedures to introduce 

the finalized procedure and updated 


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efficiency standards in ASHRAE 90.1. 

(MIAQ, No. 23 at p. 9) 

Trane recommended that DOE move 

from a full-load metric and test 

procedure to one that is more 

representative of an energy use cycle, 

such as a part-load test procedure. 

(Trane, No. 28 at p. 3) Trane commented 

that the most accurate and 

representative test procedure is AHRI 

600, not AHRI 340/360–2022 as 

proposed in the August 2022 NOPR. 

(Id.) Trane noted that AHRI 600 draft is 

now published and seeking public 

comments for the final version. (Id. at p. 

2) 

As discussed, in this final rule, DOE 

is adopting an amended test procedure 

for WSHPs incorporating by reference 

AHRI 600–2023. As noted in the 

previous discussion, the methodology 

specified in ISO 13256–1 has been 

incorporated into the AHRI 600–2023, 

which represents the latest industry 

consensus test standard for WSHPs and 

moves away from using ISO 13256–1, 

thus rendering unnecessary a national 

deviation to ISO 13256–1. Having been 

developed through an industry 

consensus process subsequent to the 

timing of the August 2022 NOPR 

comment period, DOE surmises that the 

testing approach specified in AHRI 600– 

2023 represents the prevailing industry 

consensus regarding the most 

appropriate method of testing WSHPs. 

6. Finalized DOE Test Procedure 

In summary, DOE is adopting an 

amended test procedure for WSHPs that 

incorporates by reference AHRI 600– 

2023, with minor deviations, in this 

final rule. DOE has determined that the 

test methods specified in AHRI 600– 

2023 (which are largely consistent with 

the provisions adopted in appendix C1 

of this final rule) would produce test 

results that better reflect energy 

efficiency of WSHPs during a 

representative average use cycle than 

the current DOE test procedure and ISO 

13256–1:1998. DOE notes that the IEER 

metric is representative of cooling 

efficiency for WSHPs on an annual basis 

and is more representative than the 

current EER metric, which captures the 

system performance at a single, full-load 

operating point. DOE also notes that the 

other test procedure amendments 

incorporated in this final rule better 

ensure accurate and repeatable 

measurements and ensure that 

representative test conditions are 

maintained during testing. These 

changes include: 

(1) Minimum ESP requirements, 

instructions for setting airflow and ESP, 

and tolerances for airflow and ESP; 

(2) Operating tolerance for voltage; 

(3) Different indoor air conditions for 

testing; 

(4) Refrigerant charging instructions 

for cases where they are not provided by 

the manufacturer; 

(5) Use of the primary capacity 

measurement (i.e., indoor air enthalpy 

method) as the value for capacity, and 

different provisions for required 

agreement between primary and 

secondary capacity measurements; 

(6) Provisions for split systems, such 

as accounting for compressor heat and 

refrigerant line losses; 

(7) Measurement of duct losses for 

ducted units; 

(8) Standardized heat capacity of 

water and brine; and 

(9) A calculation for discharge 

coefficients. 

The subsequent sections of this final 

rule discuss aspects of the finalized test 

procedure that differ from the proposal 

in the August 2022 NOPR. DOE has 

determined that these updates improve 

the representativeness of the test 

procedure for WSHPs. These include 

but are not limited to: 

(1) Updated pump power adder, 

developed during the AHRI 600–2023 

process; 

(2) ESP requirements for large units 

>65,000 Btu/h consistent with levels 

from the December 2022 term sheet of 

recommendations regarding test 

procedures for air-cooled commercial 

unitary air conditioners and heat pumps 

(‘‘ACUACs and ACUHPs’’), referred to 

hereafter as ‘‘the ACUAC and ACUHP 

Working Group TP Term Sheet’’ (See 

Document No. 65 in Docket No. EERE– 

2022–BT–STD–0015); 

(3) No option to physically test at the 

IEER conditions and to instead require 

testing at all three ISO 13256–1:1998 

conditions; 

(4) Updated part-load EWT; 

(5) Specifying a maximum water flow 

rate instead of fixed inlet and outlet 

water conditions; 

(6) Different test provisions for coilonly units, including adjustments to 

default fan power; 

(7) Different required fluid—a 

methanol solution—and different fluid 

properties specified; 

(8) Some changes to airflow 

provisions, which are consistent with 

DOE’s test procedure for central air 

conditioners and heat pumps at 

appendix M1 to subpart B of 10 CFR 

part 430 instead of AHRI 340/360–2022; 

(9) IEER cyclic degradation equation 

that does not assume continuous fan 

operation; and 

(10) Heating test temperature of 50 °F 

instead of 55 °F. 

As discussed, DOE recognizes that the 

test method in AHRI 600–2023 and 

incorporated by reference into appendix 

C1 represents an industry consensus test 

procedure that is likely to be considered 

for future updates to ASHRAE 90.1. 

Accordingly, for the foregoing reasons 

and those discussed in the subsequent 

sections of this final rule, DOE is 

incorporating by reference AHRI 600– 

2023 into the amended Federal test 

procedure for WSHPs. DOE has 

determined that the amended test 

procedure is reasonably designed to 

produce results that are representative 

of the energy efficiency of that covered 

equipment during an average use cycle 

and is not unduly burdensome to 

conduct. DOE notes also that use of 

appendix C1 will not be required until 

the compliance date of any amended 

standards denominated in terms of 

IEER, should DOE adopt such standards. 

E. Efficiency Metrics 

1. IEER 

As discussed previously, DOE’s 

current test procedure for WSHPs 

measures cooling-mode performance in 

terms of the EER metric, the current 

regulatory metric. 10 CFR 431.96. EER 

captures WSHP performance at a single, 

full-load operating point in cooling 

mode (i.e., a single EWT) and does not 

provide a seasonal or load-weighted 

measure of energy efficiency. A seasonal 

metric is a weighted average of the 

performance of cooling or heating 

systems at different outdoor conditions 

intended to represent average efficiency 

over a full cooling or heating season. 

Several categories of commercial 

package air-conditioning and heating 

equipment are rated using a seasonal or 

part-load metric, such as IEER. IEER is 

a weighted average of efficiency at four 

load levels representing 100, 75, 50, and 

25 percent of full-load capacity, each 

measured at a specified outdoor 

condition that is representative of field 

operation at the given load level. In 

general, the IEER metric provides a 

more representative measure of field 

performance than EER by weighting the 

full-load and part-load efficiencies by 

the average amount of time equipment 

spends operating at each load level. 

Table 1 of ISO 13256–1:1998, the 

industry test standard incorporated by 

reference into DOE’s current WSHP test 

procedure, and Table 2 of ISO 13256– 

1:2021 both specify EWT conditions to 

be used for developing part-load ratings 

of EER for WSHPs with capacity control 

(tested at minimum compressor speed). 

However, part-load EER ratings are not 

addressed in the current DOE test 

procedure. Further, each part-load 

rating captures operation only at a 

single compressor speed and EWT 


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condition rather than operation across a 

range of temperatures and compressor 

speeds, as would be captured by an 

IEER metric. Neither ISO 13256–1:1998 

nor ISO 13256–1:2021 include seasonal 

metrics. 

In the August 2022 NOPR, DOE 

tentatively determined that use of a 

seasonal efficiency metric would be 

more representative of the average use 

cycle of a unit as compared to the 

current EER metric. 87 FR 53302, 53313. 

Accordingly, DOE proposed to adopt 

certain provisions of AHRI 340/360– 

2022 and use the IEER metric specified 

in section 6.2 of AHRI 340/360–2022 for 

WSHPs. Id. Specifically, DOE proposed 

that IEER for WSHPs be calculated 

based on the EWT conditions specified 

in Table 9 of AHRI 340/360–2022 (i.e., 

85 °F, 73.5 °F, 62 °F, and 55 °F). Id. DOE 

referred to the approach of testing at 

these AHRI 340/360–2022 EWTs as 

‘‘option 1’’ in the August 2022 NOPR. 

Id. at 87 FR 53316. 

In addition, DOE acknowledged in the 

August 2022 NOPR that adopting the 

IEER metric for WSHPs would increase 

the number of required cooling-mode 

tests from one to four. Id. at 87 FR 

53313. DOE also discussed its 

understanding that the future updated 

version of AHRI 600 would provide for 

calculating IEER from test results 

measured at the EWTs specified in 

Table 1 of ISO 13256–1:1998. Id. DOE 

stated that determining IEER via 

interpolation and extrapolation from 

testing at the ISO 13256–1:1998 EWTs, 

rather than from additional testing at the 

IEER EWTs specified in AHRI 340/360– 

2022, may reduce overall testing burden 

for manufacturers. Id. at 87 FR 53314. 

Consistent with this approach, DOE also 

proposed to allow determination of 

IEER via interpolation and extrapolation 

(‘‘option 2’’) based on testing at the fullload and part-load EWT conditions 

specified in Table 1 of ISO 13256– 

1:1998 (i.e., 86 °F, 77 °F, and 59 °F for 

full-load tests and 86 °F, 68 °F, and 59 °F 

for part-load tests). Id. at 87 FR 53316. 

DOE proposed that the tests for option 

2 would be performed using the same 

test provisions (aside from the EWTs) 

from AHRI 340/360–2022, ANSI/ 

ASHRAE 37–2009, and sections 2 

through 4 and 7 of proposed appendix 

C1 as the tests for option 1. Id. 

In the August 2022 NOPR, DOE 

presented test data that indicated that 

determining EER by interpolating/ 

extrapolating cooling capacity and total 

power would result in closer agreement 

to tested values than directly 

interpolating/extrapolating EER. Id. at 

87 FR 53314–53315. Based on these 

findings, DOE proposed to specify 

interpolation/extrapolation using the 

cooling capacity and total power as 

opposed to EER directly. Id. at 87 FR 

53316. DOE also presented data in the 

August 2022 NOPR indicating that for 

variable-speed WSHPs with higher (i.e., 

better) EER performance at intermediate 

compressor speeds than at maximum or 

minimum compressor speeds, the 

proposed interpolation and 

extrapolation method would result in a 

lower (i.e., worse) calculated IEER than 

testing at the IEER conditions specified 

in AHRI 340/360–2022. Id. at 87 FR 

53315–53316. DOE discussed its 

understanding from participation in 

AHRI 600 committee meetings that 

many manufacturers would prefer the 

option to use the interpolation and 

extrapolation method for variable-speed 

WSHPs, even if it results in lower IEER 

ratings, because it would result in less 

overall testing burden than testing at 

each of the AHRI 340/360–2022 

conditions. Id. at 87 FR 53316. 

DOE also proposed that if represented 

values for a basic model are determined 

with an AEDM, the AEDM could use 

either option 1 or option 2 for 

determining IEER per the proposed test 

procedure in appendix C1. Id. 

DOE requested comment on the 

proposal to allow determination of IEER 

using two different methods: (1) testing 

in accordance with AHRI 340/360–2022; 

or (2) interpolation and extrapolation of 

cooling capacity and power values 

based on testing in accordance with the 

proposed test procedure at the EWTs 

specified in Table 1 of ISO 13256– 

1:1998. Id. DOE sought feedback on the 

proposed method for calculating IEER 

via interpolation and extrapolation, and 

on whether this approach would serve 

as a potential burden-reducing option as 

compared to testing at the AHRI 340/ 

360–2022 conditions. Id. DOE also 

requested comment on whether the 

proposed methodology to determine 

IEER based on interpolation and 

extrapolation is appropriate for variablespeed units. Id. DOE noted it would 

consider requiring variable-speed 

equipment be tested only according to 

AHRI 340/360–2022 and, thus, testing 

physically at the IEER EWTs, if 

suggested by commenters. Id. Finally, 

DOE sought feedback on whether the 

proposed interpolation and 

extrapolation method should be based 

on testing at the ISO 13256–1:2021 

EWTs (which differ from the ISO 

13256–1:1998 EWTs for certain test 

points). Id. 

Some commenters opposed DOE’s 

proposals regarding the IEER metric in 

the August 2022 NOPR. ClimateMaster, 

MIAQ, and WaterFurnace recommended 

that DOE adopt the test methods 

specified in AHRI 600 instead of AHRI 

340/360–2022 for calculating the IEER 

of WSHPs. (ClimateMaster, No. 22 at pp. 

3–5; MIAQ, No. 23 at p. 4; 

Waterfurnace, No. 20 at pp. 6–7) MIAQ 

stated that AHRI 600 will provide a 

method for calculating a seasonal 

cooling efficiency metric for WSHPs 

(i.e., IEER) based on testing conducted 

according to ISO 13256–1:1998. (MIAQ, 

No. 23 at p. 4) MIAQ stated that that the 

estimated AHRI 600 approval date of 

October 1, 2023 would meet DOE’s 

timeline for adopting the standard. (Id.) 

ClimateMaster commented that 

adopting the test methods specified in 

AHRI 340/360–2022 would require 

manufacturers to certify products under 

two programs (i.e., AHRI 340–360 and 

ISO/AHRI 13256), which is 

unprecedented in the industry, and 

would pose challenges for 

manufacturers, third-party labs, and 

partners to test and maintain two 

certification programs. (ClimateMaster, 

No. 22 at p. 3) 

ClimateMaster recommended that 

DOE utilize data created through ISO 

13256–1:1998 to interpolate per the 

procedure provided in AHRI 600. 

(ClimateMaster, No. 22 at p. 4) 

ClimateMaster disagreed with DOE’s 

proposal for ‘‘option 2’’ to interpolate 

and extrapolate cooling capacity and 

total power instead of directly 

interpolating/extrapolating EER and 

argued that the method in the draft 

AHRI 600 at the time should be used, 

which is based on directly 

interpolating/extrapolating EER. (Id.) 

ClimateMaster further argued that the 

difference between the two 

methodologies is within the uncertainty 

of measurement for testing WSHPs and, 

therefore, that DOE’s proposed 

deviation from the methodology in 

AHRI 600 (at the time) is unnecessary. 

(Id.) ClimateMaster further commented 

that their analysis of a random sample 

of performance data for five systems 

tested in their labs showed that, on 

average, interpolating/extrapolating 

based on EER resulted in slightly more 

accurate numbers than interpolating/ 

extrapolating based on capacity and 

power. (Id. at pp. 4–5) 

ClimateMaster recommended that 

DOE maintain the existing ISO 13256– 

1:1998 standard until the WSHP 

industry adopts the updated standard 

and suggested that DOE adopting a 

national deviation of ISO 13256–1:2021 

would be practical as long 

manufacturers are given significant time 

to adopt the new test procedure. 

(ClimateMaster, No. 22 at p. 5) 

ClimateMaster commented that there are 

several changes introduced in ISO 

13256–1:2021 that it believes provide a 

more effective performance map for a 


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7As discussed later in this section, the lowest 

EWT in AHRI 600–2023 is 50 °F, which is lower 

than the lowest IEER EWT (55 °F), such that the 

AHRI 600–2023 approach does not require 

extrapolation for determining IEER. 

WSHP system, but that this standard has 

not yet been adopted by the WSHP 

industry. (Id.) ClimateMaster further 

commented that the EWTs utilized for 

determining IEER via interpolation/ 

extrapolation are irrelevant as long as 

DOE requires that the entering air 

temperatures and other items are 

inconsistent from the current ISO 

13256–1:1998 test program. (Id.) 

Regarding DOE’s request for comment 

on variable-speed unit testing, 

ClimateMaster commented that DOE’s 

test results from the units sampled and 

tested at a third-party lab should be 

shared with stakeholders for review and 

comment—particularly regarding 

variable speed units, as most of these 

require hardware and software from the 

manufacturer to allow for proper testing, 

and test instructions were not provided 

to DOE for the department’s testing of 

variable-speed units as would be done 

for normal certification testing. 

(ClimateMaster, No. 22 at p. 4) 

MIAQ commented that the proposed 

interpolation and extrapolation method 

should be based on testing at the ISO 

13256–1:2021 EWTs. (MIAQ, NO. 23 at 

p. 4) Regarding the proposed ‘‘option 2’’ 

approach for determining IEER via 

interpolation/extrapolation for variablespeed units, MIAQ recommended DOE 

use the latest edition of ISO 13256– 

1:2021 as the test procedure and 

continue to use AHRI 340/360–2022 for 

IEER calculations. (Id.) 

Other commenters supported DOE’s 

proposals regarding the IEER metric in 

the August 2022 NOPR. The Joint 

Commenters supported adopting a partload metric to measure cooling 

efficiency performance, stating that 

WSHPs, like many other commercial air 

conditioners and heat pumps, operate a 

significant percent of the time at partload conditions, and that a part-load 

metric could incentivize designs that 

reduce annual energy consumption. 

(Joint Commenters, No. 27 at pp. 1–2) 

The Joint Commenters recommended 

DOE ensure that an adopted part-load 

metric reflects the total cooling 

provided divided by the total energy 

consumed and noted that they have 

previously commented that the IEER 

metric likely does not reflect the total 

cooling provided divided by the total 

energy consumed, and instead weights 

efficiencies calculated at different loadpoints. (Id.) 

NEEA supported DOE’s proposed 

transition from regulating WSHP 

efficiency based on a full-load EER 

metric to a multi-capacity IEER metric. 

(NEEA, No. 25 at p. 2) NEEA 

commented that an IEER metric is more 

representative of overall equipment 

performance, and that optimizing partload efficiencies is beneficial to both 

consumers and utilities because 

heating/cooling equipment operates at 

peak capacity for a small number of 

hours. (Id.) NEEA recommended that 

DOE move to the IEER metric for 

regulatory purposes while still 

encouraging manufacturers to also 

publish full-load EER data, given the 

importance of EER data for peak load 

performance and planning for utilities. 

(Id.) NEEA commented that it is 

encouraged by DOE’s monitoring of the 

development of the AHRI Standard 600 

and stated that this standard will allow 

for even more representative ratings of 

regional seasonal heating and cooling 

efficiencies. (Id.) 

NYSERDA supported DOE’s proposal 

to adopt for WSHPs the testing methods 

specified in AHRI 340/360–2022 for 

calculating IEER, stating that a seasonal 

efficiency metric is more representative 

of the part-load operation and varying 

temperature conditions seen in actual 

field performance of WSHPs. 

(NYSERDA, No. 21 at p. 2) 

As discussed in section III.D, DOE is 

incorporating by reference AHRI 600– 

2023 into its amended WSHP test 

procedure. Section 6.3 of AHRI 600– 

2023 uses a method for determining 

IEER that is similar to the interpolation 

method proposed in the August 2022 

NOPR, including tests at three EWTs, 

interpolating from those EWTs to the 

IEER EWTs specified in AHRI 340/360– 

2022, and adjusting the efficiency from 

the tested and interpolated load 

percentages to the IEER load 

percentages. 

With regards to ClimateMaster’s 

comment on the interpolation 

methodology (i.e., interpolating the 

capacity and power vs. interpolating 

EER directly), DOE discussed this issue 

with stakeholders in AHRI 600 meetings 

after publication of the August 2022 

NOPR, and section 6.3.4 of AHRI 600– 

2023 includes interpolation of capacity 

and power, consistent with the 

approach proposed in the August 2022 

NOPR.7 Having been developed through 

an industry consensus process 

subsequent to the timing of the August 

2022 NOPR comment period, DOE 

surmises that the interpolation approach 

specified in AHRI 600–2023 represents 

the prevailing industry consensus 

regarding the most appropriate method 

of performing the interpolation of 

capacity and power and addresses the 

issues raised by commenters regarding 

DOE’s proposed methodology for the 

interpolation method in the August 

2022 NOPR. 

With regards to the comment from the 

Joint Commenters recommending that 

DOE adopt a part-load metric that 

reflects the total cooling provided 

divided by the total energy consumed, 

DOE notes that no industry test 

procedures for WSHPs include a metric 

using such an equation format instead of 

the equation format for IEER (which is 

a weighted average of EERs at four 

different EWTs) and the Joint 

Commenters did not provide sufficient 

information to support development of 

such an equation format for WSHPs. 

Therefore, at this time, DOE has 

concluded that it lacks the necessary 

information to adopt an integrated 

metric other than IEER for WSHPs. 

While much of the methodology to 

determine IEER adopted in this final 

rule is consistent technically with the 

proposal from the August 2022 NOPR, 

DOE notes the following differences 

between the approach adopted in this 

final rule (consistent with AHRI 600– 

2023) and the proposals in the August 

2022 NOPR: 

(1) Removal of option for testing 

directly at IEER EWTs. In this final rule, 

DOE is not adopting the proposed 

option 1 methodology of directly testing 

at the IEER EWTs (i.e., 85 °F, 73.5 °F, 

62 °F, 55 °F). Rather, consistent with 

section 6.3 of AHRI 600–2023, the test 

procedure adopted in this final rule 

specifies that IEER is determined via 

interpolation from tests at ISO 13256–1 

EWTs, which is similar to option 2 as 

proposed in the August 2022 NOPR. 

With regards to NYSERDA’s comment 

supporting adopting AHRI 340/360– 

2022 to calculate IEER, DOE notes that 

the methodology specified in AHRI 

600–2023 is very similar and produces 

near identical results to the 

methodology of AHRI 340/360–2022, as 

demonstrated through DOE’s data 

presented in the August 2022 NOPR. 

See 87 FR 53302, 53316. 

(2) Change in full-load test EWTs. The 

full-load test temperatures used for 

interpolation in section 6.2.1 of AHRI 

600–2023 are consistent with ISO 

13256–1:2021 (i.e., 86 °F, 68 °F, 50 °F) 

instead of ISO 13256–1:1998 (i.e., 86 °F, 

77 °F, 59 °F), which was proposed in the 

August 2022 NOPR. This is also 

consistent with the comment from 

MIAQ that encouraged the use of ISO 

13256–1:2021 EWTs. 

(3) Change in part-load test EWTs. 

The part-load test EWTs used for 

interpolation in section 6.3.2 of AHRI 

600–2023 are the same as the full-load 

EWTs (i.e., 86 °F, 68 °F, 50 °F). This 

differs from the approach in the August 

2022 NOPR, which proposed to align 


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8Section 6.3.2.4 of AHRI 600–2023 further 

specifies that if the continuous capacities of two 

compressor modulation levels allowed by the 

controls at a single set of operating conditions are 

equidistant from the arithmetic mean of the 

capacities from the minimum and maximum 

compressor modulation levels at the same set of 

operating conditions, the intermediate compressor 

modulation level used for testing is the compressor 

modulation level with the lower capacity. 

with the EWTs specified in ISO 13256– 

1:1998 (i.e., 86 °F, 77 °F, and 59 °F for 

full-load tests; 86 °F, 68 °F, and 59 °F for 

part-load tests). MIAQ encouraged the 

use of ISO 13256–1:2021, which 

specifies part-load test EWTs of 77 °F, 

59 °F, and 41 °F. The part-load EWTs in 

section 6.3.2 of AHRI 600–2023 (86 °F, 

68 °F, 50 °F) are not consistent with 

either the 1998 or 2021 versions of ISO 

13256–1, and instead reflect the 

conclusion of discussions in AHRI 600 

committee meetings that conducting 

part-load tests at the same EWTs as fullload tests would reduce testing burden 

(by reducing the number of times the 

water temperature would need to be 

reconditioned between tests) and better 

align with the IEER methodology in 

AHRI 340/360–2022. DOE surmises that 

the part-load EWTs specified in section 

6.3.2 of AHRI 600–2023 represent the 

prevailing industry consensus regarding 

the most appropriate EWTs for testing 

WSHPs. In addition, as compared to the 

part-load EWTs proposed in the August 

2022 NOPR (the lowest of which was 

59 °F), the lowest part-load EWT in 

AHRI 600–2023 (50 °F) is lower than the 

lowest IEER EWT (55 °F). Therefore, use 

of the part-load EWTs in AHRI 600– 

2023 means that all IEER EWTs can be 

interpolated from the tested EWTs, 

instead of requiring any extrapolation. 

As a result, in this final rule DOE is 

adopting the part-load EWTs as outlined 

in the AHRI 600–2023 through 

incorporation by reference. 

(4) Updated provisions for variable 

speed units. The approach for 

determining IEER for variable-speed 

WSHPs specified in AHRI 600–2023 

differs from the approach proposed in 

the August 2022 NOPR in that 

additional tests are required at 

intermediate compressor speeds. 

Specifically, section 6.3.2 of AHRI 600– 

2023 requires that three tests be 

performed at each EWT, at the three 

following compressor speeds: (1) 

maximum compressor speed (i.e., fullload test); (2) minimum compressor 

speed; and (3) an intermediate 

compressor speed that reflects the 

compressor stage with a capacity closest 

to half-way between the capacities 

measured at the minimum and 

maximum compressor speeds. This 

third test reduces the range of 

compressor speeds over which 

interpolation must be conducted (i.e., 

interpolating between intermediate 

compressor speed and maximum or 

minimum compressor speeds, instead of 

between maximum compressor speed 

and minimum compressor speed), thus 

reducing the extent to which 

interpolated results might differ from 

unit performance at the IEER EWTs. 

DOE surmises that the approach for 

variable speed units specified in section 

6.3.2 of AHRI 600–2023 represents the 

prevailing industry consensus regarding 

the most appropriate method. Therefore, 

in this final rule, DOE is adopting the 

IEER determination method for variablespeed units from AHRI 600–2023 

through incorporation by reference into 

appendix C1 of section 6.3.2. 

Additionally, DOE presumes this 

updated methodology resolves 

Climatemaster’s request for DOE’s 

variable speed test data, as DOE is 

adopting the industry consensus 

methodology.8

(5) Change in cyclic degradation 

equation. See section III.E.1.a of this 

document for detailed discussion. 

Finally, DOE is defining ‘‘IEER’’ in 10 

CFR 431.92 as a weighted average 

calculation of mechanical cooling EERs 

determined for four load levels and 

corresponding rating conditions, 

expressed in Btu/watt-hour and that 

IEER is measured per appendix C1 to 

subpart F of part 431 for water-source 

heat pumps. 

a. Cyclic Degradation 

In the August 2022 NOPR, DOE 

proposed to adopt specific sections of 

AHRI 340/360–2022 in its amended test 

procedure for WSHPs, including section 

6.2.3.2. 87 FR 53302, 53327. Equation 4 

in section 6.2.3.2 of AHRI 340/360–2022 

is used to calculate part-load EER for a 

unit that needs to cycle in order to meet 

the 75-percent, 50-percent, and/or 25- 

percent load conditions required for the 

IEER metric. Id. Cycling is the term used 

to describe the process in which a unit’s 

compressor is repeatedly turned off and 

on in order to meet a load that is lower 

than the unit’s capacity at its lowest 

compressor stage. Id. Equation 4 of 

AHRI 340/360–2022 multiplies only the 

compressor power and condenser 

section power by the load factor and the 

coefficient of degradation, while the 

indoor fan power and controls power 

are not multiplied by these variables. Id. 

This means that equation 4 of AHRI 

340/360–2022 assumes that the indoor 

fan continues to operate when the 

compressor cycles off. Id. 

DOE requested comment on the 

proposal to adopt the cyclic degradation 

equation specified in section 6.2.3.2 of 

AHRI 340/360–2022 for WSHPs, which 

assumes continuous indoor fan 

operation when the compressor cycles 

off. Id. at 87 FR 53328. 

ClimateMaster commented that the 

assumption of continuous fan operation 

in the AHRI 340/360 IEER calculations 

is neither representative of field 

operation nor is it in alignment with 

guidance provided by ASHRAE 90.1. 

(ClimateMaster, No. 22 at p. 3) 

ClimateMaster stated that, according to 

data it collected through consumer 

surveys, 16 percent of installed systems 

cycle fan operation with the 

compressor, 52 percent operate the fan 

continuously while a building is 

occupied but cycle the fan with the 

compressor when unoccupied, and only 

14 percent of installed WSHPs run the 

fan continuously regardless of 

occupancy and compressor operation, 

while the remaining 18 percent 

responded that they were unaware of 

how their WSHP system cycles 

operated. (Id. at p. 3) ClimateMaster 

recommended that DOE instead use 

AHRI 600 method that does not assume 

continuous fan operation. (Id. at p. 8) 

ClimateMaster commented that, for 

WSHPs that are installed to operate the 

fan continuously, models with a multispeed motor will operate at the cooling 

fan speed, while variable-speed models 

have an option to adjust the continuous 

fan speed to a lower value. (Id.) 

WaterFurnace commented that 

supporting ISO 13256 and AHRI 600 

would solve the issue. (WaterFurnace, 

No. 20 at p. 8) WaterFurnace stated that 

continuous indoor fan operation is not 

the most appropriate logic in coolingdominated environments and 

recommended demand controls 

ventilation as a better use of energy that 

improves latent moisture removal. (Id.) 

In response to these comments, DOE 

notes that section 6.3.6.4 of AHRI 600– 

2023 has an equation similar to equation 

4 of AHRI 340/360–2022, but the 

equation in AHRI 600–2023 assumes 

that the indoor fan stops operating 

whenever the compressor cycles off. 

The data provided by ClimateMaster 

suggest that the vast majority of 

installed WSHPs do not operate the fan 

continuously in all operating modes, but 

that many installed WSHPs do operate 

the fan continuously during occupied 

hours (i.e., regardless of whether the 

compressor is cycled on or off). At the 

time of publication of the August 2022 

NOPR, there were no WSHP industry 

consensus test procedures that included 

IEER. However, at this time, DOE 

surmises that the method in section 

6.3.6.4 of AHRI 600–2023, which 

assumes the fan does not run when the 

compressor is cycled off, represents 


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industry consensus on the appropriate 

method for determining IEER for 

WSHPs. At this time, DOE has 

concluded that it lacks sufficient 

information to justify deviating from the 

approach in AHRI 600–2023 regarding 

fan operation. DOE is therefore 

incorporated by reference the cyclic 

degradation equation from section 

6.3.6.4 of AHRI 600–2023 into its 

amended test procedure in this final 

rule. 

2. ACOP 

DOE’s current test procedure for 

WSHPs measures heating-mode 

performance in terms of the COP metric. 

COP is a full-load heating efficiency 

metric for WSHP water-loop 

applications, meaning that it represents 

the heating efficiency for a WSHP 

operating at its maximum capacity at an 

EWT that is typical of heating operation 

in water-loop applications. DOE’s 

current test procedure specifies an EWT 

of 68 °F for measuring COP. 10 CFR 

431.96. 

In the August 2022 NOPR, DOE 

discussed its understanding that while 

in the past water-loop temperatures 

were maintained at temperatures above 

60 °F via heat provided by a system 

boiler, in current practice WSHP 

installations are typically controlled to 

allow water-loop temperatures to drop 

to temperatures closer to 50 °F. 87 FR 

53302, 53316. Therefore, while the 

current EWT of 68 °F for the COP metric 

may have been more representative of 

how WSHP systems were controlled in 

the past (i.e., with a boiler maintaining 

water-loop temperatures above 60 °F), 

DOE tentatively determined in the 

August 2022 NOPR that the EWT 

specified for determining COP should 

be no higher than the lowest EWT used 

in the IEER metric, which is 55 °F (for 

the 25-percent load point). Id. 

Therefore, DOE tentatively concluded in 

the August 2022 NOPR that the COP 

metric would be more representative of 

water-loop WSHP applications if based 

on an EWT of 55 °F. Id. at 87 FR 53317. 

Accordingly, in the August 2022 NOPR, 

DOE proposed use an EWT of 55 °F for 

the COP metric in appendix C1. Id. 

DOE also considered whether an EWT 

below 55 °F, specifically 50 °F, might be 

more representative for determining 

COP, depending upon typical heating 

conditions for water-loop WSHPs. Id. 

However, DOE noted in the August 2022 

NOPR that it lacked data or evidence 

indicating that 50 °F would be a more 

representative heating EWT than 55 °F 

for WSHPs. Id. 

Additionally, DOE proposed to 

include an alternate method in 

appendix C1 that would allow 

manufacturers to determine COP at the 

proposed EWT of 55 °F by interpolation 

from results of testing at the EWTs 

specified in Table 2 of ISO 13256– 

1:1998 (i.e., 50 °F and 68 °F). Id. In the 

August 2022 NOPR, DOE presented the 

results of investigative testing 

demonstrating that COP calculated from 

interpolated values of cooling capacity 

and total power differed from measured 

COP by an average of less than 1 

percent. Id. Based on these test results, 

DOE tentatively concluded that 

determining COP at 55 °F via 

interpolation from testing at the ISO 

13256–1:1998 EWTs (in accordance 

with DOE’s proposed test procedure) 

would provide appropriately 

representative results that are 

comparable to testing at 55 °F. Id. 

In summary, DOE proposed in section 

6.2 of the proposed appendix C1 to 

allow that COP for WSHPs can be 

calculated from either of two methods: 

(1) ‘‘option A’’—testing at 55 °F; or (2) 

‘‘option B’’—interpolation of heating 

capacity and power values based on 

testing in accordance with the proposed 

test procedure at EWTs of 50 °F and 

68 °F. Id. 

DOE sought comment and data on the 

representativeness of 55 °F as the EWT 

condition for determining COP. Id. 

Specifically, DOE requested feedback 

and data on whether a lower EWT, such 

as 50 °F, would be more representative 

of heating operation of WSHPs. Id. DOE 

stated that it would further consider any 

alternate EWT suggested by comments 

in developing any final rule. Id. DOE 

also requested comment on the proposal 

to allow determination of COP using the 

two different methods. Id. Specifically, 

DOE sought feedback on the proposed 

method for calculating COP via 

interpolation and on whether this 

approach would serve as a potential 

burden reducing option as compared to 

testing at 55 °F. Id. 

In response to the August 2022 NOPR, 

ClimateMaster recommended that DOE 

maintain use of the ISO 13256–1:1998 

EWT of 68 °F as the basis for the 

regulated metric, asserting that this 

would take into account the fact that 

building designers select and simulate 

system equipment and performance 

based upon data published by 

manufacturers. (ClimateMaster, No. 22 

at p. 5) ClimateMaster stated that the 

EWT used for heating operation in a 

WSHP is dependent on many factors 

(e.g., building design, location, system 

design, system operation, and building 

occupancy or use) and that, due to these 

factors, there are no data available to 

determine the representativeness of 

55 °F as the EWT condition in contrast 

to a lower or higher EWT. (Id.) 

Regarding DOE’s proposal to allow 

two different options for determining 

COP, ClimateMaster stated that it 

disagreed with both proposed options 

for allowing determination of COP, 

stating that neither option would 

provide a reduction in burden 

considering DOE’s proposal to change 

entering air temperatures. (Id.) 

ClimateMaster further commented that 

the proposed changes would require the 

industry to test under multiple 

standards to meet both certification 

programs. (Id. at pp. 5–6) 

MIAQ recommended aligning the 

EWT conditions with the latest edition 

of ISO standard EWT conditions. 

(MIAQ, No. 23 at p. 4) 

WaterFurnace commented that nonexpansion valve products typically 

cannot operate below an EWT of 60 °F 

and that a percentage of the market has 

always had limited water temperature 

range capability. (WaterFurnace, No. 20 

at p. 7) WaterFurnace also commented 

that adopting ISO 13256–1 and AHRI 

600 would solve the issue of COP test 

temperature. (Id.) 

Regarding considerations for selecting 

the EWT condition for determining 

COP, FHP commented that the use of 

higher EWTs is focused on water loop 

condition only and the move to 

electrification for commercial buildings 

will shift commercial designs for water 

source products toward ground coupled 

systems, driving temperatures closer to 

ISO 13256–1 ground loops conditions 

(e.g., 32 °F entering water). (FHP, No. 26 

at p. 4) 

NYSERDA agreed with DOE’s 

proposal to adopt an EWT of 55 °F or 

lower, stating that geothermal 

technology research and development 

undertaken by NYSERDA and the 

Cleaner, Greener Communities Program 

in Syracuse revealed the average EWT 

for the average mixed-use building was 

48 °F when heating. (NYSERDA, No. 21 

at p. 3) NYSERDA commented that it 

had collected data supporting that the 

average building consistently uses 

EWTs of 55 °F or lower and presented 

these data in a table that suggested the 

current EWT test condition of 68 °F is 

unrepresentatively high. (Id. at pp. 3–4) 

In response to WaterFurnace’s 

comment that some products cannot 

operate below 60 °F, DOE notes that the 

heating temperatures in section 6.2.1 of 

AHRI 600–2023 include temperatures 

below 60 °F, at 50 °F and 32 °F. 

Inclusion of these EWTs in the updated 

industry standard suggests that there is 

industry agreement that WSHPs can 

generally operate below 60 °F. DOE is 

not aware of any WSHPs that cannot 

operate in heating mode at 50 °F and 

notes that the issue was not raised in 


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AHRI 600 committee meetings after the 

August 2022 NOPR. As discussed earlier 

in this section, comments from other 

interested parties also supported the use 

of a lower temperature. 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023. Section 6.2.1 

of AHRI 600–2023 includes EWTs of 

68 °F, 50 °F, and 32 °F for measuring 

COP. Additionally included in section 

6.4.5 of AHRI 600–2023 is a new metric, 

ACOP, which is only measured at 50 °F. 

This new metric is similar to COP but 

includes provisions accounting for 

system pump power, which better 

accounts for total energy use of WSHPs 

and aligns with changes made to the 

cooling efficiency metric (see section 

III.F.3 of this document for more 

details). Further, ACOP is included in 

section 7.1 of AHRI 600–2023 as a 

minimum requirement for published 

ratings. Therefore, ACOP, measured at 

50 °F, is the heating metric required for 

WSHPs according to AHRI 600–2023. 

Having been developed through an 

industry consensus process subsequent 

to the timing of the August 2022 NOPR 

comment period, DOE surmises that 

ACOP tested at an EWT of 50 °F 

specified in AHRI 600–2023 represents 

the prevailing industry consensus 

regarding the most appropriate metric 

for measuring heating performance. 

Therefore, in this final rule, DOE is 

incorporating by reference sections 6.2.1 

and 6.4.5 of AHRI 600–2023 into 

appendix C1 adopting the ACOP metric, 

tested at an EWT of 50 °F. 

DOE notes that no heating EWT of 

55 °F is included in section 6.2.1 of 

AHRI 600–2023 and, instead, Table 8 of 

the document maintains the same 

heating test temperatures as ISO 13256– 

1:1998 (68 °F, 50 °F, and 32 °F). 

Therefore, due to the lack of support of 

a test temperature at 55 °F, the exclusion 

of that temperature in AHRI 600–2023, 

and the support for aligning with ISO 

13256–1:1998 test temperatures (which 

include 50 °F), DOE is finalizing the 

ACOP metric based on a test at 50 °F, 

consistent with AHRI 600–2023. 

As discussed, use of the amended test 

procedure in appendix C1 and rating to 

ACOP at 50 °F are not required until the 

compliance date of amended standards 

denominated in terms of ACOP, should 

DOE adopt such standards. DOE is 

defining ‘‘ACOP’’ in 10 CFR 431.92 as 

the ratio of the heating capacity to the 

power input, including system pump 

power, for water-source heat pumps and 

that ACOP is expressed in watts per 

watt and determined according to 

appendix C1 of subpart F of part 431. 

Because AHRI 600–2023 requires a 

heating test at 50 °F, there is no need for 

an interpolation method to determine 

ACOP at an EWT different from the 

tested EWT, and, therefore, AHRI 600– 

2023 includes no such interpolation 

method for ACOP. Correspondingly, 

because DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1 to require a heating test be 

conducted at 50 °F and to adopt the 

ACOP metric based on the same EWT, 

the COP interpolation method proposed 

in the August 2022 NOPR is no longer 

applicable. Therefore, DOE is not 

adopting an interpolation method for 

determining ACOP in this final rule. 

3. Optional Representations 

In the August 2022 NOPR, DOE 

proposed provisions to allow for 

optional representations of EER 

conducted per the proposed test 

procedure (sections 2 through 4 and 7 

of proposed appendix C1) at the fullload and part-load EWT conditions 

specified in Table 1 of ISO 13256– 

1:1998 (i.e., full load tests at 86 °F, 77 °F, 

and 59 °F and part-load tests at 86 °F, 

68 °F, and 59 °F). 87 FR 53302, 53314. 

Additionally, DOE proposed provisions 

to provide for optional representations 

of COP based on testing conducted per 

the proposed test procedure (sections 2 

through 4 and 7 of proposed appendix 

C1) at the full-load and part-load EWT 

conditions specified in Table 2 of ISO 

13256–1:1998 (i.e., 68 °F, 50 °F, 41 °F, 

and 32 °F). Id. at 87 FR 53317. 

AHRI 600–2023 includes provisions 

allowing for optional representations of 

EER and COP in sections 6.3.12 and 

6.4.7, respectively. Optional 

representations can be made at any of 

the cooling and heating full-load and 

part-load EWT conditions in Table 8 of 

AHRI 600–2023. DOE notes that the 

AHRI 600–2023 includes new metrics 

applied energy efficiency ratio 

(‘‘AEER’’) and ACOP (see section III.E.2 

of this final rule for more details about 

ACOP). Each of these metrics include a 

power adder representing system pumps 

and the adder for AEER also includes 

cooling tower power. DOE notes that 

AHRI 600–2023 does not have 

provisions for optional representations 

of these metrics and instead requires 

them to be published. The optional 

representations of EER and COP allowed 

for by AHRI 600–2023 do not include 

the power adder for system pumps and 

cooling tower power. 

As discussed in section III.E.1 and 

III.E.2 of this final rule, DOE is 

incorporating by reference AHRI 600– 

2023 for IEER and ACOP into appendix 

C1 as the cooling and heating metrics 

for WSHPs. The IEER metric as 

determined according to AHRI 600– 

2023 includes a power adder for system 

pumps and cooling tower power. DOE 

notes that the metrics it is adopting are 

intended to best reflect WSHP 

performance, using representative EWTs 

and including power for all components 

that are needed for operation of WSHP 

systems in a representative application 

(i.e., external pumps and cooling 

towers). Optional representations of EER 

and COP are intended to provide more 

information to consumers across a range 

of temperature conditions such that 

performance can be assessed for specific 

applications. DOE is adopting the 

provisions for optional representations 

of EER and COP from sections 6.3.12 

and 6.4.7 from AHRI 600–2023 by 

incorporating by reference AHRI 600– 

2023 into appendix C1. These 

provisions allow optional 

representations to be made consistent 

with AHRI 600–2023 at full-load or partload at any of the standard rating 

conditions for WSHPs (i.e., 86 °F, 68 °F, 

and 50 °F for cooling and 68 °F, 50 °F, 

and 32 °F for heating). DOE notes that 

these temperatures vary slightly from 

the proposals in the August 2022 NOPR 

for optional representations, but 

represent the same intent of allowing for 

optional representations of a range of 

operating conditions. Having been 

developed through an industry 

consensus process subsequent to the 

timing of the August 2022 NOPR 

comment period, DOE has determined 

that the EWTs specified in AHRI 600– 

2023 represent the prevailing industry 

consensus regarding the most 

appropriate EWTs for optional 

performance test points. 

4. Entering Air Conditions 

The current DOE WSHP test 

procedure references ISO 13256–1:1998, 

which specifies in Table 1 that EER is 

measured with entering air at 27 °C 

(80.6 °F) dry-bulb temperature and 19 °C 

(66.2 °F) wet-bulb temperature and in 

Table 2 that COP is measured with 

entering air at 20 °C (68 °F) dry-bulb 

temperature and 15 °C (59 °F) wet-bulb 

temperature. 

In the August 2022 NOPR, DOE 

proposed to use the entering air 

conditions in Table 6 of AHRI 340/360– 

2022, which specify that cooling tests 

are measured with entering air at 80 °F 

dry-bulb temperature and 67 °F wet-bulb 

temperature heating tests are measured 

with entering air at 70 °F dry-bulb 

temperature and a maximum of 60 °F 

wet-bulb temperature. 87 FR 53302, 

53318. DOE discussed in the August 

2022 NOPR that the entering air 

conditions specified in AHRI 340/360– 

2022 are similar to the conditions 

specified in ISO 13256–1:1998 and ISO 

13256–1:2021, differing for cooling by 


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0.6 °F for dry-bulb temperature and 

0.8 °F for wet-bulb temperature and for 

heating by 2 °F for dry-bulb temperature 

and 1 °F for wet-bulb temperature. Id. 

DOE surmised that these differences are 

likely due to the conditions in ISO 

13256–1 (1998 and 2021 versions) being 

specified in terms of degrees Celsius, 

whereas the conditions in AHRI 340/ 

360–2022 are specified in degrees 

Fahrenheit. Id. DOE also noted that the 

entering air conditions specified in 

AHRI 340/360–2022 are the same as in 

previous versions of AHRI 340/360, 

including AHRI 340/360–2007, which is 

referenced in the current DOE test 

procedure for CUAC/HP equipment. Id. 

Further, the most common application 

for WSHPs (and the application DOE 

understands that the WSHP industry is 

intending to represent via use of the 

IEER metric in AHRI 600) is commercial 

buildings, similar to CUAC/HP 

equipment. Id. Therefore, DOE 

tentatively determined in the August 

2022 NOPR that the entering air 

conditions in AHRI 340/360–2022 are 

appropriately representative of the 

average conditions in which WSHPs 

operate in the field. Id. 

DOE requested comment on its 

proposal to specify use of the cooling 

entering air conditions from AHRI 340/ 

360–2022 (i.e., 80 °F dry-bulb 

temperature and 67 °F wet-bulb 

temperature) and the heating entering 

air conditions from AHRI 340/360–2022 

(i.e., 70 °F dry-bulb temperature and a 

maximum of 60 °F wet-bulb 

temperature). Id. 

In response to the August 2022 NOPR, 

ClimateMaster recommended that DOE 

keep the existing entering air 

temperature conditions for both heating 

and cooling tests from ISO 13256– 

1:1998 to avoid the requirement to test 

equipment under two separate 

certification programs. (ClimateMaster, 

No. 22 at p. 6) ClimateMaster stated that 

the use of 80.6 °F and 66.2 °F entering 

air conditions for cooling would be 

more conservative (i.e., result in lower 

efficiency ratings) than those at 80 °F 

and 67 °F as specified in AHRI 340/360– 

2022. (Id.) 

WaterFurnace commented that 

adopting ISO 13256 and AHRI 600 

would solve the issue of which entering 

air conditions to use. (WaterFurnace, 

No. 20 at p. 7) WaterFurnace further 

commented that DOE’s proposal would 

essentially require all new testing due to 

the different entering air conditions. 

(Id.) WaterFurnace stated that the 

existing entering air conditions of 

AHRI/ISO 13256 could be used and 

would result in a more conservative 

performance prediction. (Id.) 

MIAQ commented that it generally 

agrees with DOE’s proposal to adopt the 

entering air conditions in AHRI 340/ 

360–2022. (MIAQ, No. 23 at p. 5) 

As discussed, DOE is adopting 

provisions for determining IEER and 

ACOP by incorporating by reference 

AHRI 600–2023 into appendix C1. The 

entering air conditions in section 6.2.1 

of AHRI 600–2023 align with the 

entering air conditions specified in 

AHRI 340/360–2022 (and therefore align 

with DOE’s August 2022 NOPR 

proposal). DOE surmises that inclusion 

of the AHRI 340/360–2022 entering air 

conditions in AHRI 600–2023 indicates 

industry consensus with these test 

conditions. Therefore, DOE is adopting 

provisions for determining IEER and 

ACOP consistent with AHRI 600–2023, 

including entering air conditions of 

80 °F dry bulb and 67 °F wet bulb for 

cooling tests and 70 °F dry bulb and a 

maximum of 60 °F wet bulb for heating 

tests, in this final rule, by incorporating 

by reference into appendix C1 section 

6.2.1 of AHRI 600–2023. 

F. Test Method 

1. Airflow and External Static Pressure 

a. Fan Power Adjustment and Required 

Air External Static Pressures 

For ducted units, the current DOE 

WSHP test procedure, which 

incorporates by reference ISO 13256– 

1:1998, specifies a fan power adjustment 

calculation that does not account for fan 

power used for overcoming external 

resistance. As a result, the calculation of 

efficiency includes only the fan power 

required to overcome the internal 

resistance of the unit. In addition, ISO 

13256–1:1998 does not specify ESP 

requirements for ducted equipment, 

instead allowing manufacturers to 

specify a rated ESP. In the August 2022 

NOPR, DOE proposed provisions to 

reflect fan power to overcome a 

representative ESP when calculating 

efficiency for ducted units to account 

for the impacts of ESP typically 

encountered in the field. 87 FR 53302, 

53321. DOE determined that, to best 

reflect field operation, ducted WSHPs 

should be tested with minimum ESPs, 

the power for overcoming ESP should 

be included in efficiency calculations, 

and all equipment should be tested with 

an ESP upper tolerance. Id. DOE 

determined that the method in AHRI 

340/360–2022 is more representative of 

field energy use than the methods used 

in ISO 13256–1:1998 for WSHPs. Id. 

DOE proposed to adopt AHRI 340/360– 

2022 for WSHPs, including section 

6.1.3.3 and Table 7 of AHRI 340/360– 

2022, which specify minimum ESPs for 

ducted units, a tolerance on ESP of 

¥0.00/+0.05 in H2O, and no fan power 

adjustment. Id. DOE requested comment 

on the proposal to adopt provisions 

from AHRI 340/360–2022 such that for 

ducted units testing would be 

conducted within tolerance of the AHRI 

340/360–2022 minimum ESP 

requirements, and efficiency ratings 

would include the fan power measured 

to overcome the tested ESP. Id. at 87 FR 

53322. 

In response to the August 2022 NOPR, 

ClimateMaster recommended that DOE 

keep the existing ISO 13256–1:1998 

standard and develop an IEER rating per 

AHRI 600 that offers provisions for 

complying with the required minimum 

external pressure as given in AHRI 340/ 

360–2022. (ClimateMaster, No. 22 at p. 

6) ClimateMaster stated that there are 

multiple reasons why the current ISO 

13256–1:1998 standard excludes 

external static pressure, including that 

the methodology was created to rate 

different motor options for varying static 

requirements in the market space, 

which is especially problematic with 

non-variable speed motors as they are 

limited in output capability over a 

narrow static range. (Id.) MIAQ 

recommended DOE reference the ESP 

requirements in the latest edition of ISO 

13256–1. (MIAQ, No. 23 at p. 5) 

WaterFurnace commented that 

supporting ISO 13256 and AHRI 600 

would solve the issue and that it 

believes the required information can be 

calculated from AHRI/ISO 13256 data 

without retesting. (WaterFurnace, No. 

20 at p. 7) WaterFurnace additionally 

commented that the minimum ESP 

requirements specified in AHRI 340/360 

are adequate for most commercial 

WSHPs because most are installed with 

common plenum returns with little to 

no return ductwork. (Id.) 

FHP recommended that instead of 

requiring testing at minimum ESP 

requirements, DOE develop a revised 

fan power adjustment that incorporates 

accurate fan efficiencies and allows 

testing at a range of ESPs but adjusts fan 

performance to reflect performance at 

the minimum ESPs specified in AHRI 

340/360–2022. (FHP, No. 26 at pp. 3–4) 

FHP asserted that such a revised fan 

power adjustment would allow for 

variations in tested ESP to achieve rated 

airflow to account for limitations of the 

fan-motor combination and variation in 

manufacturing tolerances, while still 

ensuring ratings are based on an ESP 

more representative than zero ESP. (Id.) 

The Joint Commenters supported 

DOE’s proposal that WSHPs be tested at 

the ESPs specified in the proposed test 

procedure. (Joint Commenters, No. 27 at 

p. 2) The Joint Commenters stated that 

maintaining the current test procedure, 


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which applies a correction factor that 

adjusts fan power measured at the 

manufacturer-specified ESP is adjusted 

down to reflect fan power at zero ESP 

and incentivizes testing with higherthan-representative ESPs, would be 

inconsistent with the recommendation 

in the ASRAC Fans and Blowers 

Working Group term sheet to capture 

fan energy more fully across commercial 

HVAC product categories. (Id.) 

NEEA supported DOE’s proposal to 

include additional fan energy in the 

WSHP efficiency metric, but also 

encouraged DOE to consider increasing 

the proposed ESP requirements to be 

more representative of current industry 

practice. (NEEA, No. 25 at pp. 2–3) 

NEEA stated that during the 2015 

CUAC/HP energy conservation standard 

ASRAC negotiations, DOE’s energy use 

analysis used ESP values 2 to 3 times 

higher than the ESP requirements in the 

current test procedure because DOE 

found the values to be more realistic 

and representative of field conditions. 

(Id. at p. 3) NEEA further recommended 

that DOE consider aligning WSHP ESP 

requirements with the updated CUAC/ 

HP ESP requirements when they are 

finalized by the ASRAC Working Group. 

(Id.) 

With regards to these comments, DOE 

notes that section 5.5.1 of AHRI 600– 

2023 includes ESPs to be used for 

testing for ducted units. The ESPs are 

equivalent to those outlined in AHRI 

340/360–2022 for units less than 75,000 

Btu/h cooling capacity, but the ESPs for 

units above 75,000 Btu/h cooling 

capacity (i.e., 0.75 in. H2O for units from 

75,000 Btu/h to 134,000 Btu/h; 1.00 in. 

H2O for units from 135,000 Btu/h to 

280,000 Btu/h; and 1.50 in. H2O for 

units greater than 280,000 Btu/h) are 

significantly higher than those in AHRI 

340/360–2022 and align with the ESP 

requirements recommended in the 

ACUAC and ACUHP Working Group TP 

Term Sheet. (See Document No. 65 in 

Docket No. EERE–2022–BT–STD–0015) 

Section 5.7 of AHRI 600–2023 also 

includes a tolerance of ESP of ¥0.00/ 

+0.05 in H2O and sections 6.3 and 6.4 

of AHRI 600–2023 include no fan power 

adjustment. DOE notes also that the 

approach set forth in AHRI 600–2023 is 

mostly consistent with the approach 

proposed in the August 2022 NOPR, 

with the only difference being higher 

ESP requirements for units greater than 

75,000 Btu/h in cooling capacity. DOE 

has determined that the inclusion of 

ESP requirements, an ESP tolerance, 

and no fan power adjustment in AHRI 

600–2023 represents industry consensus 

that these provisions provide the most 

appropriate and representative method 

for testing WSHPs. As discussed in 

section III.D of this final rule, DOE is 

incorporating by reference AHRI 600– 

2023 into appendix C1, including these 

ESP provisions. DOE notes that 

including these provisions is consistent 

with commenters’ suggestions to adopt 

AHRI 600. 

Regarding the higher ESP 

requirements for units with a cooling 

capacity greater than 75,000 Btu/h, 

adopting these values is consistent with 

NEEA’s recommendation to align with 

the recommendations from the ASRAC 

Working Group for test procedures for 

CUAC/HPs. These ESP requirements 

were developed as part of a joint effort 

between manufacturers, efficiency 

advocates, utilities, and DOE to create a 

more representative efficiency metric for 

CUACs/HPs. DOE understands that 

WSHPs greater than 75,000 Btu/h are 

installed in similar applications to 

CUACs/HPs and, as such, DOE finds the 

AHRI 600–2023 ESP requirements to be 

representative for WSHPs with a cooling 

capacity greater than 75,000 Btu/h. 

DOE notes that the ACUAC and 

ACUHP Working Group TP Term Sheet 

recommends an ESP requirement of 0.75 

in. H2O for units with a cooling capacity 

between 65,000 to 135,000 Btu/h, while 

the lower capacity limit for this 

requirement in section 5.5.1 of AHRI 

600–2023 is 75,000 Btu/h. Based on 

discussions in AHRI 600 committee 

meetings, DOE understands that there 

are WSHP model lines that span up to 

6 tons that typically use fan/motor 

combinations that are designed for 

lower ESP applications and cannot 

operate at the rated airflow at an ESP as 

high as 0.75 in. H2O. Therefore, AHRI 

600–2023 specifies a lower capacity 

limit for this ESP requirement of 75,000 

Btu/h rather than 65,000 Btu/h so that 

these 6-ton models are tested with a 

more representative ESP. DOE 

understands this issue to be unique to 

WSHPs and does not apply to ACUACs 

and ACUHPs, for which models with a 

cooling capacity between 65,000 Btu/h 

and 75,000 Btu/h typically have 

different designs than three-phase 

ACUACs and ACUHPs (which typically 

have comparable designs to CAC/HPs) 

and are typically designed for 

installations for which an ESP of 0.75 

in. H2O is representative. Therefore, in 

this final rule, DOE is incorporating by 

reference the requirements specified in 

Table 7 of section 5.5.1 of AHRI 600– 

2023 for all WSHPs with a cooling 

capacity less than 760,000 Btu/h. 

With regard to comments from 

ClimateMaster and FHP expressing 

concern over ability of different fan/ 

motor combinations to test at an ESP 

requirement at the rated airflow, DOE 

notes that this issue is addressed by the 

provisions for (1) non-standard highstatic indoor fan motors and fan/motor 

combinations proposed in the August 

2022 NOPR, included in section D4 of 

AHRI 600–2023 (discussed in section 

III.G.3 of this final rule); and (2) nonstandard low-static motors included in 

sections 3.2.30 and 5.7.4.3 of AHRI 600– 

2023 (discussed in section III.F.12 of 

this final rule). DOE has concluded that 

the inclusion of ESP requirements and 

provisions in AHRI 600–2023 for (1) 

non-standard high-static indoor fan 

motors and fan/motor combinations and 

(2) non-standard low-static motors 

reflect industry consensus that these 

provisions provide an appropriate 

method for testing and rating WSHPs. 

DOE notes that section 5.5.1.2 of 

AHRI 600–2023 specifies a minimum 

ESP of 0.5 in. H2O for residential 

representations, but that the residential 

representations have not yet been fully 

developed for WSHPs (see section 

III.A.2 of this document for more 

details). DOE will continue to work with 

AHRI 600 committee to develop 

provisions for determining such ratings. 

b. Setting Airflow and ESP 

DOE’s current WSHP test procedure 

does not include provisions on how to 

simultaneously set airflow and ESP 

because there are no required ESPs for 

testing. Because DOE proposed to 

include minimum ESPs in its test 

procedure in the August 2022 NOPR, it 

also proposed provisions to address 

how to simultaneously set airflow and 

ESP. 87 FR 53302, 53322–53324. The 

proposals were broken into three 

groups: 

(1) For ducted units with 

continuously variable speed fans, DOE 

proposed to use relevant provisions 

from AHRI 340/360–2022 in sections 

6.1.3.3 through 6.1.3.5. 

(2) For ducted units with discrete step 

fans, DOE proposed instructions for 

setting the fan speed in the scenario in 

which: (1) tolerances for airflow and 

ESP could not be met simultaneously, 

and (2) adjacent fan control settings 

result in airflow or ESP too low at the 

lower fan control setting and too high at 

the higher fan control setting. 

(3) For non-ducted units, DOE 

proposed units to be tested with a target 

ESP of 0.00 in H2O within a tolerance 

of ¥0.00/+0.05 in H2O. 

Id. 

For all three types of units, the 

proposed airflow tolerance was 3 

percent. Id. 

DOE requested comment on the 

proposed adoption of provisions from 

AHRI 340/360–2022 for setting airflow 

and ESP for testing WSHP units with 


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9 DOE notes that the AHRI WSHP Certification 

Operations Manual is available at: https://

www.ahrinet.org/sites/default/files/2022-06/WSHP_

OM.pdf (Last accessed April 25, 2023). 

continuously variable speed fans. Id. at 

87 FR 53323. DOE also requested 

comment on its proposed instructions 

(distinct from provisions in AHRI 340/ 

360–2022) for setting airflow and ESP 

for ducted WSHP units with discretestep fans. Id. Finally, DOE requested 

comment on its proposal for setting 

airflow and ESP for non-ducted WSHP 

units. Id. at 87 FR 53324. 

In response to the August 2022 NOPR, 

ClimateMaster recommended that DOE 

work with industry to create a national 

deviation of ISO 13256–1:1998 that 

adopts the applicable parts of AHRI 

340/360 for fully variable-speed motor 

systems and systems with adjustable 

sheaves, while still providing separate 

provisions for setting airflow for fan 

motor systems that are not continuously 

variable. (ClimateMaster, No. 22 at p. 7) 

ClimateMaster stated that it disagrees 

with the use of AHRI 340/360–2022 for 

all indoor blower systems, arguing that 

these provisions were developed to 

accommodate only continuously 

variable-speed blower systems and 

asserted that the proposed 3 percent 

tolerance would not be feasible for 

larger WSHP systems without 

continuously variable motors or WSHPs 

with discrete-step or constant volume 

fan motors. (Id. at p. 6) ClimateMaster 

stated that Table B1 of the AHRI WSHP 

Operations Manual 9 specifies a 5 

percent airflow tolerance for discretestep motors. (Id. at p. 7) ClimateMaster 

further commented that the provisions 

for setting airflow in AHRI 210/240– 

2023 are more appropriate for the fan 

motors utilized in most WSHP systems 

(i.e., not continuously variable), stating 

that the AHRI 210/240–2023 provisions 

use manufacturer-specified fan motor 

settings and allow airflow to decrease to 

10 percent below the target airflow. (Id. 

at p. 7) 

FHP commented that the combination 

of a minimum ESP requirement and a 3 

percent airflow tolerance would require 

additional testing and significant design 

constraints and changes at the 

component level for WSHPs with directdrive motors and questioned whether a 

3 percent airflow tolerance at a 

minimum ESP requirement is 

technologically feasible. (FHP, No. 26 at 

p. 4) FHP further commented that units 

with constant-torque direct-drive fan 

motors (e.g., permanent split capacitor 

(‘‘PSC’’) motors, electrically 

commutated motors (‘‘ECMs’’)) do not 

allow for adjustments to airflow without 

adjustments to ESP, making it difficult 

to consistently hit the airflow target 

within 3 percent. (Id.) FHP also noted 

that the AHRI WSHP Operations 

Manual allows for adjustments to ESP to 

meet a 5-percent airflow tolerance for 

these systems. (Id.) 

WaterFurnace commented that 

adopting ISO 13256 and AHRI 600 

would solve the issue. (WaterFurnace, 

No. 20 at p. 8) WaterFurnace stated that 

a test procedure for models fans with 

ECMs would have to be added to AHRI 

340/360 because the standard does not 

address setting airflow and ESP for such 

models, which it stated are typical for 

smaller WSHPs. (Id.) MIAQ 

recommended DOE reference the latest 

edition of ISO 13256–1, stating that this 

standard is the industry test procedure 

currently used by manufacturers and 

laboratories for WSHP testing. (MIAQ, 

No. 23 at p. 5) 

ClimateMaster stated that the WSHP 

Operations Manual covers available 

provisions with what they consider to 

be a proper allowance for airflow 

variation and that non-ducted WSHPs 

are available with motors that have 

multiple set speeds either through 

software or by utilizing a tapped motor 

winding. (ClimateMaster, No. 22 at p. 7) 

ClimateMaster stated that these 

provisions are slightly different from 

those proposed in the August 2022 

NOPR and requested further 

clarification to the meaning of ‘‘as close 

as possible’’. (Id.) ClimateMaster noted 

that they expect that the speed tap 

specified by the manufacturer would be 

utilized and that, if this is the case, then 

there should not be any concern if the 

airflow is ‘‘as close as possible’’ to the 

rated point. (Id.) 

In response to the comment from 

ClimateMaster, DOE notes that the ‘‘as 

close to the target as possible’’ language 

in the August 2022 NOPR is used in 

situations when the airflow and ESP 

requirements cannot be simultaneously 

met. Specifically, for non-ducted units, 

the August 2022 NOPR provisions 

specify that if airflow and ESP 

requirements cannot be met 

simultaneously, the ESP requirement 

takes precedence (i.e., ESP must be 

maintained within tolerance) and the 

airflow is maintained as close as 

possible to the target airflow (but 

outside of tolerance). Section 5.8 of 

AHRI 600–2023 similarly specifies that 

in this situation the ESP must be 

maintained within tolerance and that 

there is no condition tolerance for 

airflow. 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes sections 5.7 and 5.8 

of AHRI 600–2023. This language 

includes provisions generally consistent 

with provisions outlined in the August 

2022 NOPR, specifically a tolerance of 

3 percent for setting airflow, separate 

provisions for continuously variable 

speed fans and discrete-step fans, and a 

method for non-ducted units. Section 

5.7 of AHRI 600–2023 also includes 

provisions for setting airflow and ESP 

for constant-volume fans, but DOE notes 

that these provisions were not proposed 

in the August 2022 NOPR and are 

consistent with provisions in appendix 

M1 for central air conditioners and heat 

pumps. 

Regarding commenter’s concerns 

about models with non-continuouslyvariable fan motors, the comments 

received suggest that the commenters 

interpreted DOE’s proposal to be 

adopting the provisions for setting 

airflow and ESP in AHRI 340/360–2022 

without modification. However, as 

discussed in the August 2022 NOPR, 

DOE proposed additional provisions to 

allow a larger airflow tolerance for 

models with non-continuously-variable 

fan motors that align more closely with 

the provisions for setting airflow in 

AHRI 210/240–2023 (as recommended 

by ClimateMaster). See 87 FR 53302, 

53323. Similar provisions are included 

in AHRI 600–2023. DOE has concluded 

that these provisions, along with the 

previously mentioned provisions for 

constant-volume fans, provide an 

appropriate method for setting airflow 

and ESP for WSHPs of all fan motor 

types. 

DOE has determined that 

incorporating by reference AHRI 600– 

2023 for setting airflow and ESP 

addresses commenters’ concerns. DOE 

surmises that the inclusion of these 

provisions for setting airflow and ESP in 

AHRI 600–2023 indicates industry 

consensus that these provisions provide 

an appropriate method for testing 

WSHPs. Therefore, in this final rule, 

DOE is incorporating by reference into 

appendix C1 sections 5.7 and 5.8 of 

AHRI 600–2023 for setting airflow and 

ESP. 

c. Coil-Only Units 

For units without integral fans (i.e., 

coil-only units), section 4.1.3.1 of ISO 

13256–1:1998, which is referenced in 

the current DOE WSHP test procedure, 

specifies that a fan power adjustment be 

added to the total power of the unit, and 

that this value be added to the heating 

capacity and subtracted from the 

cooling capacity. The fan power 

adjustment equation to determine fan 

power estimates fan power to overcome 

internal pressure drop within the unit, 

using a similar methodology to the fan 

power adjustment equation used for 


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units with integral fans to subtract out 

the fan power to overcome ESP. As 

discussed in section III.F.1.a of this final 

rule, the amended test procedure 

adopted in appendix C1 (incorporating 

by reference AHRI 600–2023) does not 

use a fan power adjustment for units 

with integral fans and requires testing at 

representative minimum external static 

pressures and ratings reflect 

performance at the tested ESP. 

As part of DOE’s proposal to adopt 

AHRI 340/360–2022, in the August 2022 

NOPR, DOE proposed to adopt sections 

6.1.1.6, 6.1.3.3 and 6.1.3.4 of AHRI 340/ 

360–2022, which contain provisions for 

how to test coil-only units. 87 FR 53302, 

53322. In particular, section 6.1.3.3.4 

specifies that coil-only units shall not 

have a pressure drop exceeding 0.30 in 

H2O for the full load cooling test. 

Section 6.1.3.4.6 outlines that coil-only 

units are to be tested at manufacturer 

specified airflow rates, not exceeding 

450 standard cubic feet per minute 

(‘‘scfm’’) per ton of cooling capacity and 

if there is no manufacturer specified 

airflow rate, they are to be tested at 400 

scfm per ton of rated cooling capacity. 

Finally, section 6.1.1.6 specifies that 

1,250 Btu/h per 1,000 scfm is to be 

removed from the measured cooling 

capacity and 365 Watts (‘‘W’’) per 1,000 

scfm is to be added to the measured 

power for ducted coil-only units. 

AHRI 600–2023 includes provisions 

for coil-only units, which are defined as 

units without an indoor fan or separate 

designated air mover. The provisions 

are nearly identical to those proposed in 

the August 2022 NOPR. Section 5.5.2 

specifies that coil-only units shall not 

have a pressure drop exceeding 0.30 in 

H2O for the full-load cooling test. 

Section 5.6.3 outlines that coil-only 

units are to be tested at manufacturer 

specified airflow rates, not exceeding 

450 scfm per ton of cooling capacity and 

if there is no manufacturer specified 

airflow rate, they are to be tested at 400 

scfm per ton of rated cooling capacity. 

Finally, sections 6.3.3.4 and 6.4.3.4 

specify that for ducted coil-only units, 

measured capacity is adjusted by 1,245 

Btu/h per 1,000 scfm (subtracted from 

cooling capacity and added to heating 

capacity) and measured power is 

adjusted by adding 365 W per 1,000 

scfm. Additionally, AHRI 600–2023 

includes provisions for non-ducted coil 

only units—for these, the values are 940 

Btu/h per 1,000 scfm for capacity 

adjustment and 275 W per 1,000 scfm 

for power adder respectively. 

DOE notes that the provisions 

outlined in AHRI 600–2023 are 

consistent with those proposed in the 

August 2022 NOPR except for a minor 

deviation in the capacity reduction for 

ducted coil-only units and the inclusion 

of provisions for non-ducted coil-only 

units. Based on discussion in AHRI 600 

committee meetings, DOE understands 

that non-ducted coil-only WSHP models 

exist on the market, and therefore, DOE 

has determined that the addition of 

provisions for testing such units is 

warranted. As discussed in section III.D 

of this final rule, DOE is incorporating 

by reference AHRI 600–2023 into 

appendix C1. This includes section 

5.5.2, 5.6.3, and 6.3.3.4 of AHRI 600– 

2023. DOE notes the inclusion of these 

provisions in AHRI 600–2023 indicates 

industry consensus with these 

provisions and provides an appropriate 

method for testing coil-only WSHPs. 

Therefore, DOE is incorporating by 

reference into appendix C1 the 

provisions for coil-only units from AHRI 

600–2023 in this final rule. 

2. Capacity Measurement 

The current DOE WSHP test 

procedure, through adoption of section 

6.1 of ISO 13256–1:1998, specifies that 

total cooling and heating capacities are 

to be determined by averaging the 

results obtained using two test methods: 

the liquid enthalpy test method for the 

liquid side tests and the indoor air 

enthalpy test method for the air side 

tests. 10 CFR 431.96. For non-ducted 

equipment, section 6.1 of ISO 13256– 

1:1998 includes an option for 

conducting the air-side tests using the 

calorimeter room test method instead of 

the air enthalpy test method. Section 6.1 

of ISO 13256–1:1998 also specifies that, 

for a test to be valid, the results obtained 

by the two methods used must agree 

within 5 percent. ANSI/ASHRAE 37– 

2009 is similar to the test method in ISO 

13256–1:1998. ANSI/ASHRAE 37–2009 

requires two capacity measurements for 

units with cooling capacity less than 

135,000 Btu/h; the first method of 

measurement (i.e., the primary method) 

is used as the determination of the 

unit’s capacity, while the second 

measurement (i.e., the secondary 

method) is used to confirm rather than 

to be averaged with the primary 

measurement (see section 10.1 and 

Table 1 of ANSI/ASHRAE 37–2009). 

In the August 2022 NOPR, DOE 

proposed to adopt specific sections of 

AHRI 340/360–2022 for use in the 

WSHP test procedure, including section 

E6, which specifies test methods for 

capacity measurement. 87 FR 53302, 

53325–53327. Section E6.1 of AHRI 

340/360–2022 requires use of the indoor 

air enthalpy method specified in section 

7.3 of ANSI/ASHRAE 37–2009 as the 

primary method for capacity 

measurement. This is the measurement 

used to determine capacity, as required 

in section 10.1.2 of ANSI/ASHRAE 37– 

2009. Section E6.2.2 of AHRI 340/360– 

2022 requires use of one of the 

applicable ‘‘Group B’’ methods specified 

in Table 1 of ANSI/ASHRAE 37–2009 as 

a secondary method for capacity 

measurement. The group B methods that 

are applicable to WSHPs are the outdoor 

liquid coil method (similar to the liquid 

enthalpy method included in the 1998 

and 2021 versions of ISO 13256–1), the 

refrigerant enthalpy method, and the 

compressor calibration method. Section 

E6.4.2 of AHRI 340/360–2022 requires 

that the primary and secondary 

measurements match for full-load 

cooling and heating tests, within 6 

percent of the primary measurement. No 

match is required between primary and 

secondary measurements for part-load 

cooling tests. DOE proposed to adopt all 

of these provisions by incorporating by 

reference AHRI 340/360–2022. Id. at 87 

FR 53325. DOE requested comment on 

this approach to adopt the provisions in 

AHRI 340/360–2022 and ANSI/ 

ASHRAE 37–2009 regarding primary 

and secondary capacity measurements. 

Id. at 87 FR 53326. 

In response to the August 2022 NOPR, 

ClimateMaster commented that it agrees 

with the intent of DOE’s proposed 

approach but disagrees with some 

specifics and recommended that DOE 

work with industry to create a national 

deviation of ISO 13256–1:1998 that 

adopts the provisions of ANSI/ASHRAE 

37–2009 for primary and secondary 

capacity measurements, with certain 

modifications. (ClimateMaster, No. 22 at 

pp. 7–8) ClimateMaster commented 

additionally that it disagrees with the 

provisions in AHRI 340/360–2022 that 

only require agreement between the 

primary and secondary capacity 

measurements for full-load tests. (Id. at 

p. 8) ClimateMaster noted that the 

current ISO standard allows for a 5 

percent tolerance between the two 

measurements, and that in its internal 

testing ClimateMaster strives for 

agreement within 3–4 percent, stating 

that anything over that limit indicates 

an issue in equipment setup and/or the 

measurement system. (Id.) 

ClimateMaster commented that 

neglecting to include a match 

requirement for part-load tests could 

lead to inaccurate representations of 

system performance. (Id.) 

ClimateMaster further commented 

that the uncertainty of measurement for 

the liquid coil method is lower than for 

the indoor air enthalpy method, and 

that the WSHP industry considers the 

liquid coil method to be the more 

accurate measurement method. (Id.) 

ClimateMaster also stated that the liquid 

coil method does not include the 


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limitations regarding refrigerant subcooling that are specified for the 

refrigerant enthalpy method (in section 

7.5.1.3 of ANSI/ASHRAE 37–2009), and 

stated that low values of refrigerant 

subcooling are typically seen in partload tests. (Id.) ClimateMaster 

commented that it disagrees with 

section 7.6.1.2 of ANSI/ASHRAE 37– 

2009 because this provision specifies 

that the outdoor liquid coil method 

cannot be used for outdoor compressor 

systems, and therefore makes the 

refrigerant enthalpy method necessary 

as the secondary capacity measurement 

method for such systems. (Id.) 

ClimateMaster stated that while it agrees 

in theory that the compressor and 

associated refrigerant lines will lose 

heat when an uninsulated compressor 

section is installed outdoors, requiring 

the use of the refrigerant enthalpy 

method is not representative of installed 

outdoor compressor systems because for 

testing the outdoor section of a split 

WSHP system is installed in the same 

psychrometric room as the indoor air 

handler. (Id.) ClimateMaster added that 

there are currently no specified outdoor 

conditions or requirements for 

placement of the outdoor unit in a 

differently conditioned room and that 

the difference between the current 

liquid coil method and the proposed 

refrigerant enthalpy method is 

negligible without specifying conditions 

more thoroughly. (Id.) ClimateMaster 

further commented that the insulation 

requirements in ANSI/ASHRAE 37– 

2009 only specify 1 inch of fiberglass 

insulation and do not specify a 

minimum R-value for the insulation. 

(Id.) 

In summary, ClimateMaster 

recommended that DOE adopt the 

indoor air enthalpy method for the 

primary capacity measurement, and that 

the outdoor coil liquid method be used 

for the secondary capacity measurement 

if the unit either (1) meets the 

requirements of section 7.6.1.2 of ANSI/ 

ASHRAE 37–2009 using fiberglass 

insulation or an equivalent material 

with an R-value of 8.0, or (2) is an 

outdoor unit installed in the same test 

chamber as the indoor coil. (Id.) 

ClimateMaster further recommended a 

requirement for agreement within 5 

percent between primary and secondary 

capacity measurements for full-load and 

part-load tests. (Id.) 

MIAQ commented that DOE’s 

proposed approach in the August 2022 

NOPR of adopting the provisions in 

AHRI 340/360 and ANSI/ASHRAE 37– 

2009 regarding primary and secondary 

capacity measurements deviates from 

the industry test procedure ISO 13256– 

1 and therefore will require 

manufactures to retest their products, 

resulting in increased burden. (MIAQ, 

No. 23 at p. 6) 

WaterFurnace commented that 

adopting ISO 13256 and AHRI 600 

would solve the issue and that the 

liquid enthalpy test method is widely 

accepted as the most accurate method 

for capacity measurement for WSHPs. 

(WaterFurnace, No. 20 at p. 8) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into 

Appendix C1, including provisions in 

Section 5.2 of AHRI 600–2023 regarding 

primary and secondary capacity 

measurement methods. Specifically, 

Section 5.2 states that the indoor air 

enthalpy method be used as the primary 

measurement of capacity, and that 

secondary capacity measurements be 

conducting using one of the following 

methods: outdoor liquid coil method, 

refrigerant enthalpy method, or 

compressor calibration method. Section 

5.2.2 of AHRI 600–2023 also states that, 

when using the outdoor liquid coil 

method, the secondary measurement 

must agree within 6 percent of the 

primary measurement of capacity on all 

tests, including part-load tests. 

Incorporating by reference this language 

addresses comments in response to the 

August 2022 NOPR that DOE should 

adopt AHRI 600. The provisions in 

AHRI 600–2023 also address 

ClimateMaster’s concerns about not 

having a match for part-load tests 

because AHRI 600–2023 does require a 

match between primary and secondary 

capacity measurements for part-load 

tests if the outdoor liquid coil method 

is used. 

Regarding agreement between primary 

and secondary measurements, DOE has 

concluded that the requirement in AHRI 

600–2023 that secondary capacity 

measurements agree within 6 percent of 

primary capacity measurements 

(consistent with AHRI 340/360–2022, 

which DOE proposed to reference in the 

August 2022 NOPR) provides a 

representative measure of efficiency for 

WSHPs. 

Regarding ClimateMaster’s concerns 

about the outdoor liquid coil method 

provisions in ANSI/ASHRAE 37–2009, 

DOE notes that section 5.2.2.1.1 of AHRI 

600–2023 specifies to follow all 

requirements in section 7.6 of ANSI/ 

ASHRAE 37–2009 when using the 

outdoor liquid coil method and does not 

include any provisions that deviate from 

ANSI/ASHRAE 37–2009 with regard to 

outdoor compressor systems or 

insulation R-value. Regarding 

ClimateMaster’s concern that ANSI/ 

ASHRAE 37–2009 requires use of the 

refrigerant enthalpy method for 

secondary capacity measurements for 

systems in which the compressor is 

located outdoors, DOE further notes that 

for a split system WSHP with the 

compressor and liquid coil contained in 

the outdoor unit intended for outdoor 

installation, shell losses from the 

compressor could impact capacity 

measurements using the outdoor liquid 

coil method but would not impact 

capacity measurements using the 

refrigerant enthalpy method. Therefore, 

at this time, DOE does not have 

sufficient evidence or justification to 

deviate from the provisions in AHRI 

600–2023 regarding the outdoor liquid 

coil method and has concluded that 

these provisions provide for appropriate 

and representative measurements of 

efficiency for WSHPs. 

Additionally, AHRI 600–2023 was 

developed through an industry 

consensus process subsequent to the 

timing of the August 2022 NOPR 

comment period, and DOE surmises that 

the capacity measurement approach 

specified in section 5.2 of AHRI 600– 

2023 sufficiently addresses the concerns 

raised in comments to the August 2022 

NOPR. Consequently, DOE is 

incorporating by reference into 

appendix C1 section 5.2 of AHRI 600– 

2023 regarding primary and secondary 

capacity measurements in this final 

rule. 

3. Pump Power Adjustment and Liquid 

External Static Pressure 

ISO 13256–1:1998 does not reflect the 

pump power needed to overcome liquid 

ESP from the water loop that pipes 

water to and from the WSHP. Instead, 

section 4.1.4 of ISO 13256–1:1998 

includes a pump power adjustment 

(which assumes a pump efficiency of 

0.3 for all units) to be applied such that 

only the pump power required to 

overcome the liquid internal static 

pressure of the unit is included in 

calculation of efficiency ratings. ISO 

13256–1:1998 also does not specify any 

liquid ESP requirements for testing. The 

exclusion of pump power to overcome 

ESP from system water loop piping in 

ISO 13256–1:1998 ratings results in 

higher efficiency ratings than would be 

measured if ratings reflected pump 

power to overcome ESP. ISO 13256– 

1:1998 also does not specify a minimum 

liquid ESP during testing for units with 

integral pumps. For units without 

integral pumps, the pump power 

adjustment in ISO 13256–1:1998 

estimates pump power at zero liquid 

external static pressure. 

As discussed previously, ISO 13256– 

1:1998 was updated. However, the 

pump power and liquid ESP provisions 

in sections 5.1.4 and 5.1.6 of ISO 


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13256–1:2021 are the same as those in 

sections 4.1.4 and 4.1.6 of ISO 13256– 

1:1998. 

In the August 2022 NOPR, DOE 

proposed to adopt provisions for 

WSHPs in appendix C1 that align with 

the recently adopted provisions for 

water-source dedicated outdoor air 

systems (‘‘DOASes’’). 87 FR 53302, 

53328–53329. The proposed provisions 

would require that all WSHPs with an 

integral pump be tested with a liquid 

ESP of 20 ft of water column, with a 

¥0/+1 ft condition tolerance and a 1 ft 

operating tolerance. Id. at 87 FR 53328. 

For units without integral pumps, DOE 

proposed to require that a ‘‘total 

pumping effect’’ (calculated using the 

same equation as in section 6.1.6.4 of 

AHRI 920–2020) be added to the unit’s 

measured power to account for the 

pump power to overcome the internal 

static pressure of the unit and a liquid 

ESP of 20 ft of water column. Id. at 87 

FR 53328–53329. Further, DOE 

proposed to require that the measured 

pump power or the pump effect 

addition, as applicable, be included in 

the condenser section power for units of 

all capacities when performing cyclic 

degradation during calculation of IEER. 

Id. at 87 FR 53329. DOE requested 

commented on the proposed provisions 

to account for pump power to overcome 

both internal pressure drop and a 

representative level of liquid ESP for 

WSHPs with and without integral 

pumps. Id. DOE specifically requested 

comment on the representativeness of 

20 ft of water column as the liquid ESP 

for WSHPs. Id. 

In response to the August 20222 

NOPR, ClimateMaster disagreed with 

DOE’s proposed values for the liquid 

ESP for WSHPs, arguing that the 

pumping and cooling tower fan power 

adder specified in AHRI 920–2020 is 

incorrect. (ClimateMaster, No. 22 at p. 8) 

ClimateMaster commented that, 

according to a 2014 study conducted by 

S. Kavanaugh and K. Rafferty, pumping 

power for a closed loop ground-source 

heat pump (‘‘GSHP’’) system can reach 

3.75 W/kBtu/h but not exceed 10 W/ 

1kBtu/h, and that the values given in 

AHRI 920 are much higher than these 

values and are thus not representative of 

an installed system. (Id. at pp. 8–9) 

ClimateMaster recommended that DOE 

use the approach in AHRI 600, which 

includes pumping power for the 

internal pressure drop and adds a 

representative value for building pump 

and cooling tower operation. (Id. at p. 9) 

ClimateMaster commented that this 

AHRI 600 power adder for building 

pump and cooling tower energy 

consumption is based on the results of 

an analysis conducted of typical closed 

loop systems during the development of 

the AHRI 600 standard, which resulted 

in calculated power adders of 5.5 W/ 

kBtu/h for full-load conditions and 1 W/ 

kBtu/h for part-load conditions. (Id.) 

FHP commented that the work done 

by the AHRI 600 working group took a 

more accurate approach to today’s 

systems that allows for varying the fans 

and pumping energy required during 

part-load conditions. (FHP, No. 26 at p. 

5) FHP recommended that DOE review 

the values assigned to tower/pump 

penalty in AHRI 600 for guidance on 

this topic, stating that a single-head 

pressure as a means of estimating the 

pumping penalty does not allow for the 

variations expected at part-load 

conditions. (Id.) WaterFurnace 

commented that adopting ISO 13256 

and AHRI 600 would solve the issue, 

noting that the pump power is 

accounted for in AHRI 600. 

(WaterFurnace, No. 20 at p.8) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. AHRI 600–2023 includes provisions 

to separately account for pump power to 

overcome liquid internal and external 

static pressure. 

Sections 6.3.3 and 6.4.3 of AHRI 600– 

2023 specify to include pump power to 

overcome the liquid internal static 

pressure of the WSHP in all cooling and 

heating ratings. The calculation for 

pump power adjustment to account for 

liquid internal static pressure uses a 

similar methodology to ISO 13256– 

1:1998, but uses a higher pump 

efficiency of 75% (as compared to 30% 

in ISO 13256–1:1998) to better represent 

the efficiency of system pumps in 

commercial water-loop installations. 

Specifically, for units without integral 

pumps, the AHRI 600–2023 approach 

adds pump power to overcome liquid 

internal static pressure. For units with 

integral pumps, section 5.4.13 of AHRI 

600–2023 specifies a liquid ESP value of 

zero to use when testing WSHPs with an 

integral pump for commercial ratings 

and specifies to test at the minimum 

liquid ESP if the minimum is higher 

than zero ESP. In the case of testing a 

unit with an integral pump at a liquid 

ESP above zero, sections 6.3.3 and 6.4.3 

of AHRI 600–2023 specify to subtract 

pump power to overcome liquid ESP 

using a similar methodology to the 

approach for calculating pump power 

adjustment for units without integral 

pumps. 

Sections 6.3.7 (for IEER), 6.3.11 (for 

AEER), and 6.4.4 (for ACOP) of AHRI 

600–2023 specify to include power to 

account for power required for a system 

pump to overcome liquid ESP 

representative of a commercial waterloop installations. As discussed in 

section III.E.3 of this final rule, AHRI 

600–2023 specifies these provisions to 

account for system pump power for 

calculation of AEER, IEER, and ACOP, 

but not for optional representations of 

EER and COP. 

The provisions for accounting for 

pump power (to overcome liquid 

internal and external static pressure) 

were developed in AHRI 600 committee 

meetings after publication of the August 

2022 NOPR. While the AHRI 600–2023 

approach is not the same as that 

proposed in the August 2022 NOPR in 

that it uses a different calculation 

method and assumes a different liquid 

ESP, it is consistent with the August 

2022 NOPR proposal to include power 

to represent power consumed by pumps 

to overcome both liquid internal and 

external static pressure. The AHRI 600– 

2023 pump power adders are different 

than those suggested by ClimateMaster. 

However, having been developed 

through an industry consensus process 

subsequent to the timing of the August 

2022 NOPR comment period, DOE 

surmises that the pump power approach 

specified in AHRI 600–2023 represents 

the prevailing industry consensus 

regarding the most appropriate method 

for addressing pump power. Further, 

DOE has concluded based on discussion 

in AHRI 600 committee meetings that 

the AHRI 600–2023 pump power 

approach is representative of typical 

water-loop WSHP applications. As a 

result, in this final rule, DOE is 

incorporating by reference into 

appendix C1 the methods specified in 

AHRI 600–2023 for accounting for 

pump power. 

DOE notes that section 5.4.13.2 of 

AHRI 600–2023 specifies a minimum 

liquid ESP of 7.0 psi for residential 

representations. However, the 

residential representations have not yet 

been fully developed for WSHPs (see 

section III.A.2 of this document for more 

details). DOE will continue to work with 

the AHRI 600 committee to develop 

provisions for determining such ratings. 

4. Test Liquid and Specific Heat 

Capacity 

The current DOE WSHP test 

procedure, through adoption of section 

4.1.9 of ISO 13256–1:1998, requires the 

test liquid for water-loop heat pumps 

and ground-water heat pumps to be 

water, and the test liquid for groundloop heat pumps to be a 15 percent 

solution by mass of sodium chloride in 

water (i.e., brine). 10 CFR 431.96. 

Further, the liquid enthalpy test method 

in Annex C of ISO 13256–1:1998, which 

is included in the current DOE WSHP 

test procedure, requires the use of the 


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10 ‘‘HFL3’’ is the nomenclature used to define the 

32 °F full-load heating test that DOE proposed to 

add in appendix C1. 

11The ASHRAE Handbook—Fundamentals is 

available at: https://www.ashrae.org/technicalresources/ashrae-handbook. 

12MIAQ used the abbreviation NRL, but DOE 

expects that the intended term was NRTL, the 

acronym for nationally recognized testing 

laboratory. 

13Properties of Secondary Working Fluids for 

Indirect Systems, Melinder, 2010 (‘‘Melinder 

2010’’). 

specific heat capacity of the test liquid 

for calculating cooling and heating 

capacity but does not specify a value or 

method for calculating the specific heat 

capacity. 

Section 5.1.7 of ISO 13256–1:2021 

requires that the test liquid for the low 

temperature heating test (i.e., EWT of 

32 °F) must be a brine of the 

manufacturer’s specification, while the 

test liquid for all other tests may be 

water or a brine of a composition and 

concentration specified by the 

manufacturer. ISO 13256–1:2021 does 

not specify a value or method for 

calculating the specific heat capacity of 

any test liquids. 

In the August 2022 NOPR, DOE 

proposed in section 4.1 of proposed 

appendix C1 that the test liquid for all 

tests other than the proposed optional 

‘‘HFL3’’ 10 low temperature heating test 

(i.e., EWT of 32 °F) must be water, 

unless the manufacturer specifies to use 

a brine of 15-percent solution by mass 

of sodium chloride in water. 87 FR 

53302, 53329. DOE also proposed in 

section 4.1 of proposed appendix C1 

that the test liquid for the optional HFL3 

low temperature heating test must be a 

brine of 15-percent solution by mass of 

sodium chloride in water. Id. Groundloop applications of WSHPs typically 

use brine in the liquid loop because, in 

cold weather, the liquid temperature 

can reach 32 °F (i.e., the temperature at 

which water freezes) in places. A 15- 

percent solution by mass of sodium 

chloride in water can withstand 

temperatures as low as 14 °F before 

freezing. Allowing the use of brine for 

testing would provide manufacturers 

the flexibility of providing ratings more 

representative of ground-loop 

applications. Therefore, DOE proposed 

to require brine as the liquid for the 

optional HFL3 low temperature heating 

test (conducted with an EWT of 32 °F), 

consistent with section 4.1.9 of ISO 

13256–1:1998 and section 5.1.7 of ISO 

13256–1:2021, to avoid the liquid 

freezing during the test. Id. 

In the August 2022 NOPR, DOE 

tentatively concluded that a 15-percent 

solution by mass of sodium chloride, as 

specified in section 4.1.9.2 of ISO 

13256–1:1998, is a representative brine 

composition and concentration for 

applications needing brine (e.g., groundloop), and that consumers can make 

more representative comparisons 

between models when all models are 

rated with the same brine composition 

and concentration. Id. 

As discussed in section III.D.2 of the 

August 2022 NOPR, DOE proposed to 

adopt specific sections of AHRI 340/ 

360–2022 in its test procedure for 

WSHPs. Id. AHRI 340/360–2022 in turn 

references the test method in ANSI/ 

ASHRAE 37–2009, in which section 

12.2.1 requires that thermodynamic 

properties of liquids be obtained from 

the ASHRAE Handbook— 

Fundamentals.11 The ASHRAE 

Handbook—Fundamentals specifies 

specific heat capacity values for water 

and for a brine of 15 percent solution by 

mass of sodium chloride at multiple 

temperatures. The absence of provisions 

in ISO 13256–1:1998 for how to 

determine specific heat capacity for test 

liquids creates the potential for 

variation in measured values based on 

how specific heat capacity is 

determined. Therefore, to minimize any 

such variation, DOE instead proposed in 

the August 2022 NOPR to adopt relevant 

provisions of ANSI/ASHRAE 37–2009. 

Id. DOE tentatively determined that the 

specifications in ANSI/ASHRAE 37– 

2009 would be appropriate for testing 

WSHPs because they are the generally 

accepted industry method used for 

testing similar equipment, such as 

WCUACs. Id. 

In the August 2022 NOPR, DOE 

requested comment on the proposed 

requirements for using water or a brine 

of 15-percent solution by mass of 

sodium chloride as the test liquid. Id. 

DOE also requested comment on the 

representativeness and test burden 

associated with permitting the use of 

different liquids for different tests. Id. 

Finally, DOE requested comments on 

the proposal to utilize the 

thermodynamic properties specified in 

ANSI/ASHRAE 37–2009 through DOE’s 

proposed incorporation by reference of 

AHRI 340/360–2022. Id. 

In response to the August 2022 NOPR, 

MIAQ commented that sodium chloride 

is not a common anti-freeze and that 

propylene and ethylene glycol are more 

common. (MIAQ No. 23 at p. 6) MIAQ 

commented that it is unsure if 

nationally recognized testing 

laboratories 12 are equipped to deal with 

15-percent solution by mass of sodium 

chloride as the test liquid. (Id.) MIAQ 

stated that specifying a particular 

antifreeze rather than relevant thermal 

properties for the test fluid hinders 

innovation and generates a heavy 

burden to develop and test with the 

specified medium. (Id.) MIAQ argued 

that specifying sodium chloride as the 

test liquid may require redesign of the 

units to avoid corrosion. (Id.) 

WaterFurnace commented that 

supporting ISO 13256 and AHRI 600 

would solve the issue. (WaterFurnace 

No. 20 at p. 8) WaterFurnace stated that 

it prefers to use methanol or ethanol as 

the test liquid because sodium chloride 

can damage lab equipment. (Id.) 

ClimateMaster supported DOE’s 

proposal to make provisions for low 

temperature testing but disagreed with 

the proposed fluid for testing. 

(ClimateMaster, No. 22 at p. 9) 

ClimateMaster stated that sodium 

chloride is not representative of a brine 

solution used in water-source 

applications in the field and is a 

carryover from a test liquid used in 

older standards such as AHRI 330–98, 

which was corrosive to test lab facilities 

and caused premature wear of hydronic 

components. (Id.) ClimateMaster 

recommended that DOE work with 

industry to create a national deviation of 

13256–1:1998 that includes provisions 

for the use of a 15-percent solution by 

mass of methanol in water involving a 

specific gravity of methanol at 0.976 

with a solution temperature of 68 °F. 

(Id.) ClimateMaster stated that this fluid 

is commonly used in the industry and 

has been an available option in the 

AHRI 13256–1:1998 certification 

program since its inception, and if DOE 

does not select this solution, an 

alternative option would be a 20-percent 

solution of propylene glycol, which is 

also commonly used in the industry. 

(Id.) 

ClimateMaster supported DOE’s 

proposal to require a standard set of 

properties for consistent performance 

calculations but disagreed that the only 

reference allowed for sink or source 

liquids can be the 2001 ASHRAE 

Handbook, stating that it does not 

include properties for alternative testing 

fluids, such as methanol in water, and 

therefore limits the available options for 

testable brine solutions. (Id.) 

ClimateMaster recommended that DOE 

provide provisions under a national 

deviation of ISO 13256–1:1998 while 

allowing for the use of other established 

property databases in addition to the 

2001 ASHRAE handbook, such as the 

published data from Melinder 2010.13

(Id.) WaterFurnace agreed with the need 

for a specified source of properties and 

commented that supporting ISO 13256 


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and AHRI 600 would solve the issue. 

(WaterFurnace, No. 20 at p. 8) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 in appendix 

C1. Section 5.4.14 of AHRI 600–2023 

specifies that all cooling and heating 

tests be conducted with a 15 percent 

solution by mass of methanol in water, 

with a tolerance of 2 percentage points 

on the solution concentration and 

requires that the concentration be 

verified prior to and after completion of 

all standard rating tests. Section 5.4.14 

of AHRI 600–2023 also specifies to use 

Melinder 2010 as the source for all 

thermodynamic properties of the test 

liquid. Finally, sections 6.3.3.2 and 

6.4.3.2 of AHRI 600–2023 include 

provisions to remove any influence of 

the methanol solution on efficiency 

ratings, so that values are similar to 

those that would result from testing 

using pure water, which is the most 

common liquid used in non-geothermal 

installations of WSHPs. Specifically, 

these provisions specify to multiply all 

measured capacity values by 1.01 and to 

multiply all measured cooling total 

power values by 0.99. 

DOE has concluded that the 

provisions in AHRI 600–2023 regarding 

test liquid and specific heat capacity 

provide a representative and repeatable 

method for testing WSHPs. Comments 

received in response to the August 2022 

NOPR and discussion in AHRI 600 

committee meetings indicate that a 

methanol solution is a more 

representative test liquid than sodium 

chloride brine and is more practical for 

testing as it is not corrosive to laboratory 

equipment. Further, the AHRI 600–2023 

requirement to use methanol solution 

for all tests ensures repeatable results 

and minimizes test burden by avoiding 

a need to change test liquid between 

tests. By specifying use of Melinder 

2010 as the source for thermodynamic 

properties, AHRI 600–2023 also ensures 

that thermodynamic properties for the 

test fluid are applied consistently. 

Additionally, the provisions in sections 

6.3.3.2 and 6.4.3.2 of AHRI 600–2023 

adjust measured values to be more 

representative of WSHP operation in 

non-geothermal applications (which do 

not encounter freezing temperatures), 

without the need to change test liquids 

to use water for higher temperature tests 

and methanol for low-temperature 

heating tests. DOE also considers the 

inclusions of these provisions in AHRI 

600–2023 to represent industry 

consensus on the most appropriate 

method for testing WSHPs. Therefore, 

for the reasons discussed, DOE is 

incorporating by reference into 

appendix C1 the test liquid provisions 

from AHRI 600–2023 in this final rule. 

5. Liquid Flow Rate 

The current DOE test procedure, 

through adoption of section 4.1.6.2 of 

ISO 13256–1:1998, requires units with 

an integral liquid pump to be tested at 

the liquid flow rates specified by the 

manufacturer or those obtained at zero 

ESP difference, whichever provides the 

lower liquid flow rate. 10 CFR 431.96. 

Section 4.1.6.3 of ISO 13256–1:1998 

requires that units without an integral 

liquid pump be tested at a liquid flow 

rate specified by the manufacturer. 

In contrast to ISO 13256–1:1998, DOE 

noted in the June 2018 RFI that AHRI 

340/360–2022 does not use a 

manufacturer-specified liquid flow rate, 

and instead specifies inlet and outlet 

water temperatures for WCUACs to be 

85 °F and 95 °F, respectively, for 

standard-rating full-capacity operation. 

The temperature difference between 

inlet and outlet determines the liquid 

flow rate for the test. 83 FR 29048, 

29054. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

specific sections of AHRI 340/360–2022 

in its test procedure for WSHPs, 

including Table 6. 87 FR 53302, 53330. 

Table 6 of AHRI 340/360–2022 specifies 

inlet and outlet liquid temperatures of 

85 °F and 95 °F, respectively, for 

standard-rating cooling full-capacity 

operation. Id. This requires that liquid 

flow rate for the full-load cooling test is 

set at a level that results in a 10 °F 

temperature rise from the 85 °F inlet to 

the 95 °F outlet temperature. Id. Also, 

DOE proposed to adopt table 9 of AHRI 

340/360–2022, which specifies use of 

manufacturer-specified part-load water 

flow rates for part-load tests. Id. at 87 FR 

53331. In addition, DOE proposed that 

section E7 of AHRI 340/360 2022, which 

addresses units with condenser head 

pressure control stating that part-load 

liquid flow rate shall not exceed the 

liquid flow rate used for the full-load 

tests, be adopted in sections 5.1.1 and 

5.1.2.1.2 of proposed appendix C1. Id. 

For heating tests, DOE proposed to 

specify in section 6.1 of proposed 

appendix C1 that if IEER is determined 

using option 1 in section 5.1 of 

proposed appendix C1, the liquid flow 

rate determined from the ‘‘Standard 

Rating Conditions Cooling’’ test for 

water-cooled equipment, as defined in 

Table 6 of AHRI 340/360–2022, must be 

used for all heating tests. Id. If IEER is 

determined using option 2 in section 5.1 

of proposed appendix C1, DOE 

proposed in section 5.1.2.1.1 of 

proposed appendix C1 to use the liquid 

flow rate determined from the CFL3 

high temperature cooling test for all 

heating tests. Id. Lastly, relating to 

tolerances, DOE proposed to require a 

condition tolerance of 1 percent for 

liquid flow rate, consistent with the 

condition tolerance specified in Table 9 

of ISO 13256–1:1998 and adopt Table 11 

of AHRI 340/360–2022, which specifies 

an operating tolerance of 2 percent for 

liquid flow rate. Id. 

DOE requested commented on its 

proposal to adopt the AHRI 340/360– 

2022 approach for setting liquid flow 

rate for the full-load cooling test, 

namely by specifying inlet and outlet 

liquid temperature conditions rather 

than using a manufacturer-specified 

flow rate. Id. Additionally, DOE 

requested feedback on its proposals to 

use manufacturer-specified part-load 

liquid flow rates for part-load tests, that 

the part-load flow rate be no higher than 

the full-load flow rate, and to use the 

full-load liquid flow rate if no part-load 

liquid flow rate is specified. Id. In 

relation to heating tests, DOE requested 

comment on its proposal to use the 

liquid flow rate determined from the 

full-load cooling test for all heating 

tests. Id. Lastly, DOE requested 

comment on its proposal to specify an 

operating tolerance of 2 percent and a 

condition tolerance of 1 percent for 

liquid flow rate in all tests with a target 

liquid flow rate. Id. at 87 FR 53331– 

53332. 

In response to the August 2022 NOPR, 

ClimateMaster and WaterFurnace stated 

that they disagree with the proposal to 

adopt the AHRI 340/360 approach for 

setting liquid flow rate because it moves 

the test standard along a prescriptive 

path that would discourage innovation 

for improvements in pressure drop and 

flow rate in heat exchanger design. 

(ClimateMaster, No. 22 at pp. 9–10; 

WaterFurnace, No. 20 at pp. 8–9) 

ClimateMaster recommended that DOE 

allow manufacturers to specify a given 

flow rate for full-load cooling tests. 

(ClimateMaster, No. 22 at p. 10) 

ClimateMaster also commented that 

DOE should also specify a maximum 

limit of 3.5 GPM/ton, which 

ClimateMaster stated aligns with DOE’s 

statements in the August 2022 NOPR 

that 3 GPM/ton is a typical water flow 

rate for WSHPs that results in a 

temperature rise of approximately a 

10 °F. (Id. at pp. 9–10) ClimateMaster 

commented that while flowrate is 

typically used and specified when 

testing WSHP equipment, this is not the 

case for temperature rise. (Id. p. 10) 

MIAQ recommended that DOE continue 

to support ISO 13256–1. (MIAQ, No. 23 

at p. 7) 

Regarding the part-load liquid flow 

rates, ClimateMaster supported DOE’s 


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proposal to use manufacturer-specified 

part-load liquid flow rates for part-load 

tests. (ClimateMaster, No. 22 at p. 10) 

ClimateMaster recommended that the 

full-load liquid flow rate should be used 

for part-load tests if the system does not 

automatically reduce the liquid flow 

rate in part-load operation to the partload flow rate when installed. (Id.) 

WaterFurnace agreed with DOE’s 

proposal to use manufacturer-specified 

part-load liquid flow rates for part-load 

tests and commented that supporting 

ISO 13256/AHRI 600 would solve the 

issue. (WaterFurnace, No. 20 at p. 9) 

Regarding liquid flow rate for heating 

tests, ClimateMaster supported DOE’s 

proposal to use the full-load cooling 

liquid flow rate for all full-load heating 

tests. (ClimateMaster, No. 22 at p. 10) 

MIAQ commented that using the liquid 

flow rate determined from the full-load 

cooling test for all heating tests could be 

a problem in conditions where the 

saturated suction temperature is too 

high, overloading the compressor. 

(MIAQ, No. 23 at p. 7) MIAQ stated that 

this may not be an issue with a low 

enough EWT. (Id.) MIAQ commented 

that systems with inverter-driven 

compressors and active head pressure 

control may present challenges to 

fulfilling these tests. (Id.) WaterFurnace 

commented that supporting ISO 13256 

and AHRI 600 would solve the issue. 

(WaterFurnace, No. 20 at p. 9) 

WaterFurnace commented that most 

standards have abandoned the 

prescriptive approach of determining 

liquid flow rate from the full-load 

cooling test to allow innovation and 

efficiency improvement. (Id.) 

WaterFurnace stated that using 

manufacturer-specified flow rate is 

preferred. (Id.) 

Regarding tolerances liquid flow rates, 

ClimateMaster, WaterFurnace, and 

MIAQ commented in support of DOE’s 

proposal to specify an operating 

tolerance of 2 percent and a condition 

tolerance of 1 percent for liquid flow 

rate in all tests with a target liquid flow 

rate. (ClimateMaster, No. 22 at p. 10; 

WaterFurnace, No. 20 at p. 9; MIAQ, No. 

23 at p. 7) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. Section 5.4.15 of AHRI 600–2023 

includes provisions regarding liquid 

flow rate. Specifically, this section 

specifies use of a manufacturerspecified flow rate rather than a fixed 

temperature rise (as recommended by 

commenters), but, similar to 

ClimateMaster’s recommendation, 

section 5.4.15 also provides a maximum 

flow rate of 0.275 GPM per kBtu/h 

(which is equivalent to 3.3 GPM/ton, 

slightly lower than the 3.5 GPM/ton 

limit recommended in ClimateMaster’s 

comment). Section 5.4.14 also specifies 

that a single manufacturer-specified 

flow rate be used for all tests, unless the 

equipment automatic adjusts flow rate 

or the liquid flow rate is reduced for 

operation at low EWTs for head 

pressure control, per section 5.9 of 

AHRI 600–2023. Further, section 5.4.15 

specifies that if there is not a specified 

liquid flow rate and that the system 

does not provide automatic adjustment 

of the liquid flow that a liquid flow rate 

of 0.25 GPM per kBtu/h is used for all 

tests. It also specifies a liquid flow rate 

condition tolerance of 1 percent. 

DOE has concluded that the approach 

for liquid flow rate specified in AHRI 

600–2023 provides a representative and 

appropriate approach for testing 

WSHPs. The use of manufacturerspecified flow rate provides flexibility 

to manufacturers while the maximum 

liquid flow rate limit prevents 

manufacturer specification of 

unrepresentatively high flow rates for 

testing. With regards to MIAQ’s concern 

that using the liquid flow rate 

determined from the full-load cooling 

test for all heating tests could be a 

problem in conditions where the 

saturated suction temperature is too 

high, overloading the compressor, DOE 

notes that the provisions specified in 

AHRI 600–2023 and incorporated by 

reference in this final rule allow 

manufacturers to specify different flow 

rates for tests other than the full-load 

cooling test so long as the specified flow 

rates for other tests are (a) below the 

maximum flow rate of 0.275 GPM per 

kBtu/h; and (b) achieved via automatic 

adjustment of the liquid flow rate by the 

equipment under test. Therefore, a 

manufacturer would have the ability to 

set different liquid flow rates for tests 

other than full-load cooling tests to 

ensure operation representative of how 

the equipment would operate under 

such conditions in field installations. 

DOE also considers the inclusions of 

these provisions in AHRI 600–2023 to 

represent industry consensus on the 

most appropriate method for testing 

WSHPs. Therefore, for the reasons 

discussed, DOE is incorporating by 

reference into appendix C1 the liquid 

flow rate provisions from AHRI 600– 

2023 in this final rule. 

6. Refrigerant Line Losses 

Split-system WSHPs have refrigerant 

lines that can transfer heat to and from 

their surroundings, which can 

incrementally affect measured capacity. 

To account for this transfer of heat 

(referred to as ‘‘line losses’’), the current 

DOE WSHP test procedure, through 

adoption of ISO 13256–1:1998, provides 

that if line loss corrections are to be 

made, they shall be included in the 

capacity calculations (in section B4.2 for 

the indoor air enthalpy method and in 

section C3.3 for the liquid enthalpy test 

method of ISO 13256–1:1998). 10 CFR 

431.96. ISO 13256–1:1998 does not 

specify the circumstances that require 

line loss corrections nor the method to 

use to determine an appropriate 

correction. 

Section 7.3.3.4 of ANSI/ASHRAE 37– 

2009, the method of test referenced in 

AHRI 340/360–2022, specifies more 

detailed provisions to account for line 

losses of split systems in the outdoor air 

enthalpy method, and section 7.6.7.1 of 

ANSI/ASHRAE 37–2009 specifies to use 

the same provisions for the outdoor 

liquid coil method. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

specific sections of AHRI 340/360–2022. 

87 FR 53302, 53332. AHRI 340/360– 

2022 in turn references sections 7.6.7.1 

and 7.3.3.4 of ANSI/ASHRAE 37–2009. 

Id. Sections 7.6.7.1 and 7.3.3.4 of ANSI/ 

ASHRAE 37–2009 specify calculations 

for determining the line losses for bare 

copper or insulated lines. Id. DOE 

requested comment on the proposal to 

adopt the provisions for line loss 

adjustments included in sections 7.6.7.1 

and 7.3.3.4 of ANSI/ASHRAE 37–2009 

through incorporation by reference of 

AHRI 340/360–2022. Id. 

In response to the August 2022 NOPR, 

ClimateMaster commented that 

adopting the line loss adjustments in 

ASHRAE 37–2009 is acceptable, as it is 

an industry best practice, but 

ClimateMaster stated it does not 

produce any split system heat pumps 

for use in commercial applications. 

(ClimateMaster, No. 22 at p.10) 

ClimateMaster recommended that DOE 

work with industry to create a national 

deviation of ISO 13256–1:1998 that 

adopts the provisions of ANSI/ASHRAE 

37–2009. (Id.) WaterFurnace agreed 

with DOE’s proposal. (WaterFurnace, 

No. 20 at p. 9) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes section 5.1 of AHRI 

600–2023. This section in turn 

references sections 7.6.7.1 and 7.3.3.4 of 

ANSI/ASHRAE 37–2009, which is 

consistent with the proposal from the 

August 2022 NOPR. DOE considers the 

inclusion of these provisions in the 

AHRI 600–2023 to represent industry 

consensus that these provisions provide 

an appropriate method for testing 

WSHPs. As a result, DOE is 

incorporating by reference into 

appendix C1 the methods from AHRI 


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14The cited industry test standards include: ISO 

3966:1977, ‘‘Measurement of fluid flow in closed 

conduits—Velocity area method using Pitot static 

tubes;’’ ISO 5167–1:1991, ‘‘Measurement of fluid 

flow by means of pressure differential devices—Part 

1: Orifice plates, nozzles and Venturi tubes inserted 

in circular cross-section conduits running full;’’ and 

ISO 5221:1984, ‘‘Air Distribution and air 

diffusion—Rules to methods of measuring airflow 

rate in an air handling duct.’’ These standards can 

be purchased from the ISO store at https://

www.iso.org/store.html. 

15 ‘‘Reynolds number’’ is a dimensionless number 

that characterizes the flow properties of a fluid. 

Section F8.9 of ISO 13256–1:1998 includes an 

equation for calculating Reynolds number that 

depends on a temperature factor, air velocity, and 

throat diameter. 

600–2023 for calculating line loss 

adjustments in this final rule. 

7. Airflow Measurement 

The current DOE WSHP test 

procedure, through adoption of section 

D.1 of ISO 13256–1:1998, requires 

airflow measurements to be made in 

accordance with the provisions 

specified in several different industry 

test standards, ‘‘as appropriate.’’ 14 10 

CFR 431.96. However, ISO 13256– 

1:1998 is not explicit regarding the 

circumstances under which the different 

airflow measurement approaches 

included in these industry test 

standards should be used. 

Section F8 of ISO 13256–1:1998 

specifies the requirements for the nozzle 

apparatus used to measure airflow. This 

device determines airflow by measuring 

the change in pressure across a nozzle 

of known geometry. Airflow derivations 

using this approach often include a 

discharge coefficient (i.e., the ratio of 

actual discharge air to theoretical 

discharge air) to account for factors that 

reduce the actual discharge air, such as 

nozzle resistance and airflow 

turbulence. In general, as the nozzle 

throat diameter decreases, nozzle 

resistance increases, thereby reducing 

actual discharge which is characterized 

by a lower discharge coefficient. 

Turbulent airflow (as characterized by 

Reynolds numbers 15) and temperature 

also impact the discharge coefficient. 

Section F8.9 of ISO 13256–1:1998 

specifies that it is preferable to calibrate 

the nozzles in the nozzle apparatus, but 

that nozzles of a specific geometry may 

be used without calibration and by 

using the appropriate discharge 

coefficient specified in a lookup table in 

section F8.9 of ISO 13256–1:1998. ISO 

13256–1:1998 does not specify the 

method that should be applied, 

however, to determine the coefficient of 

discharge for conditions that do not 

exactly match the values provided in 

the look-up table. 

Elsewhere, sections 6.2 and 6.3 of 

ANSI/ASHRAE 37–2009 includes 

provisions regarding the nozzle airflow 

measuring apparatus that are identical 

to the provisions in section F8 of ISO 

13256–1:1998, except for the method 

used to determine the coefficient of 

discharge. Section 6.3.3 of ANSI/ 

ASHRAE 37–2009 uses a calculation in 

place of the look-up table used in ISO 

13256–1:1998, thereby allowing 

determination of the coefficient of 

discharge at any point within the 

specified range. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

specific sections of AHRI 340/360–2022. 

87 FR 53302, 53333. AHRI 340/360– 

2022 in turn references the test method 

in ANSI/ASHRAE 37–2009. Id. Sections 

6.2 and 6.3 of ANSI/ASHRAE 37–2009 

include provisions regarding the nozzle 

airflow measuring apparatus that are 

identical to the provisions in section F8 

of ISO 13256–1:1998, except for the 

method used to determine the 

coefficient of discharge. Id. Section 6.3.3 

of ANSI/ASHRAE 37–2009 uses a 

calculation to determine the coefficient 

of discharge, thereby allowing 

determination of the coefficient of 

discharge at any point within the 

specified range. Id. DOE requested 

comment on the proposal to adopt the 

calculation of discharge coefficients and 

air measurement apparatus 

requirements as specified in ANSI/ 

ASHRAE 37–2009. Id. 

In response to the August 2022 NOPR, 

ClimateMaster supported DOE’s 

proposal to adopt the calculation of 

discharge coefficients and air 

measurement apparatus requirements of 

ANSI/ASHRAE 37–2009, as it is an 

industry best practice, and 

recommended that DOE work with 

industry to create a national deviation of 

ISO 13256–1:1998 that includes the 

provisions of ANSI/ASHRAE 37–2009. 

(ClimateMaster No. 22 at p. 10) 

WaterFurnace agreed with DOE’s 

proposal. (WaterFurnace, No. 20 at p. 9) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes section 5.1 of AHRI 

600–2023. This section in turn 

references the test method in ANSI/ 

ASHRAE 37–2009, which is consistent 

with the proposal from the August 2022 

NOPR. DOE considers the inclusion of 

these provisions in AHRI 600–2023 to 

represent industry consensus that these 

provisions provide an appropriate 

method for testing WSHPs. As a result, 

DOE is incorporating by reference into 

appendix C1 the methods from AHRI 

600–2023 for measuring airflow in this 

final rule. 

8. Air Condition Measurement 

Indoor air temperature and humidity 

are key parameters that affect WSHP 

performance, and for this reason, ISO 

13256–1:1998 requires accurate indoor 

air condition measurements. However, 

informative annexes E and F of ISO 

13256–1:1998 specify few requirements 

for the methods used to measure indoor 

air temperature and humidity. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

appendix C of AHRI 340/360–2022. 87 

FR 53302, 53333. Appendix C of AHRI 

340/360–2022 provides detailed 

specifications for the measurement of 

air conditions (including indoor air), 

including aspirating psychrometer 

requirements in section C3.2.1 of AHRI 

340/360–2022 and sampling 

requirements in section C3.3 of AHRI 

340/360–2022. Id. DOE requested 

commented on the proposal to adopt the 

air condition measurement provisions 

in appendix C of AHRI 340/360–2022. 

Id. 

In response to the August 2022 NOPR, 

ClimateMaster supported DOE’s 

proposal to adopt the air condition 

measurement provisions in appendix C 

of AHRI 340/360–2022, as it is industry 

best practice, and recommended that 

DOE work with industry to create a 

national deviation of ISO 13256–1:1998 

that includes similar air condition 

measurement provisions. 

(ClimateMaster No. 22 at p. 11) 

WaterFurnace agreed with DOE’s 

proposal. (WaterFurnace No. 20 at p. 9) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes appendix C of AHRI 

600–2023. This language is consistent 

with appendix C of AHRI 340/360– 

2022, as proposed in the August 2022 

NOPR, and addresses comments that 

DOE should adopt AHRI 600. DOE 

considers the air condition 

measurement approach specified in 

AHRI 600–2023 to represent industry 

consensus regarding the most 

appropriate method for measuring air 

conditions for WSHPs. As a result, DOE 

is incorporating by reference into 

appendix C1 the methods from AHRI 

600–2023 for measuring air conditions 

in this final rule. 

9. Duct Losses 

In the calculations for cooling and 

heating capacities for the indoor air 

enthalpy test method of ISO 13256– 

1:1998, the test standard includes a 

footnote in sections B3 and B4 of annex 

B stating that the equations do not 

provide allowances for heat leakage in 

the test equipment (i.e., duct losses). In 


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contrast, section 7.3.3.3 of ANSI/ 

ASHRAE 37–2009 requires adjustments 

for such heat leakages and specifies 

methods to calculate appropriate values 

for the adjustments. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

specific sections of AHRI 340/360–2022. 

87 FR 53302, 53334. AHRI 340/360– 

2022 in turn references section 7.3.3.3 of 

ASHRAE 37–2009, which requires and 

provides equations for duct loss 

adjustments. Id. DOE requested 

comment on whether the duct loss 

adjustments as described in section 

7.3.3.3 of ANSI/ASHRAE 37–2009 or 

any other duct loss adjustments are used 

to adjust capacity measured using the 

indoor air enthalpy method when 

testing WSHPs. Id. 

In response to the August 2022 NOPR, 

ClimateMaster supported DOE’s 

proposal to adopt the duct loss 

provisions as it is an industry best 

practice for companies that produce 

split-system heat pumps for use in 

commercial applications. 

(ClimateMaster, No. 22 at p. 11) 

ClimateMaster recommended that DOE 

work with industry to create a national 

deviation of ISO 13256–1:1998 that 

includes these provisions of ANSI/ 

ASHRAE 37–2009. (Id.) WaterFurnace 

agreed with DOE’s proposal. 

(WaterFurnace, No. 20 at pp. 9) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes section 5.1 of AHRI 

600–2023. This section in turn 

references ANSI/ASHRAE 37–2009, 

including section 7.3.3.3, which is 

consistent with the proposal from the 

August 2022 NOPR. DOE considers the 

inclusion of these provisions in AHRI 

600–2023 to represent industry 

consensus that these provisions provide 

an appropriate method for testing 

WSHPs. Therefore, DOE is incorporating 

by reference into appendix C1 the 

equations for duct loss adjustments from 

section 5.1 of AHRI 600–2023 in this 

final rule. Regarding the comment from 

ClimateMaster, DOE notes that these 

provisions for calculating duct losses 

apply to testing all WSHPs, not just split 

systems. 

10. Refrigerant Charging 

The amount of refrigerant can have a 

significant impact on the system 

performance of air conditioners and 

heat pumps. DOE’s current test 

procedure for WSHPs requires that units 

be set up for test in accordance with the 

manufacturer installation and operation 

manuals. 10 CFR 431.96(e). In addition, 

the current DOE test procedure states 

that if the manufacturer specifies a 

range of superheat, sub-cooling, and/or 

refrigerant pressures in the installation 

and operation manual, any value within 

that range may be used to determine 

refrigerant charge or mass of refrigerant, 

unless the manufacturer clearly 

specifies a rating value in its installation 

or operation manual, in which case the 

specified rating value shall be used. 10 

CFR 431.96(e)(1) However, the current 

DOE test procedure for WSHPs does not 

provide charging instructions to be used 

if the manufacturer does not provide 

instructions in the manual that is 

shipped with the unit or if the provided 

instructions are unclear or incomplete. 

In addition, ISO 13256–1:1998 does not 

provide any specific guidance on setting 

and verifying the refrigerant charge of a 

unit aside from stating in section A2.3 

of that standard that equipment shall be 

evacuated and charged with the type 

and amount of refrigerant specified in 

the manufacturer’s instructions, where 

necessary. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

section 5.8 of AHRI 340/360–2022. 87 

FR 53302, 53334. This section specifies 

refrigerant charging parameters, 

including specifying which set of 

installation instructions to use for 

charging, explaining what to do if no 

instructions are provided, specifying 

that target values of parameters are the 

centers of the ranges allowed by 

installation instructions, and specifying 

tolerances for the measured values. Id. 

The approach also requires that 

refrigerant line pressure gauges be 

installed for single-package units, unless 

otherwise specified in manufacturer 

instructions. Id. DOE requested 

comment on the proposal to adopt the 

refrigerant charging requirements in 

section 5.8 of AHRI 340/360–2022. Id. at 

87 FR 53335. 

In response to the August 2022 NOPR, 

ClimateMaster commented that while 

all commercially single package WSHP 

units are developed with specific 

factory system charge weights, the only 

provision DOE proposed for a charge 

weight tolerance is in Table 4 of section 

5.8.3 of AHRI 340/360–2022, which 

specifies a tolerance of ±2 oz. 

(ClimateMaster, No. 22 at p. 11) 

ClimateMaster commented that it 

considers this tolerance unacceptable, 

as 2 oz can be upwards of 10 percent of 

the overall system charge on small 

capacity heat pumps. (Id.) 

ClimateMaster further stated that the 

procedures for charging that DOE 

provided in sections 5.8.4.1 and 5.8.4.2 

of AHRI 340/360–2022 are not 

applicable as most single package 

systems do not contain a liquid line 

service connection. (Id.) ClimateMaster 

commented that the tolerances that DOE 

provided in Table 4 of section 5.8.3 of 

AHRI 340/360–2022 reference items 

related to outdoor air conditions, which 

are not applicable to WSHPs. (Id.) 

ClimateMaster commented that DOE’s 

proposal lacks provisions for the 

possibility that the operating mode of 

the system could set the charge. (Id.) For 

these reasons, ClimateMaster 

recommended that DOE work with 

industry to create a national deviation of 

ISO 13256–1:1998 that allows the 

WSHP industry to develop a list of 

charging provisions that meet the intent 

of those found in AHRI 340/360–2022. 

(Id.) WaterFurnace agreed with DOE’s 

proposal regarding refrigerant charging. 

(WaterFurnace, No. 20 at p. 9) 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes section 5.4.11 of AHRI 

600–2023. This language is consistent 

with section 5.8 of AHRI 340/360–2022, 

as proposed for use in the August 2022 

NOPR, and addresses commenters’ 

concerns that DOE should adopt AHRI 

600. With regards to the comment from 

ClimateMaster regarding the refrigerant 

charging proposals in the August 2022 

NOPR (which are consistent with the 

provisions in AHRI 600–2023), DOE 

notes that these provisions are used 

only if the manufacturer’s charging 

instructions do not specify a tighter 

charging tolerance (as specified in 

section 5.4.11.4 of AHRI 600–2023). 

Therefore, these provisions provide 

flexibility to manufacturers to specify 

charging instructions appropriate to 

their models and serve mainly to 

address cases in which manufacturer’s 

instructions provide inadequate, 

incomplete, or conflicting charging 

instructions. Specifically, these 

provisions allow manufacturers to 

specify tighter tolerances and/or to 

specify charging based on whatever 

method is most appropriate for a given 

model. 

DOE considers the inclusion of these 

provisions in AHRI 600–2023 to 

represent industry consensus that these 

provisions provide an appropriate 

method for testing WSHPs. Therefore, 

DOE is incorporating by reference into 

appendix C1 the refrigerant charging 

requirements from section 5.4.11 of 

AHRI 600–2023 in this final rule. 

11. Voltage 

Operating voltage can affect the 

measured efficiency of air conditioners 

and heat pumps. The current DOE 

WSHP test procedure, through adoption 

of Tables 1 and 2 of ISO 13256–1:1998, 

requires units rated with dual 

nameplate voltages to be tested at both 


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voltages or at the lower voltage if only 

a single rating is to be published. 10 

CFR 431.96. 

In the August 2022 NOPR, DOE 

proposed to incorporate by reference 

section 6.1.3.1 of AHRI 340/360–2022. 

87 FR 53302, 53335. Section 6.1.3.1 of 

AHRI 340/360–2022 specifies that units 

with dual nameplate voltage ratings 

must be tested at the lower of the two 

voltages if only a single standard rating 

is to be published, or at both voltages if 

two standard ratings are to be 

published. Id. This approach is 

equivalent to the approach for dual 

nameplate voltages specified in tables 1 

and 2 of ISO 13256–1:1998 and tables 2 

and 3 of ISO 13256–1:2021. Id. DOE 

requested commented on the proposal 

to adopt the voltage provisions in 

section 6.1.3.1 of AHRI 340/360–2022. 

Id. 

In response to the August 2022 NOPR, 

ClimateMaster supported DOE’s 

proposal to adopt the voltage provisions 

in section 6.1.3.1 of AHRI 340/360–2022 

because it is industry best practice and 

recommended that DOE work with 

industry to create a national deviation of 

ISO 13256–1:1998 that includes the 

proposed language. (ClimateMaster, No. 

22 at pp. 11–12) WaterFurnace agreed 

with DOE’s proposal. (WaterFurnace, 

No. 20 at p. 9). 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

reference AHRI 600–2023 into appendix 

C1. This includes section 6.2.2 of AHRI 

600–2023. This language is consistent 

with section 6.1.3.1 of AHRI 340/360– 

2022, which was proposed in the 

August 2022 NOPR, as well as with 

tables 1 and 2 of ISO 13256–1:1998 and 

tables 2 and 3 of ISO 13256–1:2021. 

DOE considers the inclusion of these 

voltage provisions in AHRI 600–2023 to 

represent industry consensus that these 

provisions provide an appropriate 

method for testing WSHPs. As a result, 

DOE is incorporating by reference into 

appendix C1 the voltage provisions from 

AHRI 600–2023 in this final rule. 

12. Non-Standard Low-Static Indoor Fan 

Motors 

As discussed in section III.F.1.a of 

this document, DOE is adopting higher 

ESPs for WSHPs with a cooling capacity 

greater than or equal to 75,000 Btu/h 

that are included in section 5.5.1.1 of 

AHRI 600–2023 and are consistent with 

the ESP levels recommended in the 

ACUAC and ACUHP Working Group TP 

Term Sheet. However, individual 

models of WSHPs in this capacity range 

with indoor fan motors intended for 

installation in applications with a low 

ESP may not be able to operate at the 

proposed full-load ESP requirements at 

the full-load indoor rated airflow. To 

address this situation, section 3.2.30 of 

AHRI 600–2023 defines ‘‘non-standard 

low-static indoor fan motors’’ as motors 

in units with cooling capacity greater 

than or equal to 75,000 Btu/h which 

cannot maintain ESP as high as 

specified in the test procedure when 

operating at the full-load rated indoor 

airflow and that are distributed in 

commerce as part of an individual 

model within the same basic model that 

is distributed in commerce with a 

different motor specified for testing that 

can maintain the required ESP. Section 

5.7.4.3 of AHRI 600–2023 includes test 

provisions for WSHPs with nonstandard low-static indoor fan motors 

that cannot reach the ESP within 

tolerance during testing, which require 

using the maximum available fan speed 

that does not overload the motor or 

motor drive, adjusting the airflowmeasuring apparatus to maintain airflow 

within tolerance, and operating with an 

ESP as close as possible to the minimum 

ESP requirements for testing. This 

approach is consistent with the industry 

test standard referenced by the DOE test 

procedure for DX–DOASes (AHRI 920– 

2020, section 6.5.2.5). See appendix B to 

10 CFR 431.96. 

As discussed in section III.G.3 of this 

document, DOE is clarifying that 

representations for a WSHP basic model 

must be based on the least efficient 

individual model(s) distributed in 

commerce within the basic model (with 

the exception specified in 10 CFR 

429.43(a)(3)(v)(A) for certain individual 

models with the components listed in 

Table 6 to 10 CFR 429.43(a)(3)). DOE 

has concluded that the combination of 

(1) the provisions in AHRI 600–2023 for 

testing models with ‘‘non-standard lowstatic indoor fan motors’’ with (2) the 

requirement that basic models be rated 

based on the least efficient individual 

model (with certain exceptions, as 

discussed) provides an appropriate 

approach for handling WSHP models 

with these motors because if an 

individual model with a non-standard 

low-static indoor fan motor is tested, the 

test would be conducted at an indoor 

airflow representative for that model. 

But because testing at the rated airflow 

for such an individual model would 

result in testing at an ESP lower than the 

requirement and thus a lower indoor fan 

power, the representations for that basic 

model will be required to be based on 

an individual model with an indoor fan 

motor that can achieve the ESP 

requirements at the rated airflow. 

Consistent with incorporating by 

reference AHRI 600–2023 into appendix 

C1, in this final rule, DOE is adopting 

the AHRI 600–2023 provisions for 

testing models with non-standard lowstatic indoor fan motors. 

G. Configuration of Unit Under Test 

1. Background and Summary 

WSHPs are sold with a wide variety 

of components, including many that can 

optionally be installed on or within the 

unit both in the factory and in the field. 

In all cases, these components are 

distributed in commerce with the WSHP 

but can be packaged or shipped in 

different ways from the point of 

manufacturer for ease of transportation. 

Each optional component may or may 

not affect a model’s measured efficiency 

when tested to the DOE test procedure 

adopted in this final rule. For certain 

components not directly addressed in 

the DOE test procedure, DOE proposed 

to adopt more specific instructions on 

how each component should be handled 

for the purposes of making 

representations in 10 CFR part 429 in 

the August 2022 NOPR. 87 FR 53302, 

53335. Specifically, the proposed 

instructions provide manufacturers 

clarity on how components should be 

treated and how to group individual 

models with and without optional 

components for the purposes of 

representations to reduce burden. Id. 

As proposed in the August 2022 

NOPR, DOE is handling WSHP 

components in two distinct ways in this 

final rule to help manufacturers better 

understand their options for developing 

representations for their differing 

product offerings. Id. First, as proposed 

in the August 2022 NOPR, the treatment 

of some components is specified by the 

test procedure to limit their impact on 

measured efficiency. Id. For example, a 

fresh air damper must be set in the 

closed position and sealed during 

testing, resulting in a measured 

efficiency that would be similar or 

identical to the measured efficiency for 

a unit without a fresh air damper. Id. 

Second, for certain components not 

directly addressed in the DOE test 

procedure, this final rule adopts the 

specific instructions proposed in the 

August 2022 NOPR on how each 

component should be handled for the 

purposes of making representations in 

10 CFR part 429. See Id. at 87 FR 

53335–53336. Specifically, these 

instructions provide manufacturers 

clarity on how components should be 

treated and how to group individual 

models with and without optional 

components for the purposes of 

representations, in order to reduce 

burden. DOE is adopting these 

provisions in 10 CFR part 429 to allow 

for testing of certain individual models 


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16Note that in certain cases, as explained further 

in section III.G.3.c of this document, the 

representation may have to be based on an 

individual model with a steam/hydronic coil. 

17 DOE notes that in the August 2022 NOPR, DOE 

referred to this table as ‘‘Table 1 to Paragraph 

(a)(3)(ii)(A) .’’ Due to the publication of other 

regulatory documents, DOE is now referring to this 

Table as ‘‘Table 6 to Paragraph (a)(3)(v)(A).’’ 

that can be used as a proxy to represent 

the performance of equipment with 

multiple combinations of components. 

DOE is adopting provisions expressly 

allowing certain models to be grouped 

together for the purposes of making 

representations and allowing the 

performance of a model without certain 

optional components to be used as a 

proxy for models with any combinations 

of the specified components, even if 

such components would impact the 

measured efficiency of a model. Steam/ 

hydronic heat coils are an example of 

such a component. The efficiency 

representation for a model with a steam/ 

hydronic heat coil is based on the 

measured performance of the WSHP as 

tested without the component installed 

because the steam/hydronic heat coil is 

not easily removed from the WSHP for 

testing.16 Id. 

In this final rule, DOE is adopting 

these provisions in 10 CFR part 429 as 

proposed to allow for testing of certain 

individual models that can be used as 

a proxy to represent the performance of 

equipment with multiple combinations 

of components, though DOE is also 

adopting provisions that address 

additional components not included in 

the August 2022 NOPR, reflecting 

comments received in response to the 

August 2022 NOPR and provisions in 

AHRI 600–2023. 

2. Components Addressed Through Test 

Provisions of 10 CFR Part 431, Subpart 

F, Appendix C1 

In the August 2022 NOPR, DOE 

proposed test provisions for specific 

components, including all of the 

components listed in section D3 of 

AHRI 340/360–2022 for which there is 

a test procedure action which limits the 

impacts on measured efficiency (i.e., 

test procedure provisions specific to the 

component that are not addressed by 

general provisions in AHRI 340/360– 

2022 that negates the component’s 

impact on performance). Id. at 87 FR 

53336. These provisions specified how 

to test a unit with such a component 

(e.g., for a unit with hail guards, remove 

hail guards for testing). Id. The 

proposed test provisions were 

consistent with the provision in section 

D3 of AHRI 340/360–2022 but included 

revisions for further clarity and 

specificity (e.g., adding clarifying 

provisions for how to test units with 

modular economizers as opposed to 

units shipped with economizers 

installed). Id. Specifically, DOE 

proposed to require in appendix C1 that 

steps be taken during unit set-up and 

testing to limit the impacts on the 

measurement of these components: 

• Desiccant Dehumidification 

Components 

• Air Economizers 

• Fresh Air Dampers 

• Power Correction Capacitors 

• Ventilation Energy Recovery Systems 

(VERS) 

• Barometric Relief Dampers 

• UV Lights 

• Steam/Hydronic Coils 

• Refrigerant Reheat 

• Fire/Smoke/Isolation Dampers 

• Process Heat Recovery/Reclaim Coils/ 

Thermal Storage. 

Id. at 87 FR 53336–53337. 

As DOE did not receive any 

comments regarding this proposal in 

response to the August 2022 NOPR, it is 

adopting the provisions as proposed in 

this final rule. 

3. Components Addressed Through 

Representation Provisions of 10 CFR 

429.43 

In the August 2022 NOPR, consistent 

with the Commercial HVAC Term Sheet 

and the Commercial HVAC Enforcement 

Policy, DOE proposed provisions that 

explicitly allow representations for 

individual models with certain 

components to be based on testing for 

individual models without those 

components and proposed a table 

(‘‘Table 6 to Paragraph (a)(3)(v)(A)’’) 17

at 10 CFR 429.43(a)(3) listing the 

components for which these provisions 

would apply. Id. at 87 FR 53337. There 

are three components specified 

explicitly for WSHPs in the Commercial 

HVAC Enforcement Policy that are not 

included in section D3 of AHRI 340/ 

360–2022: (1) Condenser Pumps/Valves/ 

Fittings; (2) Condenser Water Reheat; 

and (3) Electric Resistance Heaters. Id. 

DOE tentatively concluded that the 

inclusion of these components as 

optional components for WSHPs is 

appropriate, except for electric 

resistance heaters. Id. DOE tentatively 

determined that electric resistance 

heaters would have a negligible effect 

on tested efficiency as they would be 

turned off for test and not impose a 

significant pressure drop. Id. DOE 

proposed the following components be 

listed in Table 6 to Paragraph 

(a)(3)(v)(A): 

• Desiccant Dehumidification 

Components, 

• Air Economizers, 

• Ventilation Energy Recovery Systems 

(VERS), 

• Steam/Hydronic Heat Coils, 

• Refrigerant Reheat, Fire/Smoke/ 

Isolation Dampers, 

• Powered Exhaust/Powered Return Air 

Fans, 

• Sound Traps/Sound Attenuators, 

• Process Heat Recovery/Reclaim Coils/ 

Thermal Storage, 

• Indirect/Direct Evaporative Cooling of 

Ventilation Air, 

• Condenser Pumps/Valves/Fittings, 

• Condenser Water Reheat, 

• Grill Options, 

• Non-Standard Indoor Fan Motors. 

Id. 

Additionally, DOE proposed to 

specify that the basic model 

representation must be based on the 

least efficient individual model that is a 

part of the basic model and clarified 

how this long-standing basic model 

provision interacts with the component 

treatment in 10 CFR 429.43 that was 

proposed. Id. DOE proposed clarifying 

instructions for instances when 

individual models within a basic model 

may have more than one of the specified 

components and there may be no 

individual model without any of the 

specified components. Id. DOE 

proposed the concept of an ‘‘otherwise 

comparable model group’’ (‘‘OCMG’’). 

Id. 

As discussed in the August 2022 

NOPR, an OCMG is a group of 

individual models within the basic 

model that do not differ in components 

that affect energy consumption as 

measured according to the applicable 

test procedure other than the specific 

components listed in Table 6 to 

Paragraph (a)(3)(v)(A) but may include 

individual models with any 

combination of such specified 

components. Id. Therefore, a basic 

model can be composed of multiple 

OCMGs, each representing a unique 

combination of components that affect 

energy consumption as measured 

according to the applicable test 

procedure, other than the specified 

excluded components listed in Table 6 

to Paragraph (a)(3)(v)(A). Id. For 

example, a manufacturer might include 

two tiers of control system within the 

same basic model, in which one of the 

control systems has sophisticated 

diagnostics capabilities that require a 

more powerful control board with a 

higher wattage input. Id. WSHP 

individual models with the ‘‘standard’’ 

control system would be part of OCMG 

A, while individual models with the 

‘‘premium’’ control system would be 

part of a different OCMG B, because the 


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18 DOE notes that in the August 2022 NOPR, DOE 

referred to this section as ‘‘10 CFR 429.134(t)(2).’’ 

Due to the publication of other regulatory 

documents, DOE is now referring to this section as 

‘‘10 CFR 429.134(dd)(2).’’ 

control system is not one of the 

specified exempt components listed in 

Table 6 to Paragraph (a)(3)(v)(A). Id. 

However, both OCMGs may include 

different combinations of specified 

exempt components. Id. Also, both 

OCMGs may include any combination 

of characteristics that do not affect the 

efficiency measurement, such as paint 

color. Id. 

Further discussed in the August 2022 

NOPR, an OCMG is used to determine 

which individual models are used to 

determine a represented value. Id. 

Specifically, when identifying the 

individual model within an OCMG for 

the purpose of determining a 

representation for the basic model, only 

the individual model(s) with the least 

number (which could be zero) of the 

specific components listed in Table 6 to 

Paragraph (a)(3)(v)(A) is considered. Id. 

This clarifies which individual models 

are exempted from consideration for 

determination of represented values in 

the case of an OCMG with multiple 

specified components and no individual 

models with zero specific components 

listed in Table 6 to (a)(3)(v)(A) (i.e., 

models with a number of specific 

components listed in Table 6 to 

(a)(3)(v)(A) greater than the least 

number in the OCMG are exempted). Id. 

In the case that the OCMG includes an 

individual model with no specific 

components listed in Table 6 to 

Paragraph (a)(3)(v)(A), then all 

individual models in the OCMG with 

specified components would be 

exempted from consideration. Id. The 

least-efficient individual model across 

the OCMGs within a basic model would 

be used to determine the representation 

of the basic model. Id. In the case where 

there are multiple individual models 

within a single OCMG with the same 

non-zero least number of specified 

components, the least efficient of these 

would be considered. Id. 

In the August 2022 NOPR, DOE relied 

on the term ‘‘comparable’’ as opposed to 

‘‘identical’’ to indicate that for the 

purpose of representations, the 

components that impact energy 

consumption as measured by the 

applicable test procedure are the 

relevant components to consider. Id. In 

other words, differences that do not 

impact energy consumption, such as 

unit color and presence of utility 

outlets, would not warrant separate 

OCMGs. Id. 

The use of the OCMG concept results 

in the represented values of 

performance that are representative of 

the individual model(s) with the lowest 

efficiency found within the basic model, 

excluding certain individual models 

with the specific components listed in 

Table 6 to Paragraph (a)(3)(v)(A). Id. at 

87 FR 53337–53338. Further, the 

approach, as proposed, was structured 

to more explicitly address individual 

models with more than one of the 

specific components listed in Table 6 to 

Paragraph (a)(3)(v)(A), as well as 

instances in which there is no 

comparable model without any of the 

specified components. Id. at 87 FR 

53338. DOE developed a document of 

examples to illustrate the approach 

proposed in the August 2022 NOPR for 

determining represented values for 

WSHPs with specific components, and 

in particular the OCMG concept. See 

EERE–2017–BT–TP–0029; 87 FR 53302, 

53338. 

In the August 2022 NOPR, DOE 

proposed provisions in 10 CFR 

429.43(a)(3)(v)(A) that included each of 

the components specified in section D3 

of AHRI 340/360–2022 for which the 

test provisions for testing a unit with 

these components may result in 

differences in ratings compared to 

testing a unit without these 

components, except for the following 

features: (1) Evaporative Pre-cooling of 

Condenser Intake Air; (2) Non-Standard 

Ducted Condenser Fans; and (3) Coated 

Coils. 87 FR 53302, 53338–53339. 

In response to the August 2022 NOPR, 

ClimateMaster commented that it agrees 

with DOE’s several proposals on this 

issue, but it believes that Table 6 in 

paragraph (a)(3) should include 

additional components, specifically 

water-side economizers and high 

effectiveness filters. (ClimateMaster, No. 

22 at p. 12) ClimateMaster 

recommended that DOE create a 

national deviation of ISO 13256–1:1998 

that adopts the proposed language with 

modifications to include water-side 

economizers and high effectiveness 

indoor filters. (Id.) WaterFurnace 

commented that the proposals may 

work for large motors but noted that the 

small volume of these larger motors 

would not justify regulation efforts and 

AHRI 340/360 omits smaller motors. 

(WaterFurnace, No. 20 at p. 10) 

With regards to the comment from 

ClimateMaster that waterside 

economizers and high effectiveness 

filters should be included in Table 6 to 

Paragraph (a)(3)(v)(A), DOE notes that 

the impact of high effectiveness filters 

can be entirely mitigated by testing with 

a standard filter, which is required by 

section 5.4.5 of AHRI 600–2023. 

Therefore, DOE has concluded that 

treatment as specific components in 

representation provisions in 10 CFR 

429.43 is not warranted for high 

effectiveness filters. With regards to 

waterside economizers, DOE has 

included waterside economizers and 

desuperheaters in the updated Table 6 

to Paragraph (a)(3)(v)(A) adopted in this 

final rule, as DOE has determined that 

it is appropriate to make representations 

for WSHPs without these components 

present, consistent with the inclusion of 

these components in section D3 of AHRI 

600–2023. 

With regard to the comment from 

WaterFurnace that only a small portion 

of the market has larger motors and 

therefore that they are not worth 

regulating, DOE notes that the approach 

for non-standard high-static indoor fan 

motors (as proposed in the August 2022 

NOPR and included in AHRI 600–2023) 

does not expand the scope of 

regulations to cover equipment with 

higher-static motors. Equipment that 

meets the DOE definition of WSHP is 

covered equipment, regardless of the 

size of indoor fan motor. The adopted 

approach reduces burden to 

manufacturers by allowing grouping of 

WSHP individual models with nonstandard high-static indoor fan motors 

in the same basic model as 

corresponding individual models with 

standard indoor fan motors (and thus 

rating all individual models in the basic 

model based on performance with the 

standard indoor fan motor), as long as 

the non-standard high-static indoor fan 

motor has the same or better relative 

efficiency performance as the standard 

motor included in the individual model 

with the standard indoor fan motor. 

4. Enforcement Provisions of 10 CFR 

429.134 

In the August 2022 NOPR, consistent 

with the Commercial HVAC Term Sheet 

and the Commercial HVAC Enforcement 

Policy, DOE proposed provisions in 10 

CFR 429.134(dd)(2) 18 regarding how 

DOE would assess compliance for basic 

models that include individual models 

distributed in commerce if DOE cannot 

obtain for testing individual models 

without the components that are the 

basis of representation. 87 FR 53302, 

53339. Specifically, DOE proposed that 

if a basic model includes individual 

models with components listed at Table 

6 to Paragraph (a)(3)(v)(A) and DOE is 

not able to obtain an individual model 

with the least number of those 

components within an OCMG (as 

defined in 10 CFR 429.43(a)(3) and 

discussed in section III.G.3.b of this 

final rule), DOE may test any individual 

model within the OCMG. Id. 

In response to the August 2022 NOPR, 

ClimateMaster stated that it disagrees 


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with the provisions proposed in 10 CFR 

429.134(dd)(2) in the August 2022 

NOPR, stating that most WSHPs are 

built for specific orders based on given 

configurations or options. 

(ClimateMaster, No. 22 at p. 12) 

ClimateMaster commented that if DOE 

requires an individual model with the 

lowest number of specific components, 

it may not be available to test, and that 

the proposal would allow DOE testing 

with a model that includes the specific 

component. (Id.) ClimateMaster 

recommended that DOE instead allow a 

manufacturer to provide an individual 

model with the least number of specific 

components within a specific and 

agreed-upon timeframe (i.e., rather than 

testing a model that includes a specific 

component). (Id.) 

With regards to the comment from 

ClimateMaster, the provisions proposed 

in the August 2022 NOPR at 10 CFR 

429.134(dd)(2) specify that DOE may 

test any individual model within the 

otherwise comparable model group if 

DOE is not able to obtain an individual 

model with the least number (which 

could be zero) of those components 

within the otherwise comparable model 

group. DOE will attempt to obtain a 

model with the least number of those 

components of specific components 

listed at Table 6 to Paragraph 

(a)(3)(v)(A). However, if DOE is unable 

to obtain such a model, DOE must retain 

the option to conduct assessment testing 

on an available model, and thus, in this 

final rule, DOE is adopting the 

provisions from the NOPR as proposed, 

at 10 CFR 429.134(dd)(2). 

H. Represented Values and Enforcement 

1. Cooling Capacity 

For WSHPs, cooling capacity 

determines equipment class, which in 

turn determines the applicable energy 

conservation standard. 10 CFR 431.97. 

In the August 2022 NOPR, DOE noted 

that while cooling capacity is a required 

represented value for WSHPs, DOE does 

not currently specify provisions for 

WSHPs regarding how close the 

represented value of cooling capacity 

must be to the tested or AEDMsimulated cooling capacity, or whether 

DOE will use measured or certified 

cooling capacity to determine 

equipment class for enforcement testing. 

87 FR 53302, 53339. DOE proposed to 

add the following provisions regarding 

cooling capacity for WSHPs: (1) a 

requirement that the represented 

cooling capacity be between 95 percent 

and 100 percent of the tested or AEDMsimulated cooling capacity; and (2) an 

enforcement provision stating that DOE 

would use the mean of measured 

cooling capacity values from testing, 

rather than the certified cooling 

capacity, to determine the applicable 

standards. Id. 

In response to the August 2022 NOPR, 

ClimateMaster commented that it 

supports DOE’s proposal for the 

published capacity to fall within 95 

percent to 100 percent of the tested 

value or the value found through the 

AEDM. (ClimateMaster, No. 22 at p. 12) 

WaterFurnace commented that it saw no 

problem with DOE’s proposal. 

(WaterFurnace, No. 20 at p. 10) MIAQ 

commented that it supports the 

tolerance of 5 percent below the rated/ 

marked capacity, but not with the 100- 

percent limit. (MIAQ, No. 23 at p. 8) 

MIAQ stated that manufacturers must 

account for many tolerances in their 

system, causing them to rate their units 

conservatively, and this conservative 

rating will not impact customers 

because the unit will perform better 

than advertised. (Id.) 

In response to the comment from 

MIAQ, DOE notes that the proposed 

cooling capacity provisions specify that 

the represented cooling capacity be 

between 95 percent and 100 percent of 

the tested or AEDM-simulated cooling 

capacity, which allows for conservative 

rating up to 5 percent—i.e., the 

represented cooling capacity may be 5 

percent lower than the tested or AEDMsimulated cooling capacity. MIAQ’s 

comment suggests MIAQ interpreted the 

proposal to mean the tested or 

simulated capacity cannot exceed 100 

percent of represented capacity, which 

would not allow conservative ratings. 

However, DOE has concluded that 

MIAQ’s concern that conservative rating 

should be allowed is addressed in the 

proposed provisions because the cooling 

capacity provisions explicitly allow 

conservative ratings up to 5 percent. 

Therefore, for the reasons discussed in 

the August 2022 NOPR and previously 

in this section, DOE is adopting the 

cooling capacity representation and 

enforcement provisions as proposed at 

10 CFR 429.43(a)(3)(v)(B) and 10 CFR 

429.134(dd)(1), respectively. 

2. Enforcement of IEER 

In the August 2022 NOPR, DOE 

proposed two options for determination 

of IEER—‘‘option 1’’ based on testing at 

the EWTs specified in AHRI 340/360– 

2022 for determining IEER, and ‘‘option 

2’’ based on testing at the EWTs 

specified in ISO 13256–1:1998 and 

interpolating/extrapolating performance 

to the EWTs specified in AHRI 340/360– 

2022. 87 FR 53302, 53339. For 

assessment or enforcement testing, DOE 

proposed provisions in 10 CFR 

429.134(t)(3) specifying that that the 

Department would determine IEER 

according to the ‘‘Option 1’’ approach, 

unless the manufacturer has specified 

that the ‘‘Option 2’’ approach should be 

used for the purposes of enforcement, in 

which case the Department would 

determine IEER according to the 

‘‘Option 2’’ approach. Id. 

As discussed in section III.E.1 of this 

final rule, DOE is not adopting two 

methods for determining IEER, and is 

instead adopting a single method for 

determining IEER by incorporating by 

reference AHRI 600–2023 into appendix 

C1. Because this final rule includes only 

one method for determining IEER, the 

proposed enforcement provisions for the 

method of determination of IEER are no 

longer applicable, and DOE is not 

adopting the proposed provisions. 

I. Test Procedure Costs 

EPCA requires that the test 

procedures for commercial package air 

conditioning and heating equipment, 

including WSHPs, be those generally 

accepted industry testing procedures or 

rating procedures developed or 

recognized by either AHRI or ASHRAE, 

as referenced in ASHRAE 90.1. (42 

U.S.C. 6314(a)(4)(A)) Further, if such an 

industry test procedure is amended, 

DOE must amend its test procedure to 

be consistent with the amended 

industry test procedure unless DOE 

determines, by rule published in the 

Federal Register and supported by clear 

and convincing evidence, that such an 

amended test procedure would not meet 

the requirements in 42 U.S.C. 

6314(a)(2)–(3) related to representative 

use and test burden. (42 U.S.C. 

6314(a)(4)(B)) EPCA also requires that, 

at least once every 7 years, DOE 

evaluate test procedures for each type of 

covered equipment, including WSHPs, 

to determine whether amended test 

procedures would more accurately or 

fully comply with the requirements for 

the test procedures to not be unduly 

burdensome to conduct and be 

reasonably designed to produce test 

results that reflect energy efficiency, 

energy use, and estimated operating 

costs during a representative average 

use cycle. (42 U.S.C. 6314(a)(1) 

In the August 2022 NOPR, DOE 

proposed to reorganize the current test 

procedure in proposed appendix C and 

to adopt generally through 

incorporation by reference the industry 

standard AHRI 340/360–2022 in 

proposed appendix C1. 87 FR 53302, 

53340. The proposed amended test 

procedure in the proposed appendix C1 

would rely on the IEER metric. Id. DOE 

tentatively determined that the 

proposed amended test procedure for 

WSHPs in appendix C1 would be 


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19 DOE estimated initial costs to validate an 

AEDM assuming 80 hours of general time to 

develop an AEDM based on existing simulation 

tools and 16 hours to validate two basic models 

within that AEDM at the cost of an engineering 

technician wage of $41 per hour plus the cost of 

third-party physical testing of two units per 

validation class (as required in 10 CFR 

429.70(c)(2)(iv)). DOE estimated the additional per 

basic model cost to determine efficiency using an 

AEDM assuming 1 hour per basic model at the cost 

of an engineering technician wage of $41 per hour. 

representative of an average use cycle 

and would not be unduly burdensome 

for manufacturers to conduct. Id. DOE 

also proposed to increase the scope of 

applicability of the test procedure to 

include all WSHPs with full-load 

cooling capacity between 135,000 Btu/h 

and 760,000 Btu/h. Id. As part of the 

August 2022 NOPR, DOE presented 

estimates of the test costs associated 

with these proposals. Id. DOE requested 

comment on its understanding of the 

impact of the test procedure proposals 

in this NOPR. Id. 

In response to the August 2022 NOPR, 

ClimateMaster commented that it 

qualifies as a small business under the 

Small Business Administration (‘‘SBA’’) 

guidelines and that the extra burden to 

rate through two programs, as would be 

required under AHRI 340/360–2022, is 

too costly for small businesses. 

(ClimateMaster, No. 22 at pp. 13–14) 

ClimateMaster recommended that DOE 

should instead use data created through 

the national deviation to ISO 13256– 

1:1998 to interpolate per the procedure 

given in AHRI 600. (Id. at p. 14) 

WaterFurnace commented that that 

the test procedure proposed in the 

August 2022 NOPR referencing AHRI 

340/360 (including changes to ESP 

requirements, flows, and entering air 

conditions) would approximately 

double its testing and certification 

management labor and costs. 

(WaterFurnace, No. 20 at p.10) 

In this final rule DOE is relocating the 

current DOE test procedure for WSHPs 

to appendix C without change. The test 

procedure adopted in appendix C for 

measuring EER and COP will result in 

no change in testing practices or burden. 

As discussed in section III.D of this 

final rule, DOE is incorporating by 

referencing AHRI 600–2023 into 

appendix C1 for measuring the IEER and 

ACOP metrics. DOE has determined that 

the amended test procedure is 

reasonably designed to produce results 

that are representative of the energy 

efficiency of that covered equipment 

during an average use cycle and is not 

unduly burdensome to conduct. The use 

of appendix C1 will not be required 

until the compliance date of any 

amended standards denominated in 

terms of IEER and ACOP, should DOE 

adopt such standards. DOE has 

concluded that the incorporation by 

reference AHRI 600–2023, the latest 

industry consensus test procedure for 

WSHPs, renders moot any expressed 

concerns related to the costs with rating 

to AHRI 340/360. 

In this final rule, DOE estimates that 

the cost for units less than 135,000 Btu/ 

h for third-party laboratory testing 

according to appendix C1 for measuring 

IEER and ACOP to be $3,700 for single 

speed units, $5,950 for two stage units, 

and $8,200 for variable speed units. The 

difference in test cost is attributable to 

the varying number of tests (i.e. 3, 6, or 

9) required to determine IEER for units 

with different compressor types. 

Additionally, DOE is increasing the 

scope of applicability of the test 

procedure to include all WSHPs with 

full-load cooling capacity between 

135,000 Btu/h and 760,000 Btu/h. DOE 

estimates the cost for third-party lab 

testing of large and very large WSHPs 

according to the test procedure adopted 

in appendix C1 for measuring IEER and 

ACOP to be $10,100 for single speed 

units, $15,500 for two stage units, and 

$20,900 for variable speed units. DOE 

estimates a substantially higher cost for 

larger WSHPs because they are generally 

more difficult to set up due to size and 

larger units typically would need to be 

set up in larger test chambers with more 

limited availability. 

As discussed in the August 2022 

NOPR, in accordance with 10 CFR 

429.70, WSHP manufacturers may elect 

to use AEDMs. 87 FR 53302, 53340. An 

AEDM is a computer modeling or 

mathematical tool that predicts the 

performance of non-tested basic models. 

These computer modeling and 

mathematical tools, when properly 

developed, can provide a means to 

predict the energy usage or efficiency 

characteristics of a basic model of a 

given covered product or equipment 

and reduce the burden and cost 

associated with testing. In the August 

2022 NOPR, DOE sought specific 

feedback on the estimated costs to rate 

WSHP models with an AEDM. Id. 

In response to the August 2022 NOPR, 

MIAQ agreed that AEDMs must be 

acceptable but stated that the need for 

AEDMs to be representative requires a 

lot of testing by manufacturers. (MIAQ, 

No. 23 at p. 9) MIAQ commented that 

DOE’s proposal to include WSHP’s with 

cooling capacities up to 760,000 Btu/h 

in scope increases the time and cost 

associated with the testing required to 

validate the AEDM. (Id.) MIAQ 

recommended that if an AEDM-rated 

unit were to fail a validation test, that 

only the failed unit should be derated 

rather than the entire AEDM-rated 

series. (Id.) MIAQ stated that the cost to 

test a full 30-ton WSHP qualification is 

around $50,000-$60,000 per basic model 

group, and that developing an AEDM 

model with sufficient trust would 

require as much as $1 million in capital 

investment. (Id.) 

DOE estimates the per-manufacturer 

cost to develop and validate an AEDM 

to be used for all WSHP equipment with 

a cooling capacity less than 135,000 

Btu/h would be $12,050 for single stage 

units, $14,300 for two stage units, and 

$16,550 for variable speed units. DOE 

estimates the per-manufacturer cost to 

develop and validate an AEDM to be 

used for all WSHPs with a cooling 

capacity between 135,000 Btu/h and 

760,000 Btu/h would be $26,000 for 

single stage units, $31,400 for two stage 

units, and $36,800 for variable speed 

units. DOE estimates an additional cost 

of approximately $41 per basic model 

for determining energy efficiency using 

the validated AEDM.19

DOE disagrees with MIAQ’s claims on 

the burden of AEDM development for 

WSHPs with a cooling capacity greater 

than 135,000 Btu/h. As discussed, based 

on quotes from third-party test 

laboratories, DOE estimates a per-unit 

test cost to the amended test procedure 

adopted in appendix C1 of $10,000– 

$21,000 for WSHPs with a cooling 

capacity greater than 135,000 Btu/h. Per 

10 CFR 429.70(c)(2), validation of an 

AEDM requires testing a minimum of 

only two basic models. Based on DOE’s 

observation of the prevalence of use of 

AEDMs for WSHP and similar 

equipment for which energy 

conservation standards currently apply 

(i.e., for equipment with a cooling 

capacity no greater than 135,000 Btu/h), 

DOE expects most WSHP manufacturers 

already have AEDMs for simulating 

WSHP performance. Further, as 

discussed in section III.A.1 of this final 

rule, the manufacturer literature for all 

identified model lines of WSHPs with a 

cooling capacity greater than 135,000 

Btu/h includes efficiency 

representations that are explicitly based 

on ISO 13256–1:1998, indicating that all 

manufacturers of this equipment already 

have the capability to generate 

efficiency representations for this 

equipment consistent with an industry 

consensus test procedure for WSHPs. 

Regarding the outcomes of failed DOE 

verification testing, in this final rule, 

DOE is not amending its regulations for 

AEDM verification, which are 

applicable to all equipment categories 

that may use AEDMs. DOE notes that 10 

CFR 429.70(c)(5)(viii) outlines required 

manufacturer actions with regard to 

AEDM use if basic models certified with 

AEDMs are determined to have invalid 


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ratings. Given that most WSHP 

manufacturers are AHRI members and 

that DOE is incorporating by reference 

the prevailing industry test procedure 

that was established for use in AHRI’s 

certification program, DOE expects that 

manufacturers will already be testing 

using AHRI 600–2023 in the timeframe 

of any potential future energy 

conservation standards in terms of IEER 

and ACOP. Based on this, DOE has 

determined that the test procedure 

amendments adopted in this final rule 

are not expected to increase the testing 

burden on WSHP manufacturers that are 

AHRI members. For the minority of 

WSHP manufacturers that are not 

members of AHRI, the test procedure 

amendments may have costs associated 

with model re-rating, to the extent that 

the manufacturers would not already be 

testing to the updated industry test 

procedure. Additionally, DOE has 

determined that the test procedure 

amendments will not require 

manufacturers to redesign any of the 

covered equipment, will not require 

changes to how the equipment is 

manufactured, and will not impact the 

utility of the equipment. 

J. Effective and Compliance Dates 

The effective date for the adopted test 

procedure amendments will be 30 days 

after publication of this final rule in the 

Federal Register. EPCA prescribes that, 

for the equipment at issue, all 

representations of energy efficiency and 

energy use, including those made on 

marketing materials and product labels, 

must be made in accordance with an 

amended test procedure, beginning 360 

days after publication of this final rule 

in the Federal Register. (42 U.S.C. 

6314(d)(1)) 

Starting 360 days after publication of 

a test procedure final rule in the Federal 

Register, and prior to the compliance 

date of amended standards for WSHPs 

that rely on IEER and ACOP, 

representations must be based on the 

test procedure in appendix C. WSHPs 

are not required to be tested according 

to the test procedure in appendix C1 

(resulting in the IEER and ACOP 

metrics) until the compliance date of 

amended energy conservation standards 

denominated in terms of the IEER and 

ACOP metrics, should DOE adopt such 

standards. 

Any voluntary representations of IEER 

and ACOP made prior to the compliance 

date of amended standards for WSHPs 

that rely on IEER and ACOP must be 

based on the test procedure in appendix 

C1 starting 360 days after publication of 

such a test procedure final rule in the 

Federal Register, and manufacturers 

may use appendix C1 to certify 

compliance with any amended 

standards based on IEER and ACOP, if 

adopted, prior to the applicable 

compliance date for those energy 

conservation standards. 

IV. Procedural Issues and Regulatory 

Review 

A. Review Under Executive Orders 

12866, 13563, and 14094 

Executive Order (‘‘E.O.’’) 12866, 

‘‘Regulatory Planning and Review,’’ 58 

FR 51735 (Oct. 4, 1993), as 

supplemented and reaffirmed by E.O. 

13563, ‘‘Improving Regulation and 

Regulatory Review,’’ 76 FR 3821 (Jan. 

21, 2011) and amended by E.O. 14094, 

‘‘Modernizing Regulatory Review,’’ 88 

FR 21879 (April 11, 2023), requires 

agencies, to the extent permitted by law, 

to: (1) propose or adopt a regulation 

only upon a reasoned determination 

that its benefits justify its costs 

(recognizing that some benefits and 

costs are difficult to quantify); (2) tailor 

regulations to impose the least burden 

on society, consistent with obtaining 

regulatory objectives, taking into 

account, among other things, and to the 

extent practicable, the costs of 

cumulative regulations; (3) select, in 

choosing among alternative regulatory 

approaches, those approaches that 

maximize net benefits (including 

potential economic, environmental, 

public health and safety, and other 

advantages; distributive impacts; and 

equity); (4) to the extent feasible, specify 

performance objectives, rather than 

specifying the behavior or manner of 

compliance that regulated entities must 

adopt; and (5) identify and assess 

available alternatives to direct 

regulation, including providing 

economic incentives to encourage the 

desired behavior, such as user fees or 

marketable permits, or providing 

information upon which choices can be 

made by the public. DOE emphasizes as 

well that E.O. 13563 requires agencies to 

use the best available techniques to 

quantify anticipated present and future 

benefits and costs as accurately as 

possible. In its guidance, the Office of 

Information and Regulatory Affairs 

(‘‘OIRA’’) in the Office of Management 

and Budget (‘‘OMB’’) has emphasized 

that such techniques may include 

identifying changing future compliance 

costs that might result from 

technological innovation or anticipated 

behavioral changes. For the reasons 

stated in this preamble, this final 

regulatory action is consistent with 

these principles. 

Section 6(a) of E.O. 12866 also 

requires agencies to submit ‘‘significant 

regulatory actions’’ to OIRA for review. 

OIRA has determined that this final 

regulatory action does not constitute a 

‘‘significant regulatory action’’ under 

section 3(f) of E.O. 12866. Accordingly, 

this action was not submitted to OIRA 

for review under E.O. 12866. 

B. Review Under the Regulatory 

Flexibility Act 

The Regulatory Flexibility Act 

(‘‘RFA’’) (5 U.S.C. 601 et seq.) requires 

preparation of a final regulatory 

flexibility analysis (‘‘FRFA’’) for any 

rule that by law must be proposed for 

public comment, unless the agency 

certifies that the rule, if promulgated, 

will not have a significant economic 

impact on a substantial number of small 

entities. As required by E.O. 13272, 

‘‘Proper Consideration of Small Entities 

in Agency Rulemaking,’’ 67 FR 53461 

(August 16, 2002), DOE published 

procedures and policies on February 19, 

2003, to ensure that the potential 

impacts of its rules on small entities are 

properly considered during the DOE 

rulemaking process. 68 FR 7990. DOE 

has made its procedures and policies 

available on the Office of the General 

Counsel’s website: www.energy.gov/gc/ 

office-general-counsel. DOE reviewed 

this final rule to amend the test 

procedure for WSHPs under the 

provisions of the RFA and the policies 

and procedures published on February 

19, 2003. 

As part of the August 2022 NOPR, 

DOE conducted its initial regulatory 

flexibility analysis (‘‘IRFA’’). The 

following sections outline DOE’s 

determination that this final rule does 

not have a ‘‘significant economic impact 

on a substantial number of small 

entities,’’ and that the preparation of a 

FRFA is not warranted. 

DOE is amending the test procedure 

for WSHPs to satisfy its statutory 

obligations under EPCA. (42 U.S.C. 

6314(a)(1)(A)) 

In this final rule, DOE is establishing 

new appendices C and C1 to subpart F 

of part 431. The current DOE test 

procedure for WSHPs is relocated to 

appendix C without change. The 

amended test procedure for WSHPs is 

established in a new appendix C1, 

which includes the following amended 

test procedure requirements for WSHPs 

for measuring the updated efficiency 

metrics: (1) IEER for WSHPs using the 

methods from AHRI 600–2023; and (2) 

ACOP using the methods specified in 

AHRI 600–2023. Use of the amended 

test procedure in appendix C1 will not 

be required until such time as 

compliance is required with amended 

energy conservation standards for 

WSHPs denominated in terms of IEER 


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84224 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

20The size standards are listed by NAICS code 

and industry description and are available at: 

www.sba.gov/document/support—table-sizestandards (Last accessed on July 16, 2021). 

21MAEDbS is available at 

www.cacertappliances.energy.ca.gov/Pages/Search/ 

AdvancedSearch.aspx (Last accessed Dec. 1, 2021). 

22Certified equipment in the CCD are listed by 

product class and can be accessed at 

www.regulations.doe.gov/certification-data/ (Last 

accessed May 1, 2023). 

and ACOP, should DOE adopt such 

standards. 

Additionally, DOE is expanding the 

scope of the test procedure to include 

WSHPs with capacities between 135,000 

and 760,000 Btu/h, as well as specifying 

the components that must be present for 

testing and amending certain provisions 

related to representations and 

enforcement in 10 CFR part 429. 

DOE uses the Small Business 

Administration (‘‘SBA’’) small business 

size standards to determine whether 

manufacturers qualify as ‘‘small 

businesses,’’ which are listed by the 

North American Industry Classification 

System (‘‘NAICS’’).20 The SBA 

considers a business entity to be small 

business if, together with its affiliates, it 

employs less than a threshold number of 

workers specified in 13 CFR part 121. 

WSHP manufacturers, who produce the 

equipment covered by this rule, are 

classified under NAICS code 333415, 

‘‘Air-Conditioning and Warm Air 

Heating Equipment and Commercial 

and Industrial Refrigeration Equipment 

Manufacturing.’’ In 13 CFR 121.201, the 

SBA sets a threshold of 1,250 employees 

or fewer for an entity to be considered 

as a small business for this category. 

This employee threshold includes all 

employees in a business’s parent 

company and any other subsidiaries. 

DOE utilized the California Energy 

Commission’s Modernized Appliance 

Efficiency Database System 

(‘‘MAEDbS’’) 21 and the DOE’s 

Certification Compliance Database 

(‘‘CCD’’) 22 in identifying manufacturers. 

DOE screened out private labelers 

because original equipment 

manufacturers (‘‘OEMs’’) would likely 

be responsible for any costs associated 

with testing to the amended test 

procedure. As a result of this inquiry, 

DOE identified a total of 25 OEMs of 

WSHPs in the United States affected by 

this rulemaking. DOE screened out 

companies that do not meet the 

definition of a ‘‘small business’’ or are 

foreign owned without substantive 

domestic operations. DOE used 

subscription-based business information 

tools to determine headcount and 

revenue of each business. Of the 25 

OEMs of WSHPs, DOE identified 6 as 

small, domestic manufacturers. 

Of the 6 small, domestic 

manufacturers identified, all certify 

their WSHP models in the AHRI 

Certification Directory for WSHPs. 

AHRI has published a new industry 

test standard for WSHPs, titled AHRI 

Standard 600, ‘‘2023 Standard for 

Performance Rating of Water/Brine to 

Air Heat Pump Equipment’’ (‘‘AHRI 

600–2023’’). DOE presumes AHRI’s 

certification program will require rating 

based on AHRI 600–2023 to develop the 

IEER and ACOP metrics. As a result, the 

test procedure amendments adopted in 

this final rule will not add any 

additional testing burden to 

manufacturers that already certify 

WSHPs to AHRI’s certification program. 

Accordingly, DOE does not expect that 

the identified small business 

manufacturers, all of whom participate 

in AHRI’s certification program, would 

see increased testing costs as a result of 

this rulemaking. 

Additionally, DOE notes these test 

procedure amendments will only affect 

voluntary representations. There is no 

existing energy conservation standard 

that requires manufacturer to certify to 

WSHP efficiency in terms of IEER and 

ACOP to DOE. Certification based on 

IEER and ACOP would only be required 

if and when DOE establishes energy 

conservation standards based on those 

metrics for WSHPs. 

Therefore, for the reasons stated in the 

preceding paragraphs, DOE concludes 

and certifies that the cost effects 

accruing from this test procedure final 

rule would not have a ‘‘significant 

economic impact on a substantial 

number of small entities,’’ and that the 

preparation of a FRFA is not warranted. 

DOE has submitted a certification and 

supporting statement of factual basis to 

the Chief Counsel for Advocacy of the 

Small Business Administration for 

review under 5 U.S.C. 605(b). 

C. Review Under the Paperwork 

Reduction Act of 1995 

Manufacturers of WSHPs must certify 

to DOE that their products comply with 

any applicable energy conservation 

standards. To certify compliance, 

manufacturers must first obtain test data 

for their products according to the DOE 

test procedures, including any 

amendments adopted for those test 

procedures. DOE has established 

regulations for the certification and 

recordkeeping requirements for all 

covered consumer products and 

commercial equipment, including 

WSHPs. (See generally 10 CFR part 

429.) The collection-of-information 

requirement for the certification and 

recordkeeping is subject to review and 

approval by OMB under the Paperwork 

Reduction Act (‘‘PRA’’). This 

requirement has been approved by OMB 

under OMB control number 1910–1400. 

Public reporting burden for the 

certification is estimated to average 35 

hours per response, including the time 

for reviewing instructions, searching 

existing data sources, gathering and 

maintaining the data needed, and 

completing and reviewing the collection 

of information. 

DOE is not amending the certification 

or reporting requirements for WSHPs in 

this final rule. Instead, DOE may 

consider proposals to amend the 

certification requirements and reporting 

for WSHPs under a separate rulemaking 

regarding appliance and equipment 

certification. DOE will address changes 

to OMB Control Number 1910–1400 at 

that time, as necessary. 

Notwithstanding any other provision 

of the law, no person is required to 

respond to, nor shall any person be 

subject to a penalty for failure to comply 

with, a collection of information subject 

to the requirements of the PRA, unless 

that collection of information displays a 

currently valid OMB Control Number. 

D. Review Under the National 

Environmental Policy Act of 1969 

In this final rule, DOE establishes test 

procedure amendments that it expects 

will be used to develop and implement 

future energy conservation standards for 

WSHPs. DOE has determined that this 

rule falls into a class of actions that are 

categorically excluded from review 

under the National Environmental 

Policy Act of 1969 (42 U.S.C. 4321 et 

seq.) and DOE’s implementing 

regulations at 10 CFR part 1021. 

Specifically, DOE has determined that 

adopting test procedures for measuring 

energy efficiency of consumer products 

and industrial equipment is consistent 

with activities identified in 10 CFR part 

1021, appendix A to subpart D, A5 and 

A6. Accordingly, neither an 

environmental assessment nor an 

environmental impact statement is 

required. 

E. Review Under Executive Order 13132 

Executive Order 13132, ‘‘Federalism,’’ 

64 FR 43255 (August 4, 1999), imposes 

certain requirements on agencies 

formulating and implementing policies 

or regulations that preempt State law or 

that have federalism implications. The 

Executive order requires agencies to 

examine the constitutional and statutory 

authority supporting any action that 

would limit the policymaking discretion 

of the States and to carefully assess the 

necessity for such actions. The 

Executive order also requires agencies to 

have an accountable process to ensure 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84225 

meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications. On March 14, 2000, DOE 

published a statement of policy 

describing the intergovernmental 

consultation process it will follow in the 

development of such regulations. 65 FR 

13735. DOE examined this final rule 

and determined that it will not have a 

substantial direct effect on the States, on 

the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government. EPCA governs and 

prescribes Federal preemption of State 

regulations as to energy conservation for 

the products that are the subject of this 

final rule. States can petition DOE for 

exemption from such preemption to the 

extent, and based on criteria, set forth in 

EPCA. (42 U.S.C. 6316(a) and 42 U.S.C. 

6316(b); 42 U.S.C. 6297(d)) No further 

action is required by Executive Order 

13132. 

F. Review Under Executive Order 12988 

Regarding the review of existing 

regulations and the promulgation of 

new regulations, section 3(a) of 

Executive Order 12988, ‘‘Civil Justice 

Reform,’’ 61 FR 4729 (Feb. 7, 1996), 

imposes on Federal agencies the general 

duty to adhere to the following 

requirements: (1) eliminate drafting 

errors and ambiguity; (2) write 

regulations to minimize litigation; (3) 

provide a clear legal standard for 

affected conduct rather than a general 

standard; and (4) promote simplification 

and burden reduction. Section 3(b) of 

Executive Order 12988 specifically 

requires that Executive agencies make 

every reasonable effort to ensure that the 

regulation (1) clearly specifies the 

preemptive effect, if any; (2) clearly 

specifies any effect on existing Federal 

law or regulation; (3) provides a clear 

legal standard for affected conduct 

while promoting simplification and 

burden reduction; (4) specifies the 

retroactive effect, if any; (5) adequately 

defines key terms; and (6) addresses 

other important issues affecting clarity 

and general draftsmanship under any 

guidelines issued by the Attorney 

General. Section 3(c) of Executive Order 

12988 requires Executive agencies to 

review regulations in light of applicable 

standards in sections 3(a) and 3(b) to 

determine whether they are met or it is 

unreasonable to meet one or more of 

them. DOE has completed the required 

review and determined that, to the 

extent permitted by law, this final rule 

meets the relevant standards of 

Executive Order 12988. 

G. Review Under the Unfunded 

Mandates Reform Act of 1995 

Title II of the Unfunded Mandates 

Reform Act of 1995 (‘‘UMRA’’) requires 

each Federal agency to assess the effects 

of Federal regulatory actions on State, 

local, and Tribal governments and the 

private sector. Public Law 104–4, sec. 

201 (codified at 2 U.S.C. 1531). For a 

regulatory action resulting in a rule that 

may cause the expenditure by State, 

local, and Tribal governments, in the 

aggregate, or by the private sector of 

$100 million or more in any one year 

(adjusted annually for inflation), section 

202 of UMRA requires a Federal agency 

to publish a written statement that 

estimates the resulting costs, benefits, 

and other effects on the national 

economy. (2 U.S.C. 1532(a), (b)) The 

UMRA also requires a Federal agency to 

develop an effective process to permit 

timely input by elected officers of State, 

local, and Tribal governments on a 

proposed ‘‘significant intergovernmental 

mandate,’’ and requires an agency plan 

for giving notice and opportunity for 

timely input to potentially affected 

small governments before establishing 

any requirements that might 

significantly or uniquely affect small 

governments. On March 18, 1997, DOE 

published a statement of policy on its 

process for intergovernmental 

consultation under UMRA. 62 FR 

12820; also available at 

www.energy.gov/gc/office-generalcounsel. DOE examined this final rule 

according to UMRA and its statement of 

policy and determined that the rule 

contains neither an intergovernmental 

mandate, nor a mandate that may result 

in the expenditure of $100 million or 

more in any year, so these requirements 

do not apply. 

H. Review Under the Treasury and 

General Government Appropriations 

Act, 1999 

Section 654 of the Treasury and 

General Government Appropriations 

Act, 1999 (Pub. L. 105–277) requires 

Federal agencies to issue a Family 

Policymaking Assessment for any rule 

that may affect family well-being. This 

final rule will not have any impact on 

the autonomy or integrity of the family 

as an institution. Accordingly, DOE has 

concluded that it is not necessary to 

prepare a Family Policymaking 

Assessment. 

I. Review Under Executive Order 12630 

DOE has determined, under Executive 

Order 12630, ‘‘Governmental Actions 

and Interference with Constitutionally 

Protected Property Rights’’ 53 FR 8859 

(March 18, 1988), that this regulation 

will not result in any takings that might 

require compensation under the Fifth 

Amendment to the U.S. Constitution. 

J. Review Under Treasury and General 

Government Appropriations Act, 2001 

Section 515 of the Treasury and 

General Government Appropriations 

Act, 2001 (44 U.S.C. 3516 note) provides 

for agencies to review most 

disseminations of information to the 

public under guidelines established by 

each agency pursuant to general 

guidelines issued by OMB. OMB’s 

guidelines were published at 67 FR 

8452 (Feb. 22, 2002), and DOE’s 

guidelines were published at 67 FR 

62446 (Oct. 7, 2002). Pursuant to OMB 

Memorandum M–19–15, Improving 

Implementation of the Information 

Quality Act (April 24, 2019), DOE 

published updated guidelines which are 

available at www.energy.gov/sites/prod/ 

files/2019/12/f70/DOE%20Final

%20Updated%20IQA%

20Guidelines%20Dec%202019.pdf. 

DOE has reviewed this final rule under 

the OMB and DOE guidelines and has 

concluded that it is consistent with 

applicable policies in those guidelines. 

K. Review Under Executive Order 13211 

Executive Order 13211, ‘‘Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use,’’ 66 FR 28355 (May 

22, 2001), requires Federal agencies to 

prepare and submit to OMB, a 

Statement of Energy Effects for any 

significant energy action. A ‘‘significant 

energy action’’ is defined as any action 

by an agency that promulgated or is 

expected to lead to promulgation of a 

final rule, and that (1) is a significant 

regulatory action under Executive Order 

12866, or any successor order; and (2) 

is likely to have a significant adverse 

effect on the supply, distribution, or use 

of energy; or (3) is designated by the 

Administrator of OIRA as a significant 

energy action. For any significant energy 

action, the agency must give a detailed 

statement of any adverse effects on 

energy supply, distribution, or use if the 

regulation is implemented, and of 

reasonable alternatives to the action and 

their expected benefits on energy 

supply, distribution, and use. 

This regulatory action is not a 

significant regulatory action under 

Executive Order 12866. Moreover, it 

would not have a significant adverse 

effect on the supply, distribution, or use 

of energy, nor has it been designated as 

a significant energy action by the 

Administrator of OIRA. Therefore, it is 

not a significant energy action, and, 

accordingly, DOE has not prepared a 

Statement of Energy Effects. 


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84226 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

L. Review Under Section 32 of the 

Federal Energy Administration Act of 

1974 

Under section 301 of the Department 

of Energy Organization Act (Pub. L. 95– 

91; 42 U.S.C. 7101), DOE must comply 

with section 32 of the Federal Energy 

Administration Act of 1974, as amended 

by the Federal Energy Administration 

Authorization Act of 1977. (15 U.S.C. 

788; ‘‘FEAA’’) Section 32 essentially 

provides in relevant part that, where a 

proposed rule authorizes or requires use 

of commercial standards, the notice of 

proposed rulemaking must inform the 

public of the use and background of 

such standards. In addition, section 

32(c) requires DOE to consult with the 

Attorney General and the Chairman of 

the Federal Trade Commission (‘‘FTC’’) 

concerning the impact of the 

commercial or industry standards on 

competition. 

The modifications to the test 

procedure for WSHPs adopted in this 

final rule incorporates testing methods 

contained in certain sections of the 

following commercial standards: AHRI 

600–2023, ANSI/ASHRAE 37–2009, ISO 

13256–1:1998, and Melinder 2010. DOE 

has evaluated these standards and is 

unable to conclude whether the 

standards fully comply with the 

requirements of section 32(b) of the 

FEAA (i.e., whether they were 

developed in a manner that fully 

provides for public participation, 

comment, and review.) DOE has 

consulted with both the Attorney 

General and the Chairman of the FTC 

about the impact on competition of 

using the methods contained in these 

standards and has received no 

comments objecting to their use. 

M. Congressional Notification 

As required by 5 U.S.C. 801, DOE will 

report to Congress on the promulgation 

of this rule before its effective date. The 

report will state that it has been 

determined that the rule is not a ‘‘major 

rule’’ as defined by 5 U.S.C. 804(2). 

N. Description of Materials Incorporated 

by Reference 

In this final rule, DOE incorporates by 

reference the following test standards 

and reference document: 

AHRI 600–2023 is an industry 

accepted test procedure for measuring 

the performance of water source heat 

pumps. AHRI 600–2023 is available on 

AHRI’s website at: https://

www.ahrinet.org/search-standards/ahri600-i-p-performance-rating-waterbrineair-heat-pump-equipment. 

ANSI/ASHRAE 37–2009 is an 

industry-accepted test procedure for 

measuring the performance of 

electrically driven unitary airconditioning and heat pump equipment. 

ANSI/ASHRAE 37–2009 is available on 

ANSI’s website at: webstore.ansi.org/ 

RecordDetail.aspx?sku=ANSI%2FA

SHRAE+Standard+37-2009. 

Errata sheet for ANSI/ASHRAE 

Standard 37–2009 dated March 27, 

2019, specifies all of the corrections to 

ANSI/ASHRAE 37–2009 identified from 

the date of publication through March 

27, 2019. Errata sheet for ANSI/ 

ASHRAE Standard 37–2009 is available 

on ASHRAE’s website at: https://

www.ashrae.org/technical-resources/ 

standards-and-guidelines/standardserrata. 

Melinder 2010 is a reference booklet 

with properties of secondary working 

fluids for indirect heating and cooling 

systems used in air conditioning, heat 

pumps, and other applications. 

Melinder 2010 is available from the 

International Institute of Refrigeration 

website at: www.iifiir.org. 

ISO 13256–1:1998 is an industryaccepted test procedure for measuring 

the performance of specific water-source 

heat pump equipment. ISO 13256– 

1:1998 is available on ISO’s website at: 

www.iso.org/store.html. 

The following standards are currently 

approved for the sections in which they 

appear in this final rule: AHRI 210/240– 

2008 and AHRI 340/360–2007. 

V. Approval of the Office of the 

Secretary 

The Secretary of Energy has approved 

publication of this final rule. 

List of Subjects 

10 CFR Part 429 

Administrative practice and 

procedure, Confidential business 

information, Energy conservation, 

Household appliances, Imports, 

Incorporation by reference, 

Intergovernmental relations, Reporting 

and recordkeeping requirements, Small 

businesses. 

10 CFR Part 431 

Administrative practice and 

procedure, Confidential business 

information, Energy conservation test 

procedures, Incorporation by reference, 

Reporting and recordkeeping 

requirements. 

Signing Authority 

This document of the Department of 

Energy was signed on November 17, 

2023, by Jeffrey Marootian, Principal 

Deputy Assistant Secretary for Energy 

Efficiency and Renewable Energy, 

pursuant to delegated authority from the 

Secretary of Energy. That document 

with the original signature and date is 

maintained by DOE. For administrative 

purposes only, and in compliance with 

requirements of the Office of the Federal 

Register, the undersigned DOE Federal 

Register Liaison Officer has been 

authorized to sign and submit the 

document in electronic format for 

publication, as an official document of 

the Department of Energy. This 

administrative process in no way alters 

the legal effect of this document upon 

publication in the Federal Register. 

Signed in Washington, DC, on November 

20, 2023. 

Treena V. Garrett, 

Federal Register Liaison Officer, U.S. 

Department of Energy. 

For the reasons stated in the 

preamble, DOE amends parts 429 and 

431 of Chapter II of Title 10, Code of 

Federal Regulations as set forth below: 

PART 429—CERTIFICATION, 

COMPLIANCE, AND ENFORCEMENT 

FOR CONSUMER PRODUCTS AND 

COMMERCIAL AND INDUSTRIAL 

EQUIPMENT 

■ 1. The authority citation for part 429 

continues to read as follows: 

Authority: 42 U.S.C. 6291–6317; 28 U.S.C. 

2461 note. 

■ 2. Amend § 429.4 by: 

■ a. Redesignating paragraphs (c)(4) 

through (6) as paragraphs (c)(5) through 

(7); and 

■ b. Adding new paragraph (c)(4). 

The addition reads as follows: 

§ 429.4 Materials incorporated by 

reference. 

* * * * * 

(c) * * * 

(4) AHRI Standard 600–2023 (I–P) 

(‘‘AHRI 600–2023’’), 2023 Standard for 

Performance Rating of Water/Brine to 

Air Heat Pump Equipment, approved 

September 11, 2023; IBR approved for 

§ 429.43. 

* * * * * 

■ 3. Amend § 429.43 by adding 

paragraph (a)(3)(v) to read as follows: 

§ 429.43 Commercial heating, ventilating, 

air conditioning (HVAC) equipment. 

(a) * * * 

(3) * * * 

(v) Water-Source Heat Pumps. When 

certifying to standards in terms of IEER 

and ACOP, the following provisions 

apply. 

(A) Individual model selection: 

(1) Representations for a basic model 

must be based on the least efficient 

individual model(s) distributed in 

commerce among all otherwise 

comparable model groups comprising 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84227 

the basic model, except as provided in 

paragraph (a)(3)(v)(A)(2) of this section 

for individual models that include 

components listed in table 6 to 

paragraph (a)(3)(v)(A) of this section. 

For the purpose of this paragraph 

(a)(3)(v)(A)(1), ‘‘otherwise comparable 

model group’’ means a group of 

individual models distributed in 

commerce within the basic model that 

do not differ in components that affect 

energy consumption as measured 

according to the applicable test 

procedure specified at 10 CFR 431.96 

other than those listed in table 6 to 

paragraph (a)(3)(v)(A) of this section. An 

otherwise comparable model group may 

include individual models distributed 

in commerce with any combination of 

the components listed in table 6 (or 

none of the components listed in table 

6) to paragraph (a)(3)(v)(A) of this 

section. An otherwise comparable 

model group may consist of only one 

individual model. 

(2) For a basic model that includes 

individual models distributed in 

commerce with components listed in 

table 6 to paragraph (a)(3)(v)(A) of this 

section, the requirements for 

determining representations apply only 

to the individual model(s) of a specific 

otherwise comparable model group 

distributed in commerce with the least 

number (which could be zero) of 

components listed in table 6 to 

paragraph (a)(3)(v)(A) of this section 

included in individual models of the 

group. Testing under this paragraph 

shall be consistent with any componentspecific test provisions specified in 

section 3 of appendix C1 to subpart F 

of 10 CFR part 431. 

TABLE 6 TO PARAGRAPH (a)(3)(v)(A)—SPECIFIC COMPONENTS FOR WATER SOURCE HEAT PUMPS

Component Description 

Air Economizers .............................. An automatic system that enables a cooling system to supply outdoor air to reduce or eliminate the need 

for mechanical cooling during mild or cold weather. 

Condenser Pumps/Valves/Fittings .. Additional components in the water circuit for water control or filtering. 

Condenser Water Reheat ............... A heat exchanger located downstream of the indoor coil that heats the supply air during cooling operation 

using water from the condenser coil in order to increase the ratio of moisture removal to cooling capacity 

provided by the equipment. 

Desiccant Dehumidification Components.An assembly that reduces the moisture content of the supply air through moisture transfer with solid or liquid desiccants. 

Desuperheater ................................ A heat exchanger located downstream of the compressor on the high-pressure vapor line that moves heat 

to an external source, such as potable water. 

Fire/Smoke/Isolation Dampers ........ A damper assembly including means to open and close the damper mounted at the supply or return duct 

opening of the equipment. 

Grill Options .................................... Special grills used to direct airflow in unique applications (such as up and away from a rear wall). 

Indirect/Direct Evaporative Cooling 

of Ventilation Air.

Water is used indirectly or directly to cool ventilation air. In a direct system the water is introduced directly 

into the ventilation air and in an indirect system the water is evaporated in secondary air stream and the 

heat is removed through a heat exchanger. 

Non-Standard High-Static Indoor 

Fan Motors.

The standard indoor fan motor is the motor specified in the manufacturer’s installation instructions for testing and shall be distributed in commerce as part of a particular model. A non-standard high-static motor 

is an indoor fan motor that is not the standard indoor fan motor and that is distributed in commerce as 

part of an individual model within the same basic model. 

For a non-standard high-static indoor fan motor(s) to be considered a specific component for a basic 

model (and thus subject to the provisions of paragraph (a)(3)(v)(A)(2) of this section), the following 2 

provisions must be met: 

1. Non-standard high-static indoor fan motor(s) must meet the minimum allowable efficiency determined 

per section D.4.1 of AHRI 600–2023 (incorporated by reference, see § 429.4) for non-standard high-static indoor fan motors, or per section D.4.2 of AHRI 600–2023 for non-standard high-static indoor integrated fan and motor combinations. 

2. If the standard indoor fan motor can vary fan speed through control system adjustment of motor speed, 

all non-standard high-static indoor fan motors must also allow speed control (including with the use of a 

variable-frequency drive). 

Powered Exhaust/Powered Return 

Air Fans.

A powered exhaust fan is a fan that transfers directly to the outside a portion of the building air that is returning to the unit, rather than allowing it to recirculate to the indoor coil and back to the building. A powered return fan is a fan that draws building air into the equipment. 

Process Heat Recovery/Reclaim 

Coils/Thermal Storage.

A heat exchanger located inside the unit that conditions the equipment’s supply air using energy transferred from an external source using a vapor, gas, or liquid. 

Refrigerant Reheat Coils ................ A heat exchanger located downstream of the indoor coil that heats the supply air during cooling operation 

using high-pressure refrigerant in order to increase the ratio of moisture removal to cooling capacity provided by the equipment. 

Sound Traps/Sound Attenuators .... An assembly of structures through which the supply air passes before leaving the equipment or through 

which the return air from the building passes immediately after entering the equipment for which the 

sound insertion loss is at least 6 dB for the 125 Hz octave band frequency range. 

Steam/Hydronic Heat Coils ............. Coils used to provide supplemental heating. 

Ventilation Energy Recovery System (VERS).An assembly that preconditions outdoor air entering the equipment through direct or indirect thermal and/or 

moisture exchange with the exhaust air, which is defined as the building air being exhausted to the outside from the equipment. 

Waterside Economizer .................... A heat exchanger located upstream of the indoor coil that conditions the supply air when system water 

loop conditions are favorable so as not to utilize compressor operation. 

(B) The represented value of cooling 

capacity must be between 95 percent 

and 100 percent of the mean of the 

cooling capacities measured for the 

units in the sample selected as 

described in paragraph (a)(1)(ii) of this 

section, or between 95 percent and 100 

percent of the cooling capacity output 

simulated by the AEDM as described in 

paragraph (a)(2) of this section. 

* * * * * 


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84228 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

■ 4. Amend § 429.134 by adding 

paragraph (dd) to read as follows: 

§ 429.134 Product-specific enforcement 

provisions. 

* * * * * 

(dd) Water-Source Heat Pumps. The 

following provisions apply for 

assessment and enforcement testing of 

models subject to standards in terms of 

IEER and ACOP. 

(1) Verification of Cooling Capacity. 

The cooling capacity of each tested unit 

of the basic model will be measured 

pursuant to the test requirements of 

appendix C1 to subpart F of 10 CFR part 

431. The mean of the measurements will 

be used to determine the applicable 

standards for purposes of compliance. 

(2) Specific Components. If a basic 

model includes individual models with 

components listed at table 6 to 

§ 429.43(a)(3)(v)(A) and DOE is not able 

to obtain an individual model with the 

least number (which could be zero) of 

those components within an otherwise 

comparable model group (as defined in 

§ 429.43(a)(3)(v)(A)(1)), DOE may test 

any individual model within the 

otherwise comparable model group. 

PART 431—ENERGY EFFICIENCY 

PROGRAM FOR CERTAIN 

COMMERCIAL AND INDUSTRIAL 

EQUIPMENT 

■ 5. The authority citation for part 431 

continues to read as follows: 

Authority: 42 U.S.C. 6291–6317; 28 U.S.C. 

2461 note. 

■ 6. Amend § 431.92 by: 

■ a. Adding in alphabetical order a 

definition of ‘‘Applied Coefficient of 

performance, or ACOP’’; and 

■ b. Revising the definitions of 

‘‘Integrated energy efficiency ratio, or 

IEER,’’ and ‘‘Water-source heat pump’’. 

The addition and revisions read as 

follows: 

§ 431.92 Definitions concerning 

commercial air conditioners and heat 

pumps. 

* * * * * 

Applied Coefficient of performance, 

or ACOP means the ratio of the heating 

capacity to the power input, including 

system pump power, for water-source 

heat pumps. ACOP is expressed in watts 

per watt and determined according to 

appendix C1 of this subpart. 

* * * * * 

Integrated energy efficiency ratio, or 

IEER, means a weighted average 

calculation of mechanical cooling EERs 

determined for four load levels and 

corresponding rating conditions, 

expressed in Btu/watt-hour. IEER is 

measured: 

(1) Per appendix A to this subpart for 

air-cooled small (≥65,000 Btu/h), large, 

and very large commercial package air 

conditioning and heating equipment; 

(2) Per appendix C1 to this subpart for 

water-source heat pumps; 

(3) Per appendix D1 to this subpart for 

variable refrigerant flow multi-split air 

conditioners and heat pumps (other 

than air-cooled with rated cooling 

capacity less than 65,000 Btu/h); and 

(4) Per appendix G1 to this subpart for 

single package vertical air conditioners 

and single package vertical heat pumps. 

* * * * * 

Water-source heat pump means 

commercial package air-conditioning 

and heating equipment that is a singlephase or three-phase reverse-cycle heat 

pump that uses a circulating water loop 

as the heat source for heating and as the 

heat sink for cooling. The main 

components are a compressor, 

refrigerant-to-water heat exchanger, 

refrigerant-to-air heat exchanger, 

refrigerant expansion devices, 

refrigerant reversing valve, and indoor 

fan (except that coil-only units do not 

include an indoor fan). Such equipment 

includes, but is not limited to, water-toair water-loop heat pumps. 

■ 7. Amend § 431.95 by: 

■ a. Redesignating paragraphs (b)(6) 

through (10) as paragraphs (b)(7) 

through (11); 

■ b. Adding new paragraph (b)(6); 

■ c. In paragraph (c)(2), removing the 

text ‘‘B, D1’’ and adding, in its place, the 

text ‘‘B, C1, D1’’; 

■ d. In paragraph (c)(3), removing the 

text ‘‘appendix D1’’ and adding, in its 

place, the text ‘‘appendices C1 and D1’’; 

■ e. Revising paragraph (d); and 

■ f. Adding paragraph (e). 

The additions and revision read as 

follows: 

§ 431.95 Materials incorporated by 

reference. 

* * * * * 

(b) * * * 

(6) AHRI Standard 600–2023 (I–P) 

(‘‘AHRI 600–2023’’), 2023 Standard for 

Performance Rating of Water/Brine to 

Air Heat Pump Equipment, AHRIapproved September 11, 2023; IBR 

approved for appendix C1 to this 

subpart. 

* * * * * 

(d) IIR. International Institute of 

Refrigeration, 177 Boulevard 

Malesherbes 75017 Paris, France; +33 

(0)1 42 27 32 35; www.iifiir.org. 

(1) Properties of Secondary Working 

Fluids for Indirect Systems, including 

Section 2.3 Errata Sheet, Melinder, 

published 2010 (‘‘Melinder 2010’’), IBR 

approved for appendix C1 to this 

subpart. 

(2) [Reserved] 

(e) ISO. International Organization for 

Standardization, Chemin de Blandonnet 

8, CP 401, 1214 Vernier, Geneva, 

Switzerland; +41 22 749 01 11; 

www.iso.org/store.html. 

(1) ISO Standard 13256–1 (‘‘ISO 

13256–1:1998’’), ‘‘Water-source heat 

pumps—Testing and rating for 

performance—Part 1: Water-to-air and 

brine-to-air heat pumps,’’ approved 

1998; IBR approved for appendix C to 

this subpart. 

(2) [Reserved] 

* * * * * 

■ 8. Amend § 431.96 by revising table 1 

to paragraph (b) to read as follows: 

§ 431.96 Uniform test method for the 

measurement of energy efficiency of 

commercial air conditioners and heat 

pumps. 

* * * * * 

(b) * * * 

TABLE 1 TO PARAGRAPH (b)—TEST PROCEDURES FOR COMMERCIAL AIR CONDITIONERS AND HEAT PUMPS

Equipment type Category 

Cooling capacity or 

moisture removal 

capacity 2

Energy efficiency 

descriptor 

Use tests, conditions, 

and procedures in 

Additional test 

procedure 

provisions as 

indicated in the 

listed 

paragraphs 

of this section 

Small Commercial 

Package Air-Conditioning and Heating 

Equipment.

Air-Cooled, 3-Phase, 

AC and HP.

<65,000 Btu/h ............. SEER and HSPF ........ Appendix F to this 

subpart 3.

None. 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84229 

TABLE 1 TO PARAGRAPH (b)—TEST PROCEDURES FOR COMMERCIAL AIR CONDITIONERS AND HEAT PUMPS—Continued 

Equipment type Category 

Cooling capacity or 

moisture removal 

capacity 2

Energy efficiency 

descriptor 

Use tests, conditions, 

and procedures in 

Additional test 

procedure 

provisions as 

indicated in the 

listed 

paragraphs 

of this section 

SEER2 and HSPF2 .... Appendix F1 to this 

subpart 3.

None. 

Air-Cooled AC and HP ≥65,000 Btu/h and 

<135,000 Btu/h.

EER, IEER, and COP Appendix A to this 

subpart.

None. 

Water-Cooled and 

EvaporativelyCooled AC.

<65,000 Btu/h ............. EER ............................ AHRI 210/240–2008 1

(omit section 6.5).

Paragraphs (c) 

and (e). 

EER ............................ AHRI 340/360–2007 1

(omit section 6.3).

Paragraphs (c) 

and (e). 

Water-Source HP ....... <135,000 Btu/h ........... EER and COP ............ Appendix C to this 

subpart 3.

None. 

Water-Source HP ....... <135,000 Btu/h ........... IEER and ACOP ......... Appendix C1 to this 

subpart 3.

None. 

Large Commercial 

Package Air-Conditioning and Heating 

Equipment.

Air-Cooled AC and HP ≥135,000 Btu/h and 

<240,000 Btu/h.

EER, IEER and COP .. Appendix A to this 

subpart.

None. 

Water-Cooled and 

EvaporativelyCooled AC.

≥135,000 Btu/h and 

<240,000 Btu/h.

EER ............................ AHRI 340/360–2007 1

(omit section 6.3).

Paragraphs (c) 

and (e). 

Water-Source HP ....... ≥135,000 Btu/h and 

<240,000 Btu/h.

EER and COP ............ Appendix C to this 

subpart 3.

None. 

Water-Source HP ....... ≥135,000 Btu/h and 

<240,000 Btu/h.

IEER and ACOP ......... Appendix C1 to this 

subpart 3.

None. 

Very Large Commercial 

Package Air-Conditioning and Heating 

Equipment.

Air-Cooled AC and HP ≥240,000 Btu/h and 

<760,000 Btu/h.

EER, IEER and COP .. Appendix A to this 

subpart.

None. 

Water-Cooled and 

EvaporativelyCooled AC.

≥240,000 Btu/h and 

<760,000 Btu/h.

EER ............................ AHRI 340/360–2007 1

(omit section 6.3).

Paragraphs (c) 

and (e). 

Water-Source HP ....... ≥240,000 Btu/h and 

<760,000 Btu/h.

EER and COP ............ Appendix C to this 

subpart 3.

None. 

Water-Source HP ....... ≥240,000 Btu/h and 

<760,000 Btu/h.

IEER and ACOP ......... Appendix C1 to this 

subpart 3.

None. 

Packaged Terminal Air 

Conditioners and 

Heat Pumps.

AC and HP ................. <760,000 Btu/h ........... EER and COP ............ Paragraph (g) of this 

section.

Paragraphs (c), 

(e), and (g). 

Computer Room Air 

Conditioners.

AC ............................... <760,000 Btu/h ........... SCOP .......................... Appendix E to this 

subpart 3.

None. 

<760,000 Btu/h or 

<930,000 Btu/h 4.

NSenCOP ................... Appendix E1 to this 

subpart 3.

None. 

Variable Refrigerant 

Flow Multi-split Systems.

AC ............................... <65,000 Btu/h (3- 

phase).

SEER .......................... Appendix F to this 

subpart 3.

None. 

SEER2 ........................ Appendix F1 to this 

subpart 3.

None. 

Variable Refrigerant 

Flow Multi-split Systems, Air-cooled.

HP ............................... <65,000 Btu/h (3- 

phase).

SEER and HSPF ........ Appendix F to this 

subpart 3.

None. 

SEER2 and HSPF2 .... Appendix F1 to this 

subpart 3.

None. 

Variable Refrigerant 

Flow Multi-split Systems, Air-cooled.

AC and HP ................. ≥65,000 Btu/h and 

<760,000 Btu/h.

EER and COP ............ Appendix D to this 

subpart 3.

None. 

IEER and COP ........... Appendix D1 to this 

subpart 3.

None. 

Variable Refrigerant 

Flow Multi-split Systems, Water-source.

HP ............................... <760,000 Btu/h ........... EER and COP ............ Appendix D to this 

subpart 3.

None. 

IEER and COP ........... Appendix D1 to this 

subpart 3.

None. 

Single Package Vertical 

Air Conditioners and 

Single Package 

Vertical Heat Pumps.

AC and HP ................. <760,000 Btu/h ........... EER and COP ............ Appendix G to this 

subpart 3.

None. 


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84230 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

TABLE 1 TO PARAGRAPH (b)—TEST PROCEDURES FOR COMMERCIAL AIR CONDITIONERS AND HEAT PUMPS—Continued 

Equipment type Category 

Cooling capacity or 

moisture removal 

capacity 2

Energy efficiency 

descriptor 

Use tests, conditions, 

and procedures in 

Additional test 

procedure 

provisions as 

indicated in the 

listed 

paragraphs 

of this section 

EER, IEER, and COP Appendix G1 to this 

subpart 3.

None. 

Direct Expansion-Dedicated Outdoor Air 

Systems.

All ................................ <324 lbs. of moisture 

removal/hr.

ISMRE2 and ISCOP2 Appendix B to this 

subpart.

None. 

1 Incorporated by reference; see § 431.95. 

2 Moisture removal capacity applies only to direct expansion-dedicated outdoor air systems. 

3For equipment with multiple appendices listed in this Table 1, consult the notes at the beginning of those appendices to determine the applicable appendix to use for testing. 4For upflow ducted and downflow floor-mounted computer room air conditioners, the test procedure in appendix E1 of this subpart applies to 

equipment with net sensible cooling capacity less than 930,000 Btu/h. For all other configurations of computer room air conditioners, the test procedure in appendix E1 applies to equipment with net sensible cooling capacity less than 760,000 Btu/h. 

* * * * * 

■ 9. Add appendix C to subpart F of part 

431 to read as follows: 

Appendix C to Subpart F of Part 431— 

Uniform Test Method for Measuring the 

Energy Consumption of Water-Source 

Heat Pumps 

Note: Manufacturers must use the results of 

testing under this appendix to determine 

compliance with the relevant standard at 

§ 431.97 as that standard appeared in the 

January 1, 2023 edition of 10 CFR parts 200– 

499. Specifically, representations must be 

based on testing according to either this 

appendix or 10 CFR 431.96 as it appeared in 

the 10 CFR parts 200–499 edition revised as 

of January 1, 2023. 

Starting on November 29, 2024, voluntary 

representations with respect to energy use or 

efficiency of water-source heat pumps with 

cooling capacity greater than or equal to 

135,000 Btu/h and less than 760,000 Btu/h 

must be based on testing according to this 

appendix. Manufacturers may also use this 

appendix to make voluntary representations 

with respect to energy use or efficiency prior 

to November 29, 2024. 

Starting on November 29, 2024, voluntary 

representations with respect to the integrated 

energy efficiency ratio (IEER) and applied 

coefficient of performance (ACOP) of watersource heat pumps must be based on testing 

according to appendix C1 of this subpart. 

Manufacturers may also use appendix C1 to 

make voluntary representations with respect 

to IEER and ACOP prior to November 29, 

2024. 

Starting on the compliance date for any 

amended energy conservation standards for 

water-source heat pumps based on IEER and 

ACOP, any representations, including 

compliance certifications, made with respect 

to the energy use or energy efficiency of 

water-source heat pumps must be based on 

testing according to appendix C1 of this 

subpart. 

Manufacturers may also certify compliance 

with any amended energy conservation 

standards for water-source heat pumps based 

on IEER and ACOP prior to the applicable 

compliance date for those standards, and 

those compliance certifications must be 

based on testing according to appendix C1 of 

this subpart. 

1. Incorporation by Reference 

DOE incorporated by reference in 

§ 431.95, the entire standard for ISO 

13256–1:1998. To the extent there is a 

conflict between the terms or provisions 

of a referenced industry standard and 

this appendix, the appendix provisions 

control. 

2. General 

Determine the energy efficiency ratio 

(EER) and coefficient of performance 

(COP) in accordance with ISO 13256– 

1:1998. 

Section 3 of this appendix provides 

additional instructions for determining 

EER and COP. 

3. Additional Provisions for Equipment 

Set-Up 

The only additional specifications 

that may be used in setting up the basic 

model for testing are those set forth in 

the installation and operation manual 

shipped with the unit. Each unit should 

be set up for test in accordance with the 

manufacturer installation and operation 

manuals. Sections 3.1 through 3.2 of 

this appendix provide specifications for 

addressing key information typically 

found in the installation and operation 

manuals. 

3.1. If a manufacturer specifies a range 

of superheat, sub-cooling, and/or 

refrigerant pressure in its installation 

and operation manual for a given basic 

model, any value(s) within that range 

may be used to determine refrigerant 

charge or mass of refrigerant, unless the 

manufacturer clearly specifies a rating 

value in its installation and operation 

manual, in which case the specified 

rating value must be used. 

3.2. The airflow rate used for testing 

must be that set forth in the installation 

and operation manuals being shipped to 

the commercial customer with the basic 

model and clearly identified as that 

used to generate the DOE performance 

ratings. If a rated airflow value for 

testing is not clearly identified, a value 

of 400 standard cubic feet per minute 

(scfm) per ton must be used. 

■ 10. Add appendix C1 to subpart F of 

part 431 to read as follows: 

Appendix C1 to Subpart F of Part 431— 

Uniform Test Method for Measuring the 

Energy Consumption of Water-Source 

Heat Pumps 

Note: Prior to the compliance date of 

amended standards for water-source heat 

pumps that rely on integrated energy 

efficiency ratio (IEER) and applied coefficient 

of performance (ACOP) published after 

January 1, 2023, representations with respect 

to the energy use or energy efficiency of 

water-source heat pumps, including 

compliance certifications, must be based on 

testing according to appendix C of this 

subpart. 

Starting on November 29, 2024, voluntary 

representations with respect to the IEER and 

ACOP of water-source heat pumps must be 

based on testing according to this appendix. 

Manufacturers may also use this appendix to 

make voluntary representations with respect 

to IEER and ACOP prior to November 29, 

2024. 

Starting on the compliance date for any 

amended energy conservation standards for 

water-source heat pumps based on IEER and 

ACOP, any representations, including 

compliance certifications, made with respect 

to the energy use or energy efficiency of 

water-source heat pumps must be based on 

testing according to this appendix. 

Manufacturers may also certify compliance 

with any amended energy conservation 

standards for water-source heat pumps based 

on IEER and ACOP prior to the applicable 

compliance date for those standards, and 


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Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 84231 

those compliance certifications must be 

based on testing according to this appendix. 

1. Incorporation by Reference 

DOE incorporated by reference in 

§ 431.95 the entire standards for AHRI 

600–2023, ANSI/ASHRAE 37–2009 (as 

corrected by the Errata sheet for ANSI/ 

ASHRAE 37–2009), and Melinder 2010. 

However, certain enumerated provisions 

of AHRI 600–2023 and ASHRAE 37– 

2009, as listed in this section 1, are 

inapplicable. 

To the extent there is a conflict 

between the terms or provisions of a 

referenced industry standard and the 

CFR, the CFR provisions control. 

1.1. AHRI 600–2023 

(a) Section 1 Purpose is inapplicable, 

(b) Section 2 Scope is inapplicable, 

(c) The following subsections of 

section 3 Definitions are inapplicable: 

(1) 3.2.1 (Air Economizer), 

(2) 3.2.3 (Barometric Relief Dampers), 

(3) 3.2.4 (Basic Model), 

(4) 3.2.5 (Coated Coils), 

(5) 3.2.6 (Coefficients of Performance), 

(6) 3.2.9 (Condenser Pump/Valves/ 

Fittings), 

(7) 3.2.10 (Condenser Water Reheat), 

(8) 3.2.13 (Desiccant 

Dehumidification Components), 

(9) 3.2.14 (Desuperheater), 

(10) 3.2.15.1 (Energy Efficiency Ratio), 

(11) 3.2.16 (Evaporative Cooling of 

Ventilation Air), 

(12) 3.2.17 (Fire/Smoke/Isolation 

Dampers), 

(13) 3.2.19 (Fresh Air Dampers), 

(14) 3.2.21 (Grill Options), 

(15) 3.2.23 (High-effectiveness Indoor 

Air Filtration), 

(16) 3.2.24 (Hot Gas Bypass), 

(17) 3.2.27 (Integrated Energy 

Efficiency Ratio), 

(18) 3.2.28 (Low-static Heat Pump), 

(19) 3.2.35 (Power Correction 

Capacitors), 

(20) 3.2.36 (Powered Exhaust Air 

Fan), 

(21) 3.2.37 (Powered Return Air Fan), 

(22) 3.2.38 (Process Heat Recovery/ 

Reclaim Coils/Thermal Storage), 

(23) 3.2.40 (Published Rating), 

(24) 3.2.42 (Refrigerant Reheat Coils), 

(25) 3.2.43 (Single Package Heat 

Pumps), 

(26) 3.2.44 (Sound Traps/Sound 

Attenuators), 

(27) 3.2.45 (Split System Heat Pump), 

(28) 3.2.51 (Steam/Hydronic Heat 

Coils), 

(29) 3.2.53 (UV Lights), 

(30) 3.2.54 (Ventilation Energy 

Recovery System), 

(31) 3.2.55 (Water/Brine to Air Heat 

Pump Equipment), and 

(32) 3.2.56 (Waterside Economizer), 

(d) The following subsections of 

section 6 Rating Requirements are 

inapplicable: 

(1) 6.5 (Residential Cooling Capacity 

and Efficiency), 

(2) 6.6 (Residential Heating Capacity 

and Efficiency), 

(3) 6.7 (Test Data vs Computer 

Simulation), 

(4) 6.8 (Rounding and Precision), 

(5) 6.9 (Uncertainty), and 

(6) 6.10 (Verification Testing), 

(e) Section 7 Minimum Data 

Requirements for Published Ratings is 

inapplicable 

(f) Section 8 Operating Requirements 

is inapplicable, 

(g) Section 9 Marking and Nameplate 

Data is inapplicable, 

(h) Section 10 Conformance 

Conditions is inapplicable, 

(i) Appendix B References— 

Informative is inapplicable, 

(j) Sections D.1 (Purpose), D.2 

(Configuration Requirements), and D.3 

(Optional System Features) of Appendix 

D Unit Configuration For Standard 

Efficiency Determination—Normative 

are inapplicable, and 

(k) Appendix F Example of 

Determination of Fan and Motor 

Efficiency for Non-standard Integrated 

Indoor Fan and Motors—Informative is 

inapplicable. 

1.2. ANSI/ASHRAE 37–2009 (Even if 

Corrected by the Errata Sheet) 

(a) Section 1 Purpose is inapplicable. 

(b) Section 2 Scope is inapplicable. 

(c) Section 4 Classification is 

inapplicable. 

2. General 

Determine integrated energy 

efficiency ratio (IEER) and heating 

applied coefficient of performance 

(ACOP) in accordance with this 

appendix and the applicable sections of 

AHRI 600–2023, ANSI/ASHRAE 37– 

2009, and Melinder 2010. 

Representations of AEER, EER, and COP 

may optionally be made. 

Section 3 of this appendix provides 

additional instructions for testing. In 

cases where there is a conflict, the 

language of this appendix takes highest 

precedence, followed by AHRI 600– 

2023, followed by ANSI/ASHRAE 37– 

2009. Any subsequent amendment to a 

referenced document by the standardsetting organization will not affect the 

test procedure in this appendix, unless 

and until the test procedure is amended 

by DOE. Material is incorporated as it 

exists on the date of the approval, and 

a notification of any change in the 

incorporation must be published in the 

Federal Register. 

3. Setup and Test Provisions for Specific 

Components 

When testing a water-source heat 

pump that includes any of the features 

listed in table 1 to this appendix, test in 

accordance with the setup and test 

provisions specified in table 1 to this 

appendix. 

TABLE 1 TO APPENDIX C1—SETUP AND TEST PROVISIONS FOR SPECIFIC COMPONENTS

Component Description Setup and test provisions 

Air Economizers ................... An automatic system that enables a cooling system to 

supply outdoor air to reduce or eliminate the need for 

mechanical cooling during mild or cold weather.

For any air economizer that is factory-installed, place 

the economizer in the 100 percent return position 

and close and seal the outside air dampers for testing. For any modular air economizer shipped with the 

unit but not factory-installed, do not install the economizer for testing. 

Barometric Relief Dampers .. An assembly with dampers and means to automatically 

set the damper position in a closed position and one 

or more open positions to allow venting directly to the 

outside a portion of the building air that is returning 

to the unit, rather than allowing it to recirculate to the 

indoor coil and back to the building.

For any barometric relief dampers that are factory-installed, close and seal the dampers for testing. For 

any modular barometric relief dampers shipped with 

the unit but not factory-installed, do not install the 

dampers for testing. 

Desiccant Dehumidification 

Components.

An assembly that reduces the moisture content of the 

supply air through moisture transfer with solid or liquid desiccants.

Disable desiccant dehumidification components for testing. 


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84232 Federal Register / Vol. 88, No. 231 / Monday, December 4, 2023 / Rules and Regulations 

TABLE 1 TO APPENDIX C1—SETUP AND TEST PROVISIONS FOR SPECIFIC COMPONENTS—Continued 

Component Description Setup and test provisions 

Fire/Smoke/Isolation 

Dampers.

A damper assembly including means to open and close 

the damper mounted at the supply or return duct 

opening of the equipment.

For any fire/smoke/isolation dampers that are factoryinstalled, set the dampers in the fully open position 

for testing. For any modular fire/smoke/isolation 

dampers shipped with the unit but not factory-installed, do not install the dampers for testing. 

Fresh Air Dampers ............... An assembly with dampers and means to set the 

damper position in a closed and one open position to 

allow air to be drawn into the equipment when the indoor fan is operating.

For any fresh air dampers that are factory-installed, 

close and seal the dampers for testing. For any modular fresh air dampers shipped with the unit but not 

factory-installed, do not install the dampers for testing. 

Power Correction Capacitors A capacitor that increases the power factor measured 

at the line connection to the equipment.

Remove power correction capacitors for testing. 

Process Heat recovery/Reclaim Coils/Thermal Storage.A heat exchanger located inside the unit that conditions 

the equipment’s supply air using energy transferred 

from an external source using a vapor, gas, or liquid.

Disconnect the heat exchanger from its heat source for 

testing. 

Refrigerant Reheat Coils ..... A heat exchanger located downstream of the indoor 

coil that heats the supply air during cooling operation 

using high-pressure refrigerant in order to increase 

the ratio of moisture removal to cooling capacity provided by the equipment.

De-activate refrigerant reheat coils for testing so as to 

provide the minimum (none if possible) reheat 

achievable by the system controls. 

Steam/Hydronic Heat Coils .. Coils used to provide supplemental heating ................... Test with steam/hydronic heat coils in place but providing no heat. 

UV Lights ............................. A lighting fixture and lamp mounted so that it shines 

light on the indoor coil, that emits ultraviolet light to 

inhibit growth of organisms on the indoor coil surfaces, the condensate drip pan, and/other locations 

within the equipment.

Turn off UV lights for testing. 

Ventilation Energy Recovery 

System (VERS).

An assembly that preconditions outdoor air entering the 

equipment through direct or indirect thermal and/or 

moisture exchange with the exhaust air, which is defined as the building air being exhausted to the outside from the equipment.

For any VERS that is factory-installed, place the VERS 

in the 100 percent return position and close and seal 

the outside air dampers and exhaust air dampers for 

testing, and do not energize any VERS subcomponents (e.g., energy recovery wheel motors). For any 

VERS module shipped with the unit but not factoryinstalled, do not install the VERS for testing. 

[FR Doc. 2023–25921 Filed 12–1–23; 8:45 am] 

BILLING CODE 6450–01–P 


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