May 27, 2008 

Mr. Michael G. Raymond 

U.S. Department of Energy 

Building Technology Program, Mail-stop EE-2J 

1000 Independence Avenue, SW 

Washington, DC 20585-0121 

Re: Proposed Technical Corrections to “Energy Conservation Program for 

Consumer Products: Test Procedures for Central Air Conditioners and Heat 

Pumps, Federal Register Notice 72FR59906” 

Dear Mr. Raymond: 

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) requests, 

though this submission, that several amendments be made to the test 

procedures for central air conditioners and heat published in the Federal Register 

Notice on October 22, 2007 (72FR59906). After further review of the test 

procedures, we believe that clarifications as well as corrections to the test 

procedures are necessary to ensure that central air conditioners and heat pumps 

are properly and accurately tested. More specifically, we have the following 

suggestions: 

General

Throughout the text the term “capacity” should be referred to as “nominal cooling 

capacity”. This correction is necessary to clarify that the test procedures are 

based on the cooling (vs. heating) capacity of the equipment, and to recognize 

that nominal means the cooling capacity of the system at 95 F ambient, 80/67 F 

indoor conditions. 

Tested Combination

The definition of “Tested combination” in 10 CFR 430.2 should be amended to 

clarify that if the system has a capacity of 24,000 Btu/h or less, the 50% rule for 

any one unit does not apply. With smaller systems less than 24,000 Btu/h, it is 

difficult to comply with the range 95-105 % of nominal cooling capacity and at the 

same time meet the requirement that one unit cannot be greater than 50% of the 

nominal cooling capacity system. For example, Manufacturer A has a nominal 

cooling capacity of 20,000 Btu/h. The available indoor units are 9,000 and 12,000 

Btu/h. Two 9,000 Btu/h units would be less than 95% and a 9,000 and 12,000 

Btu/h within 105%; however, the 12,000 Btu/h is more than 50% of the nominal 

cooling capacity. 

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AHRI Proposed Corrections – Federal Test Procedures for Central Air Conditioners and Heat Pumps 

May 27, 2008 

Page 2 of 5 

In addition, we recommend that the number of connected indoor units 

requirements in the tested combination definition for multi-splits be amended to 

allow the use of up to eight (8) non-ducted units to reach nominal capacity. Nonducted variable refrigerant flow (VRF) system indoor units typically have a 

nominal cooling capacity threshold of up to 36,000 Btu/h for ceiling cassettes and 

30,000 Btu/h for wall-mounted, and therefore, additional units are needed to 

reach capacities of up to 300,000 Btu/h. It is the industry experience that testing 

more than three (3) ceiling cassettes is impractical. AHRI recognizes that this 

capacity is beyond the cooling capacity limit of 65,000 Btu/h for residential central 

air conditioners but many manufacturers have been granted waivers in which this 

tested combination definition applies. This clarification is needed in order to fulfill 

the testing requirements of non-ducted combinations. 

Therefore the revised definition for “Tested combination” would read as follows 

(suggested changes are underlined and italicized in blue below): 

“Tested combination means a multi-split system with multiple indoor coils 

having the following features: 

(1) The basic model of a system used as a tested combination shall 

consist of one outdoor unit, with one or more compressors, that is 

matched with between 2 and 5 indoor units (for systems with nominal 

cooling capacities greater than 150,000 Btu/h, the number of indoor units 

may be as high as 8 to be able to test non-ducted indoor unit 

combinations); for multi-split systems, each of these indoor units shall be 

designed for individual operation. 

(2) The indoor units shall— 

(i) Represent the highest sales model family, or another indoor model 

family if the highest sales model family does not provide sufficient 

capacity (see ii); 

 (ii) Together, have a nominal cooling capacity that is between 95% 

and 105% of the nominal cooling capacity of the outdoor unit; 

(iii) Not, individually, have a nominal cooling capacity that is greater 

than 50% of the nominal capacity of the outdoor unit, unless the 

nominal cooling capacity of the outdoor unit is 24,000 Btu/h or less;

(iv) Operate at fan speeds that are consistent with the manufacturer’s 

specifications; and 

(v) All be subject to the same minimum external static pressure 

requirement (i.e., 0 inches of water column for non-ducted, see Table 

2 in Appendix M to Subpart B of this part for ducted indoor units) 

while being configurable to produce the same static pressure at the 

exit of each outlet plenum when manifolded as per section 2.4.1 of 

Appendix M. 

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AHRI Proposed Corrections – Federal Test Procedures for Central Air Conditioners and Heat Pumps 

May 27, 2008 

Page 3 of 5 

Minimum External Static Pressure

As discussed with DOE staff in our meeting last November 2007, many ductless

manufacturers have “ducted” indoor units that are intended for minimum (less 

than a few feet) or no duct runs and as a result have a rated external static 

pressure capability of less than 0.10 ESP and usually around 0.02 ESP. AHRI is 

suggesting the amend Table 2 by adding a new footnote 6 (see below). AHRI 

intends to add the same footnote in Table 5 of ARI Standard 1230. 

TABLE 2.—MINIMUM EXTERNAL STATIC PRESSURE FOR DUCTED SYSTEMS TESTED WITH AN INDOOR 

FAN INSTALLED

Minimum external resistance3

(Inches of water)

Rated Cooling1 or Heating2

 Capacity 

(Btu/h)

All other systems6 Small-duct, high 

velocity\systems4,5 

Up Thru 28,800.............................................................................................. 

29,000 to 42,500........................................................................................... 

43,000 and Above.........................................................................................

0.10 

0.15

0.20

1.10 

1.15

1.20

1 For air conditioners and heat pumps, the value cited by the manufacturer in published literature for the unit’s capacity 

when operated at the A or A2 Test conditions.

2 For heating-only heat pumps, the value the manufacturer cites in published literature for the unit’s capacity when 

operated at the H1 or H12Test conditions.

3 For ducted units tested without an air filter installed, increase the applicable tabular value by 0.08 inch of water. 

4 See Definition 1.35 to determine if the equipment qualifies as a small-duct, high-velocity system. 

5 If a closed-loop, air-enthalpy test apparatus is used on the indoor side, limit the resistance to airflow on the inlet side of 

the indoor blower coil to a maximum value of 0.1 inch of water. Impose the balance of the airflow resistance on the outlet 

side of the indoor blower 

6 If the manufacturer’s rated external static pressure is less than 0.10 in H2O (25 pa) then the indoor unit should be tested 

at that rated external static pressure.

Proposed changes to Section 3.1.4.1.1

The combination of newer constant torque motor technology and barometric 

pressure effects (especially between most manufacturing facilities and ITS’s 

main facility in Cortland, New York) causes the new 5 percent tolerance on air 

volume rate to be marginal with regard to achieving the desired goal: obtaining 

the same equipment set-up regardless of the location of the test facility and 

regardless of which unit of a particular model type is selected for testing (i.e, 

account for manufacturing tolerances and have the equipment setup not change 

due to barometric effects). 

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AHRI Proposed Corrections – Federal Test Procedures for Central Air Conditioners and Heat Pumps 

May 27, 2008 

Page 4 of 5 

The 5 percent tolerance is not special. It was selected based on the consensus 

that it was large enough to capture these two effects while having an insignificant 

effect on capacity and efficiency. Admittedly, most of the experience at the time 

of this 5 percent selection was with PSC motors (FYI: ECM motors are not 

subject to this tolerance). For a given speed tap, the air volume rate achieved 

using a constant torque motors is comparatively more variable; also, the change 

in power draw as a function of an incremental change in the speed tap is also 

comparatively greater so the impact on efficiency will be more pronounced if the 

tests are conducted on two different units where, because of the set-up algorithm, 

they end up at different speed tap settings. 

 

Another detail learned since the publication of the October 22, 2007 Federal 

Register notice is that some indoor units implement more than a motor 

configuration change when changing the speed tap setting. As an example, 

some speed tap settings may equate to a specific duration of fan delay whereas 

other settings may translate to no fan delay. Thus, the test procedure should 

clarify that when a speed tap change is conducted in accordance with the 

specified DOE equipment set-up algorithm, that it be conducted in an incremental 

process among speed taps that yield the same operating features. 

The proposed modifications to Section 3.1.4.1.1 of the DOE Test Procedure are 

shown below in blue strikeout and underline.

3.1.4.1.1 Cooling Full-Load Air Volume Rate for Ducted Units. The 

manufacturer must specify the Cooling Full-load Air Volume Rate. Use this 

value as long as the following two requirements are satisfied. First, when 

conducting the A or A2 Test (exclusively), the measured air volume rate, 

when divided by the measured indoor air-side total cooling capacity must 

not exceed 37.5 cubic feet per minute of standard air (scfm) per 1000 Btu/h. 

If this ratio is exceeded, reduce the air volume rate until this ratio is equaled. 

Use this reduced air volume rate for all tests that call for using the Cooling 

Full-load Air Volume Rate. The second requirement is as follows: 

 a. For all ducted units tested with an indoor fan installed, except those 

having a variable-speed, constant-air-volume-rate indoor fan. The 

second requirement applies exclusively to the A or A2 Test and is met 

as follows. 

1. Achieve the Cooling Full-load Air Volume Rate, determined in 

accordance with the previous paragraph; 

2. Measure the external static pressure; 

3. If this pressure is equal to or greater than the applicable 

minimum external static pressure cited in Table 2, this second 

requirement is satisfied. Use the current air volume rate for all 

tests that require the Cooling Full-load Air Volume Rate. 

4. If the Table 2 minimum is not equaled or exceeded, 

4a. reduce the air volume rate until the applicable Table 2 

minimum is equaled or 

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 EE-RM/TP-02-002 COMMENT 27
AHRI Proposed Corrections – Federal Test Procedures for Central Air Conditioners and Heat Pumps 

May 27, 2008 

Page 5 of 5 

4b. until the measured air volume rate equals 950 percent of the 

air volume rate from step 1, whichever occurs first. 

5. If the conditions of step 4a occur first, this second requirement 

is satisfied. Use the step 4a reduced air volume rate for all tests 

that require the Cooling Full-load Air Volume Rate. 

6. If the conditions of step 4b occur first, make an incremental 

change to the set-up of the indoor fan (e.g., next highest fan 

motor pin setting, next highest fan motor speed) that otherwise 

maintains the operating features (e.g, fan delay is not toggled 

off or on) and repeat the evaluation process beginning at above 

step 1. If the indoor fan set-up cannot be further changed, 

reduce the air volume rate until the applicable Table 2 minimum 

is equaled. Use this reduced air volume rate for all tests that 

require the Cooling Full-load Air Volume Rate. 

b. For ducted units that are tested with a variable-speed, constant-airvolume-rate indoor fan installed. 

* * * 

We sincerely hope that the above clarifications and proposed modifications to the 

DOE test procedures will be taken into consideration. Given the significance of 

these proposed changes, AHRI urges DOE to issue a technical amendment to 

the test procedures as soon as possible. If you have any questions regarding 

this submission, please feel free to contact me. 

Sincerely, 

Karim Amrane 

Vice President, Regulatory & Research 

Tel: 703/524-8800 ext.307 

Email: kamrane@ahrinet.org

 

Cc: Wes Anderson, DOE 

 Ron Lewis, DOE 

 Brian Dougherty, NIST 

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