May 27, 2008

Mr. Michael G. Raymond U.S. Department of Energy Building Technology Pr ogram, 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 fo r Central Air Conditioners and Heat Pumps, Federal Register Notice 72FR59906”

Dear Mr. Raymond:

The Air-Conditioning, Heating, and Refr igeration Institute (A HRI) requests, though this submission, that severa l 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 conditi oners and heat pumps are properly and accurately tested. More specifically, we have the following suggestions:

General

Throughout the text the term “capacity” s hould be referred to as “nominal cooling capacity”. This correction is necessary to clarify that the test procedures are based on the cooling (vs. heating) capacit y of the equipment, and to recognize

that nominal means the coo ling 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 syste m 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 require ment that one unit cannot be greater than 50% of the nominal cooling capacity system. For ex ample, Manufacturer A has a nominal cooling capacity of 20,000 Btu/h. The av ailable 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.AHRI Proposed Corrections – Federal Test Proce dures 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-duct ed 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-mount ed, and therefore, additi onal units are needed to reach capacities of up to 300,000 Btu/h. It is the industr y experience that testing more than three (3) ceiling cassettes is impractical. AHRI recognizes that this capacity is beyond the cooli ng capacity limit of 65,000 Btu/h for re sidential 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 “Test ed combination” would read as follows (suggested changes are underlined and italicized in blue below):

“ Tested combination means a multi-split system wit h 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 capacit y 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 mi nimum ex ternal static pressure requirement (i.e., 0 inches of wa ter column for non-ducted, see Table 2 in Appendix M to Subpart B of th is part for ducted indoor units) while being configurable to produce t he same static pressure at the exit of each outlet plenum when mani folded as per section 2.4.1 of Appendix M.

2AHRI Proposed Corrections – Federal Test Proce dures 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 meeti ng 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 ar ound 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.

T ABLE 2.—M INIMUM E XTERNAL S TATIC P RESSURE FOR D UCTED S YSTEMS T ESTED W ITH AN I NDOOR
F AN I NSTALLED

Minimum external resistance 3
(Inches of water) Rated Cooling 1 or Heating 2 Capacity (Btu/h)

All other systems 6 Small-duct, high velocity \systems 4,5

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 A 2 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 H1 2 Test conditions.

3 For ducted units tested without an air filter installed, incr ease 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 resi stance to airflow on the inlet side of

the indoor blower coil to a maximum value of 0.1 inch of wa ter. 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 H 2 O (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 mo st manufacturing facilit ies and ITS’s main facility in Cortland, New York) c auses 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).

3AHRI Proposed Corrections – Federal Test Proce dures 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 effici ency. 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 compar atively more variable; also, the change in power draw as a function of an incr emental change in the speed tap is also comparatively greater so t he 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 si nce the publication of t he October 22, 2007 Federal Register notice is that some indoor units implement more than a motor configuration change when changing the speed tap setti ng. A s 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 co nducted 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 st rikeout 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 requi rements are satisfied. First, when conducting the A or A 2 Test (exclusively), the measured air volume rate, when divided by the measured indoor ai r-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 a ll tests that call fo r using the Cooling

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

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

having a variable-speed, constant-a ir-volume-rate indoor fan. The second requirement applies exc lusively to the A or A 2 Test and is met

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

accordanc e with the previous paragraph;

2. Measure the exter nal static pressure; 3. If this pressure is equal to or greater t han the applicable minimum external static pressure cited in Table 2, this second requirement is satisfied. Use t he current air volume rate for all tests that require the Cooli ng 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

4AHRI Proposed Corrections – Federal Test Proce dures for Central Air Conditioners and Heat Pumps May 27, 2008

Page 5 of 5

4b. until the measured air volume rate equals 9 5 0 percent of the air volume rate from step 1, whichever occurs first. 5. If the conditions of step 4a occu r first, this second requir ement is satisfied. Use the step 4a reduc ed 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 pr ocess 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 vo lume 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 tak en into cons ideration. 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

5