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Federal Register / Vol. 86, No. 58 / Monday, March 29, 2021 / Rules and Regulations discussed in section III.C.3.a of this document, DOE is requiring that the manufacturer provide in the certification reports the control settings to achieve the fixed compressor speed at only the 87 F and 82 F test conditions, thus minimizing certification burden on manufacturers.
c. Boost Compressor Speed DOE is aware that a variable-speed room ACs full compressor speed may not be its fastest speed. In particular, the fastest compressor speed may be one that is automatically initiated and used for a brief period of time to rapidly reduce the indoor temperature to within typical range of the setpoint. This compressor speed is referred to as Boost Compressor Speed in AHRI
Standard 210/240 and is defined as a speed faster than full compressor speed, at which the unit will operate to achieve increased capacity.
Manufacturers have described boost compressor speed as used for limited periods of time on occasions where the indoor room temperature is far out of normal operating range of the setpoint.
Once the indoor room temperature is within the typical operating range of the setpoint, the room AC returns to the Full Compressor Speed, as defined in AHRI Standard 210/240. Because of the typical limited duration of boost compressor speed, it would not significantly contribute to annual energy consumption. AHRI Standard 210/240
does not measure boost compressor speed energy use, and in a final rule published on June 8, 2016, DOE
declined to include provisions for measuring boost compressor speed energy use in the central air conditioner test procedure. 81 FR 36992, 37029.
DOE stated that accurately accounting for boost compressor speed requires more careful consideration of test procedure changes beyond simply allowing the compressor speed to vary for the test conditions required by the previous procedure, and that DOE
would consider such revisions in a future rulemaking. Id.
Accordingly, DOE did not propose to measure boost compressor speed performance and energy consumption in appendix F in the June 2020 NOPR, because of the minimal expected operating hours in boost compressor mode and the subsequent insignificant impact on annual energy consumption and performance, to harmonize with AHRI Standard 210/240, the industry approach for variable-speed compressor testing, and because DOE has previously opted to forgo including it for other air conditioning products. 85 FR 35700, 35710 Jun. 11, 2020.

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AHAM supported DOEs proposal to forgo measuring boost compressor speed for variable-speed room ACs. AHAM
commented that boost compressor speed is used for limited periods of time on occasions where the indoor room temperature is far out of normal operating range of the setpoint. AHAM
stated that once the indoor temperature is within the typical operating range of the setpoint, the room AC will return to full compressor speed. AHAM asserted that accounting for boost compressor speed would likely not impact annual energy consumption and performance and, thus, additional test burden would not have a corresponding energy savings or consumer benefit. According to AHAM, EPCA does not require testing of every available mode; EPCA only requires testing of the average consumer use cycle, which boost mode is not according to data available. AHAM, Public Meeting Transcript, No. 12 at p.
53; AHAM, No. 13 at p. 5
The Joint Commenters, the California IOUs, NEAA, and Rice commented in favor of capturing boost compressor speed operation in the test procedure.
ASAP, Public Meeting Transcript, No.
12 at p. 12; Joint Commenters, No. 15 at pp. 23; California IOUs, Public Meeting Transcript, No. 12 at pp. 2324; NEAA, Public Meeting Transcript, No. 12 at pp.
4248, 56; Rice, No. 17 at p. 3 The California IOUs commented that boost mode operation may be a significant portion of how consumers actually use the product. California IOUs, Public Meeting Transcript, No. 12 at pp. 2324
Rice commented that boost compressor capability requires the inverter/motor drives to be oversized to handle the increased torque and power draw, resulting in more performance drop off at lighter loads. Rice stated that this performance drop-off supports why limiting variable-speed rating tests to no lower than 82 F may preclude future introduction of more efficient variablespeed drive/motor combinations in compressors that have larger performance advantages below 50percent capacity reduction. Rice commented that boost compressor speed capability not only can result in unnecessary energy use and increased power demand during rapid cooldown but can also penalize unit performance at lower outdoor temperatures where significant amounts of cooling are delivered. Rice further commented that there is no incentive for manufacturers to limit or drop boost compressor speed features from their designs without some performance penalty applied to units with boost operation, especially if the lowest test point remains at the 82
F test condition with 50 percent of
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rated capacity loading. Rice suggested provisions might also be included for suitable performance credits for variable-speed units that allow boost mode to be turned off by the homeowner or utility to reduce unnecessary energy use and/or peak demand. Rice, No. 17 at pp. 23
ASAP, NEAA, the Joint Commenters, and Rice encouraged DOE to further investigate the use and timing of boost compressor speed, expressing concern that not testing it may result in excluding a significant component of the energy use of these units. ASAP, Public Meeting Transcript, No. 12 at p.
12; NEAA, Public Meeting Transcript, No. 12 at pp. 4248; Joint Commenters, No. 15 at pp. 23; Rice, No. 17 at p. 3
Specifically, NEAA recommended that DOE conduct tests to determine the setpoint differential that would cause boost mode to kick in and the difficulty at which that is under normal or extreme operating conditions. NEAA, Public Meeting Transcript, No. 12 at pp.
4248 Rice recommended that DOE
conduct additional load-based testing to estimate the added energy use and peak demand from boost compressor speed operation from a typical daytime setback, evening setup schedule.31
Rice, No. 17 at p. 3
As discussed, boost compressor speed is a temporary period of elevated compressor speed that occurs to quickly reduce the indoor temperature of a room, typically upon startup or after a service interruption. DOE is not aware of any publicly available data on the frequency or duration of boost compressor speed operation in the field.
As such, DOE is unable to ensure the representativeness of a test procedure that addresses boost compressor speed operation.
Further, in limited investigative testing of boost compressor speeds for two variable-speed room ACs, DOE was not able to induce a compressor speed higher than the full compressor speed, either by increasing the cooling load to greater than 100 percent or by adjusting the temperature setpoint during cooling mode operation. As such, it is unclear what test procedure provisions would be necessary to test boost compressor speed operation, or if there exists a compressor speed greater than that already activated by the settings in appendix F, without being unduly 31 Setback typically refers to when the temperature setting on a thermostat is adjusted to a higher temperature for a period of time when the space will not be occupied or wont require as much cooling, and setup refers to when the thermostat setpoint is adjusted back to its original setting, at which the desired level of comfort is provided when the conditioned space is occupied.

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