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khammond on DSKJM1Z7X2PROD with PROPOSALS3

Federal Register / Vol. 86, No. 127 / Wednesday, July 7, 2021 / Proposed Rules through the VERS is negligible, so this issue would not affect these other VERS. ANSI/AHRI 9202015 includes tracer gas tests for measuring EATR in its standard rating requirements see section 5.1. As part of the July 2017
ASHRAE TP RFI, DOE raised this issue, while recognizing that such leakage may be low enough in most energy recovery wheels that the EATR measurement could represent an unnecessary addition to test burden. 82 FR 34427, 34437 July 25 2017. DOE requested comment on whether EATR should be included in the test procedure for DDXDOASes and, if so, how it should be used in determining DXDOAS ratings. Id.
In response to the RFI, on this issue, AHRI commented that the intent of the DOE test procedure for DDXDOASes should not be to quantify energy recovery performance. AHRI pointed out that the AHRI certification directory publishes EATR values based on AHRI
1060. AHRI, No. 11 at p. 15 In addition, AHRI argued that test laboratories of sufficient size for testing DDXDOASes are not currently equipped with tracer gas test equipment, as specified in ANSI/
ASHRAE 842013. AHRI, No. 11 at p.
14 No other comments were received on this issue.
Since the July 2017 ASHRAE TP RFI, further refinements were made to the industry consensus test standard which have bearing on this matter.
Specifically, sections 6 and C4 of AHRI
9202020 were revised to include methods to estimate EATR without requiring a tracer gas measurement, and to account for EATRs impact on DDX
DOAS performance, using calculations tailored for testing under either Option 1 or Option 2. These include using an EATR value that is based on testing in accordance with ANSI/AHRI 10602018
with zero purge angle,32 zero return-tosupply pressure differential, and 100percent of nominal energy recovery wheel supply airflow, and adjusting the EATR value for the DDXDOAS supply airflow rate based on an assumption that the leakage/transfer flow is not affected by the supply and return air flow rates.
The adjusted value of EATR is then used in the calculation of DDXDOAS
performance. Specifically, the MRC
calculations in section 6.9 of AHRI 920
2020 take into account the conditioning 32 A purge mechanism cleans the portion of the wheel that has had contact with return air before it is used to precondition outdoor air. The cleaning is provided by outdoor air that passes through this portion of the wheel and is diverted into the return plenum to be discharged through the exhaust blower. Most purge mechanisms allow adjustment of the angle of the wheel sector that is subject to this cleaning function. At zero purge angle, there is no purge cleaning provided.

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of the air that leaked or transferred from the return plenum to the supply plenum equal to adjusted EATR multiplied by supply airflow only from return conditions to supply conditions to reflect the fact that this air did not enter the DDXDOAS unit at outdoor air conditions. In cases where EATR rating information based on ANSI/AHRI 1060
2018 is not available, or if, for an energy recovery wheel, the rotational speed has been changed from the speed used to determine performance ratings using ANSI/AHRI 10602018, sections 6.5 and C4 of AHRI 9202020 provide a default value of EATR that would be used to rate the DDXDOAS.
DOE has tentatively determined that the use of default or certified values for EATR in AHRI 9202020 instead of tracer gas tests has addressed AHRIs comments on quantifying energy recovery performance. Accordingly, DOE is proposing to adopt these changes made by AHRI 9202020
section 6.5 Determination of EATR, as enumerated in section 2.2.1c of the proposed Appendix B; and Appendix C
of AHRI 9202020 which includes section C4 Simulated Ventilation Air Conditions for Testing Under Option 2, as enumerated in section 2.2.1f of the proposed Appendix B.
ii. Purge Angle Setting Section 6.6 of ANSI/ASHRAE 198
2013 requires that for any DDXDOAS
equipped with an energy recovery wheel, the purge angle of such feature must be set to zero when testing the DDXDOAS unit. As part of the July 2017 ASHRAE TP RFI, DOE requested comment on whether all purge devices are adjustable to zero purge and whether it is always clear how to set them to zero purge. 82 FR 34427, 34439 July 25, 2017. DOE also requested comment on whether it is appropriate to set purge to zero or whether it would be more appropriate to set purge to its highest setting or to some other standard setting.
Id.
None of the comments on the RFI
indicated that there are purge devices that are not adjustable to zero angle, nor that it is unclear how to adjust purge angle to zero. Carrier commented that for the short period of time required for a performance test, it should not be a problem to set the purge angle to zero.
Carrier, No. 6 at p. 8 As discussed previously, AHRI stated that there are no independent laboratories capable of testing DDXDOAS units with VERS. As a result, AHRI argued that this issue does not need to be addressed at this time. However, AHRI stated, if in the future laboratories are able to test DDX
DOASes equipped with VERS, then
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manufacturers should be allowed to specify the purge setting for testing, as is done in AHRI 1060. AHRI, No. 11 at p. 20
DOE has tentatively concluded that a zero purge angle aligns with the selection that manufacturers would generally make i.e., a zero purge angle, because non-zero purge prevents the purge portion of the wheel from contributing to energy recovery effectiveness since outdoor ventilation air passing through it is ejected out of the unit to the exhaust rather than becoming part of the supply airflow.
Also, the purge section restricts the flow area for the remaining outdoor air that becomes supply air, thus increasing pressure drop and fan power. For these reasons, energy recovery wheel performance and likewise DDXDOAS
performance and efficiency will be reduced when operating with a non-zero purge angle. Furthermore, basing DDX
DOAS performance ratings on a zero purge angle provides greater consistency in testing. DOE notes that section C4.1
of AHRI 9202020the industry consensus test standardincludes a requirement for testing DDXDOAS
units using zero purge angle, whether testing using Option 1 or Option 2
through inclusion of EATR0, which is defined in section 11 of AHRI 9202020
as being determined using zero purge angle. For these reasons, DOE is proposing to adopt the requirement in AHRI 9202020 to use a zero purge angle for testing DDXDOAS with energy recovery wheels section C4.1 of Appendix C of AHRI 9202020, as enumerated in section 2.2.1f of the proposed Appendix B.
iii. Return Air External Static Pressure Requirements ANSI/ASHRAE 1982013 specifies testing DDXDOASes with VERS with return air passing into the unit and exiting at the exhaust air connection.
DOE noted in the July 2017 ASHRAE TP
RFI that ANSI/AHRI 9202015 does not address setting the external static pressure ESP for the return airflow. 82
FR 34427, 34437 July 25, 2017. DDX
DOAS units are typically installed and operated in the field with return air ducting. Therefore, when in operation, the return air fans consume additional energy to overcome the static pressure imposed by the return air ducts. As part of the July 2017 ASHRAE TP RFI, DOE
requested comment on the ESP levels that should be used for return airflow.
Id.
In response, AHRI stated that Table 4
of ANSI/AHRI 9202015 was intended to represent ESP of both supply and return airflow. AHRI also stated that
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