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Federal Register / Vol. 86, No. 127 / Wednesday, July 7, 2021 / Proposed Rules from their target values. If this occurs, it is not clear how manufacturers would correct the issue without being able to adjust the fan speed and ESP, since such action is precluded by section 5.2.2.4 of ANSI/AHRI 9202015.
In the July 2017 ASHRAE TP RFI, DOE noted that the 5-percent condition tolerance on airflow rate is less stringent than the 3-percent condition tolerance adopted in DOEs test procedure for more typical commercial package air equipment. 82 FR 344271, 34439 July 25, 2017. On August 6, 2015, DOE
published a test procedure NOPR that proposed to apply a 5-percent condition tolerance on cooling full-load indoor airflow rate for more typical commercial package air conditioning equipment. 80 FR 46870, 46873. In response to the proposed tolerance for more typical commercial package air conditioning equipment, DOE received several comments suggesting that a 5percent tolerance would result in too much variation in the measurement of energy efficiency ratio and cooling capacity. After considering stakeholder comments, DOE adopted a 3-percent tolerance in a final rule published on December 23, 2015. 80 FR 79655, 7965979660. As part of the July 2017
ASHRAE TP RFI, DOE expressed concern that that the 5-percent condition tolerance on airflow in ANSI/
ASHRAE 1982013 may result in too much test variability for DDXDOASes and requested comment on whether this airflow tolerance is acceptable. 82 FR
34427, 34439 July 25, 2017.
AHRI commented in response to the July 2017 ASHRAE TP RFI that manufacturers who have performed testing have stated that meeting the tolerances specified in ANSI/AHRI 920
2015 and ASHRAE 1982013 is not feasible due to how the testing is performed. Once the refrigeration system is engaged for determining ISMRE and ISCOP ratings, changes in moisture present on the cooling coil and air density affect the standard airflow and associated ESP. AHRI
recommended that the 0.05 in H2O ESP
tolerance and a 3-percent airflow tolerance be observed during the airflow and fan speed setting at Standard Rating Condition C without the refrigeration system operating. AHRI also stated that during the Standard Rating Condition tests, the DDXDOAS fan speeds and airflow-measuring apparatus fan speeds shall not be adjusted, consistent with airflow setting and operation in the field. Nevertheless, AHRI stated that the average measured airflows should be required to be within 5 percent of the manufacturers rated standard airflow during all rating tests and that the
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average measured ESPs should be within 15 percent of the required ESP to indicate a valid test, but the commenter did not indicate whether the fans of the test unit or the airflow-measuring apparatus should be adjusted to maintain these tolerances. AHRI, No.
11 at p. 18
DOE notes that AHRI 9202020
revised the test condition and operating tolerances for airflow and ESP. Section 6.1.5 of AHRI 9202020 specifies airflow test condition tolerances of 3
percent of the manufacturer-provided airflow rate for all DDXDOASes when setting the airflow, provided that this airflow rate meets the supply air dew point temperature requirement, as discussed in section III.B.4.d.i of this NOPR. For setting the return airflow rate, section 6.1.5 of AHRI 9202020
specifies the same test condition tolerances as for supply airflow rate, except that for return airflow rate, the target is equal to the measured supply airflow rate. This specification ensures that supply and return airflows remain balanced, as discussed in section III.B.3.h.iv of this NOPR. These test condition tolerances for airflow and ESP
are only required when setting the airflow. Once the airflow rate is set, the dehumidification and heating tests are then conducted without further adjustments to the supply fan, return fan, or airflow measuring apparatus.
Section 6.1.5 and Table 9 of AHRI 920
2020 indicate that the supply and return airflow and ESP condition tolerances are not required to be maintained during the dehumidification and heating tests.
While these provisions are contrary to AHRIs recommendation in response to the July 2017 ASHRAE TP RFI to impose a 5-percent airflow condition tolerance and a 15-percent ESP
condition tolerance during dehumidification and heating tests, DOE
believes these changes in AHRI 920
2020 address AHRIs concerns about testing problems associated with the tolerances in ANSI/AHRI 9202015 and ASHRAE 1982013.
AHRI 9202020 additionally includes a list of test operating tolerances, including those for external static pressure and airflow nozzle differential pressure. AHRI 9202020 does not include changes to the test operating tolerance for ESP 0.05 in H2O total observed range, specified in Table 9 of AHRI 9202020. Whereas ANSI/
ASHRAE 1982013 provides a 5-percent operating tolerance directly on the airflow rate, Table 9 of AHRI 9202020
provides a 5-percent operating tolerance for airflow rate in the form of airflow nozzle differential pressure. DOE has initially determined that the airflow
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operating tolerance approach in AHRI
9202020 is preferable because the airflow nozzle differential pressure provides a more direct indication of the airflow variation, since airflow is calculated based on this value.
Additionally, other industry test standards such as ANSI/ASHRAE 37
2009 include an operating tolerance on the nozzle pressure drop rather than directly on airflow. DOE believes that these operating tolerances, in addition to the condition tolerances for setting airflow, would maintain repeatable and reproducible results while ensuring that testing is representative of field use.
Accordingly, DOE is proposing to adopt the test condition and operating tolerances for airflow and ESP specified in AHRI 9202020 section 6.1.5 Supply and Return Airflow Rates and section 6.6.2 Test Measurement Tolerances, which contains Table 9, as enumerated in section 2.2.1c of the proposed Appendix B.
k. Secondary Dehumidification and Heating Capacity Tests Commercial package air-conditioners and heat pumps with cooling capacity less than 135,000 Btu/h are required to undergo a secondary test to verify the cooling or heating capacity and energy efficiency results see, e.g., ANSI/
ASHRAE 372009 section 7.2.1, which is referenced by appendix A to subpart F of 10 CFR part 431. Neither ANSI/
AHRI 9202015 nor ANSI/ASHRAE
1982013 specify a secondary test method for verifying the dehumidification and heating capacity of DDXDOAS, but section 6.7 of AHRI
9202020 does specify secondary tests.
The measurement of dehumidification and heating performance of DDX
DOASes is based on measurements of airflow rate, temperature, and humidity, which have uncertainties associated with them. Thus, a secondary test method may be essential to confirm the accuracy of the primary test method.
As part of the July 2017 ASHRAE TP
RFI, DOE requested comment on the need for a secondary test method requirement for DDXDOAS testing. 82
FR 34427, 34439 July 25, 2017. AHRI
commented that condensate measurement would be appropriate as a secondary method, if energy recovery units are excluded from the test procedure. AHRI, No. 11 at p. 19
Section C5.1 of AHRI 9202020
includes a condensate-based test method as a secondary measure of dehumidification capacity. The method measures the weight of the condensate i.e., water vapor in the outdoor ventilation air that condenses on the conditioning coil and is removed from
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