Comparisons of load-based and AHRI 210/240 testing and rating for residential heat pumps

Abstract

The current testing and rating procedure for residential air conditioners and heat pumps is based on a steady-state performance measurement approach with a degradation coefficient to account for cycling losses at part-load conditions. Test equipment performance is measured under various ambient conditions with varying compressor and fan speeds, and the results are propagated through a temperature-bin method to estimate seasonal performance. Although the current rating approach offers a standardized performance metric for comparing the relative performances of different equipment, it involves disabling the native controls and, as a result, does not consider the impact of integrated controls for test units and their dynamic interactions with representative building loads. As an alternative, a load-based testing methodology (CSA EXP07) has been developed in which the dynamic performance of equipment is measured in a test facility by allowing it to respond to a simulated virtual building model. This study compares the steady-state and dynamic load-based performance measurement methodologies for use on a 5-ton residential heat pump system in order to understand the differences and their significance for the next-generation rating procedure. The differences in the two test methodologies' performance evaluation results are discussed with a causal analysis of the observed differences.

Acknowledgments

This research was funded by the Center for High Performance Buildings (CHPB) at Purdue, and the authors are grateful for the funding and guidance of CHPB members who provided feedback and direction. The authors would also like to thank the engineering staff at Herrick Lab, particularly Frank Lee, for their assistance and contribution to the experimental work. This work would not have been possible without the manufacturer's proprietary control settings for conducting tests based on the current rating methodology.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Center for High Performance Buildings (CHPB) at Purdue.