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Title: Building America Case Study: Field Performance of Inverter-Driven Heat Pumps in Cold Climates - Connecticut, Massachusetts, and Vermont

New inverter-driven ASHPs are gaining ground in colder climates. These systems operate at sub-zero temperatures without the use of electric resistance backup. There are still uncertainties, however, about cold-climate capacity and efficiency in cold weather and questions such as measuring: power consumption, supply, return, and outdoor air temperatures, and air flow through the indoor fan coil. CARB observed a wide range of operating efficiencies and outputs from site to site. Maximum capacities were found to be generally in line with manufacturer's claims as outdoor temperatures fell to -10 degrees F. The reasons for the wide range in heating performance likely include: low indoor air flow rates, poor placement of outdoor units, relatively high return air temperatures, thermostat set back, integration with existing heating systems, and occupants limiting indoor fan speed. Even with lower efficiencies than published in other studies, most of the heat pumps here still provide heat at lower cost than oil, propane, or certainly electric resistance systems.
Publication Date:
OSTI Identifier:
Report Number(s):
NREL/FS-5500-63914; DOE/GO-102015-4643
DOE Contract Number:
Research Org:
NREL (National Renewable Energy Laboratory (NREL)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; Residential; Residential Buildings; CARB; Building America; Inverter-driven; Air-source heat pumps; Steven Winter Associates, Inc.; Consortium for Advanced Residential Buildings; SWA; COPs; Cold climate; Northeast; Performance; Heating; Air flow measurement; Heat pump; ASHP