CH-12-013 -- Parametric Laboratory Evaluation of Residential Heat Pump Water Heater PDF

Three Heat Pump Water Heater (HPWH) units, representing the initial domestic offerings by the major manufacturers, were evaluated using a parametric test matrix. The three units tested vary in: refrigerant used, compressor size, evaporator fan size, amount of onboard electric resistance heat, condenser design, storage tank size, number and type of appliance (control) settings, and other factors that influence performance. The focus of this laboratory testing was the influence of appliance setting and hot water draw pattern on HPWH performance and efficiency, with limited variation of ambient enthalpy (within an environmental chamber), water main temperature, and thermostat setpoint. Additionally, the space conditioning effect of each unit was quantified through extended testing at stable conditions. A range of performance and efficiency was observed for each unit, both above and below results under standardized test metrics. Observations were also made of the manner in which the three HPWHs manage their thermal stores across varied demand, operational conditions, and HPWH system designs.