24 June 2014

Development of a Variable-Speed Residential Air-Source Integrated Heat Pump

A residential air-source integrated heat pump (AS-IHP) is under development in
partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variablespeed unit, the system provides both space conditioning and water heating. This multifunctional
unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vaporcompression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures and temperatures within allowable operating envelopes. Annual
simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum
efficiency baseline system while meeting total annual space conditioning and water heating
loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.