Presentation No 192 – Enabling Electrification of Domestic Hot Water and Space Conditioning with Multi-function Heat Pumps – 14th IEA Heat Pump Conference, Chicago, USA
Heat Pumps, although imperative to eliminate building onsite emissions, are required to be both energy efficient and capable of retrofitting in existing homes. In this study, we focus on Multi-function Heat Pump (MFHP) system, that uses one outdoor unit to provide both domestic hot water (DHW) along with space cooling and heating. An air-to-air MFHP, demonstrated in this study, reduces barriers to home electrification by avoiding electric resistance and lowering peak demand. The MFHP system is retrofitted in a 2000 sq-ft residential home to evaluate ease of installation, reliability, energy efficiency, and thermal comfort in terms of the space and water temperatures. Performance metrics of the MFHP are monitored over the summer in various modes and reported in this study. Coefficient of Performance (COP) of the AC mode was observed to be about 2.8 for an outdoor dry bulb of 35°C and COP of the water heating mode was observed to be about 2.3 for an outdoor dry bulb of 19.7°C. MFHP system provides a unique opportunity to move the heat from space into the DHW tank while operating in a simultaneous space cooling and hot water heating mode. The simultaneous mode performed 36% better than individual two modes if operated separately. The study demonstrates energy savings potential with MFHP while adequately meeting multiple loads in residential buildings without electric resistance heating. Refrigerant charge optimization and advanced controls to increase the run-time of the simultaneous AC and DHW mode are the next steps to improve the air-to-air MFHP system.