This paper presents field-monitored performance data from a school where a heat pump water heater (HPWH) was installed with a storage tank to preheat water for a gas-fired hot water system with multiple recirculation loops. The results demonstrated the effectiveness of HPWH preheating for high water use areas in the school and confirmed the high thermal losses from the recirculation loop system. The authors discuss the implications of this work as it relates to the overall design strategy for service water heating systems in schools.

Units: Dual