Two groundwater heat pumps were installed in existing residences in central Pennsylvania in climates of more than 6,000 heating degree-days (F). Both heat pumps remove heat from supply water via a vapor compression refrigeration cycle to heat air in a forced-air distribution system. Both units were retrofit into forced-air fossil-fuel-fired heating systems. Electric furnace units were installed to conveniently measure backup heat requirements and for calibration. Both units exhibited heating season coefficients of performance (COP) less than COPs published by the manufacturers. No significant supplemental heat was required by either system. The COPs include a penalty for pumping the water required by the heat pump with a common head of 100 ft (30 m) at a wire-to-water efficiency of 29%. The impact of these heating systems utility load shapes is analyzed.

Units: Dual