A groundwater heat pump monitoring program was undertaken to obtain the on-site operational thermal efficiency (seasonal performance factor) of typical groundwater source heat pumps. The collected data were desired to predict potential effects of large-scale application of groundwater heat pumps on aquifers and on the demand loads of electric utility companies. In addition, data on the net energy savings of a groundwater heat pump were desired for comparison to data on the conventional heating systems of typical residences. The two-year study also documents methods of water handling and operational problems.

Ten groundwater heat pump sites were monitored, providing a variation in systems configuration, geographical location, well depth, and water temperature and disposal methods. Records of thermal energy usage, water requirements, electrical energy consumption, inlet well water temperature, and operating problems were maintained.

From the collected data, the heat pump performance levels appear to be operating within the ranges specified by the heat pump manufacturers, with an approximate 50% savings over electric-resistance heating systems. Energy savings of groundwater heat pumps over conventional vapor compression air-to-air air conditioning units is highly dependent on the parasitic energy requirements of the groundwater heat pump system.