Groundwater heat pump performance can be significantly improved by more effective utilization of shallow groundwater. An experimental system demonstrates that a 10% to 15% improvement is possible by precooling the return air with 55 F to 67 F (13° to 20°C) water. Direct cooling without a heat pump is recommended when groundwater is below 55 F (13°C). The precooler was designed so that no increases in indoor fan or water pump power requirements were necessary. System efficiency was further enhanced by designing a low-pressure water circulation loop that allowed the de-staging of a standard one-third horsepower (0.25 kW) submersible pump. addition to reducing pump energy consumption, de-staging extends motor life. Approximate costs are $400 for the precooler and $50 for pump de-staging for a nominal 36,000 Btu/h (10.6 kW) system.

Units: Dual