NT-87-05-5 -- Groundwater Heat Pump Performance Enhancement with Precoolers and Water Pump Optimization PDF

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.

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