HI-85-26-2 -- Solar Goes Underground — The SERI Packaged Ground-Coupled Heat Pump PDF

Independently monitored data from an innovative ground-coupled heat pump system in a test house is given. Testing was conducted in association with the SERI residential packaged solar heating system program. Innovations included: shallow horizontal slit trenches; multiple small counterflow tubes covered with concrete; two-speed compressor and blower; use of the ground as both heat source and sink; a small-tube vertical heat exchanger serving as both evaporator and condenser; superheat coming only from a suction line heat exchanger; only 110 feet of 4-foot-spaced trenching per ton; elimination of any back-up system; utilization of full night setback ; and packaging of system components. Results fully met expectations with performance far better than air-to-air heat pumps since annual heating/cooling compressor COPs were near 3.5. It is felt this compact horizontal trenching system meets a broad requirement.

Units: I-P