NT-87-19-4 -- Seasonal Performance Evaluation of Two Horizontal-Coil Ground-Coupled Heat Pump Systems PDF

Performance of two different ground-coupled heat pump installations in occupied single family residences in a Tennessee experimental facility is reported for the 1984-85 heating season and the 1985 cooling season. Hourly measurements of various power consumptions, heat flows, and temperatures were made over the entire seasons in order to determine overall system performance.

The system in House I is a heating-only unit (field modified for cooling operation), which has been operating continuously since 1982. The second system is a water-air unit in House V of the facility. It was designed and installed by the private sector in November 1984 and has been tested over only one season.

The seasonal performance factors of the House I system were found to be 2.23 and 1.51 for heating and cooling, respectively. The corresponding seasonal performance values of the new GCHPsy stem in House V were found to be 2.84 and 2.59.

System V performance is superior to system I primarily due to an increased length of ground coil and a heat pump unit having better cooling performance characteristics.

A comparison of the GCHP system in House V with previously tested air-air heat pump systems shows that a well-designed GCHPsy stem (with the ground coil sized for summer design conditions) offers a significant performance improvement over even a high efficiency air-air unit.

Units: Dual