During 1990-91 a large gas distribution company in the southeast United States participated in a year-long field test of a 3-refrigerant-ton (10.5 kW) gas engine heat pump (GEHP) designed as a packaged, split system for centrally ducted HVAC systems. The GEHP ran well with the exception of a persistent low-speed stalling problem and the failure of the bronze bushings in the engine-compressor linkage. However, the GEHP achieved 4,619 hours of engine operation-59% heating and 41% cooling. A total of 750 therms (21.975 kWh) of gas was consumed, 63% of which was for heating and 37% of which was for cooling. Overall coefficients of performance were measured at 1.37 for heating and 1.15 for cooling. Fuel usage and operating costs for the GEHP were compared to an NAECA minimum split system-gas furnace (78% AFUE) and an electric air conditioner (SEER 10) system. Use of the GEHP decreased the overall gas load 15% below that which would have been required by the gas furnace. During the heating season a 46% decrease in gas consumption resulted from using the GEHP in lieu of a gas furnace. This reduced winter gas load was not fully compensated by the addition of gas cooling. Overall conditioning costs (gas furnace plus electric air-conditioner) were reduced by 28% with the GEHP installed. Gas usage was also compared with a high-efficiency split system - gas furnace (92% AFUE) and an electric air conditioning (SEER 12) system. The GEHP's overall gas usage - heating and cooling gas consumption - was approximately equal the gas use of the 92% AFUE gas furnace. However, overall operating costs for the GEHP were calculated 135 dollars less than the high-efficiency split system.

KEYWORDS: year 1995, gas engine heat pumps, heat pumps, performance, testing, heating, cooling, gas consumption, coefficient of performance, operations, costs, comparing, electricity consumption, air conditioning, service life, economics