A gas engine heat pump (GEHP) represents one of the most practicable systems which improve the overall energy utilization efficiency and reduce the operating cost for heating and cooling applications. The present work aimed at evaluating the performance of a GEHP for air-conditioning and hot water supply. In order to achieve this objective, a test facility was developed and experiments were performed over a wide range of engine speed (1200 rpm-1750 rpm), ambient air temperature (24.1 degrees C-34.8 degrees C), evaporator water flow rate (1.99 m(3)/11-3.6 m(3)/h) and evaporator water inlet temperature (12.2 degrees C 23 degrees C). Performance characteristics of the GEHP were characterized by water outlet temperatures, cooling capacity, heating capacity and primary energy ratio (PER). The results showed that the effect of evaporator water inlet temperature on the system performance is more significant than the effects of ambient air temperature and evaporator water flow rate. PER of the considered system at evaporator water inlet temperature of 23 degrees C is higher than that one at evaporator water inlet temperature of 12.2 degrees C by about 22%. PER of the system decreases by 16% when engine speed changes from 1200 rpm to 1750 rpm. (C) 2010 Elsevier Ltd. All rights reserved.