The ability of three computer models to predict the performance of a sample air-to-air heat pump is analysed. It is found that in order to adequately predict performance, some actual test data are needed. Computer simulations by themselves at best predict trends and approximate levels. The major uncertainties are suspected to be in the evaporator and compressor simulations.

KEYWORDS: comparing, steady state, heat pumps, air air heat pumps, calculating, performance, testing, data, evaporators, compressors.