A water-to-water geothermal heat pump (GHP) running on R-22 was designed to evaluate disposed geothermal water from geothermal health resort centres in Erzurum. The GHP uses geothermal water at 35 degreesC temperature and provides clean water at 45 degreesC for a floor heating network. The GHP heating capacity was around 7.2 kW. and an electric driven hermetic R-22 compressor was used. The overall coefficient of performance was determined as 2.8. (C) 2000 Elsevier Science Ltd. All rights reserved.