Abstract: A heating and cooling system for heating water contained in a swimming pool while providing a means for cooling or heating the interior of a building. The system includes a compressor connected through suitable conduits to a condenser located in a swimming pool and an evaporator such that, when a fluid heat-transfer medium, such as ammonia, is communicated under high pressure to the condenser, heat is given off thereby, while evaporation of the medium in the evaporator results in a reduction in temperature surrounding the evaporator which, in conjunction with a suitable fan arrangement, may be used to cool the interior of a building. A second condenser is provided with suitable valving and conduit means for selectively communicating the second condenser to the compressor and the evaporator whereby the building may be cooled while not heating the water in the pool.