Abstract: A system for automatically regulating both temperature and humidity within an enclosure for a swimming pool or the like where the atmosphere and the pool water are to be maintained at a selected temperature differential, including a pool water recirculating system having a remote source for the introduction of makeup water, an air recirculating system and a refrigerant recirculating system including an evaporator disposed within the air recirculating system, and the pool water recirculating system including a heat exchange coil disposed within the air recirculating system downstream from the evaporator and a valve assembly for selectively directing the recirculated water to the coil including a bypass conduit for bypassing same, electrical resistance heaters in thermal exchange relation with the air in the air recirculating system downstream from the coil and a thermostat and dehumidistat for controlling and sensing the temperature and humidity of the atmosphere within the enclosure.