To save power required for motion by providing a condensation side heat exchanger for exchanging heat with water in the water storage tank of water closet.

High pressure low melting point refrigerant compressed through a compressor 6 is introduced through refrigerant piping 3 to a condensation side heat exchanger 2 where it is heat exchanged with cold water in a hot water storage tank 4 and liquefied by discharging latent heat to the water. High pressure refrigerant liquid is introduced through the refrigerant piping 3 to an evaporation side heat exchanger 1 where it is heat exchanged with air in a toilet room 7 and vaporized by robbing vaporization heat from the air in a toilet room 7. Air passing through the evaporation side heat exchanger 1 is cooled with evaporation latent heat and the toilet room 7 is cooled by supplying the air by means of a fan 8. Normal pressure refrigerant gas is introduced through the refrigerant piping 3 to the compressor 6 where it is compressed again to produce high pressure refrigerant gas.