To shorten a refrigerant pipe by installing a heat exchanger of an air conditioning device on close position of an outdoor unit, to unify a temperature of hot water in a hot water storage tank by forcibly circulating the hot water by a pump, and to utilize a commercially-available general-purpose tank not needing special maintenance service as the hot water storage tank.

A water-cooled heat exchanger composed of a coaxial double-pipe is disposed between an outdoor unit condenser and a compressor in the air conditioning device, a refrigerant is circulated in one of the pipes, the cooling water is circulated in the other pipe, and the cooling water is heated by a high-pressure high-temperature gas pressurized by the compressor to be effectively utilized in hot water supply and the like, thus it becomes unnecessary to immerse the heat exchanger in the hot water storage tank, which has been conventionally done, the heat exchanger and the hot water storage tank can be disposed in a separated state easily, and the commercially-available general-purpose tank can be utilized as the hot water storage tank.