PURPOSE:To improve the performance of the hot water supplier by providing a subtank within a main tank, and heating a heat medium within the subtank to a temperature in a degree utilizable for hot water supply by means of a condenser of a heat pump device thereby to effectively shift the heat medium to the main tank by the operation of a stream flux diffusion apparatus. CONSTITUTION:A heat medium within a subtank passes through a pump and circulates from a condenser 23 to a stream flux diffusion apparatus 7 disposed at the lower part of the subtank 2. Meanwhile, the heat medium is heated in the condenser, and the temperature of the heat medium within the subtank is gradually increased. When the temperature of the heat medium within the subtank reaches a feed hot water utilizable temperature, an opening and closing valve 31 by a temperature sensor 38. The discharge pressure of the pump is applied to a subtank 29 to produce a differential pressure between the subtank 29 and a main tank 28. Then, a valve 41 provided in the diaphragm 40 of the subtank is opened by the differential pressure, and the heat medium whose temperature is raised flows into the upper part of the main tank. The low-temperature heat medium passes through the condenser 23 from the lower part of the main tank and passes through a stream flux diffusion apparatus 37. Thus, the high-temperature heat medium and the low-temperature heat medium can flow into the main tank without being mixed with each other. Therefore, the high performance of the hot water supplier can be obtained. |