| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a heat pump water heater of a build-up boiling type using a refrigerant-water heat exchanger for heating water taken out of the lower part of a hot water storage tank and then returning it to the upper part of the hot water storage tank, wherein the water in the hot water storage tank can be uniformly and highly efficiently boiled up to a high temperature. <P>SOLUTION: When a temperature at the water side pipe inlet of the refrigerant-water heat exchanger, namely, a temperature detected by an inflow water temperature sensor is lower than a preset temperature, a heat pump unit is operated. When the temperature detected by the inflow water temperature sensor is the preset temperature or higher, the operation of the heat pump unit is stopped and an auxiliary heating device is operated only for a preset time. Thus, water in the hot water storage tank can be uniformly and highly efficiently boiled up to a high temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
