| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hot water storage type water heater capable of ensuring the heating value in a hot water storage tank to the maximum at the end of a midnight power time zone with low power cost. <P>SOLUTION: This water heater comprises a circulating passage 19 having a heat exchanger 21, which circulates hot water from the lower part of the hot water storage tank 14 to the upper part thereof, a heat pump unit 13 boiling up the hot water passing in the circulating passage 19 through the heat exchanger 21 to a laminated state from the upper part in the hot water storage tank 14, and an electric heater 18 provided in the lower part in the hot water storage tank. In the midnight power time zone with low power cost, the hot water in the tank 14 is boiled up first by carrying current to the heat pump unit 13, and then re-boiled up by carrying current to the electric heater so that the whole quantity in the tank is uniformly heated to a high temperature at the end of the midnight power time zone, whereby the heating value in the tank is ensured. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
