HOT WATER STORAGE TYPE WATER HEATER

PROBLEM TO BE SOLVED: To provide a hot water storage type water heater that prevents hot water of high temperature from flowing backward from a heating means to a hot water storage tank after operation of the heating means stops.SOLUTION: After an operating heat pump unit 1 is stopped, a selector valve 29 is positioned at an intermediate point between a first state in which water flows to a lower part of a hot water storage tank 21 from a heat pump supply pipe 26 through a bypass pipe 28 for a specified period, and a second state in which water flows to the upper part of the hot water storage tank 21 from the heat pump supply pipe 26. Consequently, the hot water of high temperature having been heated in a coolant-water heat exchanger 12 of the heat pump unit 1 is prevented from flowing back to the lower part of the hot water storage tank 21 to raise the temperature of water in the lower part of the hot water storage tank 21. The temperature of water supplied to the heat pump unit 1 is prevented from increasing to reduce COP of the heat pump unit 1.