| 摘要 |
PURPOSE:To prevent feed hot water in a heat accumulating tank from being stored in a laminar temperature distribution state irrespective of a fluctuation in open air environment, by providing a hot gas bypass circuit, in which a pressure reducing mechanism is located, and a during-defrosting-operation suction circuit in which a solenoid valve is located. CONSTITUTION:During defrosting operation, a 4-way valve 8 energized by means of a temperature sensor 18 is switched, a water circulating pump 10 is stopped, and a solenoid valve 15 situated in a during-defrosting-operation suction circuit 17 is opened. A part of a coolant discharged from a compressor 1 does not flow into a 4-way valve 8 but is bypassed to a hot bypass circuit 16. A coolant entering the 4-way valve 8 goes to a heat collector 6 to perform defrosting. A coolant in a high temperature high pressure state, bypassed to the hot gas bypass circuit 16, flows in a heat exchanger 2 between a coolant and water, and flows all the way through to the inlet of the during-defrosting-operation suction circuit 17. This constitution stops the water circulating pump 10, and prevents low temperature feed hot water from being fed to the upper part of a heat accumulating tank 9.
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