PROBLEM TO BE SOLVED: To provide a hot water supply machine using a heat pump unit suitable for continuous operation throughout a year.;SOLUTION: A needle valve 46 is displaced with using pressure balance between an operation chamber 47b which inert gas is filled in and a drive chamber 47a which high pressure side coolant flows into to control high pressure side coolant pressure roughly constant. Although temperature of supplied water during winter of low air temperature drops as compared with that during summer of high air temperature, it is not a problem in a practical use. Since it is not necessary to increase pressure tightness of high pressure side equipment such as a water coolant heat exchanger and compressor more than necessary level to meet requirement for summer of high air temperature, pressure tightness reliability of the hot water supply machine can be increased while reducing manufacturing cost of the hot water supply machine. Since restriction opening of a nozzle 41 is controlled by an actuator of a simple structure having inert gas filled in the operation chamber 47b, high pressure side coolant pressure can be control at low cost.;COPYRIGHT: (C)2004,JPO
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