To achieve a proper switching operation of a four-way selector valve without requiring a command signal for controlling each circuit for a secondary refrigerant system having a heat source side circuit and a use side circuit.
The use side refrigerant circuit B of a secondary refrigerant 3 system is composed by connecting a pump 11, a four-way selector valve 12, an indoor heat exchanger 13 and the using heat transfer pipe 5B of an intermediate heat exchanger 5 through a refrigerant piping 14. The liquid side of the using side heat transfer pipe 5B is connected to one of a pair of operating chambers 16a and 16b formed at both sides of the piston 17 of the four-way selector valve 12 and the liquid side of the indoor heat exchanger 13 is connected to the other. During circulation of refrigernat, the refrigerant is evaporated by one of the indoor heat exchanger 13 and the use side heat transfer pipe 5B and the refrigerant is condensed by the other, the piston 17 is moved by pressure applied to the operating chambers 16a and 16b to switch the four-way selector valve 12.
WATABE YUJI
YONEMOTO KAZUO
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