PURPOSE: To enable low pressure operation of circulation system thus to reduce the cost, by heating refrigerant through engine waste heat then using it as the operating steam of ejector under cooling while as the heat medium under warming and also using for warming machine.

CONSTITUTION: Refrigerant heated when passing through an water jacket of engine 10 is further heated by a heater 15 provided on an exhaust pipe 14 to produce overheat steam which is used as the operating steam for an ejector 21. The delivery side of ejector 21 is coupled to a condenser 23 while the suction side is coupled to an evaporator 28. Furthermore, the operating steam inlet side of ejector 21 is coupled through a warming heat-exchanger 33 to the inlet side of condenser 23 while the outlet side of condenser 23 is coupled through a coolant circulation pump 12 to the inlet side of water jacket.