First circulation portions switch a flow of a heat transfer medium such that one of the heat transfer media for two systems selectively circulates through a radiator flow path or a first bypass flow path. Second circulation portions switch the flow of the heat transfer medium such that the heat transfer media for the two systems selectively circulate with respect to a second flow path group. The first circulation portions and the second circulation portions are adapted to switch the flow of the heat transfer medium so as to form a first circulation circuit for allowing the heat transfer medium to circulate among a first flow path group, the second flow path group, and a first pump, as well as a second circulation circuit for allowing the heat transfer medium to circulate among the first flow path group, the second flow path group, and a second pump.

A cabin heating circuit includes a first pump, a heat source, and a heater core. A battery heating circuit includes a first flow path that branches off from the cabin heating circuit at a three-way flow control valve. The battery heating circuit further includes a second flow path that is independent of the first flow path. The first flow path and the second flow path are thermally coupled by a heat exchanger. The second flow path includes the heat exchanger, a second pump, and a battery heat exchanger. The control unit adjusts an output of the heat source, an opening degree of the three-way flow control valve, an output of the first pump, and an output of the second pump. If a cabin and a battery are heated simultaneously, the control unit regulates the output of the first pump and/or the output of the second pump.

A cabin heating circuit includes a first pump, a heat source, and a heater core. A battery heating circuit includes a first flow path that branches off from the cabin heating circuit at a three-way flow control valve. The battery heating circuit further includes a second flow path that is independent of the first flow path. The first flow path and the second flow path are thermally coupled by a heat exchanger. The second flow path includes the heat exchanger, a second pump, and a battery heat exchanger. The control unit adjusts an output of the heat source, an opening degree of the three-way flow control valve, an output of the first pump, and an output of the second pump. If a cabin and a battery are heated simultaneously, the control unit regulates the output of the first pump and/or the output of the second pump.