A radiator ( 50 ) cools and/or heats by sucking cold water or hot water from a heat source unit ( 10 ). In addition, the radiator ( 50 ) comprises a heat exchanger ( 52 ), a first piping ( 5a ), a three-way valve ( 54 ), a heat exchanger temperature detection unit ( 56 ), and a control unit ( 60 ). The first piping ( 5a ) is a piping wherethrough water flows from the heat source unit ( 10 ) side to the heat exchanger ( 52 ) side. The three-way valve ( 54 ) assumes a first state and a second state. In the first state, a flow of the water from the heat source unit ( 10 ) side to the heat exchanger ( 52 ) side is permitted. In addition, in the second state, the flow of the water from the heat source unit ( 10 ) side to the heat exchanger ( 52 ) side is blocked. The heat exchanger temperature detection unit ( 56 ) is capable of detecting a water temperature. The water temperature is the temperature of the water flowing to the heat exchanger ( 52 ). The control unit ( 60 ) comprises a water temperature determination unit ( 66 ) and an operation unit ( 64 ). The water temperature determination unit ( 66 ) determines whether the water temperature detected by the heat exchanger temperature detection unit ( 56 ) is within a prescribed temperature range. The operation unit ( 64 ), based on a determination result of the water temperature determination unit ( 66 ), sets the three-way valve ( 54 ) to a state selected from the group consisting of the first state and the second state.