The purpose of the invention is to efficiently control scaling inside a heat exchanger that exchanges heat between water and a refrigerant. A heat exchanging device comprises: a second heat exchanger 5 that exchanges heat between water and a refrigerant; a pulsation generating unit that is disposed in a water pipe 13 by which the water flows into the second heat exchanger 5 and that generates a pulse in the water passing through the water pipe 13; and a controlling unit 16 that controls the pulsation generating unit. The controlling unit 16 controls the pulsation generating unit with a target flow volume ratio based on a maximum allowable flow rate.
