The present invention is equipped with: a first flow path (1) in which a first heat medium for heating hot water flows; a pump (4) provided in the first flow path (1) for transporting the first heat medium; a hot-water supply flow path (2) in which hot water to be supplied to a hot-water supply terminal flows; a heat exchanger (3) that exchanges heat between the first heat medium flowing in the first flow path (1) and the hot water flowing in the hot-water supply flow path (2); a flow volume detection means (5) provided in the hot-water supply flow path (2); and a control means (9). The control means (9) estimates the amount of potential heat of the heat exchanger (3) when the flow volume detection means (5) detects a flow volume equal to or greater than a prescribed flow volume, and controls the fluid transport means (4) such that when the amount of potential heat is relatively large the transport flow volume of the first heat medium decreases as the hot water supply temperature approaches a set temperature. Thus, the temperature of the hot water supplied to the hot-water supply terminal can quickly be brought to the set temperature.
