A distribution valve controls a distribution ratio of a heat transfer medium between a hot water supply path including a heat exchanger for hot water supply and a beating circulation path through which the heat transfer medium is supplied to a heating terminal. A bypass flow rate control valve controls a bypass ratio which is a ratio of a flow rate of low temperature water introduced into a bypass pipe that bypasses the heat exchanger for hot water supply to a flow rate of low temperature water introduced into a water inlet pipe. The bypass ratio is regulated so that a hot water temperature detected by a temperature sensor reaches a hot water target temperature. During a simultaneous operation of hot water supply and heating, the distribution valve is controlled so that, when a bypass ratio is low, a distribution ratio is higher than when a bypass ratio is high.