HOT WATER SUPPLY HEATING SYSTEM

摘要

Provided is a hot water supply heating system capable of properly suppressing freezing of piping even if the atmospheric temperature is lowered to the extent of being inappropriate for the operation of a heat pump. The hot water supply heating system (2) comprises: a heat pump (50); a tank (10); a tank water circulating path (20); a warm water circulating path (71); a burner heating device (82); a heater (76); a three-fluid heat exchanger (58); and an atmospheric temperature sensor (40). The three-fluid heat exchanger (58) executes heat exchange between a heat medium circulating path (52) of the heat pump (50) and the tank water circulating path (20), and between the heat medium circulating path (52) and the warm water circulating path (71). When the atmospheric temperature is lower than a certain critical value, a first freezing preventive operation is executed, wherein the water in the warm water circulating path (71) is circulated by operating the burner heating device (82) rather than operating the heat pump (50) and the water in the tank water circulating path (20) is circulated.