JP2658918B

PURPOSE: To prevent execution of an unnecessary freezing preventing operation by a construction wherein an indoor heat exchanger of a hot water type air conditioner equipped with refrigerant and hot water circulation circuits starts a freezing preventing operation when the temperature thereof is a freezing preventing control start temperature set beforehand or below and when a set time or a time longer than it passes after a compressor stops. CONSTITUTION: When an indoor heat exchanger temperature Th detected by a heat exchanger temperature detecting thermistor is a freezing preventing control start temperature T0 (e.g. 10 deg.C) set beforehand or below and when a predetermined set time (t) (e.g. two hours) or a time longer than it passes after a compressor stops, a hot water valve is opened and a heat source machine (including a circulating pump) is started. While the circulating pump is turned ON, in other words, combustion of a hot water producing part of the heat source machine is turned ON and thereby a freezing preventing operation is started. Herein the freezing preventing control start temperature T0 is set at a value (e.g. 10 deg.C) lower than a cooling set temperature Ts . Freezing of a hot water circulation circuit can be prevented reliably without conducting an unnecessary freezing preventing operation.