HEAT PUMP DEVICE

PURPOSE:To prevent a backflow of a liquid and an abnormal rise in the temperature of a discharge gas and to maintain a highly reliable operation condition by a method wherein when a heating operation is performed in a condition in which the temperature of the open air is low, the heating operation is so controlled that the temperature of hot water is made lower than when the temperature of the open air is normal. CONSTITUTION:A cooling temperature detector 14, a higher side heating temperature detector 15 and a lower side heating temperature detector 16 open their contacts when, for example, the temperature of water flowing through a water side heat exchanger 4 becomes 7 deg.C, 55 deg.C and 50 deg.C, respectively. The open air temperature detector 17 opens its contact when the open air temperature drops down to, for example, around -5 deg.C. Thus, when the open air temperature drops down below -5 deg.C so that the contact of the open air temperature detector 17 is opened, a coil 11 is controlled by a series circuit of an operating switch 12, a cooling and heating changeover switch 13 and the lower side heating temperature detector 16 and accordingly, the starting and stopping of a motor 10 of a compressor 1 at a temperture around 50 deg.C which is the operating point temperature of the lower side heating temperature detector 16.