| 摘要 |
PURPOSE:To enable an efficient defrosting operation to be made possible without using heat in a hot water storage tank by a method wherein a defrosting circuit is provided in a heat pump heating unit and the defrosting circuit is opened at the time of defrosting operation for the unit so that the gas discharged from a compressor is introduced directly into a heat exchanger as an air heat source. CONSTITUTION:When a frost sensor 18 detects a frosted condition, a relay switch 24 is closed by a defrosting control circuit 19 so that a contact 21 of the relay 20 is closed and a contact 22 is opened. Accordingly, an electromagnetic valve 9 is opened to thereby open the defrosting circuit and the gas discharged from the compressor 2 is supplied directly into the heat exchanger 5 as the air heat source for performing the defrosting operation. Further, with the opening of the contact 22, a circulation pump 12 is stopped. At this time, a coolant hardly flows into a water heating heat exchanger 3 because the resistance of a throttle mechanism 4 is great and since the temperature of the heat exchanger is kept high, there is no fear of the coolant pooling in the heat exchanger. As a consequence, it is possible to start the heat exchanger 3 quickly at the time of re-starting the heating operation and also to prevent the lowering of the temperature of the hot water at the upper part of the hot water storage tank 11. |
