| 摘要 |
PURPOSE:To make it possible to switch the operation of a heat pump to that of a boiler and vise versa automatically in the title heat pump unit used in a hot water heating system by using an open air temperature detecting thermostat. CONSTITUTION:In case a heating operation is started, an operating switch 10 is operated, a selective switch 11 is turned on the side of a contact 11b and the open air temperature detecting thermostat 12 is set at a contact 12b so that a fan contactor 15 is energized to drive a fan in an outdoor heat exchanger. In this case,a hot water thermostat 18 is closed, a timer relay 16 is energized and after a lapse of a predetermined time, a delay contact 16a of the timer relay is closed to energize a compressor contactor 14 to thereby operate the heat pump. After the above processes, when the temperature of the open air falls and a sufficient heating capacity is not obtained by the operation of the heat pump, the open air temperature detecting thermostat 12 is set at a contact 12a at a predetermined temperature so that a boiler relay 17 is energized and the operation of the heat pump is switched to that of the boiler. |
