| 摘要 |
PROBLEM TO BE SOLVED: To surely operate the load during the night time by providing on a solar radiation sensor a load to start the operation based on the detected signal not exceeding the prescribed illuminance from one light-receiving surface with one of a plurality of light receiving surfaces to detect the illuminance toward the ground to make a correct judgment on the day or the night. SOLUTION: A feed water pipe P1 is connected to a lower part of a hot water storage tank 1 through a pressure reducing valve, and a hot water feed pipe P2 is arranged so as to constantly feed hot water of the prescribed temperature from an upper part of the hot water storage tank 1. A supply pipe P3 and a return pipe P4 are connected to an upper part and a lower part of the hot water storage tank 1 through a heat pump unit 2 so that hot water heated by the heat pump unit 2 is supplied to circulate hot water by the pipes P3, P4. A solar radiation sensor 3 is arranged above the heat pump unit 2, and the heat pump unit 2 is started based on the detected signal not exceeding the prescribed illuminance from one light receiving surface of the solar radiation sensor 3 to operate the load without misoperation. |
