| 摘要 |
PURPOSE:To perform an automatic prevention of freezing by a method wherein a valve is opened when a temperature of surrounding atmosphere reaches such a temperature as one in which a circulation pipe is freezed and in turn when the temperature of the surrounding atmosphere is increased more than such a temperature as one in which the circulating pipe is to be freezed, the valve is closed. CONSTITUTION:When a temperature of surrounding atmosphere is gradually decreased lower than 0 deg.C, for example, and a circulation pipe or the like is freezed, an 'H' level signal is outputted from a comparator 12. Then, a motor 15 is rotated to cause a valve to open a circulation pipe. In this way, water or the like is circulated in the circulation pipe, resulting in that the circulation pipe can be prevented from being freezed. In addition, when the temperature of the surrounding atmosphere in increased over 0 deg.C, an 'L' level signal is outputted from a comparator 12. At this time, a normal-reverse rotation switch 29 may rotate a motor 15 in a reverse direction in response to the 'L' level signal from a flip-flop circuit 22. The valve may close the circulation pipe under a rotation of the motor 15. |
