| 摘要 |
<p>PURPOSE:To prevent a hot water boiler from freezing efficiently without fail by the operation of the boiler in a short time by a method wherein a burner is operated forcibly during a period of time from the detection of a freezing incurring temperature T1 by a temperature detecting section up to the detection of a temperature T2 which is higher than the temperature T1. CONSTITUTION:A freezing preventive thermostat 10 detects the temperature of a downward pipe 5, a part of the hot water boiler which is most liable to freeze, and shortcircuits a resistor 21 and a temperature setting volume 12 during the time in which the temperature of the above-mentioned part changes from T1 to T2. Then a set temperature Ts is made to be Tsm and the burner 8 is ignited forcibly to thereby prevent the freezing of the water boiler at low cost by providing at the input section (a bridge circuit 16) of the temperature control device 11 the freezing preventive thermostat 10 in the form of a thermosensitive reed switch or the like singly or in a plurality of numbers as the case may be.</p> |
