| 摘要 |
<p>PURPOSE:To enable a complete automatic prevention of freezing by a method wherein a parallel resistor is connected to an input part of a hot water temperature adjusting comparator. CONSTITUTION:A resistor 16 is set in parallel with a resistor 13 and a switch 12. Therefore, when a bath switch 12 is OFF, an input of a comparator is set under ratio between resistors 14 and 16. Setting of a resistor value of the resistor 16 by ten times of that of the resistor 14 causes a high voltage of about 7.3V to be applied to the comparator 11. Thus, if a hot water temperature in a heat exchanger case 6 is high, a resistance value of a thermistor 10 is low, a voltage applied to + terminal of the comparator 11 is lower than 7.3V and its output becomes L. Therefore, a circulating pump 7 is terminated. To the contrary, when temperature in the heat exchanger case 6 becomes a low temperature of about 0 deg.C, resistance value of the thermistor 10 becomes high, a voltage higher than 7.3V is applied to + terminal of the comparater 11 to cause its output become ON(H). Therefore, the circulation pump 7 becomes an operating condition to enable a prevention of freezing.</p> |
