| 摘要 |
<p>PURPOSE:To prevent boiling in a heat exchanger by eliminating hunting and stabilizing the output temperature of the hot water. CONSTITUTION:A high temperature side thermistor 5 on an upper part of a hot water storing tank 1, a low temperature side thermistor 6 in an outgoing pipe 6, and a boiling prevention thermistor 7 in a returning pipe are connected to resistors 8-10 in series. A power source voltage is divided into voltages E1-E3, and they are applied to comparators 11-13, 14-16, and 17, respectively. Reference voltage V118-V724 are applied to the other terminals of the respective comparators. The reference voltages V118-V320 determine the temperatures of the stored hot water. When E1>V1, V1> E1>V2, V2>E1>V3, and V3>E1, the capacity changes from large medium small stop of burning, respectively. The voltages V421-V623 select the capacity based on the temperature of the water inputted to the water heater 2. When E2>V4, V4>E2>V5, V5>E2>E6, and V6>E2, the capacity changes from large medium small stop of burning stop, respectively. When the boiling state is obtained, burning is stopped when V7>E3. Transistors 31-33 are operated through logic gates 25-27. Relays 28-30 are opened and closed, and fuel valves 39 and 40 and a circulating pump 3 are controlled.</p> |
