| 摘要 |
<p>PURPOSE:To perform a positive anti-freezing operation and get a more economical consumption power by a method wherein a water level in a tank is detected by a sensor, when the detected level is higher than a predetermined level, water in the tank is heated by a burner and is turn when the detected water level is lower than the predetermined water level, water in the tank is heated by an electrical heater. CONSTITUTION:In the event that an anti-freezing operation mode is selected, as a detected temperature of a water temperature sensor 32 is lower than 5 deg.C, either an electrical heater 46 or a burner 16 is operated. That is, when a detected signal of a water level sensor 30 is higher than a predetermined water level, the burner 16 is operated, when the detected water level is lower than a predetermined water level, the electrical heater 46 is operated. When a detected temperature of the water temperature sensor 32 exceeds 10 deg.C, neither the burner 16 nor the heater 46 is operated. Water temperature in the tank 18 is detected to perform an anti-freezing operation, and it is also possible to perform an anti-freezing operation after detecting the air temperature.</p> |
