| 摘要 |
PURPOSE:To provide a low NOx content, improve a responsive characteristic of an air ratio control and detect a back-fire by a method wherein a thermocouple is arranged at a bottom part of flame hole portion of a burner and a damper having driving mechanism is arranged at an air suction passage including a fan motor. CONSTITUTION:A thermocouple 14 is arranged at a bottom part of flame hole portion 10, a damper 19 driven by a motor 18 is installed at a suction port, and both a discharge port and a mixture chamber 11 of a burner 9 are connected by a mixing pipe 20. Flame temperature is detected by the thermocouple 14 and its value is outputted to a circuit 24. An air ratio enables a high first combustion to be performed with a combustion fan motor 17, resulting in that a combustion temperature can be decreased and further an amount of production of NOx can be restricted. When a difference between the combustion temperature and a set value exceeds a specified range, the motor 18 is controlled and a degree of opening of the damper 19 is varied. Since the damper has a lower inertia moment than that of the fan, its responsive speed is high. When a back-fire occurs, a cold contact point 16 of the thermocouple 14 placed adjacent to the mixture room 11 is heated and an electromotive force of the thermocouple 14 is decreased less than that at normal time, so that the back-fire can be detected. |
