| 摘要 |
PURPOSE:To prevent unexpected continuation of imperfect combustion operation by a method wherein intercepting operation of valve mechanism, effected by an imperfect combustion preventing means, is precluded during a set time from the time point of burner ignition operation to decide whether a sensor has detected the condition of imperfect combustion immediately after the ignition operation. CONSTITUTION:A time limit restraint circuit 13D, precluding the gas valve closing operation of an imperfect combustion preventing circuit 13C during a set time DELTAt from the time point of ignition operation in spite of the value of density detected by sensor 10, is incorporated into a control unit 13 to avoid unnecessary extinction of the burber 3 due to the condition of imperfect combus tion (temporary reduction of measured resistance value (r)) which is caused inevitably immediately after the ignition operation. According to this method, the sensor 10 is checked through self-diagnosis whether it functions normally utilizing the imperfect combustion condition caused inevitably immediately after the ignition operation to avoid previously the unexpected imperfect combus tion operation due to deterioration of sintered film 16 of SnO2, disconnection of electrode wires 17, malfunction of an electric heater 18 or the like.
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