| 摘要 |
PURPOSE:To detect the abnormality with high reliability by a method wherein a means for detecting the abnormality in speed of rotation of a blower by comparing the output voltage proportional to the speed of rotation of the blower with the reference voltage is provided and said reference voltage in said means is rendered to be variable in response to the rotation showing excessively high speed or of excessively low speed. CONSTITUTION:The proportional combustion controlling device has a combustion controlling device, which performs the control of combustion by ON-OFF control based upon the signal of a negative characterstic thermistor 22 to sense the hot water temperature, a proportional amplifier circuit 1, which outputs the signal proportional to the difference between the hot water temperature and the reference temperature, a guarantee circuit 5 for minimum speed of rotation of the blower, a sensing circuit 60 for abnormality of speed of rotation and the like. In addition, said sensing circuit 60 sets the reference voltage proportional to the reference speed of rotation between the respective output voltages at the maximum speed of revolution within the proportional combustion range under normal operation and at the excessively high speed of revolution in response to the excessively high speed of revolution. On the other hand, said reference voltage is dtermined to be set between the respective voltages at the minimum speed of rotation within the proportional combustion ragne under normal operation and at the excessively low speed of rotation in response to the excessively low speed of rotation. |
