| 摘要 |
PURPOSE:To inform the replacement of an ultraviolet ray detector at an early stage and at a proper period, by monitoring the detection number of times of a flame during pre-purging and/or post-purging performed within a predetermined time. CONSTITUTION:A combustion control circuit 6 issues a blow control signal 6a to a fan 2a on the basis of the combustion start order of a controller 5 to enter pre-purging operation and the residual gas in a combustion chamber 2 is discharged. When a dummy flame is generated in said chamber 2, a discharge current is sent to a flame circuit 3 from an ultraviolet ray detector 1 and a flame detection pulse signal is outputted to a counter 4 and the controller 5 through lines 3a, 3b. At the time of the finish of pre-purging, the controller 5 compares count data 4a and the judge number-of-time data D of ROM 5b and, at the time of 4a>D, CPU 5a judges the deterioration of the detector 1 to inform the same to an operation part and stops the transfer to combustion sequence operation. When 4a<D and a detection pulse signal is outputted, it is judged that deterioration is not advanced to start usual combustion sequence operation.
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