| 摘要 |
PROBLEM TO BE SOLVED: To detect oxygen deficiency in a specified oxygen concentration by conducting an interval control of increasing a predetermined time combustion amount from a delay of a predetermined time at the time of small combustion and periodically repeating a combustion for reducing an air supply amount to heat quantity of a high burner port load side from the vicinity of a predetermined value of a burner port load as a boundary. SOLUTION: At the time of small combustion, an interval control of measuring flame current sensed by a flame rod 6, increasing a combustion amount at a predetermined interval from ordinary small combustion specification, and decelerating a rotational speed of a blower 5 for a given time to heat quantity of a high burner port load side near 1.0 kcal/mm<2> of a burner port load as a boundary to decrease the air supply amount is executed. Such an interval control is periodically repeated. Thus, primary air amount for combustion is reduced and combustion velocity is decelerated, and hence a flame 12 is easily lifted. Then, since a decrease in flame current value is fastened, delayed OFF at the time of the small combustion can be prevented, and hence an oxygen deficiency sensing level satisfies a specified oxygen concentration (16 deg.C or higher). |
