| 摘要 |
PURPOSE:To prevent a a transient overheating of a heat exchanger at an initial operation of a heater and make a stable hot air temperature under a normal condition by a method wherein a correction item based upon a variation of temperature of blowing hot air is applied to change-over a range of combustion control as early as possible. CONSTITUTION:A correction item MT to be applied when performing a combustion control of a heater is calculated. It is checked whether the correction value is larger than 0 or not and if the item is larger than 0, a blowing hot air temperature is being increased, so that a blowing hot air temperature T is compared with a value of (T13-MT). T13 is a temperature where a range of combustion control at an increased temperature is changed over from its low value to a flame diminishing state. When a blowing hot air temperature T is larger than the set value, the combustion is diminished and in turn if it is lower than the set value, it is compared with a value of (T12-MT). T12 is a temperature where a range of a combustion control during an increasing temperature is changed over from its medium temperature value to its low temperature. When the blowing hot air temperature T is higher than the set value, the combustion state is made low and when it is low, it is compared with a value of (T11-MT). T11 is a changing-over temperature where a high temperature at an increased temperature is changed over to its medium state. When the blowing hot air temperature T is higher than the set value, the combustion control is set to its medium state, and in turn when it is lower than the set value, the combustion control is made high, a combustion state within the combustion chamber 14 is strengthened to feed combustion gas to a heat exchanger 18 so as to increase the blowing hot air temperature T.
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