| 摘要 |
PROBLEM TO BE SOLVED: To prevent the overheat of a hot air heater by quickly detecting the abnormality of a fan as the amount of combustion is increased. SOLUTION: A combustion control unit 30 controls the amount of combustion of a burning instrument 4 while a fan control unit 31 sets the number of rotation of a ventilating fan 3 in accordance with the amount of combustion of the burning instrument 4. A number of rotation sensor 16 outputs a signal in accordance with the number of rotation of the ventilating fan 3. An abnormality detecting unit 32 detects the abnormality of the ventilating fan 3 when the number of rotation of the ventilating fan 3 is recognized that the same is lower than a predetermined lock number of rotation, which is lower than the set number of rotation. The abnormality detecting unit 32 is provided with the lock number of rotation at every set numbers of rotation in accordance with the amount of combustion while a difference between a set number of rotation and the lock number of rotation is reduced as the amount of combustion is increased. The combustion control unit 30 reduces the amount of combustion or stops the combustion when the abnormality detecting unit 32 has detected the abnormality of the ventilating fan 3.
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