| 摘要 |
PURPOSE:To prevent low temperature corrosion, by a method wherein when conditional quantity is detected above the determined condition far from the generation of condition of low temperature corrosion, valve mechanism is changed to the valve closing direction, and when a detector detected conditional quantity under the determined condition, said valve mechanism is changed to the valve opening direction. CONSTITUTION:The detector 7 provided in a discharging room 19 detects temperature, and, for instance, when at the cold starting of a heating furnace 9 the detected temperature will be under the determined temperature (b) because the temperature of combustion gas which is discharged from the heating furnace 9 is low. The detected temperature is sent as a signal to a control circuit 8, and said circuit 8 drives a motor 6 and opens a changeover damper 5. Herewith, a part of air of determined supply air volume flows to a bypass passage 4, and supplying air volume into a main body 1 decreases. As a result of this, amount of heat which are taken off by combustion discharging gas air can be reduced, and temperature rising speed can be accelerrated until to the determined temperature (b) above acid dew point (a) at which temperature low temperature corrosion generates, and dew generating time can be reduced. |
