| 摘要 |
PURPOSE:To prevent dewing on an exhaust extension pipe at the time of low load operation also, by a method wherein a dewing prevention suction hole is provided on an exhaust pipe including an exhaust extension adapter and a valve body, which opens the suction hole when discharge pressure is dropped lower than a predetermined value and is openable and closable, is provided. CONSTITUTION:A dewing prevention suction hole 11 is provided at the front of the bottom part of an exhaust extension adapter 3 and an exhaust passage is in such constitution that it is partitioned by an exhaust guide 9 and exhaust wall 10. In case of an operation mode at the time of low load, an exhaust fan 2 is revolved weakly, the exhaust guide 9 is pushd back from the exhaust wall 10 by force of a spring 8 through its weak air pressure and a small gap P is generated. Air arrives at the exhaust passage, which has become negative pressure, from an open air, which is in atmospheric pressure, through the dewing prevention suction hole 11 and mixed with combustion exhaust gas. In consequence of the above, the dew point in the inside of an exhaust extension pipe 4 is raised along with a rise in excess air factor of the combustion exhaust gas and it becomes that dewing in the inside of the pipe is prevented. In all sorts, therefore, of operation modes of a gas hot water supply device body 1, the dewing in the inside of the exhaust extension pipe 4 is prevented.
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