||12-05-2009 12:49 PM
Furnace only works with door off
I have a Governaire standard efficiency furnace. The furnace has been cycling every three minutes or so. I noticed that the furnace runs fine with the burner access door off. If i slowly start to put it back on, I can feel a lot of suction and I can see the flame blow out. It seems like the sensors and switches work okay and the furnace is shutting down (correctly) because the flame sensor cannot detect a flame.
Any ideas about what the problem is and how to fix it? Any help is greatly appreciated.
BERVIN 306 - I think you are on the right track. There is no intake pipe. The furnace is in a crawlspace and there is plenty of ventilation, but I think there may be a restriction in the flue causing a pressure drop. I think the inducer fan can produce enough static pressure to overcome the restriction, but not with extra restriction of the access door.