Originally Posted by High Center Hancho
how does it over heat with the power off? the draft door would be closed
This specific wood furnace, which is the only central boiler that I have heard this of, has problems with the draft door sticking open, the door, servo motor all of it has been replaced. So it sticks open.
When the power goes out, it simply over heats from no circulation, he has always operated the furnace at 180 so it is closer to boiling than others operating at 160 etc.
So the boiling over thing is a real problem when the power goes out, as it blows the water out then their is no way to get water to pour into it after over heating,
He has had the service tech out to look at the door and replaced several parts, in the last eight years, I have even believed that the stack is to short and allows it to down draft in the chimney because it goes under vacuum, I know you believe that is impossible, but I really believe it starts down drafting under draft door closed condition, when their is a large fire in the furnace.