CWLee wrote:


"The Daring Dufas" wrote:

Is this a wall furnace?

Yes.

Would the model number start with "GWT" instead
of "GW"?

I may have failed to record the letter T - I do make mistakes now and
then - but I'm pretty sure it is as I listed it. I'll have a chance to
double check later today, or perhaps tomorrow.

If it is what I think it is and the vent safety switch is not
defective, the vent cap on the roof could be messed up. Of course it
would help to know if it's a gravity vented wall furnace.

Yes, it appears to be gravity vented. Here is more info I recorded but
failed to post:

Gravity Vented Wall Furnace
ANS Z21.49b-1995 wall furnace
Model# GW-25-6
Serial# P-43-451101
Input btu/hr 25,000
Gas nat

Does that additional info help you?

Thanks.



Yea, I thought it may be a wall furnace. The newest models are the
"GWT". The vent safety switch is a simple bi-metal manual reset
thermal switch. It is the equivalent of the "roll out switch" on
forced air furnaces that will shut one of that type down if the
flames roll out of the burner assembly. In your case, the baffle
where the safety switch is located will overheat when the hot flue
exhaust spills out into the living space. If the pipe that vents
the furnace through the roof is somehow damaged or blocked, this
could be causing the problem. You could probably feel the hot exhaust
spilling out past the baffle with your hand when the burners light
up. You might get something like a yucky cigarette to watch if the
smoke from it is blown back into the room instead of being pulled up
the stack by the draft. If you get a good draft up the vent stack,
there is a possibility that the safety switch has become too sensitive.
I've seen it happen before to temperature switches but it's rare.

TDD