On my natural gas furnace there is some kind of box on the furnace exhaust
pipe wired to the main unit. What is this and what is it supposed to do?
Does it measure heat going up the chimney or gasses? How does the furnace
respond based on the reading? What are the implications for maintenance.
I realize this is probably more complex than it seems, but I'm trying to get
a handle on how the furnace operates. It's a Peerless boiler furnace, about
7 years old.
That makes sense! I just patched a 1 foot diameter hole in the chimney left
by the prior owner so I could keep exhaust gasses and cold out of the
basement. I guess it just didn't occur to me such an intelligent thing might
be on the furnace under such circumstances :)
It's hard to tell without looking at it, but it's probably a blocked
flue/spillage switch. If the flue ever gets blocked ( by squirrels building
a nest or the chimney collapsing) the switch will open up and keep the unit
If the unit has stopped working because of the switch, call a pro to look at
it. Make sure s/he checks the chimney. Don't jump it out or you and/or
your family make wake up dead....
Probably says Honeywell on it too..
Might have 2, or 4 wires leaving it, and its got a cover that pops off and
has a board behind it right?
Thats a flue dampner. Required in some areas for code, and it should open
fully when the thermostat calls for heat, and not allow the furnace to fire
until it is open fully.
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