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[GMCnet] New furnace [message #331530] Sun, 29 April 2018 22:18 Go to previous message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma:
Senior Member
So, at Bean Station last year, we were...chilly. The furnace hasn’t worked
in several years, but I had put it off, because the heat strip in the roof
air has usually been enough to take the chill off and we don’t camp in the
winter. But we can’t pull that kind of power at Bean Station, and we didn’t
want to run the generator, so we were chilly.

Last week, between trips, I saw a Suburban NT30SP on eBay—same as the
furnace in the coach. It was new, but a scratch and dent special, having
been bent up a bit during shipping during a return from a previous
customer. Price was well under $300, which is pretty cheap for a new
furnace. I took the risk.

It arrived on Saturday. It was pretty beat up, and the igniter was broken,
but I was able to straighten everything pretty well. I decided I could
leave the existing sheet metal case in place, but even pulling the guts of
the old one exposed a previous mistake. I have replaced the end of the
kitchen cabinet within which the furnace is installed. And a PO had built
the cabinet around the furnace, so both of us had left no means of
extraction. I therefore had to cut a 13x13” hole in the end of the cabinet,
which allowed me to extract the guts of the old furnace.

And I found an issue with the old one. A wire going to the motor was
showing copper for an inch, as if the insulation had burned off. That was
the part of the wire running through the remains of a large and complex
mouse next. I swear it was an apartment complex. After vacuuming all that
up, I tried to prevent a future occurance. Stainless steel wool in the gaps
around the inlet and exhaust, 1/4” hardware cloth over all the case vents,
and more stainless steel wool around the wiring harness and all other
openings. Eventually, I’ll have the coach stuffed with steel wool.

The new furnace went in fairly smoothly. After getting the gas and wiring
harness connected, I tested it. Nothing. No fan, even after the expected
delay.

So, I starting troubleshooting the wiring, and eventually discovered that
the thermostat wiring has a discontinuity. It’s wired in series with the
sail switch and the limit switch, so the module never had the signal to
turn on. The old thermostat wire was typical 18-gauge solid-core wire
sandwiched between wall materials between the galley and the bathroom, and
I’ll bet some stress point fatigued the wire and it broke. PO’s—what are
you gonna do? So I fished a new pair of wires (16-ga stranded) down the
chute used by the plumbing vent stack and now everything works.

Of course, Bean Station will be warm and sunny an we won’t need the furnace
at all. But at least one more hidden mouse nest is now gone.

Rick “now I gotta figure how to cover the hole in the end of the counter”
Denney

My suspicion is that the old
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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