by Squigie » Fri Jan 17, 2020 12:54 pm
There's some irony in this thread being revived yesterday. I had to use the RV furnace yesterday. I should have taken a picture. I wish I had.
Yesterday morning, I awoke about 2 hours early to a very cold house.
Thermostat was working and showed that it was heating. The furnace blower motor could be heard running.
Perhaps there was a power outage and the furnace is trying to catch back up now?
No. No signs of a power failure elsewhere in the house.
I went down to the furnace and saw the blinking light of doom. "Great, we've got another igniter or flame sensor failure. Six flashes, here we go..." methinks.
Blink-blink-blink-blink. Blink-blink-blink-blink.
Four. Where's that chart? What does four mean?
(Of course, the fault chart is upside down and hidden around a corner inside the furnace cabinet.)
"OPEN ..." -scrub some dust off the sticker- "... LIMIT SWITCH ... " -contort body in terrible ways, while pushing wiring out of the way to read more- "... OR IMPROPER ... VOLTAGE."
Okay... A transformer failure is very unlikely, and I would have to replace the whole control board for a voltage regulator failure. So, ...where are the limit switches?
And thus began about 5 hours of chasing my tail, as all parts were testing good, but the error code was different every time I reapplied power to the furnace.
In the mean time, the house was about to drop into the 50s (F). For humans, that's annoying. But there was a more pressing issue. My wife has a bearded dragon that is only kept warm with heat lamps and ambient temperature in the house. We have no 'heat stones' or other heaters for the prickly reptile. That lizard needs 60+ F, and 65 F is better for a 'low' temperature. Lucky the lizard needed heat.
I knew my electric garage heaters wouldn't be able to heat the open space in the house while I was occasionally cycling the furnace and redistributing the warmer air throughout the house.
But... But! Yea, I know what might work.
I dug the RV furnace out of its box, shoved the rear end (intake/exhaust) through the cat door that leads outside, slipped on the exhaust pipe that I don't intend to use (I have two), propped the front up, hooked up the propane (and leak-checked), hooked the power wires up to a 12V power supply from my parts bin, alligator-clipped the thermostat wires together (so I could cycle the furnace without twisting and untwisting wires), and let 'er eat.
It did pretty well. By the time I got the house furnace working well enough to feel that I could walk away from it, at least for an hour or two, the little RV furnace had gotten us back to about 67 F, and it was heating about 1,800 square feet.
Unfortunately, the house furnace is still questionable. I can touch almost any wire inside that cabinet and cause a fault that shuts it down. There seems to be a major issue with loose connectors, or actual wire breakage inside the insulation (my brother had that happen). It's 30+ years old and would certainly be replaced by the average home owner. But about 50% of its parts are also new, and I know this dumb furnace pretty well at this point. I'm still debating whether or not to replace the whole wire harness, wire by wire or pigtail by pigtail. (Replacement harnesses are not available for this furnace.)
Whatever I do, I'm going to nurse it along as long as I can - hopefully until spring - so I don't have to worry about working in short windows of opportunity.