Furance - Ever had an issue like this?

[wvcampincpl]

Camping last week was first time used furnace. Tried it out week before and worked fine. Got to campsite and was around 34 outside. Thermometer on furance was as low as would go (50). Anyway thermostat is a cheaper one, no seperate on/off or fan on/auto just the thermometer and the slide to adjust the temperature.

Turned thermostat up to about 65 and nothing. Checked breaker, fuse, knew gas was on, everything seemed fine. Finally, as a complete "I wonder" I took the cover off, held it over up over the stove until the thermometer read about 60. Put it back on, turned the thermostat all the way down and then back up and it worked.

Also, one night it quit working because of the battery being discharged too low and the temperature dropped down to about 50. Had to do the same thing again to get the furnace to come on.

My conclusion is, probably due to some relay or safety feature (which is a good thing) the furnace is trying to kick on when the thermometer is that low and it can't because of no gas, power and it basically won't come on until the thermostat can go below the thermometer reading and then be moved up above it.

Or that seems to be the case anyway or do I just have a screwy thermostat? Or user?

[Herk7769]

Wow, that is a new one on me...
Anyone?

[LadyWindrider]

I can understand the low battery. I also had a thermostat one time, in the ouse, that failed every year to switch to heat and start the furnace. Turns out the screws holding the wires on were one type of metal, and the wire was copper. This combination set up a galvanic reaction, which caused enough corrosion for the thing not to work. Loosen, then re tighten the wires, and all was well for another year. The corrosion is very hard to detect, more of a white powder. Finally replaced the thermostat with a digital one. All is well now.

All this thinking maybe when you pulled the cover and put it back on, you shook something, and made things work. Just a theory, you'll have to prove it right or wrong.

[schrederman]

I had a problem with my Tstat and it turned out to be the contacts in the Tstat that starts the fan and opens the gas valve. When the Tstat setting is all the way to the left, there's a bump on the left side of it that opens this pair of contacts. Mine had not gone under it but had pushed it out of alignment, instead. If not out of alignment, the contact may also be dirty. They are rather cheaply made and just dragging a piece of paper between them will clean them. I used the edge of a dollar bill on mine the last time I was out.

Also, when I was trying to get this figured out, I had one tank filled. The service guy told me to open the valves as slowly as possible to avoid the safety valve's operation. He said if opened too quickly, the safety valve might close and shut off the gas.

Hope that helps...

[grandpaofthree]

I have had similar issues with my furnace. When I posted my issue on this forum a long time ago, I was given feedback from those much more knowledgeable than I that makes a lot of sense. The low voltage and no gas is precisely the issue. The furnace has something called a sail switch. When the thermostat calls for heat, the furnace blower kicks in and gets up to full speed. When it reaches the proper speed, the sail switch allows the gas flow to open to be ignited. If there is low voltage the fan will never get up to proper speed. If there is no gas flow there won't be any ignition. The furnace will try three times to ignite then it will lock itself out. I was told to reset you have to disconnect from 12v for several seconds then reconnect.