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CarnationSailor's avatar
Sep 18, 2018

Flaky Furnace Thermostat

I have a Suburban gas furnace in my 4-year old 5th-wheel. The thermostat name on the front panel is "RVComfort.HP". When heating on propane only (that is, not using the heat pump), four times in the past two days the thermostat has changed the temp setting from our daytime setting of 69 or our night time setting of 66 degrees to 72 degrees. All by itself.

I believe that 72 degrees is the thermostat's default setting; i.e., when I first turn on the batteries, the thermostat sets itself to 72 degrees. I suspect that something is causing the thermostat to reset to it's default setting. It could be a momentary loss of 12-volts to it, but I doubt that is the reason because I can't think of anything that would interrupt the voltage from the batteries. (We are dry camping.)

Has any seen this before?
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    The Furnace needs only a switch closure. For like 20 bucks ACE or ACO hardware (Or True Value) has a 100% mechanical mercury free T-Stat that does NOT need to be leveled.. Works great. No batteries needed. NOT, however, digital.
  • Yes, the 72 degrees is the default when 12 volt power is off or disrupted. I would say you have a intermittent power problem supply to the Tstat system. Hard to run down, but a starting point would be the fuse connection at the 12 volt fuse panel and then the connections behind the Tstat and then the connections at the AC control board. Doug
  • For the furnace, any old battery powered digital thermostat will do just fine and is an easy install. For many air conditioners, you can also use such thermostats, but some others require a dedicated manufacturer-specific thermostat.

    (Actually, an unpowered bimetallic strip thermostat would also work fine for the furnace, but many of them are sensitive to vibration and/or rely on being level for proper calibration and generally are not as precise or satisfactory as digital ones.)
  • If you have a 4 wire thermostat simply replace it with a quality piece. If its one of the crappy flat wire things there pushing now, good luck.

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