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denis007's avatar
denis007
Explorer
Apr 08, 2016

Built in Propane Heater thermostat not functioning

Good morning everyone, hope you're all anxious to hit the roads this summer !

I've got a problem with the built in heater in my old 1980 Holiday 20' travel trailer. It's just a "hot box", not a forced air system. When we first got the camper, the temperature adjustment knob would turn but not "click" the thermostat to a temperature setting. I've since adjusted the knob to make the heater turn on & off, so now it's at least functional.

The problem is, the thermostat doesn't actually do anything. Turning the knob turns on or off the burner, but the thermostat (a pen-sized tube attached to a hard copper temperature signal wire) doesn't seem to actually do anything. No matter where the temp is adjusted to, the unit is either on, or off.

Does anyone know anything about testing or replacing the thermostat, or if anything on the unit is adjustable to make the thermostat functional ?

I'll go grab a model # later today, don't have it handy.

Thanks in advance all.
  • That copper pipe is not a thermostat. I would bet that it is some type of expansion tube for a limit switch. These old furnaces are beyond my pay grade but practical sense goes a long way. I'd suggest to locate that pipe as it was originally and to inspect the thermostat/valve combination. It may be that the adjustment is only for the amount of gas fed to the burner and you really don't have what would be considered a true "thermostat".
  • Its on the off/pilot/on valve block behind the swing open panel at the bottom (where you light the pilot). Separate knob for temperature control, very much similar to manually lit water heaters.

    The thermostat was pretty level with the floor, but not much in there is level with anything else, if you catch my drift .....
  • I would bet that the tube contains mercury and yes, it needs to be mounted on an exact angle to function. Mercury thermostats are no longer being made so be careful with it. Could it be that the initial testing, before you relocated that tube, were done with the trailer off-level? That may have contributed to it's non-function. Where is the knob part of this to adjust?
  • westend wrote:
    Is it a mercury based thermostat or does it have a bi-metal coil?


    Couldn't say.

    It's a Hydro Flame Furnace Model BRC-10A, 10000 btu input, 7000 btu output. Originally the thermostat was horizontal just above the floor level, I moved it up vertically next to the furnace (no difference).




    Is it possible that the thermostat must remain horizontal, in order to function ? Once we get out of the deep freeze (it's -20°C with the wind today) I'll fire it up and put heat to the thermostat with a hair dryer, just to see if it actually does anything.

    I'd like to look at some other way to activate the thermostat, either with an external electric deal or some other way.

    Someone somewhere must have gone through this and come up with a solution .....
  • Is it a mercury based thermostat or does it have a bi-metal coil?
  • After you grab a make and model number the group here will be able to help you more.

    But, I just wanted to warn you that I once had a older TT and I found they did not make parts for the furnace anymore.

    Sucked too, I loved that style of furnace.

    You may be able to get parts for yours I'm just warning you to not be surprised if you can't.