Duo-Therm furnace: Thermostat does not shut off heat

[MrJoeG]

1970's Duo-Therm trailer furnace. Worked well until a very cold wet trip, around midnight the temperature was close to 90F in the cabin, furnace thermostat appears to have failed in the on position.

This is a Duo-Therm 11HRU LPG unit without external thermostat.

Question 1: Where is the thermostat hidden?
Question 2: Where is a replacement available from?

[Spanke]

That little black knob below the red knob is basically your thermostat. It is integral with your main valve. There is probably a probe looking device that is the temperature sensor.



It is that metal thing kind of coiled up in this this picture.

You may need a new valve. Probably worth having it checked out by a pro.

Here's a chart showing replacement valves for your heater.

http://www.ntpdistribution.com/PDF/V...kchart1of2.pdf



Spanke

[MrJoeG]

I located the probe. Are these replaceable or is valve assembly replacement the only viable option?

[David Tilston]

I am not familiar with your furnace, but I think that what you show in your picture would be the thermocouple for the pilot light. Not the temperature sensor.

[MrJoeG]

I found the sensor (just like your photo), it is on the back of the control valve