Old Duo Therm Furnace fan needed

I have a 1972 GlobeStar I just got and am in the process of restoring it. All the systems seem to work except for the heater. It's an older Duo Therm heater. It's a model 16mhu I think.

At first, it needed a thermostat, so I replaced that, and got the pilot light lit, and when the thermostat kicks on, the burner kicks in, but there is no fan on this heater. It looks like one was once there, but I can't find any information about this heater on the net.

Does anyone know about these heaters? Do you have a manual? Or know what type of fans they used?

Thanks for any help!


Gary B

Senior Member
Old Duo Therm Furnace fan needed

Hi Jamie, welcome to the forum :laugh: , in 1972 a furnace/heater may not have had a blower fan many of the vintage did not have fans they were radiant heats. Does it have duct work attached to the furnace or does the heat come out the front grill? Here is a site that maybe of some help to you
http://bryantrv.com/ Good luck with the restoration. :) :laugh: :cool: :bleh: ;) :approve:
Old Duo Therm Furnace fan needed

Thanks for the welcome and the link. I will look into the information they offer and maybe will find something that will help guide me in the right direction.

it does not have duct work , there is a grill in the front of it only. After installing the thermostat, before I realized there was no fan, I turned it on and waited for 10-15 minutes thinking the fan would eventually come on, but it didn't. :eek: In that time, it didn't seem like it would heat the TT without some kind of fan.

I *think* from my limited experience that it should have a fan. There are two wire with spade clips on them that aren't connected to anything. Beside them there is a place that looks like a fan/heat sensor type of switch would be attached. I could be wrong, it could be a high limit switch. From what people have told me, there is something a fan/heat sensor switch that will pop on the fan when the air is hot, and this will prevent the fan from blowing cold air. There also, sometimes is a high limit switch that will shut off the LP when the heater gets too hot. (overloaded)

I am not sure which switch if either goes to where the missing thing is.

Is there such a thing as a heater/water heater all in one? If I can't get this one working, I will be looking for a replacement and since my TT doesn't have a water heater, I would want to include one.

Thanks again for the help!



Senior Member
Old Duo Therm Furnace fan needed

While I don't remember the model, it sounds to me as though you have the same furnace that we had in our 73 Starcraft. It too was from Duo-Them and back then it was a seperate company, but it is part of Dometic today. The frunace that we had was just as you describe and it had a blower with thermostat available as an option. Ours did not come with one and it also did not have the thermostat. I did look into adding the kit, which was not difficult because all that it involved was to install the thermostat, run the wires and plug everything in at the furnace. The way that it worked was the thermostat would reach the set point and turn on the blower. The cool air that was then drawn through the furnace would cool the bulb that controled the flame and the gas valve would open and a pilot would light the flame. The gas control was just like is on the old style water heater where you had to turn the knob to pilot, push it and hold it while lighting the pilot. Then you hold the knob in until the pilot heats the thermocouple to hold the safety valve open. Once that happens, the knob is then turned to on. As I recall, it has a seperate temperature control knob. But that was a long time ago and my memory isn't as accurate as I sometimes wish it were. I would be very surprised if that furnace is still available and I suspect that parts will be difficult to locate. If you want, drop me an email and I'll send you a list of RV salvage shops that I keep to see if they can help you.