Duo Therm heater for '88 Kit 5er?

[Gary - K7GLD]

One item in our otherwise excellent '88 Kit 5er that has bugged us pretty much since bought new, is the Duo Therm heater - it will turn on with the thermostat as it should, but then after several minutes operation, will shut down prematurely, before the heat exchanger even has cooled properly. It then re-starts after a few minutes, and the cycle repeats. There is an obvious fire danger, and the steady off/on operation takes a long time to finally get the RV up to proper set temperature - and we wouldn't dare go off in cold weather and leave the heater unattended!

Fortunately, we're "fair weather Rvers", so the heater hasn't been a serious issue - but I *would* like to correct it in case we decide to give the 5er to one of our kids, or sell it.

I've replaced the thermostat, the solid state heater module inside the heater, checked the sail switch, and both of the internal heat safety sensors. I've also carefully disassembled the burner gas flow valve, and verified proper operating voltage to the heater - but nothing I have done or replaced has cured the problem - and I really suspect the gas flow valve solenoid is the problem - that's about all that's left!

SO, I'm wondering if anyone here has had a similar problem and found the cure - OR, perhaps has the guts out of the same vintage Duo Therm heater they'd part with - or a possible source for that, or a complete heater KNOWN to be in proper operating condition?

Any help or suggestions?

[RedneckExpress]

Gary, is this the old giantic Duo Therm Heater that has a mechanical thermostat on the unit itself?(Similar to the model my 74 had before the last owner ditched it and upgraded to a Suburban Propane unit).

[Gary - K7GLD]

Originally Posted by RedneckExpress

Gary, is this the old giantic Duo Therm Heater that has a mechanical thermostat on the unit itself?(Similar to the model my 74 had before the last owner ditched it and upgraded to a Suburban Propane unit).

No, ours has the standard type thermostat mounted to an adjacent wall - the thermostat itself was also replaced some while back with a much better unit when the OEM started getting intermittent - but the issue this relates to was not caused - or cured, with the later/better thermostat.

I wish there was a local RV dismantler available - could probably obtain a decent used one for a complete swapout - or perhaps for parts...

[RedneckExpress]

Honestly, you might be best served simply upgrading to a newer ducted/direct discharge furnace rather than trying to limp the old one along.

[Gary - K7GLD]

Originally Posted by RedneckExpress

Honestly, you might be best served simply upgrading to a newer ducted/direct discharge furnace rather than trying to limp the old one along.

On the face of it, that might seem true - but about the best the whole 5er is worth on the market, is $2000 - $2500, and a new replacement heating unit would undoubtedly consume a pretty fair percentage of that price, not to mention the required time/labor to adapt a different unit into the existing space.

The existing heater does an excellent heating job WHEN it works properly, and IF a used direct replacement, or perhaps only the gas flow valve assembly, could be located at a reasonable price, that would be the preferred "fix". Only real alternative, is just what we've been doing, ignore it since we seldom use it in cold weather, and often even then, we have shore power available to power a small electric ceramic heater.

That's sort of the problem with this older stuff - often the replacement cost of a needed item exceeds or consumes a substantial part of the value of the whole unit...

I guess my primary hope in posting this here, was that someone might have, or know of, a source for either the specific part (gas flow valve), or an identical whole used unit at a reasonable price...