Community Forums

cimplexsound · 03-14-2016, 12:48 PM

I have the Duo Therm 30,000 BTU furnace in my 1979 Dodge Fleetwood Tioga. It worked perfect for 4 months during my time in Pahrump. While heading north to Salt Lake City, Utah for the my summer stay, the furnace started giving me trouble. It will now only stay lit for about a minute then the flames go out and it blows cold air. I checked the propane regulator and it is just fine. I wonder if I went over a hard bump on the freeway and a short occurred in the circuit board. Any guess??? It has worked perfect forever, so why am I having trouble now??? I could defiantly use feedback here. Thanks

Vaflatlander · 03-14-2016, 01:32 PM

Just a guess but it acts as if furnace does not realize there is a flame. Check for loose wire.

mel s · 03-14-2016, 01:37 PM

Quote:

Originally Posted by Vaflatlander

Just a guess but it acts as if furnace does not realize there is a flame. Check for loose wire.

And clean the "flame sensor" and the "sail switch".

DAN L · 03-14-2016, 11:48 PM

complex...
did you recently add propane to your tank?
you could have gotten ''wet propane''.
does your stove still work OK?

cimplexsound · 03-25-2016, 02:41 PM

Quote:

Originally Posted by DAN L

complex...
did you recently add propane to your tank?
you could have gotten ''wet propane''.
does your stove still work OK?

Yes my stove works just fine. I lit the oven and it stayed on the whole time. Not having problems with any other appliance. No the same propane has been in my tank from almost 2 weeks. I didn't plan on refilling so I could use what LP gas I had left for the trip home. This is acting more like an electrical problem, like a bad sensor or something.

cimplexsound · 03-25-2016, 02:43 PM

Quote:

Originally Posted by Vaflatlander

Just a guess but it acts as if furnace does not realize there is a flame. Check for loose wire.

I wonder. Could a bad or dirty sensor in the combustion chamber of the furnace be causing the problem???

Podivin · 03-25-2016, 02:55 PM

I'm not sure if this applies to your furnace, but I just fixed mine by replacing the ECO switch. If you have an ECO (right next to the themostat on mine) it's an easy test to 'jump' the wires to see if fixes the problem (remove the two wires from the ECO and connect them together). If your furnace runs then you need a new ECO.
I'm not SURE, but I believe the ECO is an overheat switch - it turns off the furnace at 180 degree water temp.
Mine is an Atwood in a '96 coach, so none of this may apply to yours.

cimplexsound · 12-09-2016, 08:33 PM

Hey thanks for all the help. My furnace is a Atwood Hyrdo flame from the 8500 series. After close and through examination of the furnace, I found a faulty loose wire on the back of the sail switch. I did a quick fix for now and the furnace is working great, I'll go through when I have more time to hire a helper who will go through all the wires with me and replace the loose faulty ones.

cimplexsound · 12-17-2016, 08:51 PM

PROBLEM SOLVED: it was a bad sail switch. The furnace ignites with no trouble everytime and runs flawlessly.
So thanks for all the help.

wa8yxm · 12-18-2016, 09:46 AM

If it lights the sail switch is good, as is the blower and a bunch of other stiff

IF it burns for a very shore (less than a minute) then shuts off, and tries again, and again then locks out and shuts dou have two or 3 suspects.. in liner order

Flame: Dirty orifice or mal-adjustment may mean flame is not burning hot enough Clean and adjust but first inspect viauslly

Flame Sensor Rod (Thermocouple) clean, replace if necessary

CXontrol board:L What failed on MY RV, Replace with DINOSAUR BOARD control board, not oem, I got mine from American RV in California. about half the price and several times the quality of the OEM. I mean this is one well built board.

cimplexsound · 12-18-2016, 10:21 PM

Quote:

Originally Posted by wa8yxm

If it lights the sail switch is good, as is the blower and a bunch of other stiff

IF it burns for a very shore (less than a minute) then shuts off, and tries again, and again then locks out and shuts dou have two or 3 suspects.. in liner order

Flame: Dirty orifice or mal-adjustment may mean flame is not burning hot enough Clean and adjust but first inspect viauslly

Flame Sensor Rod (Thermocouple) clean, replace if necessary

CXontrol board:L What failed on MY RV, Replace with DINOSAUR BOARD control board, not oem, I got mine from American RV in California. about half the price and several times the quality of the OEM. I mean this is one well built board.

Yes I also know the motor can be suspect in the scenario you described. As they get old the bushings can go out preventing the motor running fast enough to open the sail switch. The main xcontrol board is also in very good condition as my new Motorhome only has slightly over 38,000 miles on it. However that is not the case here. The sail switch was the culprit. The furnace is very clean, hasn't been used much and I keep it regularly cleaned with compressed air. The furnace is operating properly. It lits, runs a complete cycle, completes it's cool down cycle, then shuts off after set room temperature has been achieved. Apparently Atwood is still manufacturing this furnace because this particular model has proven to be very dependable. So thanks to everyone for your troubleshooting tips.