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RV furnace troubleshooting

Seubs070

Well-known member
Joined
Aug 24, 2020
Member Number
2767
Messages
98
Have a new to me RV with and Atwood 8531 furnace. Furnace wouldnt light so I pulled it apart and the burner was bad.

Replaced the burner and igniter. Put it together and it would light and run for like 20 second then the flame would go out. It would try and relight two more times and then give three flashes for an error code.

Replaced the board and now it won’t light at all with the new board or old board. Can see the igniter sparking. Hear the gas valve click and can smell gas. Try’s to light three times and then flashes the same error code.

I was thinking it has something to do with gas pressure but the water heater lights and stove top works.

Any ideas?
 
Make sure there's no leaks (obviously) and then try to manually light it if possible. Mine is a completely different model but same thing happened and it was simply the ignitor being a hair too far away to ignite the burner.
 
Ransil said:
Check the igniter gap.
Then check the sail switch
Click to expand...
It’s about an 1/8” off the burner and I can see it sparking between the igniter and burner if I pull it out and try to light it.
 
1981K20 said:
Make sure there's no leaks (obviously) and then try to manually light it if possible. Mine is a completely different model but same thing happened and it was simply the ignitor being a hair too far away to ignite the burner.
Click to expand...
I don’t think it’s possible to manually light. It’s all sealed up.
 
Flame detect sensor? Sail switch?

Dinosaur electronics boards have onboard diagnostic lights so you can check for visual operation of these items when troubleshooting.
 
Does it have a thermocouple? Home HVAC will try to light 3 times then shut off and the power has to be interrupted.

What’s the error code? “ Low gas pressure, “ etc.
 
Seubs070 said:
It’s about an 1/8” off the burner and I can see it sparking between the igniter and burner if I pull it out and try to light it.
Click to expand...
Should be a spec on it else make it closer or further away and try it.
 
The board has a red light on it. It flashes three times after it fails to light. From what I could find that means electric problem. Igniter problem or low lp pressure. So really no help at all.
 
if you bypass the sail switch, will it run normal?
 
Not sure where the sail switch is on this one. My understanding was it wouldn’t try to light if the sail switch was bad?
 
cervelorod said:
Throw it away and put in a diesel parking lot heater. It doesn’t create so much moisture inside.
Click to expand...
That's what I'll be doing if my furnace dies.
May just do it anyway.

These propane furnaces are a pain in the ass, have to be together to test, can't test shit when they are together.
 
Seubs070 said:
Have a new to me RV with and Atwood 8531 furnace. Furnace wouldnt light so I pulled it apart and the burner was bad.

Replaced the burner and igniter. Put it together and it would light and run for like 20 second then the flame would go out. It would try and relight two more times and then give three flashes for an error code.

Replaced the board and now it won’t light at all with the new board or old board. Can see the igniter sparking. Hear the gas valve click and can smell gas. Try’s to light three times and then flashes the same error code.

I was thinking it has something to do with gas pressure but the water heater lights and stove top works.

Any ideas?
Click to expand...

Is the bottle full? If you have one, switch cylinder sets. Can you light all the stove burners and get nice crisp blue flames all at once? After the stove is on full burn, run the WH with the stove still on. How old is the reg?
 
Etyler2 said:
Is the bottle full? If you have one, switch cylinder sets. Can you light all the stove burners and get nice crisp blue flames all at once? After the stove is on full burn, run the WH with the stove still on. How old is the reg?
Click to expand...
Regulator is likely original. It’s a 2000 model year so 24 years old.

I ran two burners and they burned good. Water heater also burned good but I didn’t try them all at the same time.

It will be a couple days until I can get back there. I have a different igniter to try.

I’m thinking it has to a gas pressure issue. It was 70 degrees last weekend when I could get it to light once. Yesterday when I tried it was in the 30s. I’m thinking the cold temps lowered the lp pressure enough to fuck up the regulator?

It does have two bottles. Doesn’t work one the second bottle either.

Is there any easy way to test pressure?
 
CarterKraft said:
That's what I'll be doing if my furnace dies.
May just do it anyway.

These propane furnaces are a pain in the ass, have to be together to test, can't test shit when they are together.
Click to expand...
I’ve thought about this. So you just leave the unit outside and run the heat tube in the window? Is there less janky way to set them up?
 
Cover / restrict the exhaust with your hand when trying to ignite.
Rig it so you can work on it outside the RV PIA putting it in and out
 
Seubs070 said:
I’ve thought about this. So you just leave the unit outside and run the heat tube in the window? Is there less janky way to set them up?
Click to expand...
I would mount it in the floor like its intended, exhaust tube goes out the floor and the air blower tube gets routed/ducted in the coach to a desired outlet area.
 
As others have said. > Sail Switch. No. one problem-- Ain't no gas init. No. two problem-- Sail Switch.
 
eraser5 said:
As others have said. > Sail Switch. No. one problem-- Ain't no gas init. No. two problem-- Sail Switch.
Click to expand...

Those atwood furnaces have the sail switch buried in the rear where they are very difficult to get to, much less even see without having the heater unit out... but it may in fact be the only issue here.

IIRC the blower will run, detect no flow at the sail (if its bad), then the blower will turn off. Since his igniter tries to fire it shouldn't be a sail switch so i dunno then.
 
trampas said:
Those atwood furnaces have the sail switch buried in the rear where they are very difficult to get to, much less even see without having the heater unit out... but it may in fact be the only issue here.

IIRC the blower will run, detect no flow at the sail (if its bad), then the blower will turn off. Since his igniter tries to fire it shouldn't be a sail switch so i dunno then.
Click to expand...
The START function fires the burner. A thermal switch sees heat, turns on the fan. The sail switch sees air flow-- good to go. The sail switch does not see air flow-- safety shut down. The dinky switch may not even be able to see hurricane Helena level air. A single human hair can foul that switch.
 
Mine was intermittent, brand new trailer, I got so pissed about the difficulty to ts it when it's in the trailer I added led lights to all the relevant inputs/outputs so I could see what was going on through the grill under the cabinet.

Ultimately a new ignition board from Dinosaur fixed it for good,
 
CarterKraft said:
Mine was intermittent, brand new trailer, board from Dinosaur fixed it for good
Click to expand...

I've seen that w new trailers, shitty Chinese boards with intermittent functionality :shaking:

eraser5 said:
The START function fires the burner. A thermal switch sees heat, turns on the fan. The sail switch sees air flow-- good to go. The sail switch does not see air flow-- safety shut down. The dinky switch may not even be able to see hurricane Helena level air. A single human hair can foul that switch.
Click to expand...

Except the fan comes on first, initiating the sail, only THEN does the "start-burn" click on.
 
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