Atwood Furnace

[J.Moura]

Hello Folks, You help Please...

My Atwood Furnace don't hold the flame, start normal but the burner just works for a few seconds. I chaged the main board and the limit switch and the problem continue. Any ideas? See the pictures.
ThanksAttachment 216044Attachment 216043Video_20180822_110731.mp4

[Old-Biscuit]

Limit switch is Normally Closed........allows DC to go to Circuit Board (part of Sail Switch DC circuit---BOTH have to be CLosed for DC to Circuit Bd)


Have DC at Circuit Bd cause you get Ignition SPARK and FLAME Lights.....but flame drops out.
Typically that is due to SPARK ELECTRODE issue
Bad electrode, electrode out of position (must be engulfed by flame), bad high voltage wire connection to electrode


Could also be a obstructed/blocked exhaust, LOW LP System Pressure (11" WC measured with manometer & at least 50% of propane items in service), connections on circuit bd




WHAT MODEL?

[BFlinn181]

You didn't say what model of Atwood furnace you have, so detailed info is hard to give. The ignitor is also the flame sensor. The wires leading to the gap that the spark jumps across must be directly in the flame. You might have a mud dabber nest or spider webs in the air mixing chamber diverting the air flow. Also, the wires must be clean, you might wipe them down gently with a paper towel. You could also unplug, spray contact cleaner, and reattach the wiring to the ignitor. The fact that the flame ignites then goes out points to a failure to detect the flame, but it could be a problem with the new control board.

Use Google to search for a service manual for your Atwood model online. It includes a troubleshooting guide and can give further help.

[J.Moura]

Originally Posted by old-biscuit

limit switch is normally closed........allows dc to go to circuit board (part of sail switch dc circuit---both have to be closed for dc to circuit bd)


have dc at circuit bd cause you get ignition spark and flame lights.....but flame drops out.
Typically that is due to spark electrode issue
bad electrode, electrode out of position (must be engulfed by flame), bad high voltage wire connection to electrode


could also be a obstructed/blocked exhaust, low lp system pressure (11" wc measured with manometer & at least 50% of propane items in service), connections on circuit bd




what model?

afm d20 141

[J.Moura]

Originally Posted by BFlinn181

You didn't say what model of Atwood furnace you have, so detailed info is hard to give. The ignitor is also the flame sensor. The wires leading to the gap that the spark jumps across must be directly in the flame. You might have a mud dabber nest or spider webs in the air mixing chamber diverting the air flow. Also, the wires must be clean, you might wipe them down gently with a paper towel. You could also unplug, spray contact cleaner, and reattach the wiring to the ignitor. The fact that the flame ignites then goes out points to a failure to detect the flame, but it could be a problem with the new control board.

Use Google to search for a service manual for your Atwood model online. It includes a troubleshooting guide and can give further help.

Thanks!

[Old-Biscuit]

Originally Posted by J.Moura

afm d20 141

That is NOT a MODEL number


Atwood 8525 VI or 7912-II
Something like those

[J.Moura]

Originally Posted by Old-Biscuit

That is NOT a MODEL number


Atwood 8525 VI or 7912-II
Something like those

I read from this stick

[Old-Biscuit]

OK.........I forgot about those

That IS the model number.
Atwoods NEW designed furnace ( AFMF20141A ,AFMD3011a,AFMD20111A)


And the common issue with those new improved...
WATER Intrusion...rain/rv washing
Circuit boards do not play well with WET

[swoop]

I have an older Atwood water heater and use it mostly on propane. Did some research online and found an article that says to light a burner on the stove and let it burn until the flame is mostly blue. Then try to get the water heater pilot lit. It worked for me.

[BFlinn181]

Originally Posted by swoop

I have an older Atwood water heater and use it mostly on propane. Did some research online and found an article that says to light a burner on the stove and let it burn until the flame is mostly blue. Then try to get the water heater pilot lit. It worked for me.

That's a strategy to bleed any air out of the LP lines if the regulator at the tank has been removed. Not the same as the OPs issue.