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 > Atwood Furnace Problems

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pomology

California

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Posted: 09/10/19 08:53pm Link  |  Quote  |  Print  |  Notify Moderator

I have a problem with the Atwood furnace on my 5th wheel (2019 Montana High Country )

I just bought the unit second-hand six months old from a private seller and have never used the furnace system before. (The person I bought it from never used the furnace either because they had free electricity at the RV park). When I turn up the thermostat and go outside, the furnace blower turns on, and the sparker clicks to ignite gas. I smell pretty strong gas exiting the exhaust pipe and actually hear the flame briefly ignite for ½ second or so, and feel a brief rush of hot air. Then the flame goes out. The sparker attempts to re-ignite, I feel a rush of heat for a ½ second, and then the flame goes out. This happens repeatedly over and over again until the unit finally times out and the red LED has the 3-blink pattern.

Things I've tried:

1) All the other propane appliances work. Stove works fine, gas water heater (which is right beside the furnace) also works perfectly.

2) Propane tanks are full.

Any ideas of what I should try next would be much appreciated!

Thank you!
Randy

happy2rv

Huntsville, AL, USA

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Posted: 09/10/19 09:56pm Link  |  Quote  |  Print  |  Notify Moderator

Sounds like the flame sensor is not detecting the flame although I would expect it to stay lit longer than 1/2 second. Could be a bad sensor or bad/corroded connection. It could also be the control board.

I would also inspect for any obstructions / nests / varmints in the burner/exhaust assembly.


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DFord

Near St Louis, MO

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Posted: 09/10/19 10:01pm Link  |  Quote  |  Print  |  Notify Moderator

The control board on your furnace tries three times to prove a flame and then goes into a lock-out mode. You'll have to reset the thermostat to recycle it. It's working correctly.

Mud-dubbers and spiders like to build their nests inside the furnace and block the proper flow of things. The screens you can get at RV supply stores do a great job keeping out the wasps but do nothing for the spiders.

You'll need to open up the furnace and make sure there's nothing blocking the flame tube. There's flame rod where the spark jumps from and it must be surround by the flame rod to keep the gas valve open.


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pomology

California

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Posted: 09/11/19 07:50am Link  |  Quote  |  Print  |  Notify Moderator

Thanks. The blower runs constantly for several minutes, with the sparker attempting to light every few seconds through that time period. It's like the flame just flickers in there before going out every time. I feel a burst of heat and that hollow "whooshing" sound that happens when the flame ignites, only for it to immediately go out. Only after several minutes does my unit go into lockout mode.

I'll clean all the connections today and report back.

A1RVTraveler

North Carolina

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Posted: 09/11/19 11:48am Link  |  Quote  |  Print  |  Notify Moderator

You need to pull the furnace and inspect the burner, LP orifice and igniter. I suspect you have a bug in the LP orifice or a mud dauber nest in the burner area. This is a common problem.

joebedford

Finally back home in the north

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Posted: 09/11/19 07:12pm Link  |  Quote  |  Print  |  Notify Moderator

My furnace used to do that until I tightened all the push on spade connectors.

badsix

north bend or.

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Posted: 09/11/19 09:46pm Link  |  Quote  |  Print  |  Notify Moderator

2x above ^^^
Jay D.

maillemaker

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Posted: 09/12/19 06:37am Link  |  Quote  |  Print  |  Notify Moderator

Quote:

The blower runs constantly for several minutes, with the sparker attempting to light every few seconds through that time period. It's like the flame just flickers in there before going out every time. I feel a burst of heat and that hollow "whooshing" sound that happens when the flame ignites, only for it to immediately go out. Only after several minutes does my unit go into lockout mode.


Yup, this is all typical fail-safe stuff. When you turn on the furnace, the first thing that happens is the blower motor is turned on. Inside the furnace there is a "sail switch" that blows in the wind made by the fan. If that switch does not activate, it tells the furnace controller that the fan isn't running, and it's not safe to fire up the furnace with no airflow (it would burn up). That is check number one.

Then it opens the gas valve and fires the ignitor. If it doesn't detect a flame, it will shut things down. It will try to re-start some amount of tries before it gives up (lock out).

As others have said, either you have a bad control board, or a poor electrical connection to the flame sensor, or there is debris in the furnace causing poor gas flow and making the flame extinguish.

When you open the cover to the furnace on the outside of the RV you should see the burner inlet pipe with the ignitor. Sometimes there are two prongs - one for the spark and one is the flame sensor. Other furnaces combine both into one prong. Make sure the prongs are rust and debris free.

If you remove the bracket holding the ignitor assembly you can usually stick a vacuum pipe up the inlet pipe and suck out any debris down there. Make sure the heater is cold first of course.


1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"



dougrainer

Carrolton, Texas

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Posted: 09/12/19 07:54am Link  |  Quote  |  Print  |  Notify Moderator

If you hear the spark and smell LP and sometimes you feel heat, the Spark Electrode is to CLOSE to the burner. You will have to have the furnace pulled and the Spark Electrode gap set. 2019, the furnace is under warranty. Makes no difference you are the 2nd owner. Just find a service center that will do Atwood/Dometic warranty. Doug

almcguire

Indiana

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Posted: 09/13/19 05:03pm Link  |  Quote  |  Print  |  Notify Moderator

pomology wrote:

I have a problem with the Atwood furnace on my 5th wheel (2019 Montana High Country )

I just bought the unit second-hand six months old from a private seller and have never used the furnace system before. (The person I bought it from never used the furnace either because they had free electricity at the RV park). When I turn up the thermostat and go outside, the furnace blower turns on, and the sparker clicks to ignite gas. I smell pretty strong gas exiting the exhaust pipe and actually hear the flame briefly ignite for ½ second or so, and feel a brief rush of hot air. Then the flame goes out. The sparker attempts to re-ignite, I feel a rush of heat for a ½ second, and then the flame goes out. This happens repeatedly over and over again until the unit finally times out and the red LED has the 3-blink pattern.

Things I've tried:

1) All the other propane appliances work. Stove works fine, gas water heater (which is right beside the furnace) also works perfectly.

2) Propane tanks are full.

Any ideas of what I should try next would be much appreciated!

Thank you!
Randy



Randy
The unit is not sensing flame. Electrode 10% board 90%. Call Dometic customer service and have the model and serial of the furnace and need a replacement Board.

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