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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Jon H on December 26, 2019, 05:25:00 pm

Title: Atwood 8535-III furnace propane connection
Post by: Jon H on December 26, 2019, 05:25:00 pm
Hi All,

Needing the benefit of some forum experience again  :'(  .  Currently engaged in my semi-annual battle with the Florida mud daubers and their newly established residences in my coach furnaces.  My front furnace is a Atwood 8535-III ( now obsolete ) and the rear furnace is a 8516-III.  My problem is related to the attempted removal of the front furnace burner assembly in order to remove the mud dauber nests.  A prerequisite to removal is disconnecting the propane supply line however there no room for the flare nut, on the propane supply line, to move back far enough to allow withdrawal of the burner assembly.  Photo's attached showing configuration of both propane supply lines.
Looking, as usual, for the benefit of years of forum experience and a simple inexpensive solution  ;D
Title: Re: Atwood 8535-III furnace propane connection
Post by: wolfe10 on December 26, 2019, 05:29:01 pm
Jon,

I would be surprised if there is not enough play to push the propane line "inside".  Look from the inside of the coach and see if you can push it through the black plastic "surround" enough to clear the threads.
Title: Re: Atwood 8535-III furnace propane connection
Post by: Lance Camper on December 26, 2019, 05:52:27 pm
X2 Jon

That black wall is flexible enough (on mine) to allow you to push the brass piping out of the way. I feel your pain, I was afraid it would caused a leak.

HTH
Ed
Title: Re: Atwood 8535-III furnace propane connection
Post by: Old Toolmaker on December 26, 2019, 06:28:10 pm
Hi All,

Needing the benefit of some forum experience again  :'(  .  Currently engaged in my semi-annual battle with the Florida mud daubers and their newly established residences in my coach furnaces.  My front furnace is a Atwood 8535-III ( now obsolete ) and the rear furnace is a 8516-III.  My problem is related to the attempted removal of the front furnace burner assembly in order to remove the mud dauber nests.  A prerequisite to removal is disconnecting the propane supply line however there no room for the flare nut, on the propane supply line, to move back far enough to allow withdrawal of the burner assembly.  Photo's attached showing configuration of both propane supply lines.
Looking, as usual, for the benefit of years of forum experience and a simple inexpensive solution  ;D

Since you're taking the furnace out, you've removed the sheet metal screws and bent up, or straightened out, the tabs that hold the furnace to the face plate.  Once you've taken the inner face plate off that black plastic air seal can be pulled towards you leaving a round plastic piece around the pipe itself.

FWIW, my front furnace stopped working two days before Christmas.  I had already replaced a failed, electrically open sail switch with a replacement and I didn't transfer over the sail to the new switch because I wanted to see what happened.  So when the furnace worked less than reliably I wasn't upset.  Further trouble shooting on Christmas day pointed to a failed, original, control board.  The new Dinosaur board will be here on Monday.

While washing the Christmas morning breakfast dishes the water heater failed to light.  Concurrent with the furnace work, I had the water heating. and I noticed that the safety valve was leaking.  When the water became warmer the valve leaked a lot.  The correct 1/2"NPT safety valve will be here on Saturday. Amazon sorta said so. Doctor visits tomorrow so I have a 3/4" NPT safety valve doing temporary duty.  We're not taking showers in cold water.
Title: Re: Atwood 8535-III furnace propane connection
Post by: wolfe10 on December 26, 2019, 07:34:19 pm
No need to remove the whole furnace to service the burner assembly.
Title: Re: Atwood 8535-III furnace propane connection
Post by: Jon H on December 26, 2019, 07:48:34 pm
Not trying to remove the whole furnace - only the burner/solenoid assy.  Will try looking under the fold-out sleeper sofa to see if any additional space is available.

Jon
Title: Re: Atwood 8535-III furnace propane connection
Post by: Old Toolmaker on December 26, 2019, 09:05:20 pm
Not trying to remove the whole furnace - only the burner/solenoid assy.  Will try looking under the fold-out sleeper sofa to see if any additional space is available.

Jon
The heat shield over the exhaust pipe should wiggle free.  Undo the propane line.  Remove the sheet metal screws.  The burner assembly will slide out.  I have a little magnetic 1/4" driving tool for sheet metal screws.  Fits in my screwdriver.
Title: Re: Atwood 8535-III furnace propane connection
Post by: Jon H on December 26, 2019, 09:14:34 pm
The propane line connection is unscrewed, can feel the flare nut drop off the last thread.  Have no ability to move the propane line & flare nut to the right in order to remove burner assembly.
Title: Re: Atwood 8535-III furnace propane connection
Post by: kimosabe99 on December 26, 2019, 10:57:09 pm
I had same problem.  I finally took a long, flat screwdriver and pried a little bit and suddenly I was able to wiggle the nut back about 1" and out came the burner.  Its been fine ever since and I've had that burner out 3 - 4 times


YMMV

jk
Title: Re: Atwood 8535-III furnace propane connection
Post by: Old Toolmaker on December 27, 2019, 08:17:42 am
The propane line connection is unscrewed, can feel the flare nut drop off the last thread.  Have no ability to move the propane line & flare nut to the right in order to remove burner assembly.
That's why I pull out the plastic piece.  You can leave the round part on the tubing.  The last thing I want to do is damage the sealing surface on the fitting or the tubing flare itself.
Title: Re: Atwood 8535-III furnace propane connection
Post by: Jon H on December 28, 2019, 03:57:06 pm
UPDATE - In order to remove the propane supply line "seals" it was necessary to ( 1st)  remove the furnace faceplate (2nd) remove the black plastic panel by sliding it out the front of the furnace and ( 3rd) pull the red plastic seal free and slide it to the right. Now plenty of room to remove burner assembly and observe what was left of the perforated metal burner screen.  Can't complain too much as it's 25 years old !  :-)
Pictures attached
Title: Re: Atwood 8535-III furnace propane connection
Post by: Old Toolmaker on December 28, 2019, 07:14:19 pm
UPDATE - In order to remove the propane supply line "seals" it was necessary to ( 1st)  remove the furnace faceplate (2nd) remove the black plastic panel by sliding it out the front of the furnace and ( 3rd) pull the red plastic seal free and slide it to the right. Now plenty of room to remove burner assembly and observe what was left of the perforated metal burner screen.  Can't complain too much as it's 25 years old !  :-)
Pictures attached


From here, if you ever need to replace or oil the fan motor you can remove the fan motor, but you need to slide the fan cage down the motor shaft while you remove the motor.