Skip to main content ↑ ↓
Topic: Atwood 8535-III furnace propane connection (Read 649 times) previous topic - next topic

Atwood 8535-III furnace propane connection

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
Jon Harris
1995 U300 Unihome
Cat 3176
The selected media item is not currently available.

Re: Atwood 8535-III furnace propane connection

Reply #1 –
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.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Atwood 8535-III furnace propane connection

Reply #2 –
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
Ed and Michele
2000 U295  36'  (Build #5600)
8.3 ISC 350HP.
2012 Jeep Grand Cherokee (Toad)
2001 Lance Truck Camper (Sold)
2001 Lazy Daze (Class C). RK Floor Plan (Sold)

Re: Atwood 8535-III furnace propane connection

Reply #3 –
Quote from: Jon H –
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.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Atwood 8535-III furnace propane connection

Reply #4 –
No need to remove the whole furnace to service the burner assembly.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Atwood 8535-III furnace propane connection

Reply #5 –
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
Jon Harris
1995 U300 Unihome
Cat 3176
The selected media item is not currently available.

Re: Atwood 8535-III furnace propane connection

Reply #6 –
Quote from: Jon H –
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.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Atwood 8535-III furnace propane connection

Reply #7 –
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.
Jon Harris
1995 U300 Unihome
Cat 3176
The selected media item is not currently available.

Re: Atwood 8535-III furnace propane connection

Reply #8 –
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
Jack and Cathy
1992 U280 Unihome 36' Build #4034
Cummins 8.3 /  Allison MT647/ PacBrake
Apopka, FL / Barre Center, NY

Re: Atwood 8535-III furnace propane connection

Reply #9 –
Quote from: Jon H –
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.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Atwood 8535-III furnace propane connection

Reply #10 –
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
Jon Harris
1995 U300 Unihome
Cat 3176
The selected media item is not currently available.

Re: Atwood 8535-III furnace propane connection

Reply #11 –
Quote from: Jon H –
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.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.