Furnace cleaning

[Sea Hag]

Sent: 10/30/2003 10:00 AM

My 76 D23C  has a Colemen furnace it runs but once in a while it goes out probably the a roll out limit switch trips . the cover seems to hot . Pushed a wire in from outside and got alot of soot . I need advice on cleanning the heat exchager and exhaust . Do I have to remove the unit , if so how . Or Can  it be cleaned in in place ? It looks like the front of the firebox can be removed . ----- Sea Hag

[Beatty1950]

Sent: 10/30/2003 11:16 AM

I have similar problem with my furnace.  Hope someone out there has a solution....  I am using a portable propane heater from Camping World called Heater buddy (on sale for $86, I paid $100) .  Good backup heater but I would like to get the furnace back online. 

Dave Beatty

[DaveVA78Chieftain]

Sent: 10/30/2003 2:47 PM

I have had mine apart (defective ignitor board).  The burner assembly slides out of the case but, ..... the gas valve, electronics board, and time delay relay are all part of the assembly.  The assembly fills the front 2/3's of the case.  The blower motor/cage stays in the case.  The following is from memory when I had mine open a couple of months ago, so I could have forgotten something.  Seriously though, just take your time, be careful, it's not that difficult.
1.  From the outside, remove the outside grill assembly.  It most likely has a lot of caulking under it.  There is an inner and outer section.
2.  Remove 12VDC power to the unit and disconnect/label the wires (mine had 4; 12VDC, Ground, and the 2 thermostat wires)
3.  Shut off propane at your storage tanks.  Disconnect gas line (mine came in from the side and prevented the burner assembly from sliding out without disconnecting).  There may be a short extension between the valve and the outside line that makes it difficult to slide the burner assembly out.
4.  I suspect you will have to pull the whole unit out of it's resting place in order to get enough work room to slide the burner assembly out of the case.
5.  Remove the burner assembly to outer case screws.  There are screws buried at the back of the burner assembly that you access inside the unit.
6.  Disconnect/label the blower motor and sail switch/high temp sensor wires at the time delay relay.
7.  Disconnect the plug from the internal ON/OFF switch junction box.  This box is part of the case (external wires feed into it).
8.  Carefully slide the burner assembly out of the outer case taking care not to damage the gas fitting connection or wiring.

There is a access/viewing window on the front of the burner.  Both the window and the ignitor assembly have gaskets that could be old and fall apart on you.  You may have to replace these.  You have to remove the viewing window to see inside the burner area.  It can be vacumed out but you will need a small diameter hose to get inside.  Many portions of the burner area are not really accessable (a sealed unit).  Will need to use a combination of air blowing and vacuming to clean it out.
The ignitor board (unless you have a pilot light model) and gas valve are attached to the side of the burner assembly.  The ignitor board is held in place with 4 screws and has a electrical plug attached.  It gets power from the sail/thermal string circuit.  It powers the ignitor, controls the gas valve, powers the ignitor, and monitors the flame in the burner.  If the flame goes out, it shuts off the gas valve.  2 types of monitor circuits could be used (1 wire or 2 wire).  The 1 wire version uses the ignitor itself to monitor the burner flame.  2 wire uses a seperate probe (like a thermocouple setup) to monitor the burner flame.   Dinisour replacement boards can be configured for either type.  Hope this helps, gotta run for now.  Will provide more info later if you need it.

Dave
78 24' Chieftain