My atwood furnace runs great for acouple of days and then gets soot on the third electrode that the black wire hooks to and then won't light, the fan just continues to run till I shut it off. I have to pull out the electreode assembly and wipe off the soot. What causes this and what can I do to resolve this problem. thanks! tim
According to my Atwood manual several things can cause sooting;
1) Low gas pressure
2) Low voltage
3) air leakage at gaskets
4) Combustion wheel installed backwards or loose.
5) Blockage in heating chamber or burner head
6) Faulty motor
Most of these can be handled by a good servicing of the unit. Cleaning combustion chamber and gas orifice area.
Gas pressure can be looked at by checking other appliances to see if they are working properly on LP. Does all burners light on range and run with blue flame or is a yellow flame? Yellow flame would indicate low gas pressure. Replace the regulator on your LP tank.
Those above all sound like great places to start looking. I can't say that I know all about RV furnaces, but being a home appliance tech for 20 years, many appliances have a shutter that adjusts the gas to air mixture to give the proper burn. Not saying this has an adjustable shutter, all of the things noted above can affect the burn mixture, as well.
Tom & Beth
05,Grand Junction 35TMS
99, Dodge 3500 Dually.
You will have to pull the Burner and clean the intake and exhaust impellors. Black soot means you have a rich (too much LP) mixture. The causes of that are inadequate fresh air. Usually that means Insect nests have blocked the fresh air for mixture. There are no Air/LP shutter adjustments on an Atwood furnace. Doug
I have seen some nasty looking ignitors that still work so I would be looking at some other areas also. I personally, would just replace the ignitor and set the gap correctly, while also doing the other cleaning suggested. Check the gas pressure, clean the burner orifice, etc.
I chased this exact problem with the 16K BTU Atwood furnace in my old popup for almost a year. The furnace ran great for a day and then would start shutting down due to the flame sense not sensing a flame anymore. The flame was there and quite good but since the igniter was COVERED with soot it just couldn't detect it.
Pulling the igniter out and cleaning it would fix the problem for a day until it all started again. It really annoyed me at 3:00 AM when the furnace would start clicking on and off in 30 second intervals.
I checked/replaced just about everything on the furnace. Sail switch OK, Limit switch OK, gas valve OK, replaced gas regulator due to low LP pressure (didn't fix furnace though), igniter replaced, gaskets replaced, still could never fix the sooting.
I ended up buying a new furnace and the new one ran like a champ and had no signs of soot when used.
The ONLY thing I found that was different between the broken on and the new one was the new one had an additional 'secondary air baffle' between the gaskets on the burner assembly. Perhaps the missing air baffle caused the flame to burn incorrectly? I don't know and never bothered with the old one again. I ended up selling it for parts.
Perhaps this post may help you. If you do a search for my username in the archived messages you should see a ton of posts about my furnace with the title 'Furnace Frustrations'.
Todd
* This post was
edited 11/16/09 07:51am by daystrom *
Offline
