| [GMCnet] Furnace Finale' [message #74102] |
Tue, 16 February 2010 22:15  |
kenneth hugelier
Messages: 89
Registered: August 2008
Karma: 0
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Here I sit in the warm glow of my (finally) repaired coach furnace (just in time too, freeze warnings again tonight). Some of you may recall my posts from last fall when I had problems and thought that I had found the problem. The difficulty has been that the problem was not consistent. At times, like when I first got down here at my friends place in Florida, the furnace worked fine. Then at other times, like when it got quite cold here, the thing would not put out heat. This time, I deduced that the gas valve was stuck as the furnace quit for good. The blower worked and I could here the gas valve "click" when trying to open for a heat call...but no fire. Turns out the friend that I am staying with has a buddy who is a heating and cooling guy and only lives about a mile away. He was called and was kind enough to come over in between service calls and gave my furnace a look. We talked GMC for a while as he knows a little about them and has admired them
from afar for some time. In about ten minutes he verified my finding and said to give him a call after I installed a new gas valve if I had any more problems. Luckily a small local RV parts store had one in stock and I put it in ($150). I got fire, but it went out right away. I looked for something that verified flame but did not find anything. After another call the Mr. Service man and a little discussion over the phone, it was determined that the igniter was bad. Here is where it gets interesting! I had just replaced the igniter because I broke the porcelain while wrestling the furnace around on the floor of the coach.
I bent the igniter wires a bit as they did not match the conformation of the one I took out. I was told this was not good and to put in a new one. It seems the igniter is also the flame verifier. When heated, it generates micro voltage and sends this signal back to the board which tells the gas valve to stay open. When I bent the wires, I took them out of the correct flame path. But get this - when I put the new igniter in, I got nothing! No flame, nothing but the sound of the gas valve opening. I bent the wires of the old (new) igniter closer the that of the brand new one but not quite, installed it, and viola! It fired up and has been heating for several hours. It appears the original form of the igniter was grounding out on the burner, thus no spark. That's why the original old igniter was bent differently than the new one.
So I learned a lot about the furnace (Suburban NT 30SP), and now I hope you have too.
Hope I haven't taken up too much band width with this, but I didn't want to leave too much out.
Dan, don't give up with your furnace.
ken hugelier 77 PB Det. Mich.
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| Re: [GMCnet] Furnace Finale' [message #74104 is a reply to message #74102] |
Tue, 16 February 2010 22:35  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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Thanks for the report Ken. I figured our's out. Is a bad wire from thermostat to the furnace. rewired and all is good again.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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