Pilot going out

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digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Wed Nov 26, 2014 11:27 pm

I just installed a 7956C856 furnace today. got it running and it does a good job of heating but the pilot goes out at the end of every cycle. The pilot is blue. It's kind of hard to tell but the burner looks like the flame goes horizontally front to back, and it has more yellow in it than I usually see. Also, I thought, but didn't know for sure, that it was previously used with Natural Gas which is what I use. If it were setup with LPG, what kind of symptoms would I be seeing ? Ill leave it off for now.


digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Thu Nov 27, 2014 12:48 pm

Since the roof jack was kind of bent up on the outer 8" pipe I'm suspecting that might be the cause, starving for air. Can a bent up roof jack cause this kind of problem ?

digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Fri Nov 28, 2014 12:46 pm

I lit the pilot this morning and turned the heater on but the burner would not light. Pilot stayed on, nice blue flame with a little orange at the tip, no dancing around. When I would run the T-stat above the ambient temperature the gas valve would click. Same thing when I would run the T-stat below the ambient temperature, just a click. I tapped lightly on the gas valve when T-stat was set above the ambient temperature thinking maybe it was stuck but the burner didn't light. Gas valve ? "Thermocouple ?

minnie1967
Posts: 22
Joined: Sun Sep 14, 2014 8:05 pm

Fri Nov 28, 2014 10:18 pm

Is the light from the control board blinking and how many times?

digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Sat Nov 29, 2014 11:06 am

It's an older presidential. If it has a control board I haven't seen one. where would it be ?


digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Sun Nov 30, 2014 11:06 am

I lit the heater this morning and watched carefully as I turned the setting from pilot to on. The burner came on to what must have been low setting for a few seconds, the went to a higher, or bigger flame. It's hard to tell but it looked like the pilot might have went out when the burner went to a full or bigger flame, like maybe the gas flow to the burner might have robbed the smaller flow to the pilot. I say that because I could no longer see the pilot flame once the burner came on but it could be that I just couldn't see it. I also observed that both the pilot and burner burn mostly blue

minnie1967
Posts: 22
Joined: Sun Sep 14, 2014 8:05 pm

Sun Nov 30, 2014 10:07 pm

digifoss wrote:It's an older presidential. If it has a control board I haven't seen one. where would it be ?
It has to have one. Usually in an enclosure mounted to the furnace cabinet.

digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Mon Dec 01, 2014 9:23 pm

I opened everything inside the front covers, and while I've seen pictures of a light in the top cover to the right of the power switch, there is no light on mine. The link below has some images of the inside of my furnace and while you may be right about there being a control board, I just don't see it.
http://www.co.cibola.nm.us/mike/coleman/heater.html

minnie1967
Posts: 22
Joined: Sun Sep 14, 2014 8:05 pm

Mon Dec 01, 2014 9:59 pm

Follow the wires, they usually go to one main box. I looked at the pictures and don't see one.

jpingram5
Posts: 205
Joined: Sun Dec 05, 2010 5:34 pm
Location: Orefield, PA
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Tue Dec 02, 2014 5:48 pm

Did you verify that it is setup for Natural Gas and has not been converted to LPG? Pilot could just possibly be dirty, giving it a good blowing out usually helps. There's lot's of DIY guides for that on the internet.
2009 Skyline Sunwood Premier 14 x 80

digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Tue Dec 16, 2014 3:12 pm

It's been a while, sorry for the delay.

So since I was last here, I pulled the burner assembly out and cleaned the pilot by removing the small gas pilot gas tube and blowing it out with compressed air, didn't seem to be any plugage in the tube. On the fire end of the tube, there was a small outer sleeve over the end of the tube with what appeared to be a strainer or screen where the gas goes out the end of the tube. It appeared to be dirty and partially plugged. I cleaned it up real good and blew it dry, reassembled it and tried again. After this, the pilot looked a little bigger and the pilot would now stay on through 2 or 3 cycles, before going out. Last weekend, I pulled the burner out again and adjusted the angle of the little pilot shield that directs the flow of the pilot light upward toward the thermocouple to a little sharper angle, and I also put a new thermocouple in. Now the pilot will stay lit through about 6 or 8 cycles before going out. When I watch the burner light through the view opening, the big burner flame appears to be sucking the pilot light forward toward the burner ring of fire, and eventually the pilot gets sucked out, not blown out.

I was wondering if It might be a good idea to put a bigger piece of metal behind the small shield that I adjusted earlier as a block between the big burner fire and the small pilot fire to help prevent sucking it out.

digifoss
Posts: 13
Joined: Mon Nov 17, 2014 11:42 am

Wed Dec 17, 2014 4:25 pm

And I am also wondering - can I remove that little sleeve that goes over the end of the pilot gas tube with the screen in it and run without that screen or filter or what ever that is, or does that act similar to an orifice to slow the gas flow down ? Getting tired of lighting this pilot every morning and every evening, but I guess that's a big improvement over re-lighting every cycle.

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