Coleman Furnace lighting then shutting down on flame failure

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philhelinski
Posts: 2
Joined: Mon Feb 28, 2011 5:33 pm

Mon Feb 28, 2011 6:28 pm

Have a Coleman DGAT056BDC (SN starts with 95) that is having issues with going down on flame failure. It will light then go off within about a minute or so, then relight. The HW S86 controller will allow 3 flame failures then lock out which is happening.
Had this similar problem a couple of seasons ago and talked with a mobile home tech that said to vacuum out the flue (removed cap and vacuumed out the debris laying in the flue). This helped up until now. Looked at this first, it was clean but noticed the "plate" on top was off center. There was a gap along one side but the other side was against the outer part of the flue. Used a screwdriver to push this plate down which gave more gap all along the entire plate. Had no problems for a couple of weeks but it started to act up again. Noticed the problem seems to happen when it is breezy outside. Thought about extending the flue up higher but the furnace is 15 years old and the home has been in the same place the whole time.
Cleaned the flame rod and the igniter is new. The flame controller was changed 2 years ago before the dirty flue problem was taken care of. The flat part of the flue in the furnace beside the fan and along the top are hot like the flue gases are making their way out of the flue. Is i possible that HX is bad causing the fan to blow the flames enough to push them off the flame rod?

Thanks,
Phil


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Robert
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Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Tue Mar 01, 2011 3:58 pm

Hi Phil,


Yes, that is a possibility. Because this could be a safety issue and with all that you have done DIY to this point, I would call an hvac tech to thoroughly inspect and diagnose problem(s).


Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?

philhelinski
Posts: 2
Joined: Mon Feb 28, 2011 5:33 pm

Fri Mar 04, 2011 6:02 pm

Thanks for your reply. I am an HVAC commercial tech and not very familiar with these MH furnaces and how the exchangers are built. It looks like a barrel to me. Can the exchanger be accessed from the front to visually inspect the HX. I will grab the combustion analyzer the next time I am at the shop to get a CO read to see if it is leaking.
If HX is not problem, I think I wrote in my original post that it seems worse on windy days. Would it be worth trying to extend the flue?

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