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Snboard976 02-23-2013 06:47 PM

Soot in Furnace - Furnace not working
 
My natural gas furnace that is only 4 months old, stopped working a few days ago. The pilot light is lit and it is receiving power. When I opened it up and looked inside, there is a lot of soot on one side and some material. Any advice on how I should proceed? Here are a few pictures.

Exterior of furnace. Cover is removed.
http://farm9.staticflickr.com/8508/8...34525002ec.jpg

At the bottom where the gas is ignited
http://farm9.staticflickr.com/8384/8...aa7ab4b4_n.jpg


Looking inside on the right side of the right gas tube. Note the soot on the side.
http://farm9.staticflickr.com/8103/8...ffbca9d012.jpg

Inside the furnace on the right side looking up. The same material is on the right side but it is white. Here it is either burned or covered in soot.
http://farm9.staticflickr.com/8531/8...a708de09_n.jpg

qbert 02-23-2013 07:07 PM

\If the unit is sooted up you should call the installer back. Soot is a byproduct of improper combustion and is bad news. You may have a thermal open due to a rollout condition. Some one will have to pull the jacket and clean it out. Then find out what caused the mess.

how 02-23-2013 09:09 PM

It's good that it's not running because something is seriously wrong and should be checked out by a pro.
Sooting like that on one side only usually occurs from a bad gas/air mix on the RH burner or a partially obstructed exchanger.
Either way with a 4 month old unit...call the installer back.

ben's plumbing 02-23-2013 10:50 PM

yep agree call installer back... after only 4 months should still be in warranty...ben sr

747 02-23-2013 11:57 PM

There shouldn't be so much soot for just 4 months. Call the guy back. Now my older boiler during a once a year cleaning there is soot.

beenthere 02-24-2013 04:58 AM

Flue damper may not be opening all the way like it should.

how 02-24-2013 04:26 PM

That flue dampener is made to not engage the gas until it's confirmed fully open. A flue restriction will cause soot equally on both sides of the boiler.
A properly running boiler never soots. I have many units that are 45yr + and have never sooted. Soot equals problem.

beenthere 02-24-2013 04:37 PM

Quote:

Originally Posted by how (Post 1124004)
That flue dampener is made to not engage the gas until it's confirmed fully open. A flue restriction will cause soot equally on both sides of the boiler.
A properly running boiler never soots. I have many units that are 45yr + and have never sooted. Soot equals problem.

Sometimes those cheap end switches fail closed.

Snboard976 02-25-2013 08:49 PM

Update #1
 
Thanks for your replies.

It's a recently flipped house and new to me, so unfortunately, I have no idea who the installer is. I tried to trace it through the serial number, but the wholesaler doesn't know who the contractor is.

The pro hired by me came and said that there was a carbon build up. When the on off switch was turned on and off the furnace lit and the flames jumped out a little bit. The furnace tripped and turned itself off after about 30 seconds. One of the pink connectors on the wires just below the light in the first pictures has started to melt.

He said that he thought the likely culprit of the carbonization was dust from when the sheet rock was being installed 8 months ago. It isn't dusty now, but he thought it was sucked in when the renovation was going on. He said it would be $700 to decarbonized the furnace.

I am a little skeptical that decarbonizing the furnace will address the root cause and the price seemed a little high.

Any thoughts?

beenthere 02-25-2013 09:10 PM

He needs to check the draft in the flue. And then clean the boiler and check the drat through it. And then set up the burner.

qbert 02-25-2013 09:24 PM

i would have the tech run an analyzer on the system as well as draft test to see its performance. It will help find diagnose the cause

how 02-25-2013 11:38 PM

The important point for me is that only one side of the boiler is carboning up. Poor draft would cause carbonizing equally right across the exchanger.

I'd definately be checking out that RH burner orifice and comparing it with the unaffected burners.
I didn't see any water marks on your boiler photos but I'd also be looking for that.
Mostly I'd be looking at what could /starve the gas of one burner of sufficient oxygen/ or cool down it's burner flame/ or restrict the flame passage on one side of the exchanger.
I have never seen an exchanger refractory lining as thin as these photos show. I wonder if it's come loose above and curled over the RH of the exchanger.

I'd also stick around and unobtrusively watch the hvac guy do the work to see what he finds.


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