# black smoke out of a gas water heater



## arkyplumber (Jan 10, 2009)

Was wondering if anybody has run into this. Thanks


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## arkyplumber (Jan 10, 2009)

Just got a call, and the lady said black smoke was going up the side. I have to go check this thing out this afternoon. Just wondering if someone could save me some time running this down. I assume that it is in the burner, or the vent ( stopped up) with rust or who knows what. Anyway thought I would run this down on here just to see what yalls opinion was. Thanks


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## smellslike$tome (Jun 16, 2008)

Saw it once and it was frightening. There was a black soot trail that ran from the combustion chamber door up the face of the wh for about 18". The thermostat control on the front of the gas control valve was warped from heat. The ho had enough good sense to shut it down and call me. Someone may say different but when I see something like that, I would never trust any repair. Replace it.


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## super plumber (Oct 19, 2008)

smellslike$tome said:


> Saw it once and it was frightening. There was a black soot trail that ran from the combustion chamber door up the face of the wh for about 18". The thermostat control on the front of the gas control valve was warped from heat. The ho had enough good sense to shut it down and call me. Someone may say different but when I see something like that, I would never trust any repair. Replace it.


i agree. don't repair. replace


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## express (Nov 22, 2008)

I would check for draft. blocked exhaust.


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## uaplumber (Jun 16, 2008)

Roll out due to blocked flue. You could remove the venting and pull out the baffle to clean it.
However, if there has been damage due to this issue replace the thing.


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## smellslike$tome (Jun 16, 2008)

I have found collapsed baffles before but if I see something like that, I'm not even bothering to look at anything on the wh itself, I'm just going to tell them it has to be replaced. Too much liability at stake and as fine a plumber as I am, what if I miss something? I'm not even willing to take the risk. I'll replace it if you like, otherwise get someone else.


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## kellybhutchings (Jul 29, 2008)

you should also check combustion and ventalation air. Never try to vaccum black sute. I did it once and it shot out the back of the vacum cost my insurance company 4500 dollars.


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## arkyplumber (Jan 10, 2009)

Just got back. The water heater was a Lp gas heater. It was just a year old, so I pulled the baffle and checked the flu pipe. There was black suit, but really nothing blocking it. I fired it up to find the burner was really yellow flame. I took apart the burner got all the black mess cleaned off it, and put it back together. Fired it up and everything seemed good. It had a nice blue flame, so I figure it just needed cleaning. Wonder if butane burns more dirty than natural? Anyways heater is out in the garage, so no real danger and everything seems back the way it should be. Anymore thoughts. Thanks


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## smellslike$tome (Jun 16, 2008)

Neither propane nor ng are supposed to do what you have described in your op. There is a problem and because you cleaned it up and it appears to be burning properly does not mean that the problem has been resolved. To me it wouldn't matter if it was brand new out of the box, I would never trust this water heater, but that's just me. What part of the country are you located in and why aren't new water heater installs (you said it's only 1 year old) since 2003 required to have sealed combustion chambers. What you have described would only be found on an older water heater.


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## arkyplumber (Jan 10, 2009)

Because the home owner had this heater and said it was brand new, being he bought it for some chicken houses, and never put it in. His water heater went out so he put it in himself. I told him that I would recommend a brand new heater, but he did not seem happy with a 400 dollar heater, when this one has been in service for a year. So with that being said I did what I could do cleaned the burner, checked the flu, and baffle. No more soot, or yellow flame. Charged him and told him if any further problems call. Which honestly I would have done the same if my heater. I quess I am cheap, rather try to fix it than spend 400 on a new one.


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## smellslike$tome (Jun 16, 2008)

I really do understand your point of view, we all want to give our customers exactly what they want, but with all due respect, if his house burns down, who do you think will be the first person he blames? You were the last one to touch it and it won't matter that you didn't install it and didn't have anything to do with creating the problem. At the very least I would go back, make my professional opinion perfectly clear in writing, and have him sign a hold harmless.

It does not matter that it was brand new (and was it really?) and had never been installed before last year. At least for the IPC it is an absolute code violation, I don't know about the UPC somebody else can chime in about that. I also don't know what code you are operating under but I have to believe that all plumbing codes are requiring this now.


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## smellslike$tome (Jun 16, 2008)

You can buy a propane water heater for $400.00 or that would have been your install price?


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## express (Nov 22, 2008)

I tend to agree with smells, you clean it up and seems like it is working correctly, BUT what caused the soot? I still think its a flue problem.


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## arkyplumber (Jan 10, 2009)

That is the cheapest price for a 40 gal. gas heater I can find is around 400. Also the heater is not in the house, but in a detached garage, so no threat really of a burn down. As far as the code goes, we are under the national plumbing code. No code violations here being the heater as far as I can tell was already in operation, and not sold as a new or newly installed heater. Not to mention the fact that it is Sunday, and this location is in a town of about 2000, with no were to even get a new heater if it so needed, well shall I say about 2 hour drive to Lowes. So with that said I must say I will sleep good tonight, and if later down the road the problem pops back up, quess who will put in the new heater, hopefully me. The homeowner seems to be the kind that knows a little about everything. I am sure you know what I mean. So with that being said, I see no danger of this thing catching on fire, would be the first time I have seen it. I have heard of fires caused by things to close to a heater such as rags, or flammable substances. But never heard of a heater just burning itself up. No sign of any over heating, just burning dirty. Made sure the reg. was doing what it should. Turned off and on good. I did forget to mention that there was a dirt dobbers nest in the flue pipe. I dont think it was big enough to clog it, but could have caused the burner to get dirty, and started causing the soot problem. Anyways Thanks for the advice, and if I get called back on this thing I will sure post it so someone else can be one step ahead. Thanks


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## trick1 (Sep 18, 2008)

Typically, black soot represents unburned fuel, so it makes me wonder about the combustion air situation. Flame rollout is a draft problem, without a doubt. The draft problem can lead to a lack of combustion air as well(products of combustion remain in the chamber preventing the combustion air from entering the chamber)

Is it possible that the gas control was set up for N/G. A problem with the orifice size can lead to insufficient combustion air.


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## arkyplumber (Jan 10, 2009)

This was a thought, and I asked the homeowner of this before I read the heater to make sure. It was set up for Lp gas, so that was not the problem. I was also thinking that if it was a combustion problem, me cleaning the burner, would have not solved the flame problem, which went from yellow before I took it apart, to blue after being put back together. I did however take the flu apart at this time also, so could be I unstopped it and did not realize I did. Anyways I looked like a chimney sweeper:laughing: after it all..


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## express (Nov 22, 2008)

did you get a good look a the flue when it went trough the roof. remember the 2' x 10' rule?


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## arkyplumber (Jan 10, 2009)

Remind me of the 2'x10' rule. I am drawing a blank. They flu though went straight up and through the roof. It was I should say 8 to 10' long. It was old single wall pipe though, and did recommend a double wall for safety reasons, although he didn't see any need for it at the moment, being it has done the job for quite sometime he told me.


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## smellslike$tome (Jun 16, 2008)

:no: :no: :no:. Good luck with that. It should be tagged immediately. Trick1 is absolutely correct, soot = an uncombusted fuel air mixture. What's the difference between an uncombusted fuel air mixture and a combusted fuel air mixture? Heat. Which you have plenty of just on the other side of the inner and outer combustion chamber doors. You are quite literally playing with fire my friend and it astounds me that you don't seem to fully grasp this. Fire in the fire box good. Fire outside of the firebox bad.


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## express (Nov 22, 2008)

this is the 2nd time today I agree with smells.( I don't want to be in Mr smells fan club) OK 2' high and a horizontal line drawn across has to go 10' before it hits the roof or the flue needs to go higher.


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## arkyplumber (Jan 10, 2009)

soot is just that a thick black smoke not flames. There was no fire outside the firebox, or it would have melted the regulator right above the door. Again never seen a water heater burn up by itself. You seem a little gun shy there. I don't see any reason to convince someone to spend a extra 400 dollars when there really is no need. I myself would be more concerned about carbon monoxide poisoning than a fire.


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## arkyplumber (Jan 10, 2009)

Thanks, was drawing a blank. This vent went straight up, no horizontal lines in it.


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## arkyplumber (Jan 10, 2009)

I have come to the conclusion that maybe due to a improper vent cap that backdraft is occuring and might be the culprit in this case. But for sure no need of a new water heater. And by chance the house burns down I will be the first to admit I was wrong Thanks guys


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## kellybhutchings (Jul 29, 2008)

If the screens/filters on the water heater for combustion air are not cleaned regularly thay can start to close off do to dust and that will cause it not to burn properly.


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