The Tank › NG water heater sooting
- January 18, 2014 at 10:28 am #20479
I have a John Wood natural gas water heater model # jw6402na. Recently i have has an issue where the burner and combustion chamber will become choked with soot and then the pilot and burner go out. The first few times i cleaned the burner and combustion chamber, after that the flame is steady and blue. this lasts for roughly a week then it soots up again and goes out. this last time i removed the burner assembly and cleaned it extremely thoroughly (you could of eaten off of it), pulled the baffle out and cleaned the combustion chamber and exhaust tube. then cleaned all the piping the goes into the chimney, No obstructions. again the burner kicked on and looked good (steady and blue) The unit seems to pulling plenty of air at the draft hood, and we haven’t noticed any problem with a back draft. The only thing i have noticed is that I am getting a flame from the pilot tube where is connects into the brass nut attached the the burner assembly. I have tightened this conneciton as much as possable with out dammaging the tube or cracking the brass, would replacing this improve our situation or am i looking at a deeper problem. Thanks.January 18, 2014 at 12:47 pm #20480
Hello: When the heater first fires up, hold the back of your hand or a match you’ve just blown out up close to the draft hood and see if hot gas spills out when the heater fires up and for how long it spills. It’s best if it only spills for a second or two, but that will let us know how/if the draft is working. 😉 Natural gas almost never soots up.
Yours, LarryJanuary 19, 2014 at 2:32 pm #20487
I tested the draft with a smoking match, when the burner fires there is a slight disturbance but not enough to push any of the smoke outside of the hood. The disturbance only lasts just under a second. I have attached a photo of the combustion chamber in action, this is just over a week from the last cleaning, and will be getting one today. Needless to say my smoke and CO detector have never been tested so much.January 19, 2014 at 3:31 pm #20489
Hi: That flame is completely wrong! It should be a nice blue flame coming only from the burner. Like this: If, with cleaning and securing fittings, you can’t get to this kind of flame, a new burner is needed. This is a safety concern. It’s good you have CO detectors. Understand they are helpful, but not particularly sensitive, so you may still be getting exposed to higher levels of CO than is safe.
Yours, LarryJanuary 19, 2014 at 3:43 pm #20490
After cleaning the flame is blue and steady, the flame that is coming from the pilot tube before the brass nut remains though. Could this extra flame be the cause of all the sooting? I will be recleaning shortly and will attach a new photo. Thanks.January 19, 2014 at 4:24 pm #20491
Hi and yes. Any yellow flame is sooting. Also, I notice that the main burner orifice, or tube may be leaking, creating yellow flame under the burner. If those are damaged, a replacement is called for.
You might be able to undo the pilot connection, wrap it with two turns of yellow teflon and reassemble. That can give you a gas tight connection without too much force.
Yours, LarryJanuary 19, 2014 at 4:43 pm #20493
This is after a cleaning, the burner flame looks good (all the yellow/orange specks disappear with in 20 min of running) the flame before the pilot remains. I had thought of using yellow Teflon or pipe dope but wasn’t sure if they would last or pose a hazard in the combustion chamber.January 19, 2014 at 8:35 pm #20496
Hi: That certainly looks better! I wouldn’t use pipe dope. Teflon can take a lot of heat. If the teflon fix doesn’t work, it looks like there is enough tube to cut off the burnt end and redo it. If it just needs a ferrule, the job isn’t too hard. 😎
ps. I’ll add that it isn’t likely that the pilot leak is the cause of the bigger problem of sooting. Another thought is that low gas pressure might not shoot a stream of gas properly into the main burner, allowing it at some point to start burning before it gets to and goes through the burner.January 20, 2014 at 6:52 pm #20498
OK so I went to replace the burner end fittings of the pilot tube and the last 1/2″ came off in my hand, made the tube just short enough to not reach properly. Replacement tube and fittings are in place and we now have pretty blue flames, and only where they belong. I will continue to monitor the situation and post an update in a few days. Thanks to eleent for all the help.
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