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The gas company red flagged my water heater because of black soot being produced. What could be causing the black soot?

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A properly adjusted gas burner does not produce soot. your burner is defective. call a plumber to get it serviced or replaced.

Posted on Nov 18, 2014


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1 Answer

Flame burning too orange

You must get more air to water heater, and check venting .... immediate CO poison danger.
Call qualified plumber immediately.... because deadly carbon monoxide is not being vented properly.

Gene h

Mar 27, 2014 | Water Heaters

1 Answer


That's a dirty job! The best way is to pull the heat exchanger out and power wash it. It is not a DIY for everyone because it involves dis- assembly of the heater, and removing switches and sensors from the exchanger. If you are mechanically inclined it is not too hard, just pay close attention to how you dis-assemble it. Usually the hardest part is getting the cabinet put back together correctly!

When power washing find a place where it won't matter if if carbon black goes everywhere. It will look like someone broke open a bag of copier toner (remember that?).

The deeper issue is why did the heater soot up like that? The most likely reason is that the heater has not been getting enough gas. That will cause the yellow flame that deposits soot on the exchanger. Proper gas supply will produce a blue flame that will not soot.

Low gas is usually associated with an undersized gas meter or the gas line to the heater is too small in diameter. A plumber can tell you if this is the issue.

Nov 03, 2013 | Pool & Spa

1 Answer

Black soot is on the walls & ceiling around the baseboard heaters in the rental house that I live in. What is causing this & how do I clean this off?

If these are electric base board heaters, that is probably not soot, but instead mold. Put a little bleach in a spray bottle and try spraying it right on to the black soot looking stuff and see if it will disappear. If it does, it is mold. Bleach will kill the mold.

If these are gas heaters you need to call a service man NOW. Black soot is a sign of gas burning raw and can be very dangerous. Turn them off if this is the case.

May 18, 2011 | Heating & Cooling

2 Answers

Can a gas heater after years of good use - start emitting carbon dioxide? What about black ashes or soot?

yes yes yes. if you are having black soot build up in the burner compartment you have a problem.the air/fuel mixture has changed. you need to stop using and get the heat exchanger cleaned. this can be done with a long bottle brush coat hanger or such. remove the burners and away you go clean clean clean what a mess.anyway once cleaned reassamble burners and check all gas fittings for leakage with soapy water. after main burner comes on make sure the flames are straight up and not floating around and a nice blue in color some orange is ok but no yellow. normaly a plugged heat exchanger does not mean a bad heat exchanger. watch the flame before the fan comes on and after.the flame should not change. if it start to waver you may have a nother problem and you should not use and call a heating company

Jan 27, 2011 | Dayton Gas Furnace Heater

1 Answer

I have a hayward h200 pool heater. When runing it has black smoke and soot on top. Any ideas what the problem may be?

This will one or more things (1). You will need a manometer to check the gas pressure be sure it is at 11 inches of water collom. (27 inches in 1 PSI) at the back of the gas valve. (2) make sure you have good water flow. If you have an external by-pass this should be 80-90% closed. In the water manifold you will have an internal by-pass assembly this fine tunes the water you control with the external valve. (3) make sure you don't have any derbs around the base of the heater that will block air flow. Also be sure that your heater is away from any wall or has a draft hood.
Any one or more of these things will cause sooting. When you find the culpret and fix then you will need to clean and desoot the heater. Also to avoide this in the future you should have the heater serviced every year before you put it into service.
If you do this yourself be sure to use a plastic brush and not a wire brush as any little spark with the soot can cause an explosion.
This might be one you want to get a repairman involved with and be sure he or she is a profesional.

Sep 04, 2010 | Hayward H Series Pool & Spa Heater 200k...

1 Answer

Black Soot/low heating flame

Hi i would turn it off , sooting means it is unsafe to use you will need a service then you will be able to sort the problem , but call the gas company and get this fixed

Jan 23, 2010 | Heating & Cooling

1 Answer

Is there a way to adjust the size of the flame on a wall heater gas valve. The gas company says it is smothering. The flames creep over the side into the gas orfice output and is not completely burning all...

Hi, this is a very dangerous condition and is the cause of many carbon monoxide poisonings or deaths. Please do not use this heater. The smothering is caused by a restricted heat exchanger not an over fired flame. You need to have the heater serviced or replaced before using. The heat exchanger would need to be pulled and cleaned, it is possible that flu is also restricted with soot and would need to be cleaned as well. I'm sure the gas company red tagged this unit for good reason. Good luck.

Jan 14, 2010 | Williams Heating & Cooling

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Fire and Heaters producing soot.

no its not gas it sounds like fumes get them checked over asap the localgas company will check them out for you

Jan 10, 2010 | Cozy (W352E) Heater

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I have black soot on my walls from my baseboard heaters, is this hazardous or dangerous to my health?

same issue years ago. these heaters draw air in from the bottom and push it out the top. so any dirty air (candles burning will do it) is pulled through the heater and pushed out the top causing stains on walls.

Jan 01, 2009 | Fahrenheat Electric Convector Baseboard...

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Natural gas heater

The burners are shot. The heavy metal tubes with the holes that the burner flame comes out of, has burnt through. Instead of little rows of holes, there is at least one large hole in it. Unless someone has changed the gas>air mixture, you need new burners.

Mar 13, 2008 | Empire DV-215 Direct Vent Natural Gas...

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