Gas Logs
Gas logs, when working properly, are beautiful and convenient.

Home owners call in with questions regarding gas logs all the time, one of the most recent of which is why their gas log set is collecting soot. Most people know that gas logs are supposed to burn clean. The chimney flues through which the products of combustion from gas logs vent need not be cleaned so long as the logs are functioning properly, but the flue still needs to be inspected yearly.

Why then, does soot sometimes accumulate on gas logs? When gas logs are not functioning properly, soot can form. When gas is burned, the products are supposed to be carbon dioxide and water vapor, but hen the natural gas is not completely combusting, other byproducts, like soot, is formed and can accumulate in the flue system as well as on the logs themselves. Often times this occurs due to improperly placed logs, so that the flame is actually touching the log, cooling the flame, and preventing complete combustion.

What do you do when soot has accumulated on gas logs? First, you should have a professional come out to inspect and service the logs. The logs should be looked at and the chimney flue inspected as well. The professional will clean the gas logs and ensure that they are working properly. An improperly working gas log set which is not completely combusting gas has the potential to produce carbon monoxide as opposed to carbon dioxide, which is dangerous and potentially fatal.

You should never wash your gas logs. If you want to clean them on your own should take them out of the fireplace one by one, very carefully as to not damage them, and take them outside. I recommend cleaning them using a vacuum to clean them, although a brush with soft bristles would work as well. Remember of course to put the gas logs back exactly as they were, or refer to the manufacturer’s manual. Improper log placement will lead to incomplete combustion and all of its associated risks.

Clay Lamb

Clay Lamb is a Cincinnati Chimney Sweep contractor and the executive producer of the YouTube channel, podcast, and blog Ask the Chimney Sweep. He is also an award-winning educator and public speaker in the chimney and fireplace industry.….Educational Videos….American Chimney Cincinnati, OH

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Clay Lamb

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11 thoughts on “Soot and Gas Logs

  1. I know the pilot light has not been burning properly for awhile,it seems it burns too high,but that is not where iI am getting the problem of the soot,it is two spots in front on the logs and I will tell you I did put glowing embers in there,I guess maybe that created this recent problem ,but I have had the problem of the soot before,I have had it all apart and cleaned it with the vaccuum,but it always just comes back

  2. I have a friend that had a wood burning fireplace and replaced it with natural gas logs. The logs have a large amount of soot. Actually you can see soot on the ceiling and on top of the walls. what is the problem and how can it be corrected..George Schutt

  3. Something or things is causing this sooting problem. My first guess is what is referred to as flame impingement, this is where the logs have been stacked improperly, according to the gas log manufacture. Second possibly the orifices holes where gas is coming in below the logs is blocked with carbon deposits. I will throw out a third possibility as there may be a strong negative pressure blowing down the chimney flue.
    It is time to bring in a pro!
    Clay Lamb

  4. Hi, I have a 20 year old brick fireplace that now has 10 year old gas logs. I would like to paint the fireplace white. Do you have any advice? Debbie

  5. Debbie, I have not painted a brick fireplace white.
    I feel that if your going to use the gas-logs at all, that it will blacken the white paint rather quickly:(
    I have painted many a fireplace bricks with Hi-Temperature Black Stove paint and that seemed to hold up well.
    If you have any back-drafting issues’ you will need to consider the possible spillage of both burnt paint-odors as well as
    paint-vapors entering into the living space. The real question is, is painting the bricks really worth it or not?
    …. Sorry cont shoot the messenger

  6. Is it possible for a ventless gas fireplace to release soot into room. It seems as if the furniture etcetera. Has gotten grayish

  7. The biggest culprit we fined is that the gas-logs are “not set up” as the manufactured requires then to be set in place. This can cause what is called “flame impingement” this can cause sooting. Then the room air could possibly be moving this soot around.Your heating systems’ “cold air returns” as well as very high ceiling and stairwell can act or behave just like a chimney does with what is called the “stack effect”. Keep a Carbon Monoxide detector in place as added protection for you family plus be sure to read all of the direction regarding your fireplace equipment.
    Please note that this could be very serious situation so I would recommending seeking out a qualified technician in your area. You can find a reputable Chimney Sweep in your area by using this link to the National Chimney Sweep Guild locator : Also be sure and go online and read their customer reviews from Google, BBB and any other sites that offer customer reviews. 
    Debbie, please let us all know what happens in resolving your sooting issues!
    Clay Lamb

  8. I purchased a home & have my first natural gas fireplace. The logs were all covered in soot. I called a recommended sweep. He cleaned the logs, chimney inspected everything & reset the logs. When I asked if there was an adjustable orifice for the flam he said no & the soot is normal. It just needd to be professionally cleaned annually. That answer does not satisfy me.

  9. Ted
    I believe this would depend on the manufacture of your logs, and if they are part of a prefab fireplace, vented or none vented logs. Look for a tag on the burner pan or on a chain. Go online to that Manufactures “customer service” or their “engineer dept” and I’ll bet you will get your answer. The manufacture of the logs installation instruction are also probably online.
    . . . don’t we all just love the internet!

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