Why Am I Getting All this Build Up in My Wood Stove? - Ask the Expert Episode 243

Today's question is from Mark. "Hey Dan, I'm getting a lot of creosote and tar coming out of the top of the pipe in just one day. It's a small wood stove in an RV. I'm burning kiln-dried bundled hardwood mix. I cleaned it yesterday and (the build up) is back today."

So, he gets a lot of build up after burning wood for just one day. That's bad.

Creosote build up is a normal side effect of burning wood in a wood stove, and if it's a wetter wood or a certain type, you can have more build up than at other times. What you don't want is to have to clean the flue pipe every day. That's not normal.

Kiln-dried wood shouldn't be a problem. It doesn't really matter how the wood gets dry so long as it's suitably dry for your wood stove. A couple of things could be happening. Just because the wood was dry at one point, doesn't mean it stayed that way. If you have kiln-dried wood and you just dump it in the lake, it's going to get wet. If you store wood in a damp environment, it's going to get wet.

Wood absorbs water.

If you bought it, how do you know it's actually dry? Maybe somebody sold you some wet wood. The thing is, you're not going to get creosote build up without having wet wood.

Another thing could be that if you bought the stove and you didn't check the pipe, maybe the build up has been happening for a long time.

Also worth mentioning:

If the fire in your wood stove isn't burning hot enough, the smoke may cool too fast before it exists your chimney flue. This cooling too fast will cause the creosote to collect inside your chimney flue rather than burning hot enough to exit your chimney prior to the condensation process.

This means you can have wood dried to the minimum moisture ratio and still have issues with creosote buildup in the chimney of your wood stove.

1 comment (view/add)
  • David Bowen
    David Bowen
    Posted on 12/22/2020

    Turn up the fire ! Give it some air for a clean hot fire !
    Creosote condenses to liquid at 250*F.

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