Sticky, black liquid in woodburners

Have you found a sticky, black liquid in your wood-burning stove? Perhaps the consistency reminds you of tar, and that’s because that is exactly what it is.

You might have spotted it running down the inside walls of your appliance or settled somewhere in the firebox.

If you have seen this black liquid, it indicates that you are not operating your stove correctly, in particular, burning unsuitable fuel.

Usually, tar is created as a byproduct of burning logs on a woodburner when the moisture level of the wood is too high. Since energy is being wasted evaporating water, the stove doesn’t get up to a high enough temperature, which leads to cooler gases going up your chimney. Since they are cooler, they are prone to condense when they touch the metal of the flue liner.

The condensed gases will either solidify on the inside of the flue or drip back down into the stove in the form of sticky liquid. Whenever the tar does get the chance to solidify, it will turn into creosote. A build-up of creosote in your stove system increases the risk of chimney fires.

How to stop a sticky, black liquid from appearing in your woodburner

There are a few ways to stop the black liquid from appearing in your wood-burning stove. The first is to ensure that the only logs you burn are ones that have been correctly seasoned and have low moisture content.

Ensuring there is a strong draw up your chimney, operating your stove at full capacity and ensuring your room is well ventilated will also minimise the chance of flue gases condensing in your chimney.

It is also important to get your chimney swept regularly. This will remove any residual creosote that has built up in your chimney and prevent it from seeping back down your chimney and into the stove.

Click here to read more about tar condensation.