Time for Second Sweeping of the Wood-burning Stove Chimney

Chimney pipe clogged completely with creosote

Now that the wood-burning season is in high gear, it’s time to think about scheduling another sweeping to keep the wood stove or insert functioning properly and reduce the risk of chimney fire.

Wood-burning freestanding stoves and fireplace inserts have smaller flues and chimneys than open wood-burning fireplaces, so the interior size is reduced dramatically as creosote builds up. This reduction in available flue space can cause draft issues, performance problems, smoking and more seriously, a chimney fire.

Most modern freestanding wood-burning stoves utilize 6” diameter I.D. chimneys. Fireplace inserts normally use 5.5” or 6” diameter stainless steel flue liners. Older stoves and inserts may require an 8” flue liner.

Chimney pipe covered in creosote on the walls

 Compared to an open fireplace flue which commonly uses a 6.5” x 10.5” I.D. or 16.5” x 10.5”  I.D. liner stove liners are small. 

Wood-burning stove inserts should always be connected to a properly sized stainless steel flue liner which extends the length of the flue. Without this connection, excessive amounts of glazed baked-on third stage

creosote will likely occur. This type of creosote is highly flammable. Stove manufacturers usually require this type of installation. If a professional chimney sweep finds an insert that does not have a stainless steel liner connected he will recommend a change.

Most stove manufacturers recommend sweeping the chimney at least twice during the wood-burning season, or more often if the stove is used continuously, especially in colder climates.

Burnt puffed creosote after a chimney fire (in hand)

All types of wood create creosote, even dry hardwoods such as Oak and Hickory, so there is no way to avoid it. The creosote must be removed, and a professional chimney sweep is the most qualified person to perform this service. A trained chimney sweep knows how to remove the baffle inside the stove, disconnect connecting pipes, remove creosote from the pipe connector and flue, reconnect the pipes, and finally inspect the chimney system to make sure it is in good working order. The sweep will also check clearances to combustibles to make certain the installation is correct and to code.

Installation of wood – burning stoves or inserts should be done by a qualified installer, but a chimney sweep should check the installation at the time of sweeping service. If anything is not right he/she will notify the homeowner regarding any changes that should be made. Codes and Standards have changed over the years for good reason. As problems become apparent in the field, code changes are made. Most jurisdictions in the United States now use the International Residential Code or the NFPA 211 Standard.

Chimney fires should be avoided at all costs. Not only can a fire severely damage a flue liner or Class A stainless steel chimney system beyond repair, but if the fire escapes to nearby combustibles, a house fire may occur.

The stove should not be used for at least 24 hours prior to the chimney sweep’s visit and any remaining coals should be removed from the stove. The minor inconvenience of not having the stove for a day will give the family peace of mind knowing that the risk of fire has been greatly reduced. 

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