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Many times, it is best to replace a chimney liner if it is coated with stage three creosote.

Everyone enjoys the soft crackle of a hardwood fire and warmth that leaps from a fireplace during the cold wintertime, but few homeowners are aware of the importance of cleaning their chimneys. Every chimney requires regular maintenance. Something as simple as a bird’s nest blocking a gas-fired furnace flue is as dangerous as a highly flammable creosote deposit produced by a wood-burning stove or fireplace.

The National Fire Protection Agency has NFPA Code 211 in which it states, “Chimneys, fireplaces, and vents shall be inspected at least once a year. Connectors, spark arrestors, cleanouts, and tee fittings connected to chimneys for oil, gas, and pellet venting systems shall be inspected at least once a year for soundness and deposits. Cleaning, maintenance, and repairs shall be done if necessary.”


While creosote build-up causes most chimney fires, every chimney can pose danger to your home. Bird and animal nests, or even fallen leaves can block a chimney and direct deadly carbon monoxide from the furnace back into your home. In 1996, over 100 people died in their homes from carbon monoxide poisoning. Another 5,500 house fires resulted from chimneys and chimney connectors serving heating systems burning liquid and other fuels. (The U.S. Consumer Product Safety Commission)

Creosote Buildup In Your Chimney
Anytime a fireplace or stove is used, the burning wood deposits a thin layer of flammable creosote inside the chimney lining or flue. Since creosote is highly flammable and probably creates the biggest potential hazard when using a fireplace, it’s wise to try and minimize the amount of buildup that occurs. Failure to remove creosote from the flue can result in a deadly chimney fire, according to the National Fire Protection Association (NFPA).

Creosote Must Be Minimize – Creosote has three stages. As each stage increases, they become more hazardous and are increasingly difficult to remove from the flue.

Stage 1 – The first stage of creosote is like flaky soot that is easy to brush away with a basic chimney brush.

Stage 2 – Creosote in the second stage can be described as shiny, hard black flakes. The flakes actually contain hardened tar that is not easily brushed away, but it can be removed without extreme measures. The most popular method for removing creosote in the second stage is with a rotary loop. A powerful drill turns metal rods that get the job done.

Stage 3 – Third-stage creosote is something to be avoided. Not only is it extremely difficult to clean, it is a highly concentrated fuel that resembles a coating of tar dripping down inside of your chimney liner. This type of glazed creosote can become very thick as it hardens and is repeatedly recoated with another layer. A hot fire can easily ignite this type of creosote, which is extremely hazardous.

If stage three creosote catches fire, it becomes easy to remove because it leaves behind a spongy residue. But, a chimney fire can too easily lead to a house fire because the intense flames often cause a fire on the roof or damage the flue, causing combustible parts of the home to ignite.

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