Almost always the bottom that is where the fire is that lights it off. There are some rare occasions where an ember can get pulled up into the chimney and ignite creosote at the top but it is uncommon.
They happen every winter when creosote deposits on the smoke chamber and flue walls are set ablaze by high heat or by flames licking up the chimney. A chimney fire can be exciting and light up the night, but it is NEVER a laughing matter.
By a long shot, not everyone reports that they have had a chimney fire, yet there are more than 25,000 chimney fires reported in the U.S. annually. It's good to know the common causes of chimney fires and how to avoid them.
In fact, most chimney fires are caused by creosote, which is a by-product resulting from the incomplete combustion of wood. It builds up on the sides of your chimney as a liquid and later condenses into a solid. As it builds up it not only blocks the flue, but can ignite into a fire.
Combustion deposits can build up on the damper, smoke chamber, and flue liner. Then begin to loosen and fall into the firebox. This is a sure indication that the fireplace needs cleaning and the chimney needs servicing.
These flakes are more difficult to remove than soot and will require more complicated equipment to take care of. Third degree creosote buildup in a chimney. Hot fires kill creosote.
The NFPA recommends that all chimneys be cleaned and inspected annually because if the system is compromised, it creates a fire hazard. It's best not to merely assume that a chimney system is in good working condition, no matter the circumstances.
While chimney cleaning logs or CSLs can help reduce creosote buildup, they don't actually remove the flammable residue from the flue. So, you will still need to hire a chimney sweep to remove the loose creosote flakes inside the flue.
Apply only enough water to knock down the flames and allow the wood to be removed. In some cases, the steam from this step will travel up the chimney and extinguish the flue fire, thus making the rest of the job even easier. Some departments use multipurpose dry chemical agents to knock down the fire.
According to the Chimney Safety Institute of America, Creosote can ignite at temperatures as low as 451 degrees F (for context, a fire in your fireplace can burn in excess of 450 degrees F), and even just a 1/8” buildup of creosote is considered high enough to cause a chimney fire.
The cost of chimney sweeping varies based on the specific type of fireplace or stove. Gas fireplaces, which generally accumulate less residue than wood-burning variants, cost on average between £60 to £90 for a sweep. Wood-burning fireplaces, with their traditional design, usually range between £80 to £100.
A spark from a hot ember is all it takes to spark a chimney fire. Every winter, fire departments respond to thousands of structure fires. Sadly, failure to clean the chimney is the primary cause, nearly one-third, of all residential structure fires, according to the National Fire Protection Association.
"Ideally, you should be cleaning your fireplace after each use," Mock says. "However, we know that sometimes that is just not possible or you simply don't want to, so you should be cleaning your fireplace at least once a month."
1. CREOSOTE. The most common cause of chimney fires is creosote buildup. Creosote is a chemical byproduct of burning wood.
- Loud Roaring Sound: A loud roaring sound, similar to a blowtorch, indicates an excessively intense fire. - Deformation or Warping: Warping or deformation of metal parts is a sign of sustained high temperatures.
Chimney fires are typically handled by carefully extinguishing the logs with a very light water can spray diffused with a finger. Logs are removed via salvage tub. A dry chemical extinguisher is discharged into the chimney above the damper and the damper is closed to stop the air flow.
Cleaning a chimney isn't a chore for everyone, but many homeowners do take steps to clean their own flue and firebox. With the right tools and an understanding of your chimney's construction, anyone can learn how to perform simple maintenance to reduce soot and creosote buildup.
Patches of soot inside a fireplace are unavoidable, but they are easy to distinguish from creosote. Run your finger through any black patches while the fireplace isn't lit. If the substance is dust- or ash-like, it is soot. Greasy, tar-like stains are creosote and indicate a possible chimney blockage.