FIREPLACE AND CHIMNEY CARE
Several times a year the Paso Robles Department of Emergency Services responds to chimney fires. These fires can be dangerous due to the amount of heat they transfer to the adjacent building materials. Added to the danger is the amount of time the fire burns before being detected. This delay can lead to the fire spreading to the attic space or even the living area!
What Causes a Chimney Fire?
The cause of most chimney fires is creosote, which is a by-product resulting from the incomplete combustion of wood. Creosote is black or brown in appearance and can be crusty and flaky, tar-like, drippy and sticky, or shiny and hardened. Often, all forms will occur in the chimney. It accumulates on the side of your chimney and stove pipe as a liquid and later turns to a solid. As it builds up it not only blocks the flue, but can also ignite into a roaring fire.
A fire hazard exits if ¼-inch of creosote (or more) coats the inner walls of the chimney. You can cut down on the build-up of creosote by using your fireplace or woodstove properly.
- Burn it hot; the hotter the fire the more complete the combustion. The stove or
fireplace should be burned hot twice a day for 15 to 30 minutes to reduce the amount
of creosote build up.
- Burn hard woods, i.e. oak, almond, walnut, etc., that have been seasoned for at
least a year. Soft moist wood accelerates creosote build up, so keep your wood dry.
Do not use green wood, construction scraps, treated woods, wrapping paper or wood
- Keep air inlets on woodstoves and fireplaces open, and never restrict air supply to fireplaces. This is very important! Failure to open the damper wide enough to move heated smoke up the chimney rapidly (the longer the smoke's residence time in the flue, the more likely it is that creosote will form). A woodstove's air supply can be limited by closing down the stove damper or air inlets too soon and too much, and by improperly using the stovepipe damper to restrict air movement.
Cool flue temperatures are also a cause of chimney fires. In the case of woodstoves, fully packed loads of wood (that give large cool fires and 8 or 10 hour burn time) contribute to creosote build up. Condensation of the unburned by-products of combustion also occurs more rapidly in an exterior chimney.
How To Prevent a Chimney Fire
Each year thousands of homes experience chimney fires due to improper maintenance of their chimney. These fires can be prevented by making sure you have your chimney professionally cleaned and inspected at least once a year. If you use your fireplace or woodstove as a primary source of heat for your home, you should consider a cleaning and inspection at the beginning and end of each heating season.
More frequent cleanings may be required based on the type of wood burned, the type of appliance, and the frequency of use. In general, an older, uncertified woodstove, or any appliance used frequently, will require more than one cleaning per year.
Some Signs of a Chimney Needing Cleaning
- An odor of burned wood coming from the fireplace.
- Drafting or smoking problems with the chimney.
- Creosote covering the damper. You can check this by looking inside the fireplace near the damper. If you see any creosote, which resembles black mold, then it is most likely coating the entire smoke chamber and flue liner.
Refer to the phone book's yellow pages (under "chimney") to locate a chimney cleaning professional. Ensure your chosen professional is fully insured and has a CA State License. Even better is someone who has additionally received a Certified Sweep Certification (see www.csia.org for more information).
How Do I Know If I Have a Chimney Fire?
The first indication of a chimney fire is usually the noise - a roaring sound that grows louder as the fires intensity increases. It may sound like a low flying aircraft or a freight train.
Outside the house a cloud of black smoke and sparks will be seen exiting the top of the chimney; in severe fires, flames can extend several feet above the chimney.
However, there have also been chimney fires that homeowners did not know about. Slow burning fires do not get enough air or have enough fuel to be dramatic or visible. But the temperatures they reach are very high and can cause as much damage to the chimney structure - and nearby combustible parts of the house - as the more spectacular ones. With proper chimney care, chimney fires are preventable.
In The Event of a Chimney Fire...
Call 911 to notify the fire department immediately!
- Alert others in the house to evacuate.
If it is safe to do so...
- Close the appliances dampers and/or the primary air inlet controls, limiting the
fires air supply and reducing its intensity.
- Closely monitor all combustible surfaces near the chimney. During severe chimney fires, these surfaces can become hot enough to ignite.