"Chimneys really decorate the roofline of a home...
... and they're maintenance-free besides. Right?" -- WRONG!!
Your chimney-and the flue that lines it-may add architectural interest to your home, but their real function is to carry dangerous fireplace, wood stove or furnace gases and smoke safely out of your home. A chimney helps your household air stay breathable ... just as your windows and your bathroom, attic and kitchen vents do. Unlike those other exhaust points in your home, however, fireplace and wood stove chimneys need a special kind of care.
As you snuggle in front of a cozy fire or bask in the warmth of your wood stove, you are taking part in a ritual of comfort and enjoyment handed down through the centuries. The last thing you are likely to be thinking about is the condition of your chimney. However, if you don't give some thought to it before you light those winter fires, your enjoyment may be very short-lived. Why? Dirty chimneys can cause chimney fires, which damage structures, destroy homes and injure or kill people.
No One Welcomes a Chimney Fire
A chimney fire in action can be impressive. It has been described variously as creating:
- loud cracking and popping noise
- a lot of dense smoke, and
- an intense, hot smell
Chimney fires can burn explosively - noisy and dramatic enough to be detected by neighbors or people passing by. Flames or dense smoke may shoot from the top of the chimney. Homeowners report being startled by a low rumbling sound that reminds them of a freight train or a low flying airplane. However, those are only the chimney fires you know about. Slow-burning chimney fires don't get enough air or have 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 their more spectacular cousins.
With proper chimney system care, chimney fires are entirely preventable.
Creosote & Chimney Fires: What You MUST Know
Fireplaces and wood stoves are designed to safely contain wood-fuel fires, while providing heat for a home. The chimneys that serve them have the job of expelling the by-products of combustion - the substances produced when wood burns. These include smoke, water vapor, gases, unburned wood particles, hydrocarbon volatile, tar fog and assorted minerals. As these substances exit the fireplace or wood stove, and flow up into the relatively cooler chimney, condensation occurs. The resulting residue that sticks to the inner walls of the chimney is called creosote.
Creosote is black or brown in appearance. It can be crusty and flaky ... tar-like, drippy and sticky ... or shiny and hardened. Often, all forms will occur in one chimney system. Whatever form it takes, creosote is highly combustible. If it builds up in sufficient quantities - and catches fire inside the chimney flue instead of the firebox of the fireplace or wood stove - the result will be a chimney fire. Although any amount of creosote can burn, sweeps are concerned when creosote builds up in sufficient quantities to sustain a long, hot, destructive chimney fire.
Certain conditions encourage the buildup of creosote. Simply put, restricted air supply, unseasoned wood and cooler-than normal chimney temperatures are all factors that can accelerate the buildup of creosote on chimney flue walls. Air supplies on fireplaces may be restricted by closed glass doors or by 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 is it that creosote will form). A wood stove'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. Burning unseasoned wood - because so much energy is used initially just to drive off the water trapped in the cells of the logs- keeps the resulting smoke cooler, as it moves through the system, than if dried seasoned wood is used. In the case of wood stoves, fully packed loads of wood (that give large cool fires and 8 or 10 hour bum times) also contribute to creosote buildup. Cool flue temperatures speed creosote production, too. Condensation of the unburned byproducts of combustion occurs more rapidly in an exterior chimney, for example, than in a chimney that runs through the center of a house and exposes only the upper reaches of the flue to the elements.
Proper Maintenance is a Must!
Clean chimneys don't catch fire. Make sure a CSIA Certified Chimney Sweep like Quality Fireplace inspects your solid fuel venting system annually, and cleans and repairs it whenever needed. We have a variety of maintenance recommendations depending on how you use your fireplace or stove.
To set up a time for Quality Fireplace to come out and provide an estimate or to schedule a time for a chimney cleaning, either click or call us today.