Q: We have a large fireplace in the family room off the kitchen. Although we use it frequently, I noticed last year that smoke occasionally came back into the room. Before it's time to light fires again, I want to make sure it operates properly. What should I check to see that the draft works properly? Should the chimney be cleaned? If so, is this something I can do myself?
A: A chimney must be able to perform two tasks to operate properly: Products of combustion need to be safely exhausted into the atmosphere, and oxygen needs to be brought in to sustain combustion. If these two tasks are not taking place, there may be a risk to property or personal safety.
It's wise to have your fireplace checked out thoroughly each year and again any time you spot even minor problems. Solutions to a smoking fireplace can be as simple as adjusting the damper, opening a window or turning off a fan, or as complicated as extending the height of the chimney or reducing the size of the firebox opening.
With added insulation and weatherstripping, our homes have become more airtight. This can cause problems with back drafting in the fireplace because a lack of sufficient air movement exists. Demand for inside air from fans can also cause a downdraft.
Airtight glass doors on your fireplace and a separate combustion air supply can be a solution. Improper updraft also happens when the chimney stack isn't high enough. It should be four feet above a flat roof or two feet above the top of the highest gable on a sloping roof.
Tall trees nearby can also affect the draft when the wind is in a particular direction. Overnight, trees can suddenly reach a height taller than the chimney flue. Wind is deflected over the trees and right down the flue, rather than letting the air and smoke go up. Solutions to this problem may be as simple as a major tree trimming or may require the extension of the chimney or addition of a wind directional cap.
In an older home, it may be that the chimney lining needs to be cleaned. Soot buildup can block the air/smoke passage.
I recommend that you have a professional chimney sweep inspect your system. A professional can quickly recognize problems, evaluate the system and offer recommendations for safer, more efficient use.
Since a common problem is the buildup of creosote, which forms in different fashions and textures, it is best to have your chimney inspected once a year by a qualified chimney sweep. A buildup of only one-eighth inch of creosote means it's time to clean. Left unattended, creosote buildup will cause unpleasant odors, but more important, it can ignite easily, causing a destructive chimney fire. A professional will check for external deterioration and make sure that a two-inch clearance for combustibles exists on all sides of an internal chimney--an important safety rule.
If your chimney does need cleaning, you can expect a complete cleaning from a chimney sweep that includes removal of creosote from the flue, stovepipe and clean-out-door area. The smoke chamber and smoke shelf will also be swept and vacuumed. A professional chimney sweep will analyze the entire system, including the problems you are having with back drafting.
Although I have read articles regarding do-it-yourself cleaning methods for chimneys, this is one area where professional expertise is best. Do-it-yourself methods can easily damage the chimney lining, and often such problems as cracks in clay liner tiles, loose mortar and structural problems where the chimney connector passes through the wall--a major source of problems--go undetected.
Look for a professional chimney sweep certified by the National Chimney Sweep Guild or one that comes with good client references. For a list of certified chimney sweeps in your area, you can contact the Chimney Safety Institute of America, 16021 Industrial Dr., Suite 8, Gaithersburg, Md. 20877, or call 800-536-0118.
Q: I have a modern metal fireplace/chimney. Does a chimney of this type require frequent cleaning compared with the standard brick-fireplace installations?
A: Compared with masonry chimneys, factory-built metal chimneys usually do not generate as much creosote buildup. They are well insulated and, because the flue stays warm, very little creosote forms.
The main problem with factory-built chimneys is that many are improperly installed. Problems can also occur with overheating if synthetic logs are used and more than one is added to the firebox at a time. Instructions on synthetic logs warn against this.
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