Modern homes tend not to use wood-burning fireplaces as the main source of heat. However, many home buyers still desire them for the sense of warmth and coziness they provide.
One of the most common problems with wood-burning fireplaces, however, is that they smoke. Using a wood-fire stove for only nine hours produces as much fine-particle pollution as a car does in a year.
The purpose of the chimney is to draw the smoke upward out of the home. Ideally, smoke should draw naturally up the chimney at all times. Sometimes a fireplace smokes while it’s in use. If so, it may be that it’s not designed properly or something is blocking the chimney and not allowing the smoke to exit.
A phenomenon labeled “cold hearth syndrome” describes two of the most common times for the fireplace to smoke. The fireplace and chimney are coolest when the fire has just been started and after it has burned down. Once the chimney flue has had a chance to warm up, it will draw properly. However, in a “cold hearth” state, air will tend to flow down the chimney rather than up, a condition called back-draft. Remember, heated air rises while cool air falls. One tell-tale sign of chronic back-drafting is soot on the underside of the mantle.
Due to various reasons, some fireplaces will have more of a problem with back-drafting than others. One factor involved is chimney height. A taller chimney will draw better. Back-drafting may also occur when the fire is built too close to the front of the firebox or if the firebox is too shallow.
If a problem is indicated, here are some steps homeowners can take. First, call a local certified chimney sweep and schedule an inspection and cleaning. Second, make sure the fire grate is back as far as it will go before building a fire. Third, check to make sure the damper is open when the fireplace is in use. Next, install glass doors or a fire screen. Reducing the effective opening size of the fireplace will help it to draw better. Lastly, if the home is less than 25 years old, it may be necessary to open a window. Proper drafting depends on air flow, which may be hindered if the home is sealed too tightly.
While many smoking fireplace issues can be resolved by homeowners, it is always advised to consult a chimney professional to ensure your home is safe.