Fixing smoky wood-burning fireplaces
Although wood-burning fireplaces are no longer the main source of heat for modern homes, many home buyers still desire them. They associate fireplaces with cosy homes. Knowing the common problems with wood-burning fireplaces and how they can be fixed will help real estate professionals counsel clients on their pros and cons.
... according to a study by Environment Canada reported in the Toronto Star, "Using a wood-fire stove for only nine hours...produces as much fine-particle pollution as does a car in a year."
...there are ways that residents can eliminate the amount of smoke from a wood-burning fireplace, making them more environmentally friendly. First, they need to understand how the fireplace works. Smoke should be drawn naturally up the chimney at all times. If the fireplace smokes when it's operating, it's not designed properly, or there is something in the house that is causing the fireplace to smoke.
There are some configurations that are more likely to smoke than others. For example, chimney height has a big influence on how well the fireplace draws. A taller chimney will draw better. Also, the flue size should be at least 1/12 of the fireplace opening size in order to provide an optimal draw and eliminate smoke.
It's common for the fireplace to smoke when the fire is first lit and when the fire has burnt down. This is called the cold hearth syndrome. When the chimney flue is hot, it draws well, and when it's cold, air flows down the chimney rather than up. Somethimes this can cause soot and cold air to pour down the chimney when the fireplace is not in use, even when the damper is closed. This is indicative of a less than ideal fireplace and chimney design.
Homeowners should also check for soot under the mantel. If there is soot on the underside of the mantel, it could indicate a fireplace with chronic back-drafting.
Solutions for smoking fireplaces include:
Add glass doors: They reduce the effective fireplace opening size and volume of air going up the chimney. These both improve the fireplace draw.
Decrease the fireplace opening size: Anyghing that reduces the opening size of the fireplace will result in better draw.
Extend the chimney: A taller chimney draws better. This is a good solution, but it is more expensive than the other suggestions.
Convert to gas: If all else fails, consider installing a gas direct-vent fireplace. These fireplaces vent out the wall of the house. No chimney is needed.
Excerpt from article written by Dan Steward, President Pillar to Post - Home Inspection