Fireplaces might add the ambiance of warmth and tranquility to your home, but that cozy, crackling glow also conceals an ash pan of potential problems. Cinders, ash, volatile resins and creosote that are not routinely cleared from the fireplace can pose a dangerous fire hazard. Plus, what do you do if you don't want to have a fire burning? How can a homeowner maintain their fireplace correctly and safely while preventing their heating dollars from going up in smoke?
Because caring for chimneys and fireplaces can be both complicated and dirty, we've put together a list of tips to keep your home warm and safe.
The first place to prevent problems with your fireplace or wood stove is to select the right kind of wood. Use dried and well-seasoned wood that burns hot and completely enough so that it produces less creosote and carbon monoxide.
Chimney caps prevent leaves, debris, and animals from getting into your chimney and blocking it. They typically have some form of mesh that keeps debris out, lets smoke escape, and also arrests sparks to prevent them from starting fires outside your home. At least once a year, check over the chimney cap.
Recently cracked and discolored masonry or a warped chimney cap are signs of a chimney fire. Creosote flakes or ash are strong indicators that creosote build up in your chimney has reached a danger point. Creosote fires in fireplace flues and chimneys can reach 2000°F — hot enough to easily melt metal liners, fracture brickwork, and spread flames into your attic.
If you discover evidence of a chimney fire, you'll want to get you chimney inspected and cleaned by a professional chimney sweep as soon as possible. Trained chimney sweeps can show you how well your fireplace or woodstove is working and recommend how to get the most heat out of it safely.
The heat generated in fireplaces and woodstoves pulls air from inside your home (also called the "stack effect") and shoots hot air and gasses out the chimney. In some newer homes that are tightly sealed or those that were not built for fireplaces, the fire may be unable to draw enough air for the wood smoke to go up the chimney. This is known as backdrafting or negative pressure. Consequently, smoke, cinders, creosote, and dangerous carbon monoxide will be trapped in the home.
A similar problem happens when there are furnace return vents in the same room as the fireplace. As the HVAC sucks in air for the blower, it will also pull air from the room with the fireplace. This negative pressure stops smoke from going up the chimney. The same thing can happen if there's a clothes dryer running that is blowing air out of the house. While closing off the HVAC return vent or avoid running the clothes dryer while you have a fire going are temporary fixes, it's best to add a fresh air supply to your fireplace or wood stove. If you already have a fresh air supply for your fireplace, be sure to keep it clean so that ash and other debris don't block it off.
Fireplace dampers are designed to control the flow of exhaust from the fire. Many traditional fireplaces have built-in dampers (also called "throat dampers ") at the mouth of the flue. If you don't want to have a fire, then ideally, you can close the damper and keep out the cold weather. Over time, however, creosote and ash deposits will build up and prevent the damper from closing (or opening) properly. To test your fireplace damper, hold a lit candle in the fireplace with the damper closed. If the flame flickers, the damper isn't able to close all the way and heated air from your home is going up the chimney.
Unfortunately, because most fireplace throat dampers leak along their entire width of the fireplace, it's better to try some alternatives. You can install a chimney-top damper that fully seals your chimney. It looks much like a hatch and uses a heat-resistant gasket. Another easier and inexpensive fix is to use an inflatable fireplace damper balloon that gets stuffed inside the chimney to cut drafts.