Most chimney fires in flues serving wood-burning stoves, fireplace inserts, fireplaces and furnaces occur because of a lack of regular cleaning to remove creosote, which is the residue left behind by unburned fuel. The National Fire Protection Association recommends annual inspection and cleaning as necessary by a professionalchimney sweep. All wood produces creosote, even dry hardwoods.
If a chimney fire occurs, close the damper and doors (if possible, get out of the house, and call the fire department. DO NOT use the chimney until it has been inspected by a Certified Chimney Sweep. Note: Firemen are not trained in evaluating chimney damages. You can tell if a chimney fire is occurring if you hear a loud roaring or freight-train like sound or see flames or sparks coming from the exterior of the chimney at the top or sides, if chimney pipe turns red, or if the appliance suddenly stops drafting. However, most chimney fires occur without the homeowner's knowledge while they are out of the room. Fire damage such as cracked flue liners and blown out mortar joints is usually found during a routine annual inspection by a professional chimney sweep, and these issues make the chimney a potential hazard.
Creosote comes in four forms: Stage 1 is a light dusty coating that comes off easily with brushes, State 2 is a harder and comes in larger pieces but still comes off with heavy brushing, Stage 3 is also known as glazed, baked -on or tar glaze creosote, which is the most flammable type and does not come off with brushes. Glazed creosote bakes on the flue walls and can only be removed by power cleaning with chains or wire brushes on a drill. Removal of this type of creosote is a difficult, time-consuming, and dangerous process, so the best thing to do is avoid the accumulation of Glazed creosote altogether by using proper woodburning habits and having the right chimney or flue for the appliance. The fourth type of creosote is burnt glazed creosote, which occurs when glazed creosote catches fiire and expands to ten times its original size. It has a honeycomb appearance and is very lightweight. Sometimes burnt creosote expands inside the flue, completely or partially choking off draft. This is why sudden smoking of an appliance is an idication of a chimney fire.
Always make sure the correct size flue liner or chimney is being used for the appliance. Open fireplace require large flues, woodburning inserts require very small stainless steel flue liners, and freestanding stoves need small stainless steel chimneys, or if connected to a masonry chimney, a small steel flue liner. The manufacturer of the stove will have information about the best flue size to use. NEVER install a woodburning stove insert into a fireplace with out a stainless steel flue liner. This is the most dangerous type of installation and should be avoided.
Here are some tips for safe wood-burning:
* Don’t burn treated wood, railroad ties, trash, or colored paper since they emit toxic fumes.
* Don’t burn pine trees or railroad ties since they create excessive amounts of flammable creosote and may overheat and warp your steel or cast iron appliance.
* Burning Hedge is also discouraged since it burns very hot and can overheat your woodstove or fireplace. If you must use Hedge, use only one log to every two Oak logs.The best wood to burn is oak because it is very dense and burns slowly. However, any dry hardwood or soft wood may be used – you’ll just have to load the stove more often with soft woods.
* Burn a wood stove hot (400-700 degrees) to assure complete combustion, which is how the stove is designed to be used, and it is cleaner and better for the environment. After establishing the fire, you should see white or clear smoke coming out of the chimney. If the smoke is Grey or black, something is wrong with the wood, your burning methods, or with the chimney system. Stove thermometers are available from your stove retailer.
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