Are wood stoves safe? This article is designed to provide you with basic information on wood stove safety, including tips on installation, venting, chimneys, operation, and maintenance. By following these recommended procedures and methods, you can safely and efficiently heat your home or business with wood.
If your local code or stove manufacturer’s requirements differ from those detailed here, you must follow the stricter of the 2 sets of requirements. If in doubt, check with your local fire department or building inspector.
Wood burning stove safety installation
All operating wood stoves and furnaces require specific minimum distances or clearance between the bottom, top, sides, front and back of the stove and all combustible materials. Insufficient clearance could cause heat produced by the stove to penetrate nearby combustibles, causing a serious fire.
Installation clearances may be reduced from 36 inches or UL-listed manufactured instructions to these lower dimensions by installing a heat shield along the combustible wall.
The chimney for a wood stove must be masonry or UL-listed, and factory built. Never, under any circumstances, should an unlined, single brick chimney be used for a wood stove. Single brick chimneys are prone to deterioration, which may allow potentially dangerous situations to develop.
Many older homes have unlined chimneys constructed of double brick. These may be used for a wood stove after carefully checking for cracked mortar or loose or missing brick. Metal sleeves that are listed by the Underwriters Laboratory may be used as chimney lines if they were designed for such use.
Factory built, metal chimneys must never be used with a coal stove, as the corrosive flue gases produced by a coal fire will cause a rapid deterioration of the chimney. Metal chimneys should be completely disassembled after a chimney fire and checked for damage. Discoloration of the exterior indicates a possible breakdown of the insulating material. Any questionable section should be replaced.
A wood burning stove should never be connected to a flue which vents an oil burner. Deadly, unburned vapors from the oil burner could back up into the stove and the room where it is located.
Venting the stove is the most important part of the wood-burning system. 90% of all stove-related fires originate within the venting system. A venting system is not a chimney – it consists of lengths of 24-gauge or heavier stovepipe which connects the stove to an approved chimney.
The vent must be as short as possible, with no more than 2 right angle elbows. The sections of stovepipe should be assembled with crimped, male ends of the sections facing down, towards the stove. Stovepipe sections should be fastened with at least 3 sheet-metal screws or other fasteners. Seams must overlap and face up on inclined runs.
Stovepipe clearance is extremely important. It must never pass through an interior wall, floor, or ceiling. Stovepipe should never be used for a chimney because the elements will rust. Where possible, the stovepipe must go directly into a lined masonry or UL-listed, factory-built chimney. If stovepipe must pass through an exterior wall to reach the chimney, maintain an 18-inch minimum clearance to all combustibles. Consult fire codes and use metal thimbles designed for this purpose.
Operations and maintenance
Wood burning stoves require proper operations and regular maintenance.
Use proper fuel
Hardwoods, such as maple, beech, ash, hickory, or oak, are the best fuel for a wood stove. Wood should be cut, split and air dried for at least a year before burning. Well-seasoned hardwood will show cracks in the ends. Wood will dry faster and remain dry and protected from the elements if stored in a shed or under a tarp.
Use a wire brush to clean your stovepipe and chimney at least once a year. Also, occasionally use controlled, high-temperature fires in the stove or furnace. Don’t bother with the salt-based chemical cleaners. And never use heavy items such as chains, bricks or a brush on the end of a rope, because they could seriously damage the interior chimney lining.
Avoid creosote buildup
Creosote is a highly combustible fuel that burns intensely. A slow-burning fire such as those found in a modern, airtight stove damped way down, produces a flue temperature in the 100-200 degree Fahrenheit range. These comparatively low temperatures do not sufficiently carry all of the unburned, combustible gases into the atmosphere. Instead, they condense along the walls of the stovepipe and the chimney as creosote. Creosote may take 3 forms:
- A sticky liquid that will run down the chimney and stove pipe where it will be burned
- A flaky, black deposit which is easily removed by brushing
- A hard, glazed tar which is almost impossible to remove, except by a certified professional chimney sweep
Tips for building a fire1
Once your stove is properly installed, building an effective fire requires good firewood (using the right wood in the right amount), and good fire-building practices. Obtain the best efficiency from your wood stove by following these practical steps:
- Season wood outdoors through the hot, dry summer for at least 6 months before burning it. Properly seasoned wood is darker, has cracks in the end grain, and sounds hollow when smacked against another piece of wood.
- Store wood outdoors, stacked neatly off the ground with the top covered.
- Start fires with clean newspaper and dry kindling.
- Burn hot, bright fires. But use smaller fires in milder weather.
- Let the fire burn down to coals, then rake the coals toward the air inlet (and wood stove door), creating a mound. Do not spread the coals flat.
- Reload your wood stove by adding at least three pieces of wood each time, on and behind the mound of hot coals. Avoid adding one log at a time.
- Regularly remove ashes from the wood stove into a metal container with a cover, and store outdoors.