Installing a Wood-Burning Stove
Newer wood-burning heaters can keep a load of logs glowing for 12 hours or more. They burn so completely you need to shut down the heater only once a week to clean out the ashes. To maintain this long-burning fire, wood heaters carefully control combustion. Most feature airtight construction and an automatically regulated draft. A catalytic converter may be located inside the stove or in the flue. As a result, wood-burning heaters draw little air and lose a minimum of heat.
You do pay a price for this efficiency, however. Slow-burning fires produce creosote, which can build up in a chimney and ignite. Because of this, you need to follow strict installation and maintenance procedures. Use only a masonry chimney or a metal chimney with a Class-A rating from Underwriters Laboratories. Follow the heater and chimney manufacturers’ requirements to the letter, and check local building codes too.
Flue sections fit together with their crimped ends facing toward the heater. This allows any condensation in the vent to flow back to the fire. For an airtight assembly, seal each joint with furnace cement and secure it with three metal screws. To break in a new wood heater, light small fires the first few times you use it. Otherwise heat could crack a casting. Proper maintenance is important too. Remove ashes at recommended intervals to prevent warping and burnouts, and clean the flue annually. When a wood-burning heater smokes or won’t draw properly, make sure it’s getting enough combustion air. If that’s not the problem, your chimney might not be tall enough. A chimney contractor can help you evaluate and correct this situation.
Get the clearances right. Check installation instructions and local fire codes for minimum distances to a combustible wall. Most units must rest on a masonry or other noncombustible base. Even if a flue is rated “zero clearance,” be extra safe and keep it several inches away from wood.
Connecting to a masonry chimney. If location permits, it’s easiest to connect to a masonry chimney, as shown. Keep the flue pipe runs short, with no more than two elbows. Have the chimney inspected and cleaned at least once a year.
More safety precautions. Make sure the flue pipe doesn’t extend into the flue to create an obstruction. Make the connection at least 18 inches below the ceiling.
Alternatives to a masonry flue. If you don’t have a masonry flue, you’ll have to run a class-A metal flue through the ceiling and roof. For a proper draw, the chimney should extend above the roof peak. If that would make it unwieldy, consult local codes for minimum clearances from the roof.