Smart Wood Stove Burning Practices
Choosing a Fuel
Air-dried hardwood — seasoned for a year — is the best cord wood fuel. In B.C. though, people mainly burn softwoods. Seasoning the wood for at least six months and keeping it sheltered
from the weather is strongly advised. Freshly cut wood is between 35 and 50 percent water by weight. If you don't reduce its moisture content to below 20 percent by seasoning it, much of its heating value
will be wasted in burning off this excess moisture. Burning wet or green wood means more trips to the wood pile, potential creosote problems in your chimney (a safety hazard), and higher heating costs.
The use of properly sized pieces is equally important. Wood should be split to a maximum thickness of 10-15 cm (4-6 in), depending on stove size. This size increases the surface area exposed to flame, resulting in higher burn efficiency. Keep a good supply of the driest wood for kindling.
Know Your NO-NOs
To protect the environment and heat your home efficiently, DO NOT burn these fuels in your wood stove:
- Wet wood
- Green wood
- Pressure-treated wood
- Painted wood
- Particle board
- Household rubbish
|Paper and kiln-dried wood should be used only for starting fires. They burn too hot and
too quickly to be of any heating value.
Household wastes such as plastic, painted wood, manufactured wood products and wood treated with preservatives release very toxic chemicals when they're burned. Don't burn these materials in residential stoves or fireplaces, or in backyard fires of any kind.
Coal burns efficiently only in specially designed and CSA/ULC approved stoves and inserts, and burning it in a wood stove may produce excessive and highly toxic emissions. Coal also burns hotter than wood, and can cause a fire hazard if you burn it in a wood stove.
The driftwood found on B.C. beaches may seem like an economically attractive heat source. Driftwood, however, is laden with salt, and burning it releases sodium and chlorine ions. The potential exists for these chlorine ions to form chlorinated compounds such as dioxins and furans, which are suspected human carcinogens. They may also corrode your stove and venting system.
Starting the Fire
Many of today's wood-burning appliances require specific lighting techniques. Always follow the manufacturer's recommendations. Here are some general tips for cordwood stoves:
- Put crumpled newspaper in the stove (don't use coloured or gloss paper). Be generous. Put 10 to 15 small pieces of finely
split dry kindling on top of it and behind it. Open the air supply vent wide.
- Light the paper in several places near the air inlet. Leave the stove door unlatched until the fire is going well. It may be necessary to leave it unlatched for up to 15 minutes until the chimney is primed and the combustion chamber and air supply pipe have been warmed up. Do not leave the stove unattended during this time. Burning embers may fall out.
- When the flames from the kindling just begin to subside, add at least three small pieces of firewood. Be careful not to smother the fire with the new pieces.
- Gradually increase the size of the pieces as the coals build up.
Maintaining the Fire
The key to maintaining a good fire is careful control of the air supply, which determines how completely the fuel is burned. When you start a fire or add wood to a fire, the fresh
fuel requires much more air for the first 10 to 15 minutes to complete the rapid combustion phase. Once the wood is well charred, it requires much less air. Loosely stacked pieces burn quickly because
the combustion air can reach all the pieces at once. Never add just one or two pieces of wood; three or more are needed to form a sheltered pocket of glowing coals that sustain the fire.
Watching both the fire and what comes out the chimney is the best way to monitor your wood stove's performance. Look at the fire first. Is it burning brightly? As your wood decomposes,
it vaporizes into smoke: a cloud of combustible gases and tar droplets. The smoke will burn over top of the main fire in a yellow/blue turbulent flame that shows the secondary combustion. Secondary combustion
produces bright, lively flames. Dull, steady flames, on the other hand, are a sign of oxygen starvation and incomplete combustion.
Excessive smoke from a chimney in the middle of a burn is another sign of incomplete combustion. Smoke is energy going to waste, and creating problems to boot. Some smoke should be visible when you light the fire, but for the remainder of the burn it should be almost invisible. If the smoke doesn't burn in the firebox, it will go up the chimney. Some of it will then condense to form flammable creosote deposits that can lead to a chimney fire, or leave as air pollution.
When you use your wood stove as an overnight heat source, it's important to load it properly to avoid a smouldering fire.
To build a long-lasting fire, rake the coals towards the air inlet and use larger pieces of wood placed compactly in the firebox behind the coals. Place the pieces close together to prevent the heat and flame from penetrating the new load, saving the buried pieces for later in the burn. Open the air inlets fully for 15 to 30 minutes, depending on the size of the load and its moisture content. When the outer pieces have acquired a thick layer of charcoal, reduce the air supply in stages to the desired level. The charcoal insulates the rest of the wood and slows down the release of combustible gases. This allows you to turn down the air control and still maintain a clean-burning fire.
Your Wood Stove:
Cut Emissions and Increase Efficiency