Wood Burning for Residential Heat
- Firebox insulation to keep temperatures high
- Primary combustion air that is preheated so that it doesn't cool the fire
- Preheated secondary air that is fed to the fire through sets of small holes in the gas- burning zone, above and behind the fuel bed
- Internal baffles that give the gases a long and hot enough route so that they can burn completely. Vancouver Island is home to Pacific Energy, one of the first innovators of this technology. CATALYTIC Catalytic stoves are built to send combustion smoke through a coated ceramic honeycomb-shaped device that is located in the top of the firebox, just inside the door. The catalyst in the coating consists of a combination of one or more precious metals, including platinum, palladium, rhodium and cerium. The catalyst chemically lowers the combustion temperature of the smoke from a wood fire, thereby allowing more smoke to burn. The result is a highly efficient unit with extremely low emissions. In order to maintain these advantages, the catalyst needs to be replaced every 6 to 10 years. One of the most popular catalytic stoves in BC is the Blaze King. It has a very large, deep firebox that can produce burn times of well over 24 hours from a single load of wood. It is especially efficient during the many months of not-so-cold weather, when the catalyst allows for a slow, even burn without the polluting ' damping down' effect. PELLET Pellet systems use dried ground wood or other biomass waste that is compressed into small cylinders that are about 1 inch long and 1/4 inch in diameter. The pressure and heat created during their production binds the pellets together with the lignin in the wood. No other binders or additives are used. Pellet burners consist of a screw auger that automatically feeds pellets at a controlled rate from a hopper (holding 40 to 100 lb of fuel) into the combustion chamber. The feed rate matches the amount of combustion air introduced and, if properly adjusted, can lead to lower emissions than natural wood appliances. Pellet stoves rely on three to four electric motors that need to operate under high temperatures. The best systems are ones with high quality, low noise motors that do not consume a lot of electricity. If you are heating your home using a wood stove made before 1994, consider buying one of the systems described above. The air quality in and around your home will be greatly improved; you will need far less wood per season; and you will enjoy the more stable, radiant heat from a flame you can watch through the ceramic door window - a standard feature of all newer models. BURN IT SMART Installing a clean burning stove is only the beginning of 'burning smarter'. The rest depends on the operator who needs to: - Cut or buy wood in the spring so it is well seasoned before use.
- Have wood cut to 4-6" diameter pieces for best loading and clean burning.
- Store wood in a well covered, ventilated area so it does not become wet again.
- Never burn household garbage, plastics, treated, coated or painted wood, rubber, plywood, particleboard, or salty beach wood.
- Minimize smoke at start up by using plenty of paper, small, dry kindling, and smaller logs to get a quick, hot, smokeless fire going.
- Burn on high airflow for 20 minutes after adding wood to the fire.
- Burn wood in cycles that end with a nice bed of hot coals to reload onto
- Avoid choking or damping down a fire.
- Keep the chimney clean. MORE INFORMATION
www.woodheat.org www.burnitsmart.com BURN IT SMART WORKSHOP TIPS There is a lot to know about managing a safe, non-polluting, wood-burning system. A common pre-inspection mistake, when installing a new woodstove, is to assume one knows it all, therefore avoiding useful information and advice that our local inspectors would be happy to share. SHAW TV BURN IT SMART TIPS Following are some tips from the Burn It Smart Workshops held in Port Alberni: CHIMNEY TIPS Clean your chimney every 6 months. (Go to www.wettinc.ca to find a certified chimney cleaner.)
Keep a record of your chimney cleaning dates and details (some insurance companies require this)
Use only a fibreglass brush to clean a stainless chimney - NOT the common wire brush that will scratch, degrade and lead to stainless pipe corrosion
Make sure your chimney is equipped with a rain cap, as the cooling influence of rain and snow falling down a hot chimney is another cause of creosote build up. COMMON FLUE PIPE MISTAKES Flue pipes carry the exhaust gases from the stove flue collar to the base of the chimney According to our inspectors, some of the most common mistakes people make with their chimney system is in the assembly and care of the flue pipe. For example:
Not screwing the pipe together (unless it is snap fit pipe).
Installing the pipe male end up instead of down is a mistake that results in creosote running down the outside of the pipe.
Putting in too many elbows. Two offsets are allowed totalling 180 degrees. The strongest, cleanest draft is straight up.
Cleaning stainless steel flue and chimney pipe with a metal brush instead of a fibreglass brush. This scratches the special inside coating of the pipe leading to damage and corrosion.
Burning out flue and chimney pipe by using salty beach wood which produces highly toxic and corrosive smoke. CLEARANCES Clearance requirements are often misunderstood or overlooked by home owners. For example, the non-combustible floor pad must extend at least 8" beyond the side and rear of the appliance, and 18" in the front of the loading door. No cutting corners here. Running a hardwood floor right up to a raised twelve-inch wide hearth in front of a fireplace insert doesn't comply with the required 18" minimum distance to combustibles. It is costly and frustrating for everyone involved to deal with this kind of planning problem. The eighteen inches is a minimum requirement, and, even at that distance, house fires have started from stray embers bursting, unnoticed, out of an opened stove. CREOSOTE Creosote expands 1,700 times when ignited. Even a thin layer catching fire in a standard 8" pipe can bubble up leaving only a pea-sized hole for air and flame to escape. At this point, the fire may choke itself off or force itself out another way - often cracking and damaging a masonry chimney. Freezing water and movement are two other factors that can cause or add to such damage. During or after a chimney fire that damage can lead to fire penetrating the walls of the house. Creosote problems are made worse by a capless chimney. Drying a wet chimney is difficult and inefficient and rain water falling on hot creosote adds to the mess, forming additional toxic compounds. Oddly enough, there is significant danger of having a chimney fire right after cleaning a dirty chimney, due to the remaining, loosened flakes of creosote. GARBAGE BURNING It is amazing how many people keep to old habits of paper and garbage burning, even after installing a new woodstove. Not only is the smoky result bad for the stove, the chimney, the environment and the health of anyone around, it is unsafe. Every year there are chimney fires due to a build up of ash and creosote from burning waste. SALTY WOOD Tragic news for all beachcomber burners - burning salty wood creates poisonous and acidic fumes that are extremely corrosive to both the woodstove and metal chimney pipes. Rob shared stories of dangerously corroded chimneys, even to the point of full collapse from burning salty wood. BUYING WOOD There are quite a few sad stories out there of people getting ripped off on the quality and volume of wood they've purchased. Remember, a cord of wood is a 4x4x8 foot cube. That completely overflows a normal pick up truck box. Know where your wood comes from and buy from a reputable supplier. DRYING WOOD For the driest and cleanest burning fuel, buy or cut your wood 1 year ahead and split it to make sure it cures all the way through before you use it. Make sure the pieces are no thicker than 4" x 4". Wood needs at least 6 months to dry in this country and it needs a well ventilated, covered area to keep it that way. Alder and hemlock take much longer to dry than fir. Wood must be stored in a covered, well-ventilated area. Wood that has dried all summer will end up as a poor fuel if it is exposed to rain. The ideal moisture content for firewood is 12%. Wood this dry feels relatively light and looks checked on the ends. Wood can regain significant amounts of ambient moisture, depending on how and where it is stored. It does help to bring small batches of wood inside for a while before loading them into the fire. STACKING WOOD Don't stack wood against or near a fireplace or stove appliance. Moveable combustibles should be at least 48" away.
Don't stack wood against the house. In the event of a house fire, this creates a huge fire load and could possibly nullify insurance coverage. The same is true for stacking more wood inside the house than is needed for a day or so.
Don't jam wood together in close, multiple rows. It really needs airflow to dry. It has been demonstrated that if the rows are only a few inches apart, the wood will only dry for an inch or so at the ends and remain wet inside.
Don't load firewood up past the height of the firebrick inside the stove. FIRE START UP Most workshop participants were fascinated with a Burn It Smart video showing cool techniques, like starting a smokeless 'top down' fire and using a starter made from 6 knots of newsprint (each sheet rolled on the diagonal and tied in a knot). To view this video and tons of other helpful information go to www.woodheat.org. BURN CYCLE Fires in efficient stoves are easy to start and are quick to ramp up heat and hold it for hours of almost smokeless operation. Opening the stove door and reloading during that period of clean burning ruins the most important and efficient part of the burn cycle and leads to unnecessary smoke pollution. SMOKE Wood smoke is made of extremely fine, toxic particulate matter that is very similar to cigarette smoke. Although exposures to wood smoke are rarely as high as sucking on the end of a cigarette, they are still a serious public health concern. This is especially true during inversion weather when smoke can be seen to fall on the ground exactly where people are living and breathing. To make matters worse, studies have shown that 70% of chimney smoke infiltrates the house (and other proximate houses) through door and window cracks and, literally, through the walls. An EPA emissions-certified stove that is operating properly makes no visible smoke. Look around. If you see smoke, especially blue or dark coloured smoke, you're seeing inefficient burning and unnecessary pollution. That is why programs, like the woodstove exchange, are so important. INSPECTIONS AND SAFETY Almost 30% of initial inspections do not comply with regulations and usually need more labour than money to resolve. About 10 wood stove inspections are completely rejected every year, often because the appliance has no smoke shelf or plate. The plate provides for better combustion and is the only protection against flame entering the chimney directly. Unfortunately, the worst-case scenarios go up in smoke. Homes and sometimes lives are lost every year due to house fires caused by faulty woodstove installation and/or operation. It makes the $100 certified woodstove inspection look like a good investment.