University of Wisconsin - Extension

If spiraling energy prices have rekindled your interest in burning wood to heat your home, you may be interested in an incentive program available this winter, according to a University of Wisconsin-Extension housing specialist.

"The program is designed to encourage people with old, inefficient wood burners to turn them in for new models that burn more efficiently, thereby reducing the pollution associated with wood smoke," says John Merrill.

Merrill says smoke from older woodburners is not only a nuisance to neighbors, but it also contains a variety of air pollutants, including hydrocarbons droplets, particles and known carcinogens, such as benzo(a)pyrene. Some of these compounds can pose serious air quality problems and can fall into lakes and rivers creating water pollution as well. Fortunately, wood burning equipment is available that reduces this pollution substantially. These newer wood burners produce only about one-seventh of the pollution of their predecessors.

The Great Wood Stove and Fireplace Changeout program is sponsored by the Wisconsin Department of Natural Resources (DNR) and the Wisconsin Energy Bureau, together with the North Central Hearth Products Association and other groups. The program runs from February 1 to April 30. During this time, hearth products dealers are promoting new, low-polluting products and offering discounts particularly to customers who turn in an old wood burner.

Product discounts during the program will be from 10 to 15%. The discounts are also available to persons who install an insert in a previously open fireplace. In addition, the DNR is offering a cash rebate to buyers in Great Lake Basin counties who turn in their old wood burners.

Since 1992, the U.S. Environmental Protection Agency has had a program to certify wood burning stoves as low polluting. These stoves run at efficiencies of up to 78%, and consequently produce a fraction of the pollution of older models.

Because interest in wood burning was spurred by the energy crisis of the 1970s and early 1980s, except for those installed in new homes, it is likely that most wood burners in use today are the older, heavily polluting models that operate at 50 percent efficiency or less.

There are three general types of technology used to meet new standards. The first uses a catalytic combuster, which is a specially coated ceramic honeycomb at the top of the fire box. In a traditional stove, 40% of the fuel goes up the chimney unburned because the units operate at relatively low temperatures of below 600 degrees F.

For complete combustion, temperatures must rise to nearly 1000 degrees F. The catalytic combuster lowers the ignition point to about 500 degrees F. so complete combustion can occur. Because the combuster restricts the flow of gases, it can not be used during start up. Stoves equipped with catalytic combusters may use at least 25% less fuel and require less frequent chimney cleaning, since much of what would become creosote is burned before it hits the chimney.

The catalytic element needs to be replaced every couple of years and care must be taken to control the stove temperature so that the combuster does not overheat.

The second type is the advanced combustion woodburner, which uses a variety of design features to more completely burn the wood. These features include a better insulated fire box, baffles and similar devices that keep gases in the hot fire box long enough that they will burn rather than being exhausted. Other features includes a system to preheat combustion air and a secondary air supply to help burn off the gases. These stoves are typically slightly less efficient that the catalytic models and require more frequent refueling.

The third new technology is the wood pellet burner. Pellets are made of wood or other biomass fibers pressed into inch-long pellets. Pressure and heat bind them together without the need for adhesives. Pellet burners feed the pellets into the fire box at a controlled rate matched with the right amount of air.

Different models require different pellets, so it is important to check with the dealer to ensure a reliable supply of the pellet type the stove requires. Pellet burners also require electricity, to run both the auger that feeds the pellets and the fan that controls the air supply. The amount of electricity needed is small, but the stove can't operate if your electricity supply is interrupted. On the other hand, pellet stoves are among the most efficient and least polluting stoves available.

For information about the Great Wood Stove and Fireplace Changeout, contact your local hearth products dealer or call 1 - 877- 81-STOVE or visit the web site for the program at http://www.woodstovechangeout.org . For more information on wood burning, check the "Yellow Pages" on the Wisconsin Energy Bureau's web site at http://www.doa.state.wi.us/depb/ .

If you have a housing question, send it to John Merrill at 1300 Linden Dr., Madison, WI 53705.