EPA sets emission standards for wood stoves. New models are clean burning and more fuel efficient

According to Environmental Protection Agency calculations, something like a million new wood stoves and fireplace inserts are being installed in United States homes each year. That figure is well down from any in the frantic oil-crisis years of a decade ago, but it still points to a steadily increasing number of Americans who look on wood heat as a pleasant and relatively inexpensive way to stay warm in winter. There's a negative side to this cheery comfort, however, and that's what disturbs the EPA and a growing number of state legislatures. It comes in the form of air pollution. In many areas there's too much potential woodsmoke for the well-being of man, beast, and even plants.

So wood stoves, or rather wood-stove emissions, are about to be regulated. In Oregon, only a given amount of smoke and particulate matter will be allowed to pass unburned up the chimney from newly manufactured stoves beginning in 1986, with Colorado legislation not far behind. And the EPA will propose federal emission standards governing wood heat by January 1987. Manufacturers will have exactly 12 months from that date to meet standards; any noncomplying stoves in dealers' hands at that time could beco me so much junk metal -- which suggests some impressive discounting by dealers with too much inventory on hand as the deadline nears.

The new efficiency standards will not mean that the popularity of wood burning will decline but rather that old smoke-belching stoves, like polluting autos of the past, will steadily give way to clean burning, more efficient models. The technology is at hand and many top-of-the-line stoves already meet the stringent standards imposed by Oregon, the first state to legislate against wood-smoke pollution.

These new stoves, in fact, will lower heating costs still further for the homeowner. Unlike autos, where the reduction of emissions lowers the mileage per gallon of gas, the reduction of wood-stove emissions improves fuel efficiency. This is because stove pollutants are actually wasted fuels (gases and particulates) that escape up the chimney before they can burn; the new models burn most of these wastes before they leave the stove, converting them into additional heat.

The difference between low-efficiency models and the newer peak-efficiency designs can mean a saving of one-third the amount of fuel burned each year.

Put another way, the newer models will burn two cords to every three by the older stoves and put out just as much heat.

Many stove purchases each year are by current wood burners who wish to ``trade up.'' These people, long sold on the merits of wood burning, are more concerned with aesthetics now than previously. They want both heat and style -- something that will complement the d'ecor even as it warms the house. Those willing to pay for looks will most likely also be prepared to pay for the greater efficiency being demanded of wood heating.

Of course, this new need for efficiency will end forever the cheap-stove era. Stoves that meet the Oregon standards start from about $800. A majority of these include catalytic converters, but a few meet the standards without a converter.

Catalytic combustors are made of a honeycombed ceramic material that either contains or is covered by a thin layer of palladium or sometimes platinum. This coating is the catalyst that enables smoke passing over it to burn at temperatures as low as 500 degrees F. (normally smoke starts to burn at around 1,100 degrees F.). Catalytic stoves generally include a smoke-burning chamber to extract the additional heat. Retrofit devices are also available that attach to the stovepipe of conventional stoves . Virtually any ``smoke belcher'' on the market today can be turned into an efficient wood burner using these add-on devices.

The honeycombed catalysts cost about $80 apiece and last for between three and six seasons. This means that unless you can buy wood at a fraction of the going rate, they readily justify the cost in saved fuel alone. In addition, the reduction of creosote in the chimney dramatically lowers the risk of a chimney fire and increases the interval between chimney cleanings. According to the Shelton Energy Research Laboratories, the reduction in creosote formation can be as high as 93 percent

because of the converter.

Those stoves that have met the Oregon standards without a catalytic converter have done so by introducing heated, turbulent fresh air into a secondary burn chamber. Enriched with oxygen in this way, the escaping smoke and gases are reignited before they pass up the chimney.

Apparently there is no universally accepted method to test emissions from wood stoves. Oregon would like what it calls its ``Method 7'' test developed by the state's Department of Environmental Quality to be adopted by the EPA. Most wood-stove manufacturers prefer a method called the ``dilution tunnel test'' developed by the American Society for Testing and Materials. Whichever method is adopted, wood-stove manufacturers and others in the wood-burning industry hope that the EPA's rulings on woodsmoke co ntrol will be adopted nationwide. The last thing any one wants is for each state to come through with its own set of standards and and its own testing procedure.

Meanwhile, Montana is doing what the Wood Heating Alliance (the national organization of wood-stove manufacturers) would love to see replicated throughout the country. It is adopting an ``all-carrot, no-stick approach'' by giving a state-tax break to all residents who buy clean-burning, wood-fired appliances. What constitutes a ``clean-burning'' appliance? Stoves emitting six grams or less of particulate matter in an hour when tested according to Oregon's wood-stove certification program.