Mother's Woodstove Advisory

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I.THE NEW GENERATION OF STOVES

IN INVENTING THE WOODstove, Ben Franklin built a freestanding fireplace with an open front and cast-iron sides. A revolutionary idea at the time, the Pennsylvania Fireplace, as it was called, soon made open fireplaces obsolete, at least in terms of heating efficiency.

For about 200 years after that, woodstoves remained basically unchanged. Then along came the energy crisis of the 1970s, and everyone clamored for alternative ways to heat homes. The woodstove industry boomed, as hundreds of companies started producing a huge range of woodburning stoves, many of which are still in commission. The major difference between these stoves and Franklin's was that they included doors with airtight gasketing for greater control of combustion and heat output.

As dramatic as these two revolutions in home-heating technology were, another revolution is upon us right now, brought about mainly by increasingly stringent air-quality regulations and helped along by the state of affairs in the Middle East and the rise in fuel costs associated with it. The fact is that when uncertainty clouds our fuel supplies, we turn to wood, mostly as a supplemental heat source but occasionally as a primary one.

Wood-smoke pollution was a byproduct of the '70 woodheating revolution. As woodstove popularity boomed, pollution from wood smoke became a serious problem. This was especially true in areas such as river valleys, where smoke from various sources collects. Wood smoke also proved troublesome in communities located at high elevations, since the smoke couldn't dissipate in the thin mountain air. Denver is a well-known example.

This pollution resulted not only from the sheer number of woodstoves in use, but also from the stoves' technology. While the airtight design of most stoves produced in the '70s made them more useful, it contributed to air pollution: With its air supply choked down to get long burn times, the lire smoldered instead of burning briskly. The result was inefficient combustion and smoke. Eventually, it became apparent that burning wood, like driving automobiles, was a social act—quite possibly one with global consequences.

Areas with poor air quality began regulating wood heating. Soon, entire states, notably Oregon and Colorado, enacted legislation controlling the sale of woodstoves. Then the federal government stepped in. By 1986, the U.S. Environmental Protection Agency had established a multiphase federal performance standard. The toughest phase of the standard takes effect this year. Any stove made or imported for sale in the United States must now meet specific emissions limits, as measured by the amount of particulates in the smoke.

In producing these new clean-burning stoves, manufacturers have taken one of two routes. One has been to include a catalytic combustor in the stove. The catalytic combustor does basically the same thing as a catalytic converter in a car. It burns off smoke and fumes that would otherwise shoot out the exhaust or drift up a chimney. The catalytic combustor consists of a honeycomb-shaped substrate coated with a catalyst, usually a precious metal such as platinum or palladium. This device is placed in the path of the smoke. When the smoke passes through the honeycomb, the catalyst lowers the smoke's burning temperature, causing it to ignite. The result is a more efficient burn and less smoke up the chimney. Most stove manufacturers now offer catalytic models in which the combustor is an integral part of the stove. It is also possible to retrofit some older stoves with combustors.

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