Ten Woodstoves Have Made The Grade

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What this means is that in a very big hurry (perhaps less than two years from now) the conventional airtight woodstove could be on its way to extinction. Today, there are ten woodstoves that have successfully completed the tests for Oregon's 1986 standard. (Only five of those can currently stand up to Oregon's 1988 regulation.) However, with the EPA threatening to halt the sale of dirty stoves on a national basis, you can expect to see the number of clean burners increase rapidly. As it's said, "Necessity is the mother of invention."

READING BETWEEN THE NUMBERS

Figures from Oregon's Department of Environmental Quality (DEQ) make up the largest body of data available. However, though numbers may not lie, they can certainly be misinterpreted. Consequently, it's important that you know what the various statistics in our listing mean.

External dimensions, used in conjunction with the listed minimum clearances to combustibles, will help you decide whether a particular heater will fit comfortably into your house. Since the majority of these heaters have either fan-forced or natural-convection heat-exchange areas surrounding their fireboxes, they require less clearance than do typical radiant stoves. So the chances are that if you're burning wood now, any of these stoves will fit where your old heater is located.

Firebox capacity, door opening, and log length are all dimensions that will help you determine how much wood the stove will hold. Because many of the new high-technology heaters use very small fireboxes to maintain high temperatures, their burn times and heat outputs may be seriously limited by capacity. These figures should be used in conjunction with the burn times listed under "Performance in Oregon DEQ Testing" to get a clear idea of what performance you should actually expect: Also, because many of the heaters use complicated combustion-air and heat-exchange passages, their doors may be relatively small. This can be a real nuisance when loading, so check the numbers carefully. The last "dimension" item, weight, will simply give you an idea of how many friends you may need to install the heater or how expensive it might be to ship.

PERFORMANCE

Several factors limit the usefulness of the Oregon performance data to consumers. For one thing, according to Paul Tiegs, the owner and senior principal scientist of Omni Environmental Services—the laboratory that did all of the testing on the ten stoves—the listed efciency figures are accurate only to within plus or minus 5%.

The average weighted efficiency/emissions categories present another complication. To develop their standard, Oregon DEQ researchers studied the habits of Oregon wood burners and determined that they tend to fire their heaters at medium-to-low burn rates (a heat output of about 13,000 Btu/hour, or about three pounds per hour at 50% efficiency) and in about six-hour cycles. Consequently, the "weighted" average is an efficiency figure that's statistically biased toward 13,000 Btu/hour. If you live in a colder climate than that of Oregon, you may require a higher average heat output . . . and as you can see from the efciency curves on the graphs, none of the stoves operates at exactly the same efficiency across its heat output range. In fact, some of them are drastically less efficient as output increases. So judge carefully what your own heat needs are in comparison to a particular stove's performance curve.

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