TESTING CREOSOTE-REDUCING DEVICES: THE RESULTS

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The Smoke Dragon reduced creosote accumulations by 41 to 51%o-again depending upon which portions of the venting system were considered-which is less than the reduction achieved with the barometric draft control.

In actual household use, however, the Smoke Dragon can be expected to perform somewhat better than it did in our lab. The Dragon is intended to be installed only on top-exit stoves. The rearexit units that we used-in consultation with the product's manufacturer-slightly increased the distance that the smoke had to travel to reach the catalyst, which caused the smoke to be a little cooler and probably made the catalysts slightly less effective.

We should also mention that the Smoke Dragon does more than simply reduce creosote. Unlike the barometric draft control, it lessens creosote accumulation by burning some of the smoke. Thus a greater portion of the fuel is used than would otherwise be the case . . . improving the energy efficiency of the entire woodheating system and reducing the emission of incompletely combusted material into the atmosphere.

The Smoke Consumer's effectiveness in limiting creosote deposits ranged from 23 to 41%. The higher figure was observed in the three feet of stovepipe just above the device. But when the entire system was included (which adds the solid residue from the liquid creosote which collected in the cap of the tee below the fabricated chimney), the reduction was 23%. This means that there was considerably more liquid creosote (basically a water/creosote mixture) condensing in the chimneys above the Smoke Consumers than in the other chimneys.

Again, an individual user might well find the Smoke Consumer's performance to be somewhat better than we observed. As was true with the Smoke Dragon, the Consumer was installed a little farther from the stove than the manufacturer recommends . . . in order to keep the amount of stovepipe above the connector equal to that in the other installations. It's possible that the devices' effectiveness was slightly reduced by this arrangement, although we had no difficulty achieving the recommended surface temperatures at that location. We also found it difficult to keep the filters clean (as explained below), and if a homeowner kept the filter very clean, the unit's performance might be somewhat improved.

Unlike the Smoke Dragon, the Smoke Consumer doesn't require a minimum temperature to be effective. However, the cooler the smoke that passes through the device, the more quickly the filter will become plugged and need cleaning.

The manufacturer recommends a daily "continuous burn reactor cycle" to clean off the accumulated creosote, and we were able to achieve the stated temperature requirement for that process with each day's hot fire. By the seventh day of testing, however, the drafts in each of the systems equipped with Smoke Consumers had become very sluggish ... because creosote had partially plugged the filter, as well as the space between the unit and the stovepipe wall.

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