TESTING CREOSOTE-REDUCING DEVICES: THE RESULTS

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THE RESULTS

The results recorded for the various matching pairs of stoves were impressively uniform: Accumulations for any two woodburners equipped with the same device (or with no device) were within 3% of being identical (thanks to the high degree of uniformity in both installation and operation of the systems). Between the different pairs, however, total creosote accumulations ranged from 0.2 to 1.1 kilograms (0.44 to 2.43 pounds)!

All three tested products did prove to reduce creosote accumulation, though. The percentages of reduction in comparison to the control stoves are given in the accompanying table, and it's clear that the barometric draft regulator was the most effective of the devices tested. Its use resulted in a 65 to 75% drop in creosote buildup . . . depending on which portions of the venting system were included (see the accompanying discussion of the chimney setups, for further explanation). In addition, the creosote deposits that did form appeared to be drier-not as shiny and with a rougher surface, and consequently easier to brush out of the chimneys-than those in the other setups.

However, stove owners who install barometric draft regulators shouldn't necessarily expect to duplicate the level of creosote reduction that we observed in our test, for two reasons:

First, the venting systems in our laboratory were more airtight than are most in the real world. (We wanted to assure that the air leakage effects were the same in all the systems . . . namely, close to zero.) After all, a barometric draft control works by adding air to the flue, and leaks in a venting system will have a similar creosote-reducing effect. Thus, adding a barometric draft control to a leaky venting system won't make as much difference as will adding one to an airtight stovepipe/ chimney setup.

Second, the systems equipped with barometric draft regulators were operated in a manner that would maximize their beneficial effect (which was the overall intent for all three devices). Each draft control was set so that the flap was open as far as possible (allowing the greatest amount of dilution air to be admitted), consistent with achieving the desired burn rate. All homeowners may not operate their barometric draft regulators in this optimum (for creosote reduction) manner.

Another important factor to keep in mind about such devices is that they won't work properly unless the chimney is capable of generating excess draft. Whenever the flap is open, the draft is being reduced. Thus the more excess draft there is available in a given chimney, the more benefit can be realized from fitting it with a regulator (both in reducing creosote and in limiting draft). If you're able to achieve very hot fires, and don't chronically spill smoke into the room, then chances are good that your system has excess draft . . . most systems do.

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