CLEANING UP WOOD HEAT FOR 1982-83

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PART II: THE CONDAR STOVETEMP THERMOSTAT

In wood heaters equipped with manual draft regulators, the quantity of air available for combustion will — unless the owner constantly changes the intake setting — be pretty much an average of the amount needed to maintain even heating during all the different stages of the burn. What's more, though there might be a fixed setting on the inlet air control, a woodburner can suddenly either flare up or smolder — depending on the conditions inside the firebox — and provide more or less heat than its owner intended. Consequently, many manufacturers equip their stoves with thermostatically controlled draft regulators.

Unfortunately, most such original-equipment thermostats use slow-reacting bimetallic coils to control their damper flaps, which often produce oscillating burns. Because there's so much delay in the reaction of such a valve, the stove will tend to overheat and underheat in a continuous cycle.

The Condar Stovetemp thermostat was designed to react to changes in stove door temperature quickly enough to effectively eliminate such oscillations. According to the manufacturers, their product — when installed on a heater that was previously operated with a manual control — can reduce fuel consumption by as much as 20% . . . both because the overall combustion efficiency of the woodburner will be improved by the device's ability to admit the right amount of air for the selected operating temperature, and because the output of the stove can be more effectively tuned to meet the demand. (Overheating, of course, causes increased BTU losses from a building . . . and thus reduces heating efficiency.)

One of MOTHER's staff members installed a Stovetemp on his Waterford Reginald 100 in the fall of 1981 and was able to compare the quantity of wood consumed through the 1981-82 heating season to that used the winter before. After taking into account differences in weather and in the amount of conventional backup heat used, he estimates that 15% fewer pounds of wood were burned with the thermostat in place. Furthermore, because the stove to question is rather small for the amount of space heated (2,600 square feet), the draft regulator was adjusted for full opening at times . . . which no doubt reduced its ability to conserve fuel.

In addition to the fact that it saved wood, the Stovetemp was very convenient to use. Our staffer found that fiddling with the heater was cut to a minimum. In fact, through all but the coldest days of the winter, it took only three fuel loadings per 24 hours — and adjustments for output in the morning and evening — to keep the stove producing at the desired rate. In addition, the thermostat made it possible, on occasion, to tune the stove for amazingly low combustion levels. Extending the burn time to more than 12 hours required only that the temperature knob be set in the 250°F area!

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