MARC ASHLEY IS BEATING THE HIGH COST OF ENERGY

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And then, as might be expected, Marc Ashley's furnace is just as miserly with those usable Btu's as it is with the smoldering fuel that produces 'em. For one thing, all the inlet air that eventually enters the firebox (as described in the last two paragraphs) must first pass through a "heat exchanger"?a completely enclosed area behind and under the combustion chamber?before getting into the oven where burning takes place. This, of course, prewarms the inlet air and?to a certain extent-recycles heat right back into the firebox as fast as it radiates from the combustion chamber's surface.

As the prewarmed inlet air is then further heated by the intensely smoldering wood in Marc Ashley's furnace, it rises and flows through another heat exchange area directly under the stove's water boiler. This transfers a certain amount of warmth to the water circulating in the boiler before the hot gases from the smoldering coals even pass into the boiler's fire tubes. Result: improved efficiency once again. By the time the fire's hot gases have flowed under the boiler and then through its fire tubes to the furnace's exhaust stack . . . they contain very little more than enough heat energy to get them up and out of the chimney.

In fact, believe it or not, 5o little heat escapes up the chimney that Marc had to insulate the stack to keep the moisture in the exhausting gases from condensing before they could get out. "The exhaust gases were cooling right inside the stack," Ashley says, "and you could see the condensed water dripping down inside the pipe. I was afraid all that water would rust it out, so I insulated the pipe heavily enough to stop the condensation. And it worked. The furnace's exhaust can get all the way up and out of the stack now—carrying its water vapor with it?and I don't have any more condensation problems."

Once Marc's super-efficient furnace has turned its supply of wood into hot gas and then transferred the gas's heat to water, the rest is easy. That hot water is just circulated through heaters in the Ashley house and greenhouse to warm both structures.

Mr. Ashley also runs some of his furnace's 160?180° water through a set of coils that he welded into the insulated copper storage tank salvaged from an old water heater. According to the Ashleys, this provides "more than enough" hot water for all their domestic needs.

Two of Marc's three sons are building contractors and the scrap wood they bring him goes a long way toward supplying his yearly heating needs. Recycled lumber that Ashley picks up himself and deadfalls from his heavily wooded property provide the rest. As Ashley notes: "We hold our house at a constant 68°?the same temperature we liked before the oil embargo?at very little cost."

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