Mother's Woodburning Hot-Oil Furnace

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Now you can fire your still and heat your home... for very little cost!

One of the major drawbacks of thermal energy is the fact that it's often difficult (and expensive) to store effectively. (This unfortunate phenomenon is by no means limited to solar-derived heat, either ... it's common to all forms of "temperature" power.)

With this problem in mind, the fellows at MOTHER's research facility set out to build a home heating unit that would incorporate thermal storage capabilities and inexpensive operation . . . and they recently came up with an affordable, compact (and actually pretty ingenious) woodburning furnace that just about any tinkerer with welding experience could cobble together in a weekend!

A BACKYARD DEEP-FRY

Put simply, MOTHER's heating device is little more than a woodstove surrounded by an oil-filled chamber which is specifically designed to expose a maximum amount of surface area to the heat source. This optimum thermal transfer is accomplished not only by encircling the cylinder-shaped firebox with the viscous liquid (we use Exxon's Caloria HT-43, which has been formulated to handle high temperatures), but by cleverly routing the stove's smoke (and hence its normally wasted heat) directly through the oil reservoir via a series of 1-1/4 "-diameter tubes.

Now some of you may question our use of oil—rather than free-for-the-taking water—as a thermal storage medium . . . but there are several good reasons why the choice was made:

[1] Oil—like water—can hold heat for an extended period of time.

[2] The boiling temperature of oil is more than twice that of water ... therefore a lot more heat can be fed into it—at atmospheric pressure—before a molecular change occurs.

[3] Oil is noncorrosive, and thus its use results in a longer life span for the furnace and for the plumbing connected to it.

Another important point to remember (for reasons of both safety and legality) is that, although MOTHER's oil-heating fur nace may look like a boiler, it is definitely not one . . . since it's open to the air and operates at atmospheric pressure. This means—in essence—that those laws, inspections, and other requirements that apply to steam boilers do not pertain to this heater. (Incidentally, because any water within the oil will be vaporized—and vented—long before the heat storage medium reaches its operating temperature, neither condensation nor the accidental introduction of water into the oil reservoir will pose a problem.)