Build a Hot Oil Wood Burning Furnace

For minimal cost, you can build a wood burning furnace that uses oil as a heat storage and heat transfer medium.

| September/October 1980

065 woodburning hot oil furnace - photo2

An alcohol still (LEFT) and wood burning furnace (RIGHT) configured to work together.


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 EARTH NEWS' 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) wood burning furnace that just about any tinkerer with welding experience could cobble together in a weekend!

A Backyard Deep-Fry

Put simply, MOTHER EARTH NEWS' heating device is little more than a wood stove 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.

robert barfield_1
1/15/2009 4:51:10 PM

I would like to buy a set of your plans for A complete set of detailed plans for building MOTHER's hot oil furnace; Please let me know where I can order from. Thank you and keep up the good work. Robert Barfield

ronald bond_2
12/5/2008 6:48:28 PM

How can I purchase these plans? I tried to send a check to the provded address but it was returned to sender by the post office.

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