Get Hot Water from Your Woodstove: The Blazing Showers Stovepipe Water Heater
(Page 2 of 3)
November/December 1976
By Sundance & Louie
Naturally, as we've already pointed out, you want a tank that's watertight and at least relatively rust-free. We've found that the ease with which the various fittings (attached pipes and connectors) can be removed from an old water heater is—quite often—a good indication of the unit's all-around health. Or, to put it the other way 'round, if its fittings are rusted so badly that you can't get them off, the heater is probably not worth fooling with.
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The Tank: Location
Once you've obtained a serviceable water tank, it's important that you install it correctly in relation to the stovepipe coil. Notice—in Fig. 2—that opening X is above opening Z . . . and that Y is above W. Obviously, Y must be higher than W because it's the rising column of hot water that forces the circulation of fluid through the system.
Note, too, that the vertical distance separating Y and W determines how far—horizontally—you can put the water tank from the stove: You can move the tank up to two feet away from the wood-burner for every foot that Y is above W.
The Tank: Insulation
Conventional water heaters lack adequate insulation, due (we believe) to the politics of consumerism and to the fact that each unit's storage drum is so close to its heating element. Because our goal is efficient heat storage (and since—in our system—the reservoir is somewhat farther from its source of heat), we can—and should—do a better insulation job.
One way to accomplish this is to [A] bundle the entire water heater—top, bottom, and sides—in four to six inches of fiberglass, [B] wrap a blanket (or sheet) around the fiberglass-clad tank, and [C] stitch the blanket's (or sheet's) edges together. Or you could build a box around your storage tank and fill the enclosure with natural materials—wood shavings, pieces of bark, sawdust, chicken feathers, rags, egg cartons, wool, etc.—that create insulating air traps.
In addition to protecting the tank from heat loss, we recommend that you also insulate all exposed pipes.
The Storage Tank Adapter
If you were to pipe the hot water coming from your Blazing Showers stovepipe coil directly into the top of your storage tank as shown in Fig. 4, any air bubbles in the pipes would soon become trapped at the system's highest point. This would impair the convection-driven circulation of liquid through the heating coil and, to prevent such an occurrence, we've designed a special adapter.
As shown in Fig. 5, our adapter assembly screws onto the hot water outflow pipe at the top of the storage tank and thereby makes it possible for newly heated water to get into the container via the same pathway by which it is drawn off to the faucets. Thus, any air in the system quickly exits to the hot water spigots and is eliminated. (Note, too, in Fig. 5, that the adapter assembly contains an anti-siphoning device to prevent cold water from being drawn from the bottom of the storage vessel when the hot water faucets are turned on.)
