Solar On A Shoestring

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MOTHER's research staffers develop so many Innovative devices that It's just not possible to give each one of them the space that it deserves. So, we've decided to present an easy-to-build, inexpensive solar project in each of our next few issues. For example, you can make this 96-square-foot collector—which will pump as many as 19,000 free Btu's per hour into your home—for just over $100!

There are some real advantages to using solar energy to heat your home's air ... rather than depending upon the transfer of the sun's heat to the air by a thermal mass. Not only do such "direct" solar systems circulate and humidify your dwelling's atmosphere, but many are also surprisingly easy to build. In fact, you can have MOTHER's convective collector (which gets an "active" boost from a small blower) ready to nail to any south—facing wall on your house in a couple of hours!

Start the construction of your sunpowered heater by locating the studs inside your frame wall and scouting for any plumbing or wiring which might get in the way of the collector's intake or exhaust vents. Once you've mapped out a suitable 8' X 12' location, just countersink holes every two feet in the 2 X 4's which will be the collector's frame. Make the holes about two inches deep (as indicated in the illustrated side view). Then fasten the parts to your wall with 3-inch nails.

Next you can add the collector's internal baffles by countersinking and nailing these 2 X 4's to the wall just as you did the frame pieces. The spacing shown in the diagram is critical ... it maintains the correct air flow through the system. (The baffle boards should—by virtue of their 24-inch separation—connect with the studs below them.)

Now that the frame is complete, cut the 3" X 12" vent holes in your wall, line them with Thermax brand insulating board, and seal the cracks with silicone caulking. If you trim a standard-sized sheet of the insulator carefully, there should be enough material left to completely cover the rest of the exposed wall space inside the frame. Make sure that the Thermax fits tightly around the boards, and seal every junction with a liberal amount of caulking. With that done, brush a coat of flat black paint on the inside of the collector.