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that it's slightly curved across its 4-inch width. Using the flashing layout lines
you drew in an earlier step, attach the flashing by stapling through the
hardboard into the center support with 1/4 inch staples. (Photo Nine, though for a
later step, shows the flashing in place.) Finally, tape the two pieces of flashing
together at their peaks with the duct tape, as shown. Once the flashing is in place, install
the Mylar, starting with the large sheet marked "D." Place this sheet,
aluminized side down, on the "D" piece of hardboard, and check that the fit is
correct. (If it isn't, trim the Mylar accordingly.) Each piece of Mylar is fastened in
sections, rather than all at once, and you'll find it helpful to have a friend
ready to assist. Photo Nine shows the correct procedure: Lift the edge of the
sheet of Mylar away from the point of the cusp, and apply a uniform coating of
spray adhesive over an area about 1 1/2 feet wide across the full length of the
hardboard. Immediately (and carefully) press the Mylar into place on the
adhesive, smoothing out trapped air bubbles with a soft, clean rag. Then fold back the
other, unglued edge of the Mylar, spray the exposed portion of the hardboard
with adhesive, and press the Mylar into place. When you've pressed out all the
air bubbles, protect the mounted Mylar with newspapers. Repeat the entire procedure
for the "C" Mylar sheet, and then stand the reflector frame assembly on end to
mount the "B" and "A" Mylar sheets on the plywood involute patterns. Use a
utility knife to trim the Mylar where it covers the holes for the plumbing and
the tank support brackets.
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Glazing Illustration F shows how we made our triple-glazing frames, and Illustration G shows the method we used to wrap the frames with different types of clear plastic to achieve an optimum combination of good solar performance and structural strength. Although we give you the dimensions we used, the final size of your glazing frames depends on your exterior enclosure. We suggest you use our materials and wrapping techniques as a general guide and alter the dimensions to suit whatever enclosure you elect to build.
Above Our triple-glazing system uses two identical frames. (One frame is illustrated.) They're assembled with brass screws and wood glue and painted with an oil-based porch and deck paint, which should be allowed to dry for about four days. One of the frames is then wrapped with two layers of solar plastic; the other with only one layer. (See Illustration G for the exact technique.) Then the turbo frames are mounted, one atop the other, and screwed to the batch heater's framework. Caulking and batten strips are added as the rest of the heater's enclosure is constructed.
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Photo Nine Once the point of the cusp has been recreated with aluminum flashing, as shown, the entire reflector assembly is ready for its surface of mirrorlike Mylar. Spray adhesive simplifies the mounting. Apply the Mylar one section at a time, working carefully to press out any trapped air bubbles as you go. PHOTO BY JIM FREEMAN
Photo Ten We used a three-sided concrete foundation for the built-in batch heater shown on our cover, al though a slab foundation would work as well. A freestanding batch heater could use pressure-treated posts or a simple cross-braced frame of 2 X 4s. Your mounting options are limited only by your budget, imagination, and taste.
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