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The panel’s rear is covered by foil-faced insulation boards.
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An adjustable insert makes it easy to install
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A pair of brackets supports the collector’s tubular framework.
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The solar collectors can be made of storm windows frames and can match any exterior.
PHOTO: MOTHEREARTH NEWS STAFF
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This list includes information about materials and design options to make solar collectors from storm windows.
MOTHER EARTH NEXT ILLUSTRATION
Over the years, MOTHER EARTH NEWS staff tinkerers have come up with a variety of solar devices, most of which have been designed for those who want to give the sun a try without incurring a lot of expense. But then–after all of our past efforts–whenever we tried to come up with some original solar projects, we were stumped for ideas. (Was there really more to the sun?
But all of a sudden, our researchers hit upon the idea of using salvaged storm windows and aluminum frames as the basis of low-cost, weather-resistant, simple-to-assemble solar collectors–and a promising, economical approach to backyard solar technology was born. After all, the triple-trackers seem almost custom-suited to the application, since they’re Perfectly shallow “collector shape,” Made from lightweight, durable and heat-resistant materials. A stagnant wooden collector might, over time, start to smolder. Already equipped with precut, tight fitting glasses They are commercially manufactured, giving them a finished appearance “marketplace” appearance.
On top of all this, secondhand frames–at least the ones appropriate for this project–can often be obtained for a few bucks apiece. Many people are upgrading their windows’ weatherizers with new or color-coordinated storm fixtures, meaning that plenty of old-but-sound frames are finding their way into the trash or to salvage houses. Even sashes without a glass pane can still be recycled. These sashes could be picked up by a smart buyer “worthless”You can buy castoffs for nearly nothing and replace broken glass with sheets made from other junk Windows.
It doesn’t matter where you source materials for storm windows, solar panels. Remember, though, that it’s to your advantage to search for large units (they don’t have to fit your own home’s windows), since they’ll naturally offer more absorber surface area.
Once you’ve latched on to one or more pairs of equal-sized storm sashes, you’ll need only to come up with a few more items–which we’ve specified in our list of materials–to make your solar project a success. The back of the collector and its absorber is a single sheet of 1″ foil-faced rigid foam insulation board. The inlet and outlet ducts consist of 4″ holes cut in that board at opposite ends. A thermostatically controlled boxA fan draws air through the collector and exhausts it into the room. A couple of clothes-dryer fittings and flexible hose complete the connection between the collector’s air ducts and the living area.
To attach your solar storm window as effortlessly as possible, you’ll probably want to use an installation similar to the one shown in our photographs. The adjustable board assembly known as the collector mount fits into any partially-open double-hung windows. Once the sash is closed tightly against this insert (foam stripping at the joint will assure a weathertight seal), it’s sturdy enough to support the weight of the solar panel on the two brackets extending from its outside face. A tubular framework is fastened around aluminum collector panels’ edges to provide structural support. “sandwich,” and–to hold the unit at an optimal angle to the sun–a pair of rubber-tipped legs stretch between the frame and the house’s exterior.
Assembling the Solar Collector
Lay the aluminum collector frame mounting on a flat surface. Measure the opening in your sash (where the framed glass panes are usually placed) and then use an utility knife to cut the foil-covered insulation boards to these dimensions.
Next, cut a 4″-diameter opening in one corner of the board (be sure to leave at least an inch or so margin from the edges), then remove a 4″-square plug from the sheet’s diagonally opposite corner. By slicing three long, narrow strips (two 2″ wide and one 6″ wide) from your leftover insulation material and using aluminum foil tape to join those pieces together, you can then make a simple heat-retaining passageway between what will be the collector’s lower (intake) duct and a point about 3 inches from its upper one. (We found that the easiest way to do this was to first determine the tunnel’s necessary length, cut the strips to fit, join them in a three-sided channel, and then tape the entire assembly to the surface of the board after that insulation sheet had been installed within its aluminum frame.)
Before you do that, though, it’d be a good idea to put the square-to-round dryer-duct fitting you purchased in place over its upper corner opening and secure it with some silicone sealant. The absorber surface can then be coated with high-temperature flatblack paint, and sealed with silicone sealant. With that done, it’s a simple matter to secure the insulated channel–making sure the lower duct is covered–and trim out some end caps that’ll fasten neatly over the tube’s open tips. (A strip of foil tape placed over each 4″ duct’s cut edge will protect the foam insulation from the long-term effects of heat.)
The dryer vent kit you bought should contain about 10″ of sheet-aluminum pipe. Cut a few inches off it and place it in the channel’s upper end. You can also cut the pipe in half and reuse it later.
Here is where you can join in the glass faceand collector frame. First, check to make certain the panes are, locked securely in their slots, then go ahead and seal all of the joints–including the one between the windows–with silicone. Run a bead of caulk (or lay sections of weatherstripping) along the frame’s faces, then fasten the halves together at the top and bottom flanges with some bolts or self-tapping screws. To shed rainwater rather than catching it, ensure that the glass is oriented so the upper pane overlaps the lower.
The tubular framework that helps to hold the collector at the correct sun-catching angle is constructed of appropriate lengths of 1/2″ electrical metallic tubing (E.M.T.). Five-foot-long side rails were just about right for the 36″ X 62″ frames we were working on. With those bolted through the right and left edges of the storm fixtures so that about 2″ of E.M.T. The collector’s top sides were visible so it was easy for the conduit length to be determined. The joints were secured by cutting the heads from two 1/4″ bolts and bending hooks in their shanks. These “claws”They could then be slipped into holes in the crosspipe. Their threaded ends would pass through the side rails. They could also be secured with nuts.
The wing nuts were placed at the bottom ends of each tube on the side rails. “catch” for the 1/4″ X 3/4″ bolts that hold the lower support legs in place. Those 1/2″ E.M.T. props are offset at one end so they’ll crisscross, and bolt together, in the middle for added stability. These dimensions aren’t important in nature. “X” brace will depend upon the size of your completed collector and your home’s latitude. Just remember that the ideal winter angle for your sun grabber’s surface is that latitude plus 10 degrees.)
Installing the Storm Windows Collector
Congratulations! The collector itself is now complete, so it’s time to move on to the insert that fits in the grooves of your home’s window. This wooden insert is now complete. “plug”The collector is supported at the top. It houses the blower fan, the air supply and return conduits, and the other components. To make it, simply cut a section of 1/2″ plywood to 12″ X 20″ and 12″ X 26″ dimensions, then fasten a 1″ X 1″ X 20″ piece of 16-gauge angle iron to each edge of the longer board–flush with one end–so the other slab can slide snugly into the track you’ve created. Bolster the outer ends of each board with 1/2″ spacers (the long one will take a 3/4″-wide strip, and the short one a hunk about 3″ wide) tacked in place on sides opposite each other.
Next, trace the openings on the plywood longer piece using the dryer duct pipes as templates. Seal and tack the metal collars into these holes so they extend to the home’s outside (away from the angle iron tracks), then bolt a shelf-and-pole bracket to each of the sliding boards. (Fasten one to the 1/2″ X 3″ X 12″ spacer, and the other about 2 inches to the inside of the ducts.) A No. 6 X 3/4″ roundhead wood screw threaded through the interior panel and forced into the exterior one will keep the sliding insert from slipping once it’s placed within the window tracks.
Your preference will determine how you use your blower fan. If it has limited delivery (under 100 cubic feet per minute), it can be mounted to the upper insert duct and connected, with dryer hose, to the fitting on the collector’s air channel. This will draw air into the room from the middle, feed it to collector’s bottom, allow it flow upward along absorber faceThen, attach the dryer hose to the lower window vent and return the fan to the house. You can also attach the fan to the lower window vent to draw air through it. The return and supply tubes can both be reversed. This will slow down the flow–and further heat the air–but be forewarned that you’ll sacrifice some efficiency by doing so.
No matter how you mount the fan, the thermostatic controller should be wired in according to our diagram. The unit should then pass through the corner tube, and be placed on top. Some protective housings–bent from sheet aluminum–can be used to cover the window vents if you want to avoid the expense of purchasing louvered grilles, and homemade foam-rubber plugs will keep those openings from leaking cold air in the evenings. (If you live in a particularly cold climate, you’ll also want to insulate the dryer hoses by wrapping batts or foam around them and covering that with duct tape. Weatherstripping can seal the joint between inserts and windows. You may also want glue scraps from the insulation board to your plywood.
Are storm window suncatchers worth the effort? You’ll have to answer that question for yourself. Each unit was built at an average cost of $50. All materials, except windows, were brand new. The heaters are expected to last at least five years. And our initial tests indicate that on a clear or partly cloudy day they’re capable of delivering 120 degrees Fahrenheit air to the house for perhaps six hours.
We’re not about to tell you that storm window collectors are super-efficient, but they definitely do work and are among the simplest-to-make collectors you could ever build. Yes sir, for the value of time and materials that you’ll put into them, these, “Btu bargains” just might be among the nicest introductions to bootstrap solar technology that you’ll run across!
Published January 1, 1984
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