How To Build A Free Energy Solar Pop Can Heater For The Winter Cold
Sometimes, low-tech solar devices are much better than high-tech ones for home use, as they not only tend to be cheaper to make, but will also last much longer before any repairs or maintenance are necessary. And even better, they can be built in part from repurposed or recycled components, which is something you don’t see very often in new solar devices. This solar space heater design uses old soda cans to increase the surface area for heat transfer inside of it, and in its most basic design, uses no external power to move the air. Double-glazed glass or polycarbonate panels make up the front of the device, allowing the sun’s rays to enter it while restricting heat loss to the outside air, and the box is also insulated for more efficiency. When exposed to the sun, the air inside the solar heater begins to warm, and as it does, it rises to the top of the box and can be ported directly into the house. For more control over the system, small fans and thermostats can be added, so that warm air enters the house only after the temperature reaches a desired range, and installing adjustable air registers at the outlet lets the system appear almost invisible from inside the living space.
1. Building a Solar Air Heating Collector from Soda-Pop Cans -Greg West This solar air heating collector uses recycled aluminum soda pop cans for the absorber. The pop cans have the tops and bottoms drilled out, and are assembled into vertical columns that the air passes through. The black painted soda pop cans are heated by the sun. The solar heat is transferred to the air passing up through the columns of can.
A manifold at the bottom supplies room air to all the can columns, and a similar manifold at the top of the collector collects the heated air for distribution back to the room. The combination of uniform air distribution to the whole collector and the large amount of heat transfer area from the cans to the air makes for an efficient collector. My collector also uses Twinwall polycarbonate glazing -- this is a type
of double glazing that reduces heat loss and increases the efficiency of the collector.
2. So let’s start from the beginning. I want to first thank a guy that goes by my2cents0 on YouTube for directing me to the Hungarian website that led me to an engineer whom I only know as Zoli. He actually speaks better French than Hungarian. I want thank Zoli for his upmost patience with me on this project, I bugged him to death back and forth for nearly three months to make sure I was doing everything right.
These are my cans siliconized together with the top manifold on and the bottom manifold you see on the table. My panel core, is 17 cans wide and 17 cans tall --this was all I could fit into a four by eight foot insulated box made from Polyisocyanurate insulation board (polyiso). The outside of the collector measures 4 ft by 8 ft. The header caps are 44 ½” with ½” bends on all ends. I drilled the manifold holes at 54mm dia. and spaced at 66mm on center and came to find out the can columns would “just fit”. Maybe 67mm O/C might work better just so things won’t be too tight. Using 67 mm spacing will make the space between holes 11 to 12 mm which, I think, will work fine. On the next collector I will use the 67 mm spacing between hole centers. Start 10mm from the header cap end before you start laying out and drilling. I drilled the bottom holes in the cans out at 44mm and the top ones at 51mm. You need to be very careful with the tops, because the hole saw will just fit, no room to mess up.
When cutting the cans with the hole saws I used in a drill press which was a learning experience in itself. It took a little while and several near miss flying objects to get the hang of it. You would be amazed how fast a hole saw can take something right out of your hand. So, safety first. Wear safety glasses and leather gloves that some cotton jersey gloves will fit into. The cans will heat up rapidly while cutting the tops and bottoms out.
3. Building the Can Columns
At first, I made some wooden jigs to hold the cans while cutting on the drill press. I used a small rotary saw to start a hole for the diameter of the end of can I was working on. Then, believe it or not, I took a small straight cut router bit in my drill press and cut out the rest of the hole.
If you have a steady hand, set the depth on your drill press this is pretty easy to do. Notice my extra hand, a screen door spring holding the router bit to it’s depth. Oh my, necessity really is the mother of invention. I made the jigs out of large stock of two 1” x 4” blocks of wood glued together, then cut them down to a size that was easy to handle.
Be sure to hang around for the great video on page 5.....