Basically, it's stacks of aluminum cans that have been painted black You punch a hole in each can so the air can circulate, then caulk them together into long tubes. Put the tubes into a box with a clear cover and insulation and you've got yourself a free solar heat collector.
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| Whoa, this thing is heating up quickly. I could feel the warm air rising up from the openings in the top of the cans and the thermometer confirmed it, Not bad for a stack of old aluminum cans. |
I did the first few steps, made the tubes and spray painted them matte black, then stuck them in a window to test. I'm impressed enough with the results that I think I will make the box for them. The tubes heated up the air to at least 120 degrees in a few minutes. (Might be higher, but that's as high as my thermometer went.) The cans are just warm to the touch and the air rises gently from the openings in the top. So they're comfortable to the touch with no danger of burning or fire, yay.
The tutorials and associated forums have all kinds of details and suggestions to make these heat an entire house. The best type of glass for maximum light transmission, the correct hole size for best air flow, the best type and thickness of paints for maximum heat gain etc.
But I'm not going to cover an entire wall with these or heat my entire house, so I'm just going to improvise without much concern for maximizing efficiency. I have some speaker cabinets I gutted and some scratched plexiglas. Perfect for a small experimental version.
I will probably just heat a small storage box with it or maybe create a warm place for the wandering neighborhood felines. I probably won't bother adding a fan or even a auto-closing vent since I'll just be letting some warm air into an otherwise unheated space.
This will be a good excuse to use up these scrap items, finally get them out of my way and make something that's actually useful all at the same time.
Like I said, I've known about these solar collectors for years. But I had always lived in warmer climates where cooling was more of a concern than heating. And buying the lumber and glass made it too expensive for a toy project (spend 20 to save 5).
Now, however, I have access to both cool weather and donations at the Maker Group. Suddenly, I have all kinds of materials at my disposal - too many sometimes, like "I need to clear out this entire room" quantities of scrap materials.
I do have some experiments I want to try. Does putting gravel inside the cans affect heat generation and retention? Do metal screens work just as well - there are tutorials that say they do. What about old floor tiles? I have half a box of broken tiles Can I paint them black and use them as collectors, or maybe use them to store the heat overnight.
Looks like we've got six more weeks of winter, so I've still got time to experiment.
