Re: Solar Water heat
Its been a few years since I read anything on it, or even built one, but dont you want to have a bit more uniform piping to run your water through than what was shown? I have heard of using a flat copper pipe that goes down and back a few times will get alot better heat transfer, and even a black garden hose will outdo that copper rig.
My problem with that instructable is that he didn't do simple things that could have improved his results by 100% at least (not counting the Gathering Box as you mentioned). Using a single sized piping all the way through, instead of that 1 3/4 and 1/4 piping, would have made more sense and heating surface. He could have slightly flattened the pipe to increase the outward facing surface area before painting it black. Having the water go through a single, point to point, run instead of the two dozen that he has would have helped heat the water a few more degrees. And, having a raised panel that fits between the pipes (or even a fine black mesh panel) that heats up the air and allows it to flow around the pipes would increase the temperatures (I always got higher temps with mesh than reflectors).
I remember someone, I think Smitty, was talking about solar heaters for the side of their bus. One of the pictured heaters had black piping in it for water heating along with air heating.