Ideas for solar hot water tank???

My issue for the tank has remained the tank itself, because I want to connect it to standard pressure. I've decided to make one myself because there's nothing suitable for scrounging around here. My plan is to take a spare propane tank that I have, flush it out and cut it in half. Take an 8ft piece of sheet metal and roll it up to make a cyclinder to slide pieces of propane tank into each end, unless bolting one end on using the overlap region would work well enough. It gives me the ability to weld in whatever fitting connections I need. This will give me a nice long 50+gal tank plenty strong. With the tank long and laying at the roof's angle and the collector below the bottom end I should be able to get a good thermo syphon circulation, so no pump is needed.

Any input on what gauge steel sheet I should get, and what if any coating I should put inside the tank?

John

That old tank I picked up a couple years back is finally in use (most of this summer, as just a direct heater for the shower only, using a separate showerhead for it's output, but now as a heater tank for the main house system).

http://www.endless-sphere.com/forums/viewtopic.php?f=41&t=64197

I did have to weld some pinhole leaks in it first, which is why they tossed it I guess. No big deal.

I actually remember you picking that up.

And I'm glad I did, too, cuz even though it took this long to get it into use, it's probably saved me a couple hundred dollars of electricity already this year.

Stoked to hear the follow up on it man.

Heya John, if you're located in Costa Rica, you might be able to preheat the intake water with fermenting mulch.
https://www.youtube.com/watch?v=f9rA10iv1Rc

What the world needs is a jean pain system that allows you to flow the waste across the heat exchanger without digging up the pile of mulch every few months when it is spent. Gravity is free.
One for any inventors reading this with some spare time.