SWH prototype project part 1

Last week my solar water heater project really got moving. Here's a quick photo tour of what we've done so far.

Job no.1 - make the planks.



















Completed outer frame. That's the easy part over with then.



















Then lots of cutting up of bits of copper tube. The white board is used in conjunction with a steel rod and a great big sledgehammer to form fins out of sheet aluminium which will fit around the copper tubes.



















We took all our bits of tube out to a chap in the bazaar who has an oxy-acetylene torch to get it soldered together. As in everything here, health and safety is a bit take-it-or-leave-it: there's a pair of dark glasses the guys sometimes shove on while they're arc-welding, but that's about it. This is our first attempt at leak testing, which wasn't entirely a success (well, the test achieved it's aim fine, but you know what I mean!). Cue a return trip to soldering man.

























I don't know much about soldering copper, but I wouldn't like to hold up our pipework as an example of the greatest quality workmanship! It does look rather beautiful though...



















Here we are starting to lay out and fix the fins over our copper opposite-of-a-radiator arrangement. The fins, having been formed by much bashing, aren't too bad a fit to the tubes, but probably nothing like as close as any of the efforts on the DIY sites I've looked at. We run lines of silicone gel next to the tubes to try and fill up any air gaps (while not a stupendously wonderful heat conductor, it's a darn sight better than an air gap; also, it should be able to cope with high temperatures and differences in thermal expansion of the different metals).

























The aluminium sheet we were able to find in Pindi is 2 or 3 times as thick as what I would have liked - at around 1.2mm or 1/20th of an inch (getting used to everything in imperial is a bit of a challenge too!) - you can bend it in your hands with a bit of effort, but getting it into a shape that'll fit snugly around the tubes was not easy. This added thickness caused all sorts of problems, as compared to the reasonably effortless-looking examples I'd been reading up on:

1. Cutting all that sheet up with only a pair of tin snips is hard work. Really hard work.

2. Shaping the fins took 5 mins or so of bashing about per fin (DIY site example time: 15 seconds).

3. Other people's fins are splendid, shiny, perfectly-formed works of art. Ours look like they've been battered with sledgehammer. Oh, wait...

4. Other people lay out all the fins and gratuitously attack them with a staple gun. Us: staples won't go through, nails won't squeeze them together, split rivets won't reach through, the pop-riveter is broken. So it's out with the drill (of course, plugged into a dodgy extension lead of bits of wire twisted together and shoved in the socket), and lots and lots of nuts and bolts. This has the benefit of pulling the fins into close contact with the tubes, but has the decided disadvantage that we have to lift the whole board up to tighten the nuts up. With a screwdriver and a pair of pliers.

A couple of days hard graft, a couple of hundred holes, and a couple of hundred two-man tightening-up-of-nuts-and-bolts later:

























The last batch of little fins drying in the sun (a little coat of paint on the contact surfaces should help prevent galvanic corrosion) - these ones will fit over the thicker manifold pipes at the end. Then, hopefully, it should be all ready for some black spray-paint.