Solar water heater collector part 1

Over the past year, I’ve had thoughts of building some sort of solar hot water heater. In fact the seed was planted well before this year. I lived in Israel for about 2.5 years ending with the end of 2000 when I moved to Oregon. If you look at most Israeli skylines, you’ll see that most buildings (I don’t want to say all) have at least one or two solar collectors. One of my apartments there had one and it meant that my electric water heater was off all but 3 months of the year. This was inspite of the fact that I took my showers in the morning.

Anyway, we got a swimming pool last summer. It’s a collapsible pool about 15′ across and 3′ tall and it often seemed a bit cold, hence this project.

So I’ve been doing a bit of surfing on the topic on da web and while I didn’t come across much, I did find some DIY project at this site. In particular this project which uses a big industrial looking press to form collector absorber plates got me thinking. The thing is I don’t have a press and don’t have much other need for one. So after thinking about it a bit, I decided to try using the weight of my pickup.

Note: each of the pictures can be clicked for a larger version.

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As you can see from the pictures, I just took a couple pieces of scrap and build a simple form. I then just drive over it. A couple things to notice:

  • I screwed a couple loose washers on each side to keep the metal lined up. (the second picture)
  • I use a couple long bolts (two right pictures) to keep the top form from sliding away when I drive up onto it.

The metal is roofing flashing bought in a roll from Lowe’s or Home depot. about $6 for a 6″x10′ roll. I got the thinnest stuff they had to ensure my truck is heavy enough to form it.

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Here are some pictures of my current progress. My intention is for water to enter one corner and leave the opposite corner. I figure this will lead to an equal resistance path through each of the tubes which are 1/2″ copper.

One thing about using dissimilar metals in contact with each other: one of them will corrode. After googling around a bit, I came across this site about metal corrosion and it looks like it will be the galvanized metal that will corrode. I figure that’s better than having the pipes spring a leak.

I have couple options on how to address this, I need to spray paint the flashing black anyway, so I’ll spray the grooves as well. Also, I’m gonna glue the pipes into the grooves which should further isolate the copper while hopefully acting as a sort of heat-sink grease.

That’s the current progress. Next, I’m gonna have to practice my copper sweating skills which I haven’t done in a couple years. I’ll also build up a box to hold it all.

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