Sunday, August 20, 2006
Rebuilding Solar Collectors
I have three used solar water heater panels, obtained from my Father-in-law who used to sell them. These three orphans were in bad shape. One of them had been allowed to freeze and burst, another had a big gash in the copper absorber plate, and the insulation had deteriorated in them. A wonderful Sunday afternoon project! Soldering up the bad spots, I've painted the collector absorber plates with black barbeque paint from the hardware store, and I'll add some fiberglass in
sulation to the backside to make them more efficient, glue on the tempered glass cover plates with silicone rubber caulk, and voila!: free hot water. They'll attach directly to the metal roof with S-5 Standing Seam roof connectors. The house is already roughed-in with two 3/4" PEX pipes to the roof, which will be insulated (PEX doesn't hold up in sunlight if it isn't covered). The system will be pumped by an ingenious little DC pump called the EL-SID. EL-SID PUMP This pump uses a 10 watt solar electric panel for it's control system. If there is enough sun to make juice to run the pump, then there is enough sun to make solar water heat. No thermostats, differential controllers, or fancy electronics. If there is half enough sun, then the pump runs at half speed, slower water has more time to pick up solar heat. There is only one moving part, the impeller. There are no brushes, commutators, bearings, shaft seals, and other stuff to fail. This is the most ingenious pump I've ever seen.
Everything goes up on the roof in a month or two, when the main construction is winding down.
// posted by Invention1 @ 3:05 AM 
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If I may ask (I don't remember if you have said) what area are you building in?
Are you concerned at all about freezing? And if so, will you have some system to provide electrical power to the pump in the middle of the night?
Here in Southern California, from October through Febuary, our experience has been that quite often, the temperature in the middle of the night will get close enough to freezing that the controler on our solar water system will turn on the pump to avoid burst pipes and thereby negate any gain in hot water that the system had built up during the day.
Hopefully, you will not have that problem. But if I had it to do over, I would use a big roll of black plastic hose and maybe one of those cool $222 pumps you are buying.
Are you concerned at all about freezing? And if so, will you have some system to provide electrical power to the pump in the middle of the night?
Here in Southern California, from October through Febuary, our experience has been that quite often, the temperature in the middle of the night will get close enough to freezing that the controler on our solar water system will turn on the pump to avoid burst pipes and thereby negate any gain in hot water that the system had built up during the day.
Hopefully, you will not have that problem. But if I had it to do over, I would use a big roll of black plastic hose and maybe one of those cool $222 pumps you are buying.
Central Missouri, and yes it freezes hard here. I'm using a glycol loop on the roof, exchanging heat through a coil of copper tubing to a tank. (50 gallon plastic drum) THe domestic water also goes through another copper coil in the tank, to feed the water heater. It is a very low tech system, and not terribly efficient, however the parts are pretty cheap so it is designed to harvest the low hanging fruit.
We've used the big roll of black plastic pipe system before, in a super low tech water heater with no pumps. THe cold water goes in, the hot water comes out the other side when you want a shower. If you use up the water on the roof, tough luck. No hot showers in the morning either. THis was in a friend's cabin, where low tech stuff was OK and there was no pressure to get to work on time.
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We've used the big roll of black plastic pipe system before, in a super low tech water heater with no pumps. THe cold water goes in, the hot water comes out the other side when you want a shower. If you use up the water on the roof, tough luck. No hot showers in the morning either. THis was in a friend's cabin, where low tech stuff was OK and there was no pressure to get to work on time.
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