Good morning, everyone. It's warm but rainy here today so it'll be an inside day, which my aches and pains appreciate. Too much heavy lifting yesterday. Coffee is on and there are always bagels around, pumpernikle, sesame and onion, and the toaster oven works well.
Order ready made panels and do the plumbing yourself. Do not forget the insulation. It would be cool if you could store heated water in a
tank. Heated by a heat exchanger, you could use it even for heating too.
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The
tank I'm looking at is a "soft
tank". It has a heavy mesh/canvas/polyester exterior shell. Inside are four layers of rigid 1" foam insulation and then a very heavy plastic liner. The result is a 200 gallon tank with an "R" rating of over 30. It's not a pressure vessel by any stretch of the imagination, but with a drainback system the storage tank is not pressurized.
The Softank Kit - American Solartechnics, LLC.
My decision about collectors will get made either today to tomorrow. I need to check price and availability of tubing and fittings. I want to use 1" copper manifolds feeding 3/8" riser tubes. I think a 4'x10' panel will do the trick. If I buy commercial I'll use panels made for heating swimming pool water. They are not insulated so they are not as efficient in colder weather. If I were to put them inside an insulated enclosure stagnation becomes a problem...their temperature could easily rise beyond what they can tolerate without degradation or damage. Putting an automatic shutter in would solve that, but increases complexity and price. A homebrew collector made of copper and insulated would not get damaged by high temperatures during stagnation periods. (stagnation occurs when the tank temperature is high enough to reach its upper limit and shut the pump down draining the water from the system allowing the collector temperature to rise uncontrollably.)
Another decision is a heat exchanger. I've seen people using PEX tubing, as in a 250 foot coil, a coil of copper tubing and a tube inside a tube for heat exchangers. There are also commercially made exchangers available. I was thinking of using some hydronic radiators, sort of in a reverse application. The large fin areas should significantly improve heat transfer compared to just a simple coil of tubing. I may setup the base system, collector, pump and tank, then try a few different heat exchanger methods to see what works best for me.