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Old 11-14-08, 07:38 PM   #11
GaryGary
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Quote:
Originally Posted by Daox View Post
This is the quote from the FAQ.




The thing is, in the design, the PEX is covered with either aluminum sheet or paint. The aluminum for sure is going to block any sunlight from degrading the PEX. The paint may not be the best blocker for sunlight, but its still not in direct light. That, or it could be covered up with something else (more aluminum perhaps).

I'm not saying the design is perfect. But, I do think you could make it totally workable and reliable.
Hi,
Right -- The PEX is all protected from exposure to UV.
The first layer of protection is the SunTuf polycarbonate glazing -- it has a very aggressive UV cut off built into the outer layer. They add this coating to protect the glazing itself, but it also protects the PEX.
The 2nd layer is the aluminum sheet that covers all of the PEX except the bends at the ends of the serpentine runs. The tubing at the bends is protected a couple coats of the same black paint that I paint the absorber with, but you could use a more bombproof protection if you are concerned about it.

On the PEX crimp tool.
I tried to make the thing so as not to require any special tools. Within the collector, there are not joints at all -- its just one continuous run of PEX. To make the connections for the supply and return, I used SharkBite push on fittings. These are really easy to use -- they literally just push on. They are approved for for residential water supply plumbing, even if hidden walls -- so, they should stand up to the almost zero pressure in a drain back system with no problem. The Home Depot in our area sells a good selection of them -- the only down side is that they run about $6 per fitting.
A 2nd small problem is that they don't fit all PEX -- I found that I had to take out the inside bushing in the SharkBite to make them work with the PEX-AL-PEX I was using.

The thing to read very carefully on the PEX collector is the cautions on avoiding high stagnation temperatures. I don't think that it should see temperatures higher than about 230F. I avoid these high temps on mine at stagnation by using a high tilt angle (about 70 degrees) -- this keeps the stagnation temps down in the summer because the sun is so high that the incidence angle is very large. This works out well for me in that it also increases winter collection (when the sun is low), and gets more benefit from reflection off the snow. But, if you can't live with the stagnation temp limitation, the copper alternative (that still uses alum fins) is only a few bucks more, and (as mentioned above) is more efficient. All in all, I think the copper collector is probably better for most people.

The solar heated water storage tank and plastic pipe coil heat exchanger actually end up saving even more money than the cheap collector, and they can be used with (just about) any collector.

Gary

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Old 11-15-08, 12:47 PM   #12
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Hey guys, the poster GaryGary I believe is the author of the builditsolar website. I invited him here to comment on the articles and projects we've been discussing from his website.

Welcome Gary. Glad to have you!
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Old 11-17-08, 08:03 AM   #13
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Hello Gary, thanks for the post and answers to some of our questions. I hope to hear more from you.
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Old 11-18-08, 09:39 AM   #14
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Hi,
Thanks for the welcome -- good forum.

If anyone goes ahead and builds the collectors, I'd like to hear how it goes.

Gary
gary AT BuildItSolar DOT com
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Old 12-17-08, 11:23 AM   #15
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I really like that web site BuildItSolar: Solar energy projects for Do It Yourselfers to save money and reduce pollution. It's what got me started on the hot air panel I have been collecting materials for. I was thinking of eventually trying a version of that hot water design. Since copper prices have dropped, it might be the material of choice. It would be neat to somehow tie it into the unused zone of my boiler to distribute the heat thru the house.
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Old 03-25-09, 12:34 AM   #16
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I would like to know what the heat output of this PEX solar hot water collector is, because I don't think it is going to be very high, real collectors are not that expensive compared to their life span and the space they take up.
I just like to see things that work, and work well, I've installed systems that were 7 3x10 panels (14sf less then 7 4x8' panels) and those 7 panels supplied 90% of the heat for a 2,000 sf super insulated house, and all of their domestic hot water, the other heat source was a small wood stove, they burned a pickup truck of sticks and twigs per year.
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Old 06-05-09, 11:55 AM   #17
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how fast does this heat the water? is it fast enough due a shower or mainly just washer, sink, and dishwasher?
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Old 06-05-09, 12:32 PM   #18
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The panel heats up a tank of water. You draw on that water just like you would a conventional water heater.
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Old 06-05-09, 12:38 PM   #19
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O ok. What would you recommend for the tank?
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Old 06-06-09, 10:20 AM   #20
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Quote:
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O ok. What would you recommend for the tank?
Most people tend to use an insulated 50-60 gallon tank with an electric heating element in it that can be used for back up, install a pressure releaf valve of course or it will not meet code.

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