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 For comparison to a more dense single layer should I
 Modify the dual layer to a dense single layer, (current winner) 3 60%
 Modify the single layer to a more dense single layer 2 40%
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Total votes: 5. This poll has been closed.


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solardan1959

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Registered: Nov 17, 2012
Posts: 1,173
Reply with quote  #1 
The subject came up again recently of a double layer cvpc water heater and I said it would be a good test to compare the output of a single layer to a double layer collector, this is the start of that project.

I had two pieces of 26" by 70" glass that I scrounged up from Craigs list last year.  I also scrounged up some OSB for the back for free. Had screws, stapes on hand.  I also bought the following materials.

3 contractor 10 pack of cvpc 1/2 inch tees  (turns out I'll need more I only counted 24 and a few extras and needed double that for the other side) 3 @ 1.71
1 contractor 10 pack of 1/2  90 degree elbows 1 @  1.97
1 contractor pack of 1/2 inch to 1/2 inch threaded (good to adapt to hose with the below item) 1 @ 2.60
2 1/2 inch threaded to garden hose adapters, brass.  (already had two for the second collector) 2 @ 2.36
4 2X4 lumber 4 @ 2.67 each 
1 3/4 inch polyiso insulation 1 @ 12.98
62.16 total but need 5.13 more for additional tees
Also I forgot 1/2 X 10 cvpc pipe 15@ 2.49 (thanks solar interested)

first I built this frame by cutting the four pieces of two by four then cutting out a small channel for the glass and the OSB to sit in so that it is flush with the edge on the front and back.  Here is the first piece of OSB installed.  It was not wide enough to fit all the way across but I felt it would be stronger this way then to have three or four smaller pieces going across. These were free scrounged pieces which is why they won't fit all the way across. but the price was right so I'll make do.


I then added the other piece


Flipped it over for a front view and added a tin patch for strength


I added the poly iso insulation 3/4 on back, 1/2 inch on sides.


I fitted the glass for the first time and of course it was 1/8 inch too big, (I thought about not telling you this but mistakes help to)



I used a plane and wood chisel to take off this little overhang and that worked a lot better.


This was my original thoughts for pipe layout, it would angle up to the second level.  This bothered me because it would not work well for a drain back so I thought about it for a while and came up with the next design.
 

With this design it will drain better but the other thing I did was to make a couple of straps out of flashing and fasten down the risers.  This will keep them more stable but also spaces them better and makes it look a little cleaner.  The end results is really a closely spaced one layer for the most part with the risers being about one inch apart.


I did not do the second strap yet as I have not glued anything yet.  I just fitted everything together to get an idea of how it would work.  I really am not sure it's worth it to do it this way.  Shorter pieces between the tees so that they about touch each other may be easier, cheaper, and work out to be somewhere between a typical single layer and this double layer collector.

And here is the glass, it has about 1/2 inch clearance between the highest cvpc points near the ends and
the glass.  the closer single layer would also keep the pipes further away from the glass which may cut down on loss out the glazing.  but it may not make much difference.


I will take it back apart and glue it then paint everything inside black.  Then paint the outside white and add some trim to hold the glass in.  I'll probably get this one working then build the second single layer the same way, of course it should be a little easier the second time around.

To be continued:
Dan
Garage_Hermit

Registered: Jan 24, 2013
Posts: 1,015
Reply with quote  #2 
Nice one, Dan, it is great to see that ! especially your glass finally coming to good use!

The metal straps look like a great idea too !

Look forward to following your progress !

Best regards,

G_H
Scott Davis

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Super Moderator
Registered: Nov 14, 2012
Posts: 664
Reply with quote  #3 
Very, very cool Dan!  I'm really excited about your test and eager to hear your comparative results!  This will be very useful information!
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Take care, Scott MD
SolarInterested

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Registered: Nov 14, 2012
Posts: 323
Reply with quote  #4 
Quote:
Originally Posted by solardan1959
Shorter pieces between the tees so that they about touch each other may be easier, cheaper, and work out to be somewhere between a typical single layer and this double layer collector.
That would be an almost like a coroplast collector. No worries about having to transfer heat (silicon caulking, fins etc)from the spaces between the pipes.

I wonder before you sealed up the glazing if you could move your straps progressively towards the headers to get the risers/hisers to lay down more? I'm thinking leave it in the sun to heat up and soften the pipe, move the straps and repeat. Not sure if it's worth the effort though.
solardan1959

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Registered: Nov 17, 2012
Posts: 1,173
Reply with quote  #5 
Solar interested,
With the 2X4, (really 1 3/4 by 3 1/2), then notching out for the glass and back, there is not a lot of room to gain.  If I just put the back on the back of the frame instead of notching it out I would have had plenty of space.  They are laying about a flat as they can get now though I'll see about a few mall extra brackets on the end to ensure as much space as possible.  The pipes are pretty flimsy now so they don't need much softening. 
Thanks for the ideas.
Dan
SolarInterested

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Registered: Nov 14, 2012
Posts: 323
Reply with quote  #6 
Quote:
Originally Posted by SolarInterested
Quote:
Originally Posted by solardan1959
Shorter pieces between the tees so that they about touch each other may be easier, cheaper, and work out to be somewhere between a typical single layer and this double layer collector.
That would be an almost like a coroplast collector. No worries about having to transfer heat (silicon caulking, fins etc)from the spaces between the pipes.
Just to clarify I meant shorter pieces between the tees on a double layer design would be almost like a coroplast sheet - a solid absorber sheet.
Keith671

Registered: April 30, 2013
Posts: 138
Reply with quote  #7 
To get the risers closer together, you may be able to find a tee with a street end on the one end.  This way you wouldn't have any short pieces, just tees.  I  looked on line and found this one at Lowes. Although you may have to go to a 3/4" header, which may help anyway.

http://www.lowes.com/pd_380005-1815-4101095RMC_4294765342__?productId=3583736&Ns=p_product_qty_sales_dollar|1

This may not be the exact one, but gives you the idea.  If any one finds the correct one please post a link as this is the way I am leaning. Looking forward to your results.

Keith R.

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Keith R. in PA.
solardan1959

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Registered: Nov 17, 2012
Posts: 1,173
Reply with quote  #8 
solarinterested,
   Your right this could easily be done, that would really eliminate the need for any flashing.  I thought some would still help now but the earlier discussion was about closer spacing would eliminate the need for flashing.  The next question is should I put it under the single layer one or is that cheating?
   It's not too late to do what you said though I'd have to get a few more pipes.  That may be a better plan to space them both a little closer. I'll think about it today.
Dan
SolarInterested

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Registered: Nov 14, 2012
Posts: 323
Reply with quote  #9 
Either way I'm looking forward to your test.

Mike
handymanhdw

Registered: Feb 21, 2013
Posts: 186
Reply with quote  #10 
The downside of just using tees at the bottom or very short pieces of pipe to join tees (as I have found out) is that if you have a leak, there is nothing to cut out and glue back on to.  You're going to have to fix that entire header (bottom or lower) ALL over!  USE PLENTY GLUE DAN!  Looks good!
handyman
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