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Poll Results
 
 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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SolarInterested

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Reply with quote  #31 
I also use Irfanview but you also can use Microsoft Paint. You probably have that on your PC already. Just open the pic in Paint, click the resize button and you can resize by percentage or by a specific pixel size. Quick and simple!

Keith R thanks for doing all the measurements and CAD work. It may not be practical but it is nice to have the info.

Mike

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Keith671

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Reply with quote  #32 
I just found Scott's post on resizing. I went into paint and resized my last file. I wasn't selecting it first. i think I got it now. Thanks for the help.

Keith R.

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Garage_Hermit

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Reply with quote  #33 
Dan

Would not dream of destabilizing U during your test, but I found this attached document interesting, you can skip direct to page 13 and page 14 in particular... 
http://www.onsitepowerinc.com/documents/supplierDocs/amercool/Basics%20of%20Air%20cooled%20Heat%20Exchangers%20rev1.pdf

In effect, while following your progress, I have been searching for a "dream" method to make a "prefabricated" header, to avoid using tees and stubs etc. at all.

What I had in mind, was a sort of "Tubular CPVC Wiggle Strip" similar to what used on rigid polyacrylate panels... for transiting from corrugations to planar.

This could be used to form a header around a group of parallel tubes spaced more or less apart.  The ideal would be to glue multiple CPVC lengths together, no airspace at all.  This would allow making a "rigid CPVC panel" for best solar absorption...

I also thought of ripping a big-diameter CPVC tube twice down its length, to make a slot, that would fit over the end of a bundle of tubes.

The problem remaining is then to seal the slot around the tubes, I guess Plastic Welding would be the way.

13 JY update goes here
===================

Then I finally found what I was looking for, the above reference.

The business end of the header would be a simple flat length, drilled to admit the tube ends.  Would still need sealing, of course...  I wonder if this "tube sheet" as they call it above, could be made out of self-sealing butyl rubber, like used for aircraft fuel tanks... (expensive, no doubt, unless U have a cousin that works at Fairchild...).

The best option might well be thick-wall auto rubber hose, as used on air-coolers, radiators etc.  Or extra-thick hose off plant or trucks. The wall could be pre-drilled with a pilot bore, then the CPVC end glued up and shoved right in to the hose.

Otherwise, I guess a header could be made of anything - such as rigid aluminum channel with end caps welded on etc.

Apologies for diving in with more theory, when you are on to the nitty-gritty build, but could not contain my enthusiasm

Best of luck with the test,

G_H

Update - 13 Jy

Maybe this stuff would be OK for fabricating the type of "split CPVC" header I refer to above...





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solardan1959

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Reply with quote  #34 
Sorry Hermit, I guess I'm lacking your imagination.
I always like this guys work from build it solar, though he's from your neck of the woods, kind of ,
http://www.devoecht.com/zonne_energie/building%20solar%20collector.htm


He drills then solders, though widely spaced he uses fins and makes a real professional looking panel.  But drilling and soldering you could get a pretty closely spaced array also.

The slotted idea is not bad, I saw something similar before and also with coroplast panels.  You could also use polycarbonate twin wall to do the same thing I think with excellent results.
Dan
Garage_Hermit

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Reply with quote  #35 
very nice, thanks for that, Dan !

====================
"though he's from my neck of the woods" ha ! ha !

(they obviously train their engineers good, in THAT neck of the woods, anyhow)
G_H

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solardan1959

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Reply with quote  #36 
Solar interested sent this to me as an email but I thought I would share"

Hi Dan

This is SolarInterested aka Mike. I didn't want to take your thread off on a tangent and down a rabbit hole so thought I'd suggest here. If you think it's relevant I can repost on the forum.

If there is a concern about the upper header being to close to the glazing couldn't the insulation under the header be notched out so both headers would rest further away from the glazing? I'm thinking if there was a notch and the pipes were strapped down close to the header it would force the lower header down into the notch and, as a result, the upper would rest lower too.

It may not be worth the effort but thought I'd mention it. Thanks for all your testing posts. It's great fun to follow along.

Regards

Mike

My response is this,
Mike,
I think that is a good relevant question and falls right into the theme of things.  By making suggestions like that, the idea may cause a redesign before it's too late.  In this case I already had thought about it and the difference in insulation would be minor but the 1/4 inch or so may be a better trade off because the 1/2 inch left would still be plenty for one small spot.  Plus the extra spacing from the glass may easily overcome any minor loss you get through the back.  I have about 1/2 inch now from the glass, the big question is does it matter and is that enough?  Right now I think it's enough but it would be nice to know what others think.  By the way the glass is single layer about 1/4 inch thick.
That strapping at the ends was already talked about, and is something that is planned.  That may give me enough clearance also and force the pipe a little into the insulation anyway.
Dan
Garage_Hermit

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Reply with quote  #37 
It sure sounds like a good idea to me !  I would never of t hought of it, that's for sure !

G_H

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Keith671

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Reply with quote  #38 
I have already started drawing in cad a copper collector with .875" spacing. Using 1" copper for header and drilling .625" holes on .875" centers. This gives you a .250" air space between uprights. I am not sure if solder would be sufficient to hold it since there is only about .040" wall, unlike a tee with plenty to hold. May be able to braze or silver solder it. Although this would be quite a bit more expensive than cpvc. 

Keith R.

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Keith671

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Reply with quote  #39 
A drawing with two ideas. One with pipe inside header other with pipe outside header. Only wonder if enough solder would get between pipes to seal on the outside idea. May try a small example to see.

Keith R.

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jpeg 1-inch-copper-header.jpg (41.40 KB, 103 views)


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Keith R. in PA.

solardan1959

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Reply with quote  #40 
Keith,
   My vote is the wider spacing.  Too close and it prevents anything getting past the mid point.  I would even be tempted to have reflective flashing to get light, heat and air to the back side of the pipe.  1/4 to 1/2 inch at most. 
Dan
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