Quote:
Originally Posted by strider3700
I'm getting ready to make some fins for my water heating collectors and was hoping to use a bunch of "old" aluminum I have lying around. I have some 12" roll flashing. some 18" valley flashing, some 12" L flashing, some 8" L flashing and a Bunch of 7.5" step flashings.
I was thinking just go with 6" cut the big stuff down to 6" and leave the 8" and 7.5" stuff big with some overlap but after forming it for my 1/2" pipe that means the width is going to be somewhere between 4 and 4.5" which seems tight. my glass which sets the collector size is 34"x76" so that's 8x76"(minus frame/gap/header) risers or 18x 34" risers depending on if I go vertical or horizontal for the glass. Horizontal is more stealth for my location(guerilla install) but it's a bunch more 1/2" 3/4" T's.
Any thoughts or suggestions?
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Hi,
Whether 4 or 5 inch total width is overkill or not depends on the thickness of your aluminum. You need about 0.018 thick aluminum to have an efficient fin that is 6 inches wide. You can run the fin efficiency for the alum you have here:
FinEficCalc.xlsx
On the 3/4 by 1/2 T's, PEXSupply.com usually has a good price on the bags of 25. But, if the collector is not too wide, you really don't need 3/4 inch header -- a half inch header with standard half inch T's is fine -- like this one:
Experimental Solar Collector Using Hybrid Copper/Aluminum Construction
I tested the flow distribution for the half inch header collector and its fine:
Copper/Aluminum Solar Collector Flow Distribution Test
The test collector is only 4 ft wide, but I think you could go somewhat wider before needing the 3/4 inch heaer.
Some people have worked out ways to join small risers to big header without using T's -- one example is Ken's system:
Homemade Tee-Extractor for Solar Collectors
Gary