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ChrisJ

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Posts: 95
Reply with quote  #1 

I am beginning to put together my copper grid for the collector. I have the fins from Tom at UP Trucking. My idea is to use the fins in reverse. Instead of putting them over the 1/2" copper pipes, slip them under the pipes and have the 25% or so of the copper, that's not touching the fins, face the glazing, painted black of course.

Any thoughts on this?

Thanks, Chris

ChrisJ

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Posts: 95
Reply with quote  #2 
My copper grid is done, the roof of the shed has the 1" layer of polyiso then 3/8" plywood overthat.

I have pretty much decided to do the same as a lot of folks have done. Strips of aluminum flashing under the 1/2" risers then the shaped fins over the 1/2" risers.

Now no one replied to my question above, don't know if I didn't describe it well enough.... I made a drawing of how I was thinking to do it.pdf Solar shed drawing 10-24-16.pdf     

Doing this the more "traditional" way, seems like the plywood will suck some heat out of the aluminum fins.  

Solar shed 4.jpg 

SolarInterested

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Reply with quote  #3 
Chris I could see the logic in what you originally proposed but don't know if it would improve efficiency appreciably.
Quote:
Originally Posted by ChrisJ
... Doing this the more "traditional" way, seems like the plywood will suck some heat out of the aluminum fins.

With poly-iso between the pipe/fins and the plywood will that be a problem?

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Both temperature rise and airflow are integral to comparing hot air collectors
ChrisJ

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Posts: 95
Reply with quote  #4 
Good idea, I could add the 1/2" layer of polyiso on top of the plywood.

Then I would not have to cut it(insulation) into 5" strips.

If I were going right over the plywood I can staple the fins with stainless steel staples (3/8" long). Adding a 1/2" of insulation between means I have to screw the fins down.

At this point I have the 1" polyiso and 3/8" plywood on the shed, over the felt paper you see in the picture above.

Here is the shed w/doors on temporarily.
Solar shed 11.jpg 

Hope pictures aren't too big

ChrisJ

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Posts: 95
Reply with quote  #5 
Gary screwed the top fin to the strip underneath using small sheet-metal screws.  

http://www.builditsolar.com/Projects/SpaceHeating/DHWplusSpace/CollectorConstruction.htm#AbsorberPlate

Here is my grid 1/2 way soldered.
Solar shed 10.jpg 


SolarInterested

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Reply with quote  #6 
Quote:
Originally Posted by ChrisJ
...Hope pictures aren't too big
They're fine. Thanks for reducing their size.

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Both temperature rise and airflow are integral to comparing hot air collectors
ChrisJ

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Posts: 95
Reply with quote  #7 
I have the copper grid installed with the aluminum fins. I used stainless steel staples to secure them to the plywood. Solar shed 14.jpg
I test sprayed some high temp grill paint at the bottom left. I was hoping to find some paint I could roll on.  

gbwillson

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Reply with quote  #8 
Chris-

You did a great job applying the fins. One of the cleanest and neatest jobs I've seen! 

You want the paint as thin as possible for better heat transfer. But over large areas such as yours you might consider a combined approach. You can purchase grill paint in quart cans and apply a VERY thin coat with a roller and brush. Follow that up with a thin second coat from a can to even things out. You will use far fewer cans than if you were to use cans only. Also, take a look at how you prep your raw aluminum fins before painting. Aluminum oxidizes very quickly, and this oxidation has been shown to reduce solar transfer. I did a search for:"Preparing aluminum for painting for solar". Below is one such article.

pdf The_preparation_and_testing_of_spectrally_selectiv.pdf     

Greg in MN

ChrisJ

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Posts: 95
Reply with quote  #9 
I washed the aluminum fins with cleaner/degreaser and a scuff pad. Cleaned and dulled the shiny fins.

Then took 1/2 the quart of high temp grill paint and thinned it. Applied it with a foam roller.  Solar shed 15.jpg The paint dried semi- glossy, then left it until the next day. I then sprayed the same kind of paint from rattle cans, that dried nice and flat.

ChrisJ

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Posts: 95
Reply with quote  #10 
Solar shed 17.jpg

The start of the water tank. I had to finish the back wall of the tank first.

Solar shed 19.jpg 
Sides have 2 layers of 1" polyiso, bottom has 2" XPS, then plywood and 1" polyiso. R13 fiberglass around the 4 sides.

Solar shed 20.jpg 
Pond liner mostly in. I do some upholstery at my day job so this was not too bad to fold and cut in the corners.

Solar shed 21.jpg 
Tank pretty much done, Still have the cover left to make. Getting the plumbing into and out of the tank. 2/21/17 Just realized I may have some trouble getting the 2 heat exchangers in. They must go in through the space between the end and the aluminum brace. I may have to let the lower one (radiant) sink to the bottom, so I can get the DHW one in. Of course I filled the tank with water.

Solar shed 18.jpg 

Testing the controller. S1 is the sensor out in the collector, S2 is the sensor that will go in the tank near the bottom. It is displaying 114*F, I sent the sensor down a piece of 1/2" copper pipe that is capped at the bottom. I put a couple gallons of hot water into a bucket and dropped the copper pipe in it.

Still need to make the first of 2 heat exchangers, One for the radiant floor heat in the garage and basement. The other for DHW. 



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