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mclark999

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Posts: 183
Reply with quote  #1 
Was out inspecting my year old collector for leaks because performance was low and I was noticing cold air coming into the house from the outlet vent even though the inlet vent was closed off.

I discovered that the 100% silicone that I had used to seal between the sheets of polycarbonate was no longer sealing along most of the joints.

I had cleaned the sheets well before I put the sealant on.  The sheets do warp as the heater comes on. It's set up to suck air out and I did not put a center brace under the sheets.  See pictures. 

I'm wondering what other people have done.  I'm thinking of using some small sheet metal screws to screw the panels together while leaving the silicone between the sheets. The silicone is nice and soft and I think would seal against leaks if the screws held everything in place.

I'm probably going to also have to take the panels off and add a center support to minimize the flexing.  Maybe it was the flexing in and out that separated the panels.
P1060425.JPG 



Ideas?


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Denver, CO

Double screen hot air collector

mclark999

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Reply with quote  #2 
Here's a picture showing how much the panels bow in when the fan is running.  At this point, they pretty much just stay in that shape even when the fan is off.

P1060424.JPG 


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Bert

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Reply with quote  #3 
Looks like it definitely needs support.   What about the H channels between seams?  I was thinking about using them on my next one.
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Bert K.
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mclark999

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Reply with quote  #4 
Quote:
Originally Posted by Bert
Looks like it definitely needs support.   What about the H channels between seams?  I was thinking about using them on my next one.


I think the H channels would work for the twin wall, but this is the thin corrugated polycarbonate which I think is normally just overlapped like I did it. 

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gbwillson

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Reply with quote  #5 
Thankfully it doesn't look too bad and it is late in the season. Unless you have relatively low flow, either pushing or pulling air you will likely need some sort of bracing. Bert its right about H-channels being for twin wall, but even they need support if the flow flexes things too much.

Is there an easy way to temporarily switch the fan to blow air? It might help counter some of the flexed poly and an exterior brace could be added if needed. And once things warm up this Spring you can do a proper inspection and repair could be done. 

Greg in MN


mclark999

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Posts: 183
Reply with quote  #6 
Love Google search!!!

Did some research on gluing polycarbonate and discovered that there is good glue for it. 

http://www.amazon.com/SCIGRIP-10315-Acrylic-Cement-Low-VOC/dp/B003HNFLMY/ref=sr_1_3?ie=UTF8&qid=1458849326&sr=8-3&keywords=acrylic+plastic+cement

They use it for gluing together and sealing aquariums so it's water and air tight.

I think take all my panels back off, remove all the silicone and glue them together with this stuff. Then I'll add a couple of support rods so the panels won't bend so much.

I'll post back when I'm done.  For a quick fix, I just used a handful of self drilling screws. I've promised my wife that I'll finish the bathroom remodel before I do any other projects.

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Double screen hot air collector
KevinH

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Reply with quote  #7 
Did you allow for expansion along the outside edges (not sure how other people have done it with this kind of polycarbonate glazing)?  It helps a little to roughen the polycarbonate surfaces before gluing with 100% silicone.  I also found that the brand can make a big difference.  On one collector that I took apart, one brand of silicone held securely and another peeled off easily.  Unfortunately, I don't know which brand was which.

Kevin H
MN
mclark999

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Posts: 183
Reply with quote  #8 
Quote:
Originally Posted by KevinH
Did you allow for expansion along the outside edges (not sure how other people have done it with this kind of polycarbonate glazing)?  It helps a little to roughen the polycarbonate surfaces before gluing with 100% silicone.  I also found that the brand can make a big difference.  On one collector that I took apart, one brand of silicone held securely and another peeled off easily.  Unfortunately, I don't know which brand was which.

Kevin H
MN


Thanks for the help Kevin.

I'll try roughing up a section and using a different brand.  I did leave room for expansion on the outside edges.



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Denver, CO

Double screen hot air collector
mclark999

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Posts: 183
Reply with quote  #9 
Quote:
Originally Posted by gbwillson
Thankfully it doesn't look too bad and it is late in the season. Unless you have relatively low flow, either pushing or pulling air you will likely need some sort of bracing. Bert its right about H-channels being for twin wall, but even they need support if the flow flexes things too much.

Is there an easy way to temporarily switch the fan to blow air? It might help counter some of the flexed poly and an exterior brace could be added if needed. And once things warm up this Spring you can do a proper inspection and repair could be done. 

Greg in MN




Thanks Greg. 

The position/spacing between windows that I used for the box doesn't leave me room to move the fan over to set it to blow.  That would have been a pretty good solution, though.

I'll take it apart this summer and fix 'er up.  

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Denver, CO

Double screen hot air collector
ChrisJ

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Reply with quote  #10 
I have read of using metal conduit to support the overlap. Drill and screw the glazing to it.

ChrisJ

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Rhode Island
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