matlocc
Registered:1420920295 Posts: 68
Posted 1510859597
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#1
I have been reading about the trouble with air contacting the glazing. Could you put your screen inside and then stretch a screen across the top and staple it tight and then place your glazing on with say a 1/4 inch gap between it and the top screen. Actually you would have 3 layers of screen. It would be glazing, 1/4 inch down screen, then the inside of the box with your two layer screen and frame.
gbwillson
Registered:1352981942 Posts: 2,311
Posted 1510869856
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#2
I'm not sure what you mean about trouble with air contacting glazing. I've never heard of this. Greg confused in MN
SolarInterested
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Registered:1352940256 Posts: 1,060
Posted 1510875243
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#3
Greg I believe it's about heat loss through the glazing when hot air is allowed to flow along the glazing. Matlocc no sure exactly what you have in mind, a drawing would help. You could have a look at the 'zero pass' collector where most of the air flows between two layers of screen.
__________________ Both temperature rise and airflow are integral to comparing hot air collectors
matlocc
Registered:1420920295 Posts: 68
Posted 1510921477
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#4
It is about heat loss through the glazing. I was thinking more about this and instead of screen the window plastic may be a better idea. It is like making the glazing a double pane window. Glazing, airspace then the clear plastic. then the interior of the box. I will try to draw something and post a pic. I am not sure how to do the drawing stuff!!!!
SolarInterested
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Registered:1352940256 Posts: 1,060
Posted 1510923068
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#5
Quote:
Originally Posted by matlocc It is about heat loss through the glazing. I was thinking more about this and instead of screen the window plastic may be a better idea. It is like making the glazing a double pane window. Glazing, airspace then the clear plastic. then the interior of the box.
I've thought about that too. The window plastic would be protected by the outer glazing but the interior airflow might cause it to bulge toward the glazing and also weaken over time. It would be an interesting experiment.
__________________ Both temperature rise and airflow are integral to comparing hot air collectors
gbwillson
Registered:1352981942 Posts: 2,311
Posted 1510931215
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#6
Sounds like you want to replace the top-most screen layer with clear plastic. I would think screen would do a far better job of transferring heat to the air. There are plenty of drawing programs available for free or very cheap online. If you can sketch it on paper you can take a pic with your phone. In either case, simply save as a JPEG to post the same as a photo. Greg in MN
matlocc
Registered:1420920295 Posts: 68
Posted 1510935564
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#7
let's see if this works
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SolarInterested
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Registered:1352940256 Posts: 1,060
Posted 1510938369
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#8
As far as the screens go it looks like the original double screen collector. The window plastic would add an extra 'pane' to the glazing and even if it bulged and partially touched the outer glazing it should still provide some benefit. Screen collector examples:
http://www.builditsolar.com/Experimental/AirColTesting/ScreenCollector/Building.htm
__________________ Both temperature rise and airflow are integral to comparing hot air collectors
stmbtwle
Registered:1388591029 Posts: 2,877
Posted 1511004868
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#9
The window plastic should do a better job of keeping the air off the glazing, but it would add another reflective surface, too. Whether it would be a net gain or loss is a matter for testing.
Same for the film vs the screen.
__________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay
gbwillson
Registered:1352981942 Posts: 2,311
Posted 1511017977
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#10
A single layer of glazing is fine in all but the coldest climates. Designs such as the downspout, backpass, and ZP, keep the air passing through a collector away from the glazing better than others. Make sure the output air temps are moderate and not too hot. Higher volumes of airflow will reduce the time air is exposed to the cold, minimize conduction though the glazing, allowing a collector to operate at maximum efficiency. Greg in MN