radiant barrier foil

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Post by Guest » Thu. Jan. 03, 2019 5:25 am

I know this will probably be a good place to get some scientific opinions on this stuff. It is the foil you place in your attic on the trusses to prevent infra red heat from coming in the attic. I was up in a garage space one time at noon ant it had this barrier. it sure felt a lot cooler than my attic.

 
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Post by scalabro » Thu. Jan. 03, 2019 6:00 am

How about a link to the mfg.....

 
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Post by AllanD » Wed. Feb. 13, 2019 2:14 am

I have a 4"x6" piece of Celotex foil-faced foam board to shield the back of my LG LED television from the radiant heat from my Harmon Stove..

FWIW standing between that foam board (It is hung from the drop ceiling frame)
and the stove is like standing in a Pizza oven.


 
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Post by Zach92r » Sat. Mar. 16, 2019 10:20 pm

I personally used radiant barrier off Amazon ( 4' x 250' rolls) in my house renovation on all the walls and attic space. My house only needs 2 window units to cool it during the summer ( 2000sqft) with full basement.

 
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Post by CoalisCoolxWarm » Sun. Mar. 17, 2019 10:38 am

Radiant barriers are much more effective when used for ceilings/roofs and with air space between it and the conditioned space.

Downside is rf signals are impeded. Cell phones, wifi, ota tv.

Upside is a thick enough barrier blocks the ir imaging of satellites, planes, and uav. Drones just fly to line up with a window, there is no privacy defense from them.

A really nice spot is in the wall behind baseboard, radiators, stoves, to reflect heat back into the room.

For attics, you can use good insulation and attic blanket, blow in some insulation to fill any gaps at about 6 inches thick, then blow in foil flakes to get a solid and continuous coverage.

I don't have the articles at my fingers right now, but that is all supported by testing.

 
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Post by rberq » Sun. Mar. 17, 2019 1:11 pm

Stand-alone foil is a great radiant barrier. The heat shield behind my stove is simply foil-faced bubble wrap on a wood frame. The surface does not heat up, and there is zero heat on the wall side. Without the foil, you can't even hold your hand on the plaster wall, even though the stove meets the proper spacing requirements.

But here's where things get fuzzy in my mind. If I put foil on studs, then put up sheetrock directly against the foil, does the foil do any good to keep heat in my house? Or does it simply trap the radiant heat at the surface of the sheetrock, raising the sheetrock temperature, then conduct the heat away from the (hotter) sheetrock and radiate it into the wall cavity? Another way to ask the question: does the foil serve any purpose without an air gap between the foil and the hot surface?


 
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Post by CoalisCoolxWarm » Sun. Mar. 17, 2019 1:49 pm

rberq wrote:
Sun. Mar. 17, 2019 1:11 pm
Or does it simply trap the radiant heat at the surface of the sheetrock, raising the sheetrock temperature, then conduct the heat away from the (hotter) sheetrock and radiate it into the wall cavity? Another way to ask the question: does the foil serve any purpose without an air gap between the foil and the hot surface?
You're on the right track. Conduction and heat radiation through the back of the foil are killers. From memory...without an airgap (foam, bubble wrap, etc count) it is very little benefit.

So think of it like this. The foil reflects some of the heat and slows some it down- enough that the insulation of air and such can stop it effectively.

The effectiveness of foil/reflective is also affected by the angle, same as any other EMR. Heat inside a room typically rises, so a large amount is vertical- hence the effectiveness in ceilings.

Close heat sources are pretty direct, such as behind stoves, radiation devices, etc.

Make sense?

 
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Post by CoalisCoolxWarm » Sun. Mar. 17, 2019 2:09 pm

Here's an informational handbook from the Reflective Insulation Trade Assoc.
HandbookAll-2014-Final-1.pdf
.PDF | 4.7MB | HandbookAll-2014-Final-1.pdf
Not the info I had saved, but should be a good start ;)

 
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Post by rberq » Sun. Mar. 17, 2019 4:10 pm

Good information. Thanks.

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