The hvac supply ducts in my attic are insulated and have a black cover.
The ducts in the basement have a silver cover. Is this normal? Or
does it matter? I would have thought that the black covered insulation
in the attic would absorb attic heat and increase the temperature of
the air supply.
Flex duct is easier to seal and usually performs better thermally.
Sheet metal will pass more air with the same static pressure. Flex
duct is quieter.
It is a trade off, depending on your situation.
With sheet metal, to have a tight system, you must seal every gore on
every elbow. You must seal every joint in the duct, plus you must seal
every longitudinal seam. Then you hust do the same thing with the
wrap. And if you install the wrap tight so it looks nice, the actual
R-value is about 1/2 rated value.
With flex duct, you just have to seal the connections at the ends, but
it must be supported at closer intervals with wider straps. But you
get full rated R-value for the entite length.
Stretch and RP answered before I could and their answers were the same mine
would have been.
I don't really care for flex because of the way it's usually run. It also
has a higher resistance than the same size hard pipe.
Timely question. I wanted to insulate the ducts in my garage. Have
seen the black, but wondered it it's just garbage bags or sheet
plastic stapled over normal attic fiberglass R11 or similar.
Anyone have a suggestion on what to use? Mine are normal galvanized
ducts, some rectangular and some round.
Local Home Depot looks at me funny, when I ask about it.
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