On Tue, 23 Oct 2007 11:58:33 -0700, wrote:

We have an over the range microwave with built in exhaust that vents
outside through the attic. It is noisy as heck and I want to quiet
it. Seems like most of the noise is coming from the front grill where
the fan would exhaust back into the room if I did not have the outside
vent. Some noise is also coming from the cabinets directly above the
microwave as the rectangular metal duct goes directly up through it
and into the ceiling.

I have access to some 1" thick very dense fiberglass insulation used
in the marine industry for thermal insulation. I am thinking of
gluing this onto the outside edges of the metal duct as well and
stuffing it inside the space in the microwave behind the grill. It
won't cost anything to try, but was wondering if there is anything
better that is readily available at the local home depot.


I used to have an over-the-range microwave and the fan did not move
much air. After 15 years of use I was glad the microwave died. I
replaced it with a model that has 5 speeds and you can program it to
run the fan for a selected number of minutes and shut off. If I want
a quiet fan I set it to "1." If I want to quickly vent I set it to
"5." It has a fan that is 3X more powerful. Whatever you use to
insulate, use something that is non-flammable.