I am planning to install a range hood. A couple of sources recommend
adding a nonmetallic thermal break between the duct that runs out to the
exterior wall cap and the duct that runs back to the range hood--placing
it as near to the wall as practical. This seems like a good idea for
someplace like Minnesota.
(kitchenaid installation instructions)
Except for the suggestion in one of the above references to use a "short
length of nonmetallic duct", I have not seen anything that actually
suggests specifically how to implement this thermal break. I have not
seen 6" diameter nonmetallic duct anywhere--unless 6-inch PVC could be used.
I was hoping to learn how someone else actually did this.