I have tried about 5 or 6 different types of insulation for the Dometic.SAVE
THE OEM INSULATION, EVEN IF IT IT TORN IN TWO. All other types were tried
without success, but with 1 that may work. The issue is the smell that the
insulation gives off.

I have tried regular pink wall insulation , green fire proofed wall
insulation, westy wall insulation, yellow wall insulation, and finally a
product called inswool ( $7 per sq ft ). All gave off so much smell that it
would drive you OUT in short order.  Allowing the Dometic operate for a week
didnt change this smell much at all.In fact, with several types the smell
lingered for a month- yuck!!

The OEM insulation works best, hands down. Dont know why , or what it is.
Maybe angel hair for aquarium filters will work. Never tried it, but the OEM
insulation seems to have this texture.

Inswool can be found on the internet by typing inswool into yahoo. It is
used to wrap exhaust manifolds in race cars and to line the furnaces that
are used to make small metal items( knife blades ) at home. One seller will
sell by the sq ft. It worked best, but still gave off a slight odor.It may
work better after a week or so.

The idea is to insulate the entire vent so the mostest heat will go out the
van.An additional,layer wrapped around the  circular heat shield, too.

I would like to know of a product that replaces teh OEM insulation.