I have a range hood that vents through a wall into my garage that is not insulated. This was installed this past Feb. My old range hood was a recirculating type. Although it has a damper which opens/closes automatically when it's on/off, I feel a draft through the range hood. I'm thinking this could have raised my heating/electric bill by 500 kW/h. I nearly messed my pants when I saw the bill!
Is there anyway that I could insulate the damper, or the ducting?
BT knows way more about drafts than I, but I have found a horizontal steel vent with weighted damper and felt seal that has made a HUGE difference for both my dryer and range hood. I would add that to his list.