Been given a Hygena cooker hood model APP2400. External diameter on top of the hood is 6 inches [see picture}]
The white plastic bit is the one way valve/flap. It sits in a metal collar that is part of the fan unit below. Apart from a gravity flap on the outside wall, any other considerations to bear in mind? Does it matter if we use flat or round trunking? Flat would make for a neater job. I'm guessing the joints are sealed with either mastic + tape or a solvent?[img]http://img101.imageshack.us/img101/347/cookerhood.jpg[/img]