Neff Cooker Hood

[TIN CAN]

So got a Neff cooker hood and have already set up extraction via 100mm piping to outside house. The questions on the outside of the house i have put a louve grill that attaches to pipe the pipe in turn comes in through the wall on to the top of the cooker hood connection. I have now noticed that where the pipes connects to the cooker hood it has a place for a non return valve however i have not got one in the box or with the vent kit.

Is the non return valve important ? whats it stop the cold air coming in? if so anyone know where i can get the 100mm valve if its needed? Just that looked around and all i can find is a very expensive valve


Thanks

[B B Leo]

the non return value would be just to stop the backflow of air comeing back into ur property when the fan not in use and peventing smells. if u are concerned m8 change the outside one to the flaps like this one
http://www.screwfix.com/prods/13161/...00mm-Flap-Vent

[B B Leo]

wee aim to amuse