Hi,

I am going to be hiring a core drill, 6 inch diameter to "pop" a
ventilator through a wall. While I am hiring the baby my thoughts turn
to "popping" a vent above the cooker extractor that currently blows
back into the kitchen and gives me a cold breeze down my neck.

So, what's the minimum diameter whole I need for the cooker hood
vent? I want to keep the hole as small as possible (2-inch?) since the
rash of holes in the wall due to installation of combination boiler
flues make me worry for the wall's structural integrity.

Clive