Hi.
We are going to install a wall-mounted fan hood (Franke Stil Alliance) on the wall, but the ventilation hole in the wall is too low. We are thinking of making a new hole about 650mm above the old one and sealing the first.
Now to the question - what is the easiest way to make a hole in the ventilation duct? And how do I make it airtight afterwards? The wall the duct goes through is made of lightweight concrete. It should be possible to knock it out.
Grateful for any tips.
We are going to install a wall-mounted fan hood (Franke Stil Alliance) on the wall, but the ventilation hole in the wall is too low. We are thinking of making a new hole about 650mm above the old one and sealing the first.
Now to the question - what is the easiest way to make a hole in the ventilation duct? And how do I make it airtight afterwards? The wall the duct goes through is made of lightweight concrete. It should be possible to knock it out.
Grateful for any tips.
Small hand mallet and chisel.
That part I can handle 
how do you seal the vent channel afterwards? The collar must seal against the drum, right?
how do you seal the vent channel afterwards? The collar must seal against the drum, right?