I’m trying to fit a new kitchen extractor. As it stated that it required 125mm ducting , I bought a 125mm ducting kit and core drilled a 127mm hole in my wall.

It turns out the external diameter of the ducting pipe is nearer 131mm.

So I go and buy a 120mm straight pipe from screwfix. Turns out the ext. diameter of that is 128mm.

Anyone know of any type of ducting or pipe with a 125mm outer diamter and not inner?

Or any way of eeking out a few more mm with the core drill?

chip away with one of these?

or this 😉

Or slit the pipe and put a bead of sealant on the overlap

Slitting the pipe and sealing it could be a last resort., might be a bit difficult in situ.

Hammer and bolster is a last resort.

There must be some sort of pipe somewhere with a 125 ext. diameter.

google is your friend 🙂

[edit] small print says it’s not.

[edit2] http://www.irrigationonline.co.uk/20mm-125mm-pvc-pipe/

Be aware that a smaller diameter duct is likely to be noisier.
If it is a long duct run, you might be looking at performance problems.
Go and have a word with some local tin bashers.
Make a bigger hole.

I am googling, but that looks promising wwaswas…thanks.

Short run, just the 300mm distance straight through the external wall. I know reducing the pipe diameter could lead to performance problems but I’m working on the assumption that a smooth pipe a mm or so smaller will have the same/close enough extraction rate as a flexi pipe.

Slit the pipe, reseal it smaller using a couple of ratchet straps / bits of string / sellotape until it’s set, then poke it through the hole?

cut a length a bit longer than the wall thickness. Slit it, slide it into the rest of the full sized pipework or a short length of the full sized pipe to act as a reducer to fit into an elbow or whatever fitting you are using. then the OD will be the ID of the existing tube. Seal the slit with some duct tape and silicone the joint to the full sized pipe.