Internal wall plate for plastic ducting - wrong size??

[Lobster]

I want to fit a 100mm duct through a wall, for linking to a hob extractor. Amongst other things I've bought a length of 100mm id circular ducting

(or ) which will line the hole throgh the wall and protrude a bit on the inside to attach a hose or ducting.

I also bought a '100mm wall plate'

(or ) to tidy things up on the inside wall, and to hide the damaged plaster/brickwork.

However, the hole in the wall plate is actually 110 mm. Therefore the matching ducting (od about 103mm) passes through the hole with a gap of about 4mm all round. In other words, the area most damaged is completely exposed. I was expecting it the ducting to be a snug fit through the hole. I contacted Toolstation about it, under the impression that the product was wrongly labelled or something, but was assured it was correct and was referred to the manufacturer's product support line. It was obvious I wasn't the first person to call with this issue, but no explanation was forthcoming other than a shrug of the shoulders.

Has anyone else come across this bizarreness? Or am I doing something totally stupid here?

David

[John MacLeod]

And the manufacturer's support line said?

[Lobster]

As I said: On 16/12/2010 22:19, Lobster wrote: > was obvious I wasn't the first person to call with this issue, but no > explanation was forthcoming other than a shrug of the shoulders.

...as in, no it's meant to be like that, either buy our £1.20 product or don't. Wasn't taken seriously, basically.

David

[Richard]

Did you *actually* use the support line, use psychic powers or simply assume?

Richard

[Lobster]

Oh, I could hear the shrug, I'm certain.

But surprised at the lack of comment here actually - what's the normal preferred method of attaching ducting to the wall, neatly, simply, and readily demountably?

David

[ARWadsworth]

I have never had a problem with the holes as the core drill usually makes a good finish. However I would be most displeased at buying a wall plate that specifically says what ducting it is for when in fact it clearly is not.

[Geo]

The Screwfix (Manrose) version seems to have a 104mm dimension:-