Was going to buy a new 150mm fan for mother's kitchen today, having a ferret in the workshop for something else, I found a brand new Silavent SDF150B still sealed in it's box,plus it's liner- great I thought, saves me a few quid. Found my 152mm core drill, went & drilled a nice hole through the kitchen wall, offered up the liner & it & to my surprise it wouldn't fit, hole too small. Had a look at the instructions & found the fan fixing kit requires a 170mm hole, not a 152mm as required for other 150mm from other makers. Don't whether to slink off & buy another fan & liner or bodge, I'm mean adapt the existing hole, well it can all wait until Monday, as I''m not in the mood for sorting it.
I assumed it was 152mm hole as it has been with previous wall fans I've fitted,like Vent Axia & Monsoon range. So, darn annoying, might carefully enlarge the hole with my Bosch breaker & then foam in the pipe.
Tsk - I'd have thought you'd be tough enough to hold a 170mm hole cutter steady with chust yer bare hands...
Can you cut a hole through 18mm ply with the correct size drill and then fix it over the smaller hole to act as a guide?
I've fitted a lot fan over the years, this Silavent is the first 6" fan which requires a 170mm diameter hole, instead of the usual 152mm hole. I've got a drill large enough to drill the hole, but I've got to go & hire 170mm core bit.
Or even use thinner plywood type stuff with just the pilot hole centered on existing holes centre and hole cut straight through both plywood and ceiling in one go.
Would be easier to just buy another fan to fit 152mm hole. Then when you next do a job use the 170mm fan for it.