Hi,

We have a laundry room that does not have an external wall. Therefore
we bought a condensing tumble drier as this did not need venting to
the outside. I am thinking that it might be useful to fit an extractor
fan because although the air does not get very humid, it can get hot
in there. The only way to do this would be a ceiling mounted fan, with
ducting under the floorboards of the room above.

I know people here recommend using 6" ducting over 4" but I am not
sure whether I will have the space to run 6" ducting between the
joists.

I know I will need a centrifugal fan but TLC and BES both list Manrose
but IIRC Manrose are not favoured here. Are they really that bad?
Otherwise can you recommend an alternative?

What are the pros and cons of ceiling mounted versus inline fans? My
worry about inline fans is that they are more inaccessible. At least
with a ceiling fan if it goes wrong, I can see that and get to it
without lifting carpets and floorboards.

I did see somewhere (can't remember where now) a collar to fit over
the ducting, which claimed to foam and seal if the ducting caught
fire. This sounds like a good idea. Is it? (It may even be required by
regs?)

TIA