Hrrrmph. I've just fitted a fan in place of the louvre ventilator
in my bathroom.

Good News: Fan works, delayed shutoff timer works.
Bad news: Goodbye to quiet soaks in the bath!

This is a Wickes 710551 4inch axial unit rated at 45dBA. I'd
expected a little whisper, instead it sounds more like somebody is
running the vacuum cleaner in an adjoining room. In fact it's so
loud I can just hear it over the sound of the radio as I type in
an adjacent room.

Aside from idly wondering what the 45dBA is referenced to, I'd be
pleased if anybody could point me at something that will shift a
cubic metre or more of air per minute without disturbing me. I do
have space for a larger fan.

--
Jan