A good extractor fan for a shower room

[endecotp]

Either fit an inline fan by breaking in to the boxing-in the other side of the wall, like this one:
http://manrose.com/specifications/mixflorange.pdf
I've personally done something like that, with the fan in the cupboard next to the bathroom and about 3 or 4 m of 100mm duct to the outside, and it works well enough.

Or fit a surface-mount centrifugal fan, like this one:
http://www.manrose.com/specifications/continuumcentrifugalfan.pdf
That avoids having to mess with the ducting. Note that because it will be on the bathroom side of the wall, you ought to get a qualified electrician to install it.

There are plenty of other options. Just don't fit a fan that is only designed to blow about 20cm through a wall; it will do badly when connected to a 2m duct.

 

[londoniese]

Either fit an inline fan by breaking in to the boxing-in the other side of the wall, like this one:
http://manrose.com/specifications/mixflorange.pdf
I've personally done something like that, with the fan in the cupboard next to the bathroom and about 3 or 4 m of 100mm duct to the outside, and it works well enough.

Or fit a surface-mount centrifugal fan, like this one:
http://www.manrose.com/specifications/continuumcentrifugalfan.pdf
That avoids having to mess with the ducting. Note that because it will be on the bathroom side of the wall, you ought to get a qualified electrician to install it.

There are plenty of other options. Just don't fit a fan that is only designed to blow about 20cm through a wall; it will do badly when connected to a 2m duct.

If I put this fan outside the wall do I still put one in shower room as well?

 

[endecotp]

If you're referring to the first one I linked to, no, that's an inline fan. You have a grille in the bathroom, duct, inline fan, more duct, then a grille to the outside atmosphere.

Most often this sort of fan is fitted in the loft, with its inlet in the bathroom ceiling above the shower. But they also work with horizontal duct runs.

Do think about where any water in the duct will go.