Properly powerful bathroom extractor fan?

[JumpJockey]

Our shower room is about 4m2 and has two outside walls (in the corner of the building). At present the bathroom fan is utterly useless, after DH and I have both had morning showers the walls are dripping and we have to leave the window open all day to dry the air - in winter this is just no good! Any recommendations for a bathroom fan that does a decent job? Not too worried about noise as the girls sleep pretty reliably through most things. It will need to be vented out through the front wall which is not a particularly thick one.

Thanks!

[PigletJohn]

have you got access to a loft above?

what size is the hole in the wall?

[JumpJockey]

Sorry, been out at work all day. We do have access to loft but it's a very slopy section in the eaves so not sure how easy to get into. Hole is about 15cm across, 1930s solid wall construction. (Hence walls and room very cold in winter and stay wet!)

[PigletJohn]

If you have room in the loft, you can fit an inline ducted fan, which will be quieter and more powerful that a wall mounted one. It will however be bigger and unsightly, hence normally put in the loft unless you have a convenient large cupboard. The duct has to exit through a wall or eaves, you must not blow steam into the loft.

Most wall holes are 100mm. If you are sure yours is 150mm you can have a larger and more powerful fan.

When looking at fans, not the extract rate (in cubic metres per hour, cheap builders fans are usually about 80 cu.m and good ducted ones about 240) and the noise, in db. You will want one that is wired to come on with the light switch, and has a timed overrun to keep sucking after you have left. So the noise is important.

Some examples on here:
silent inline

more

I couldn't see a 150mm bathroom wall fan, email Vent-Axia and others and ask for a brochure (it is easier than searching online). If you see a Centrifugal fan it will usually be quieter than an Axial of the same power.

[JumpJockey]

Thanks very much PigletJohn -tbh the hole may be smaller, I'm just guessing by looking at the bit of the existing fan under the cover. Will certainly bear your figures in mind for desired extract rates - not sure we'd want to go into the loft but will have a think.