extractor fan size

Hi all, New to this site but have a question .... We had our separate toilet and bathroom which have been knocked into one and therefore have two airbricks and two windows (with openings), I'm looking at installing an extractor fan Option a) is to replace one of the air bricks with an...

Hi, Can anyone advise on what size extractor fan I would need for my bathroom size: L=185cm W=180cm H=232cm The bathroom has no windows and is in a flat in a purpose built block. The air is vented through a straight duct about 3m long. I have had some condensation/slight mould problems with...