There are 2 types of extractor - in-line (where the fan motor sits remotely to the vent in the bathroom) and a wall/ceiling mounted fan that has the motor located at the vent point. If you have space in the loft, in-line fans tend to give a better rate of extraction and are quieter as the motor is outside the bathroom. HIB Cyclone has an extraction rate of 210 m3/hour - you should allow a minimum of 4 air changes per hour but the more the better. This fan also has a decibel rating 32db and an adjustable timer that allows the fan to over-run by up to 30 minutes. HIB also have the Breeze in wall/ceiling fan which has an extraction rate of 97m3/hr but only 25db. This model is also a available with a humidity sensor so the fan will run on longer after a shower than if put on to use the loo. The Airflow Icon ranges also offer the same with add on modules and also offer more styling options with the 'iris' shutter which opens in use and closes to stop back draughts. The range is available in several different finishes to co-ordinate with the bathroom fittings. All of these fans are IPX4 rated which means they are suitable for bathroom use. I hope this has been helpful for you - let me know if you'd like further advice on the subject. Jane x

Thank you Jane.This is most helpful. I spent a lot of time reading about them but just wasn't sure what specification to look for. Your advice has given me some clairty. X

Glad to be of help.