Bathroom fan extraction rate

[Wantitright]

Could anyone help me please with how to calculate the correct capacity fan for a bathroom with bath and shower. I have looked on the internet but am confused as different rates seem to be quoted, eg, litres per hour, cu ft per hour etc. Room is 14cu metres. Also I want to fit a ducted fan in the loft as I think it looks tidier and hopefully makes less noise, any recommendation would be appreciated.

thanks.

 

[^woody^]

I would not bother with any calcs. Any of the commonly available 100mm fans will do.

For a ducted fan, a centrifugal type would be best, and keep ducting to no more than 3m to keep it efficient. And mount it on a rubber mat to minimise vibration

 

[bathjobby]

Most fans using a 4" (100mm) vent do about 75 cubic metres per hour and max vent length is 3 metres. There is one brand (ICON) that through a standard 4" vent pipe pushes out 113 cub metres per hour upto a length of 5 metres.
See my post here for more information.
//www.diynot.com/forums/viewtopic.php?p=486949#486949

 

[jeds]

I agree, no point trying to calculate room rates etc. It's common practice to specify 15litres/s for a bathroom, which will be covered by all the standard available units.

 

[Spr0cket]

Centrifugal would be a good choice.
Many will flow in excess of 100 l/h through flex pipe over 3m or so.

If you need more, a 5" can be had for not much additional cost and soil pipe can be used to make the air flow more efficient.

http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html