extractor fans
 

Hello,

There are different applications for different fan types. Generally
centrif fans create more pressure to overcome resistance in say
ductwork than axial fans. This will depend on the shape and angle of
the blades and power of the motor...

http://www.plumbers-central-london.co.uk


On 27 Jan, 13:51, wrote:
Hello,

I'm a bit confused because I though centrifugal fans were better than
axial ones. I was looking in a catalogue and it said that for four
inch fans the axial moved 80-odd cubic metres per hour but the
centrifugal only managed 60-odd.

Is it that in optimum conditions axial fans will move more air? Is it
that centrifugal fans are better only once the ducting becomes longer?
If so, at what length of ducting should the switch from axial to
centrifugal take place?

Or is it that these are maximum values when there is nothing behind
the fan, used only for marketing? Is it that in all practical
applications the centrifugal will move more air?

Thanks.