Extraction fan rotation?

[aaran]

sorry guys im having a blonde moment here.

my extraction fans dont seem to shift loads of air (the run about 1500rpm, 3 phase but are small-ish 0.18kw units)

just look at this pic and tell me if i have the fan blade installed the right way round (it should suck from here and extract out the rear of the building)

fans face downwards into a box and extraction runs upwards and outwards via ducting. in this pic the fans are spinning clockwise, should the fan unit/blades be the other way round spinning clockwise? jsut looking at the pitch of the blades and i think they need to run the other way once filpped over)

 

[wheresmejumper]

sorry,misread

 

[wyn]

That should work ok the way you have described it.

If you turn the fan blade over it will still have the same pitch as it has now.

 

[normspanners]

viewed from the blade end of the motor ie under as in the picture they should turn anti- clock.

 

[normspanners]

the pitch is irrelevant, they are curved blades.

 

[aaran]

viewed from the blade end of the motor ie under as in the picture they should turn anti- clock.

if the blades are left that way in the pic and span anti clockwise they will push air into the booth rather than suck it out though?

 

[MattF]

if the blades are left that way in the pic and span anti clockwise they will push air into the booth rather than suck it out though?

Yes. The way you have it running at the moment is correct.

 

[normspanners]

But the motor is running the wrong way and the curved blade increase the air flow significantly so invert the complete fan assembly.

 

[MattF]

Fair point. Hadn't noted the curved faces. As Norm says, invert the whole assembly and run the motor in the opposite direction of rotation.

 

[aaran]

blades flipped over and fans spinning the other way

work great! shifting about 40% more air now than before

just need to make some large V stacks up to improve the flow a little better but working great.

Cheers!