Coker extractor hood ducting

[db69]

Hi,

I have fitted an extractor hood with a150mm vent at the top.

I was just wondering if reducing this vent to 100mm would affect the performance of the fan?

the ducting wil go from the canopy through a cladded ceiling and along the joists in the roof space above and out through a grill in the sofits (I think thats what there called). A total run of around 2m.

Also, is it ok to just push the flexible ducting through the hole in the ceiling and bend it, rather than use a plate and 90 degree bend joint.

Thanks in advance.

Davy

 

[cmother1]

Yes this will affect the performance. You will be reducing the area of the vent by more than 50%.

See "Similar Topics" below about bends and distances.

 

[db69]

Hi, thanks for the reply.

The extractor has a 900m3/hr so half of that will be fine. What i should have made clear was, will it damage the extractor?

Cheers, Davy

 

[cmother1]

Might do. The fan won't be able to shift the volume quoted with a smaller vent and the motor will have to work harder against the increased pressure.
Could also be noticeably noisier due to increased friction and turbulence.
(I think what I'm saying is don't do this if you can avoid it!)