ducted exhaust fan

[davo_scuba]

I am in the middle of putting in a ducted exhaust fan the duct is less than 3m long is it better to put the fan at the start of the duct, in the middle or at the end.
Are they best sucking or blowing (if you know what i mean )
noise is not an issue so max performance is what i'm after.
probably so go and read the instructions, but if there are any experts ???

davo

[davo_scuba]

probably so go and read the instructions, but if there are any experts ???


what i was going to say was probably should go and read the instructions

davo

[Skew ChiDAMN!!]

I'm no expert, but I wouldn't put it in any of those positions.

I'd put it a few feet in from one end so that there's a consistently smooth air-flow in the ducts into and out of the fan but the blades are still easy to access for cleaning without pulling the duct apart. I'd probably put it on the exhaust end to reduce noise; how far in depends on the fan size... from memory it should be about 3 times the dia. of the duct, minimum.

This is simply based on my personal experiences and a bit of research with a dust collector, where changing size of a duct, eg. adding a wye, immediately before or after the impeller increases turbulence at the impeller, resulting in overall loss of efficiency. [shrug]