Selecting Fans for an Air Duct System

I won't attempt to make specific suggestions as I do not know enougth about moving air thru ductwork.

Over the years however, those system I have experience with were friendlier to end users when they had large diameter fans moving slowly as opposed to smaller fans spinning faster. Air volume was the same, but the big fans were lots quieter and apparently needed less power.

The other trick the HVAC guys mentioned was to size the ductwork as the air moved downstream so the air velocty remained constant.

Perhaps others with a better understanding of this environment can explain why.

L. J.

You need lots of data - look over the attached site it should be of good use to you.

http://www.greenheck.com/pdf/fans/FanFundamentalsMay2005.pdf

My last comment did not go through.

Just go to the Library and get a copy of ASHRAE handbook (ther are 4 of them but I forget whether it is Fundamental or System). Follow the step and calculate the total pressure drop (static and velocity). Together with the air flow rate, select a fan form the catalogue to suit.

Good Luck.

thanks everyone. ok i'll do that.