Parallel use of Centrifugal fans in HVAC

Please advice the best way to use two Parallel centrifugal fans of 4000 CFM, 150 Pa each.

It depends on what you want the fans to achieve.

Please the fan bible "Woods Flakt Fan Engineering Handbook"

http://www.google.co.uk/url?sa=t&rct...95039771,d.d24

Fans in parallel = double the volume same pressure
Fans in series = same volume double the pressure

It depends on your requirement (flow and sp).
Operating fans in parallel approx. doubles the flow and increses the static pressure slightly.

dependent on what sort of centrifugal fans you are applying. Brian UK reference to Woods Flak is a good start