Fan Dischrage - perforated plate

[remp]

Hi

I am installing a heating coil directly in front of a centrifugal fan outlet in an air handler.
I want to disperse the air before it hits the coil with a perforated plate infront of the fan.
Does any one have informaiton or tech data on the idean distance between the fan and perforate plate for best results. Also how big should the holes on the perforated plate be... pressure drops etc...

Regards

remp

 

[Compositepro]

Coils are often placed on the suction side of fans and blowers to avoid the expense and energy losses of difusers.

 

[macmet]

We use perforated plates for a similar reason, unfortunately I'm not sure how the holes are sized, which is done by our thermal modeling team.

But, be careful with moving the coil from discharge to inlet as your fluid properties will have changed.

 

[willard3]

SMACNA volumes show the pressure drop for various sizes.

 

[Wilbur55]

If this is a new unit or the existing fan is in questionable condition, can you use a plenum fan or fan array? This would help to spread out the air across the face of the coil.

 

[MTES93]

Agree w/ Wilbur55, if a blow thru fan we typically use a fan array or plenum fan to avoid the plate and subsequent pressure loss. If you have your fan already and need the plate, corner an AHU mfgr's rep for help. They maybe able to help.