Volume Damper Near Exhaust Fan Entry

[AliNaseem2]

We have Installed 6 Centrifugal Exhaust fans for Multi Purposes ( Toilets Ventilation , Kitchen Hood Exhaust , Public area Exhaust ) .

we have installed dampers on each branch in the ducting system , but now the Consultant is asking us to install the Volume damper on the roof near the exhaust fan entry also for balancing purpose and something about exhaust fan amperes , i dont get it , as i told him that we have volume dampers each branches , and we will start balancing from the last branch and every thing will be ok ,

did i missed some thing or the consultant is right

 

[MintJulep]

Why not have this discussion with the consultant?

 

[willard3]

Putting a VCD at the fan inlet may give you some very unusual fan conditions, prerotation of air flow is just one.

 

[dbill74]

Direct drive fans or belt driven?
Direct drive fans should have a speed control.
Belt drive fans should have an adjustable sheave.
Both negate any need for a damper to control overall air flow.

Kitchen hood is not allowed to have damper at all.