Where do we install the Balance Valve ( DRV ) in the chilled water system , I mean at risers , FCU and AHU (Supply Or Return) and Why ?

In high rise building, chilled water pipes (supply line) vertical riser from where horizontal pipes to be taken for each floors we are providing the DRV's (n numbers of FCU's and AHU's are provided in the floor). It is provided to do the balancing of the chilled water building.

Or else it is to be provided in chilled water supply line of FCU's OR AHU's for the balancing of the system.

In the pumps to save power! DRV helps pumps to automatic On/Off when ever the pump pressure is (i.e GPM) high or low !