Hi All,
I have an hotel building serving with two chillers one is primary only and
other is primary secondary with a common chill water loop. The flow of
primary chill water pump of primary only chiller is 220 GPM and the flow of
primary chill water pump and secondary chill water pump of primary
secondary chiller is 500 GPM each. I am facing with the problem that when I
change the fan control of secondary chill water pump from one speed to
variable speed there is no reduction in the consumption i. e. VFD is not
modulating. Even on increasing the GPM of secondary chill water pump VFD
doesn't work. Please suggest how VFD can be modulated in the system and let
me know if you require any further information.

The suggestion will really be appreciated.

Thanks!
Himanshu