Purpose of two way modulating valve at chiller

[faseesh]

Hi, Can anybody tell me purpose of using 2 way modulating valve at chiller. Its 2 chillers( 1 W+ 1 S ) connected to common header. Where should it be connected, supply or return?
Is it required at condenser side also?

[R123]

It's probably there to maintain design flow through the chiller. It should be on the leaving side of the chiller.

[faseesh]

It's probably there to maintain design flow through the chiller. It should be on the leaving side of the chiller.

Its a constant primary flow chiller and Design CHW flow through evaporator is always maintained by the primary pumps. Also Balancing valve provided at the chiller outlet for flow balancing.

[Nuclrchiller]

Are you certain it is a modulating valve and not an isolation valve? One isolating valve is all that is needed to isolate if the goal is to stop flow through an idle chiller.

[Nuclrchiller]

And what does "1 W+ 1 S" mean?

[faseesh]

It's probably there to maintain design flow through the chiller. It should be on the leaving side of the chiller.

its 1 working + 1 standby, Its not motorized isolation valve..

[Nuclrchiller]

But are you certain it is a modulating valve? Have you watched it modulate? if so, what did it appear to be responding too? Hopefully there are control prints somewhere on site. They would be able to provide an answer. Also what operates the valve? A pneumatic actuator? An electric motor? An isolation valve or a modulating control valve could use either type of actuator.

[hw chiller man]

I believe it could be used to provide a constant delta T across chiller barrel, regardless ol load by varying the flow. There would be limits based on minimum and maximum allowable flow thru the chiller to maintain acceptable velocities. I can think of one existing chiller company which uses this and VFD compressor control for maximum energy conservation.