reverse return cycle-chilled water piping system

If you go from a reverse return system (3-pipe) to a two pipe system, you must have balancing valves at each take off to balance the flow of the system.

Correct. I gave you a Good Answer vote.

With higher pressure differential close to the pump the first branches would tend to get excess flow. the last branches would have a lower pressure differential, and have insufficient flow.

Some modification would be needed in the system to balance the flows to required or to design conditions.

the building is 47storey of which i have the high zone-85mtr head & the low zone-105mtr head, would a pressure differential modulating valve can work as a balancing valve on each zone for the 2risers? i was thinking that a modulating valve is somehow costly? is there any alternative?

It's also costly to remove the 3rd pipe. Curious why you would want to remove something that is working well?

Is it true that the chilled water is only 2 zones? In addition to removing the 3rd pipe could you sell the idea of an upgrade to VFD pumping, upgrade chilled water controls and get an energy payback to justify removing the pipe and changing the flow control setup?

I think a good VFD rep would jump at the chance to write the cost justification for you.

Hard Boiled,

Be so kind.

Where are you?

I have just read your post anent a sprinkler system also in a high rise building apparently under construction.

I have worked on occasion in construction and pipe fitting and as a sprinkler pipe shop foreman as well as being an industrial maintenance generalist.

I may be wrong but it seems you know very little about either of the subjects you are raising here or in the sprinkler system post.

Can you tell us more about your bona fides because in my mind you raise questions???

j.