delta t issue chilled water system

need expert advise as i am facing issues with delta T attained in one of the site to which FM services are given

District cooling supplies chilled water with 6 degree differential(supply 4.5 and return:11 degree Celsius)

In my load side we are able to get approx 4 degree delta T only

Supply been on a average of 7.5 and return 11 degree

When referred O&M manual design which was noticed was to attain 23-24 degree celcuis supply air through AHU and FCU

Client instructs to attain 20 to 21 degree celcuis on supply air

could this possibly results in getting low delta T or is it due to some other factors

5-6 degrees delta T is fine, check for clean water filters and flow.

Remind client that the system was designed for 23-24 and not 20-21.

Delta t is directly related to water flow rate

Thanks a lot for response given

whether trying to achieve low supply air temperature(like 20 and 21) limits impact delta t or does it results in starving of chilled water at the index lines

Strainers on our secondary side got cleaned recently .

Constrain is that district cooling team supply the delta t as per the contract in the range 5-6 degree differential

When it comes to our side conditions are not met(like able to attain 3 degree celcuis max. delta T).Also supply temperature to our building get served @ 7.5degree celcuis with district cooling side been 4.5 degree

could you please help me in explaining why we come across such difference

Check and reset if necessary the chilled water flow rates through chillers, higher flow rates will reduce delta T, due to high tube flow rates and water dwell / retention time, lack of heat exchange.
You have OEM manuals which should have commissioning settings per chiller set.