the factory says you can go as low as 14 degrees above the leaving chilled water setpoint with the condenser water setpoint .!what they are telling you is keep the differential to a minimum ive seen machine s running at 30 hz 8% vane 19 kw .5 delta t and 10 degrees diff between leaving chwtr 42 and 52 degree leaving condenser water. had too listen hard too hear it run!
get the design flow right, and true ," keep it stable "and it will perform greatly later that day as the load increased the machine was able too track no problem.