Need pump head calculations for chilled water pumps.

1. Measure the pipe line length (supply+return)
2. All chiller, AHU, FCU, system etc pressure drop
3. Number of bend, valves, etc
4. Then look pump supplier catalog for selecting the head.
Look height of the chiller from source is not a critical factor, pump need to overcome just the pressure drop within system & lengt

Only longest route we have to consider, branches will not be consider na?

Not actually, calculate all the pipe length and select a pump at least 10% extra capacity it will help you for further renovation and safety