Thanks for all the responses. Just to clarify to Drazen and KiwiMace, the cooling tower is indeed an open one, with the water evaporating in the atmosphere. All condensers and return piping are above the cooling tower - find the attached sketch illustrating the relative positions of the header...
I currently have a cooling tower cell with a pump delivering cooling water (at 540 m3/hr) to a header tank 35 m high from the pump. The water is then distributed to several condensers, and routed back to the cooling tower return line at a level of 10 m above the cooling tower. The water then...