Air flow is typically selected to be between 300 and 524 cfm per ton of cooling capacity. The final selection will be governed by the sensible to total load. Four hundred cfm per ton is typical.
Water flow through each unit should be designed to simplify water balancing. To do this, the system should be designed to keep unit water pressure drops as close to each other as possible.
Though the target water temperature rise is usually 12 degrees or 2.0 pgm per ton, they can range from eight to 15 degrees, equal to three to 1.6 gpm per nominal ton of cooling capacity.
The gpm per ton can derived from the following formula: 12,000 divided by the result of the temperature rise, times 500. In this formula, 500 equals water at 8.33 pound per gallon times 60 minutes per hour.