Air & Water Flows


Air flow is typically selected to be between 300 and 525 cfm per ton of cooling capacity. The final selection will be governed by the ratio of sensible to total load. 400 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 as possible to each other. Though the target water temperature rise is usually 12°F. or 2.0 gpm per ton, they can range from 8 to 15°F, equal to 3 to 1.6 gpm per nominal ton of cooling capacity.

The gpm per ton can be 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 pounds per gallon times 60 minutes per hour.

Example: A 12°F temperature rise is equal to 2 gpm per ton: = 12,000 / 12 x 500 = 2.0 gpm/ton