15
Tower Operation
General:
The cold water temperature obtained from an operating cooling tower will vary
with the following influences:
1. Heat load With the fan in full operation, if the heat load increases, the
cold water temperature will rise. If the heat load reduces, the cold water
temperature will reduce.
Note that the number of degrees (“range”) through which the tower cools
the water is established by the system heat load and the amount of water
being circulated, in accordance with the following formula:
The cooling tower establishes only the cold water temperature attainable
under any operating circumstance.
2. Air wet-bulb temperature Cold water temperature will also vary with the
wet-bulb temperature of the air entering the louvered faces of the tower.
Reduced wet-bulb temperatures will result in colder water temperatures.
However, the cold water temperature will not vary to the same extent as
the wet-bulb. For example, a 20°F reduction in wet-bulb may result in only
a 15°F reduction in cold water temperature.
3. Water flow rate Increasing the water flow rate (gpm) will cause a slight
elevation in cold water temperature, while reducing the water flow rate
will cause the cold water temperature to decrease slightly. However, at
a given heat load (see formula above), water flow reductions also cause
an increase in the incoming hot water temperature. Use care to prevent
the hot water from exceeding 125°F, in order to prevent damage to the
tower components.
4. Air flow rate Reducing air flow through the tower causes the cold wa-
ter temperature to rise. This is the approved method by which to control
leaving water temperature.
Range – °F =
Heat Load (Btu/hr)
gpm x 500
or — in SI units
Range – °C =
operation
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