During Winter operation, a cooling tower brings as much low-temperature air into contact with the flowing water as the tower fan(s) will permit. The greater the flow of cold air, the colder the water temperature will become. Fortunately, when under design process heat loads, the temperature gradients that naturally occur in counterflow cooling towers (All Delta designs) prevent the mass flow of water from reaching 32 F.
Here are some basic operating rules that should be followed for cooling tower operation in cold weather: (i) insure that the cooling tower is operating at the MAXIMUM POSSIBLE HEAT LOAD, (ii) maintain designed water flow rate over the fill; (iii) make sure a thermostat is installed to control fan operation to off at lower cold water temperatures; (iv) check cycle fans periodically to prevent ice from forming on louvers; (v) frequent visual inspection and routine maintenance during sub-freezing operation is very important; and (vi) if ice build-up occurs, use caution when removing the ice to prevent tower damage or injury to the employee.