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PVC Distribution System
To prevent damage to the PVC distribution system during cold weather shut-down, install an
automatic or manual drain line from the hot water inlet piping as close to the cooling tower inlet
as possible. The entire inlet and distribution system must be drained for shut-down in sub-
freezing weather.
Piping
When the cooling tower is located outdoors, adequate measures including the use of heating
tapes and insulation should be considered to protect water lines from freezing.
Operation at Sub-freezing Ambients
See Thermostatic On/Off control
1. Insure that the cooling tower is operating at the maximum possible heat load - An operating
cooling tower will continuously extract heat from the circulating water. Without a heat load,
the water will end up either at the air wet bulb temperature, or as ice, whichever occurs first.
2. Maintain Design Water Flow Rate Over The Fill - Reducing water flow over the fill area
can produce semi-dry regions that are subject to rapid freezing.
3. Make sure a thermostat is installed to control fan operation to off at low cold-water
temperatures.
4. If tower is equipped with two speed motors, operate at low speed to increase leaving water
temperature.
5. Cycle fans periodically to prevent ice from forming on louvers.
6. It may also be necessary to reverse fans for a short period of time to help melt ice by
forcing warm water into tower.
• De-energize the fan(s) for two full minutes before reversing.
• Reverse fan(s) no more than 2 minutes at a time (repeat as necessary). Extended
reverse operation can cause ice to form on fan blades causing an out-of-balance condition.
• If the tower is equipped with a two-speed motor, reverse only at low speed.
• On multi-cell towers, fans immediately adjacent to reversed fans should be shut off
during reversal.
• After reversal, let fan(s) stand idle 5 to 10 minutes before forward operation.
• Monitor the tower closely for unusual vibrations or sounds.
7. Frequent visual inspections and routine maintenance during sub-freezing operation is very
important and should not be overlooked.