How to Winterize Water Cooling Towers

As we approach cooler weather, it’s time to begin preparing for proper shutdown of your cooling systems. Of course, we recommend general maintenance throughout the year to ensure your water cooling systems are running smoothly, but it’s especially important to prioritize winterization tasks to avoid costly problems in the future. Delaying or ignoring these critical actions can cause issues such as unsafe working conditions, broken equipment, higher energy costs, or code violations. 

Disclaimer: The Cooling Technology Institute provides guidelines for winter operation of industrial water cooling towers, and represents the consensus of both manufacturers and owner/operators throughout the industry. However, we would like to emphasize that these are recommendations only and are not necessarily fail-safe.

Recommended Winterization Techniques for Cooling Towers

It goes without saying that proper winter operation of any water cooling system is heavily reliant upon operator inspection and control. A high degree of attention is essential for efficient performance during cooler months. When falling ambient dry bulb temperatures reach 45° F, normal operating procedures should be suspended and an appropriate winter operational plan should be implemented. Below are several recommendations for the winterizing of water cooling towers.

Induced Draft Counterflow Cooling Towers

When the ambient temperature ranges from 20˚ to 45˚ F, a visual inspection of the cooling system should be made every two to four hours — especially in the louver and fill areas. Cooling towers in environments where the air temperature falls below 20˚ F should be visually inspected every two hours. Cold (return) water temperature from the cooling tower should be monitored continually and not allowed to drop below 50˚ F. 

To guard against ice formation, adhere to the following measures: 

• Maintain plant heat load at the highest possible level
• Maintain circulating water flow at the highest possible rate
• Regulate airflow to control ice formation

Induced Draft Crossflow Cooling Towers

For Induced Crossflow Cooling Towers, the recommendations are similar to those advised for Induced Counterflow Cooling Towers. However, this type of cooling tower can be equipped with one or more of the following accessories to improve winter operation:

• Longitudinal dam (weir) in hot water basins
• Larger orifice nozzles on outboard row(s)
• Ice retainer bar on top inboard edge of louvers
• Variable-speed fan motors with reversing feature 
• Hydraulic or electric-driven variable speed fans with reversing feature
• Total hot water bypass
• Heavy-duty fill bars and fill hangers

READ MORE: Purchase Chapter 4 of the CTI Manual for additional recommendations

Natural Draft Counterflow Cooling Towers

As the ambient dry bulb temperature falls below 45˚ F, normal operating procedures should be halted. This is especially important for natural draft cooling systems because, as ambient air temperatures drop, the air velocities increase which elevates the probability of ice formation. A visual inspection of the cooling system should be made every two to four hours — especially in the louver and fill areas — when the ambient temperature reaches 20˚ to 40˚ F. Cooling towers in environments where the air temperature falls below 20˚ F should be visually inspected every two hours. Cold (return) water temperature from the cooling tower should be monitored continually and not allowed to drop below 50˚ F.

Natural Draft Crossflow Cooling Towers

For Natural Crossflow Cooling Towers, the recommendations are similar to those advised for Natural Counterflow Cooling Towers. However, this type of cooling tower can be equipped with one or more of the following accessories to improve winter operation:

• Total hot water bypass
• De-icing ring with large capacity nozzles
• Ice retainer bar on top inboard edge of louvers
• Ice screens behind louvers
• Heavy-duty fill bars and fill hangers

READ MORE: Purchase Chapter 4 of the CTI Manual for additional recommendations

Additional Cooling Tower Winterization Information

Although these recommendations are directed toward industrial cooling towers, the principles are valid — for the most part — when winterizing HVAC cooling towers. For more information regarding proper winterization techniques for cooling towers, browse our selection of papers on winter operation or purchase our chapter on winterization.