How Do Cooling Towers Work with Chillers?

In industrial and commercial environments, maintaining optimal temperatures ensures equipment reliability, process efficiency and occupant comfort. Facilities such as data centres, manufacturing plants, hospitals and office complexes all rely on robust cooling systems to keep operations running smoothly. At the heart of many of these systems are chillers and cooling towers – two components that work together to reject unwanted heat from buildings or processes.

But how do cooling towers and chillers work together, and why is their relationship so important? Understanding how a chiller works with a cooling tower is essential for facility managers, HVAC engineers and plant operators who want to optimise performance, reduce energy consumption and extend equipment lifespan.
In this guide, we’ll explain how each system operates and how they integrate into a unified, efficient cooling solution.

A chiller is a key component in many industrial cooling systems. Its primary function is to remove heat from a building, process or equipment by circulating a chiller fluid, typically water or a water/glycol mixture, through a closed-loop system. The heat absorbed by this fluid is then expelled to the environment, ensuring temperatures remain controlled and stable.

There are two main types of chillers:

• Air-cooled chillers dissipate heat directly into the ambient air using fans and coils
• Water-cooled chillers transfer heat into a secondary water loop, which is then dissipated by an air-cooled chiller or cooling tower, making them highly effective for larger-scale or high-demand applications.

For more insight into fluid choices, see our guide on why glycol is used in chillers.

A cooling tower is a heat rejection device used in HVAC systems to remove excess heat from water that has absorbed energy during a cooling process. It plays a vital role in water-cooled chiller systems by cooling the water that circulates through the chiller’s condenser, enabling the system to operate efficiently.

The basic operation of a cooling tower relies on the principle of evaporative cooling. Warm water from the chiller’s condenser enters the cooling tower and is distributed over fill media to increase surface area. Air is then drawn or forced through the tower, causing a small portion of the water to evaporate. Some of the water evaporates, absorbing heat, and cools the remaining water, which is then recirculated.

Types of Cooling Towers

Cooling towers come in several configurations, some examples are listed below:

• Open-circuit (wet) cooling towers: these systems allow direct contact between air and water, enabling heat transfer primarily through evaporation. They are widely used in industrial and HVAC applications due to their high cooling efficiency.
• Closed-circuit (dry of fluid) cooling towers: the process fluid circulates through a closed coil. Heat is removed by air flow and/or water sprayed over the coil, with evaporation assisting in cooling. These systems reduce contamination risk but may be less efficient than open-circuit towers, especially in dry mode.

Cooling towers are also classified by airflow method:

• Mechanical draft towers use fans to force or draw air through the tower.
• Natural draft towers rely on natural convection and are generally used in large-scale power plants,

Together with chillers, cooling towers maintain stable temperatures in mission-critical environments.
 

How Do Chillers and Cooling Towers Work Together?

In a water-cooled cooling system, chillers and cooling towers operate as an integrated unit to efficiently manage heat. While each plays a role, their combined function is what enables reliable temperature control in demanding settings.