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Key Terms to Understand Regarding Cooling Towers

About Cooling Towers

For those without a background in HVAC, some of the jargon used when discussing cooling towers can seem like a foreign language. Part of what we do at Cooling Tower Experts is teaching customers about their towers and cooling systems. We’ve learned over the years that in order to fully comprehend how cooling towers work, we must first focus on defining the confusing and sometimes ambiguous terms. By no means is this an inclusive list with every term you may hear in cooling tower discussions. But, it is a good starting point for understanding the basics.


Different Parts and Pieces within a Tower


Focusing on the different working parts in a tower is a great first step. Cooling towers can be broken down into a few core components. Keep in mind that there are different types of towers, so functionality between those will differ.  


Cold Water Basin

Somewhat self-explanatory, this houses cold water generated during the cooling process before it exits the tower. This basin is often referred to as a “collection basin” as well. Upon exiting the tower, the cooled water generally gets distributed into the sump or pump suction line. It’s important that this water is disposed of properly, so avoiding overflows is crucial. Many implement level control applications to prevent the water level from reaching a dangerous level.



Likely the most commonly used word when talking about cooling tower functionality is fill (or fill media). The fill is the part of the tower in which heat exchange or heat transfer occurs. It can be made of various materials, including PVC or wood. A fills main responsibility is increasing the amount of surface area as well as the length of contact time between the two flows within a tower (water and air). Doing so allows for a more efficient cooling process to occur.


Drift Eliminator

To understand the purpose of a drift eliminator, it is critical to first define the term “drift.” Drift refers to water that leaves the cooling tower via the air exhaust stream. Most water leaving cooling towers does so through the collection basin. However, some droplets do escape in that exhaust stream. These droplets can contain contaminants and bacteria. So, it is crucial to keep drift levels as low as possible. Drift eliminators do just that. They force air leaving the cooling tower to do so through a series of passages. This process helps to remove any water droplets as the air travels.


Fans (and the Different Types Used)


Everyone knows how a fan generally functions. Cooling towers use fans in a few different ways, depending on the type of tower. Some have fans at the top, which pull the air upwards during the cooling process. Others contain a blower fan which instead blows air into the tower rather than relying on a natural draft. When discussing fans, the term Fan Pitch is commonly used. You measure fan pitch in degrees, and it refers to the angle at which the fan blades operate during rotation.


Other Key Terms to Understand


In addition to the various components within a cooling tower, there are several other commonly used terms to note. The first two relate to airflow and help distinguish between the two main types of cooling tower functionality.




In crossflow cooling towers, air flows horizontally across the fill, which means it crosses the vertically falling water at virtually a 90-degree angle. The flows of water and air run perpendicular to each other, giving it its name.




Counterflow towers send air upwards vertically as the water falls in the opposite direction downwards. In this case, the flows of air and water run concurrent to one another, rather than perpendicular.


The last few terms refer to the temperature of the water within a tower throughout the cooling process.


Hot Water Temperature (HWT)


Water entering a cooling tower is hot (thus needing to be cooled). How hot the water is when it arrives is known as the Hot Water Temperature.  


Cold Water Temperature (CWT)


Once the water goes through the heat exchanging process in a tower, the water temperature in the collection basin is known as the Cold Water Temperature.


Now, not all cooling towers are created equal. Determining the best option for your system depends on the Heat Load it requires. Heat load refers to the amount of heat removed from the water during circulation through the cooling tower. Measured in BTU/hour, you calculate heat load with the following formula:


BTU/hr = GPM x 500 x (HWT – CWT)


It is important to note that GPM refers to the water flow rate (measured in gallons per minute).


No Need to Be a Cooling Tower Expert – We Can Help.

Becoming an expert in the realm of cooling towers takes years of industry experience, product knowledge acquisition, and work in the field. We know that is not feasible for all companies, so we strive to serve as the expert for our customers. We provide a variety of services, which include installation, training, and maintenance. Whether you choose to be hands-on throughout your project or want us to handle everything from start to finish, we are here to help!  Contact us today to begin your next cooling tower project.