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With the summer in full swing, performing cooling tower maintenance will keep your building comfortable for all building occupants. As cooling towers use water to remove heat from a building, they are easily susceptible to damage — which is due to their design.

According to the Centers for Disease Control and Prevention (CDC), water is sprayed throughout the tower, while air is then brought through the sides to exchange heat inside a building or facility. As a crucial component to any building or facility’s HVAC operation, ensuring the cooling tower’s health is of utmost importance. Here are 4 ways to perform cooling tower maintenance. 


As your building/facility’s cooling tower utilizes water on a regular basis, conducting cooling tower maintenance on it should become common practice. You will want to inspect for a number of contaminants, including scale, sediment, and slime. To inspect, be sure to wear a face mask with a HEPA (high efficiency particulate air) filter and shut off fans before working, as SPX Cooling notes.

Furthermore, you’ll want to be aware of potential Legionnaires’ disease outbreaks. 

Legionnaires’ disease can quickly make its way through an office or facility if a cooling tower remains unkempt. This is because standing water/water buildup, combined with the air and heat within the cooling tower, creates a prime breeding ground for legionella — the bacteria that causes Legionnaires’ disease.  The Mayo Clinic notes that Legionnaires’ disease can lead to headaches, muscle aches, fevers of 104 degrees Fahrenheit and above, on top of cognitive issues.

With such harmful biological contaminants in the cooling tower environment, it’s best to have an HVAC expert take a look. Our trained technicians at Donnelly will be more than happy to assist.

Water Treatment

When performing cooling tower maintenance, another important aspect to consider is water treatment. Given that a great amount of water runs through the cooling tower on a regular basis, you’ll want to be aware of the water’s health. This is where water treatment comes into play. 

As water can be a site for contaminants and other dangerous impurities, making sure that you not only have the right filtration, but are also using the right chemicals to treat your water will protect your cooling tower and put your employees’ health at the forefront. According to Process Cooling, there are a number of filtration options — including screen filters, disc filters, sand media filters, and centrifugal separators. The outlet notes that the former and latter are the most common.

You’ll also want to make sure that the water’s hardness is being regulated. You can do this by using a softening resin or lime. The softening resin generally contains sodium ions, which, when coming into contact with water, will latch onto calcium and other byproducts and break it down — leaving no harmful residue behind.

Clean and Disinfect Tower Basin

Cooling tower maintenance also includes cleaning and disinfecting the tower basin. Per the CDC, you should use an EPA-registered disinfectant that contains chlorine. These can come in either liquid, pellet, or granular form. Look for calcium hypochlorite (Ca[OCl]2) or sodium hypochlorite (NaOCl), as the CDC notes.

Dispersant cleaning is also advised. Most likely, you will be leaving the disinfectant and dispersant in the cooling tower overnight — monitoring the FRC (free residual chlorine) levels every two hours or so. Drain after a 24-hour period.

Overall, dispersant cleaning should remove silt, scale, and residual biofilm in your cooling tower.

Descale Cooling Tower

Cooling tower maintenance also entails descaling. As noted, since cooling towers utilize water, many contaminants and biohazards can accumulate over time. With such buildup of lime, rust, scale, and more, your cooling tower will experience decreased efficiency and suffer long-term damage over time. You’ll also incur higher energy costs from an unkempt system.

In order to descale your cooling tower, you’ll have to shut off the water valve and shut off any chemical/non-chemical water treatment, alongside corresponding meters. Be advised that you should also clean any loose mud, rust, and other debris, too. Next, lower the water level to where the pump can still operate without cavitation and shut off fans.

After that, determine the appropriate amount and deposit the descaling solution. You may notice foaming and bubbling, which is a direct result of coming in contact with scale. Test pH levels and cycle the solution out of the system when complete.

Donnelly’s Commitment to Cooling Tower Maintenance

At Donnelly, we offer a strong team of HVAC technicians trained in handling various types of HVAC issues. Whether it’s cooling tower maintenance or mold remediation, you can always trust Donnelly to get the job done.

To learn more about our services and how we can help your commercial space, please visit our website and contact us today!

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