Cooling towers play an important role in a commercial HVAC system, and proper cooling tower maintenance can help ensure their efficiency and longevity. In this article, we’ll talk about when you should expect to have your cooling tower serviced by a professional, and we’ll mention a few things that can cause poor cooling tower function if left unmaintained.
Cooling Tower Basics
Cooling towers work in tandem with water-cooled chillers. A chiller is responsible for removing heat from an area in a building, and it adds that heat to a supply of water. That heated water is pumped to the cooling tower, which sprays the water through a cool air supply. The air absorbs some of the heat, and then the cooled water collects in the bottom of the tower and makes its way back to the chiller. In evaporative cooling towers, the water is in a closed loop and runs through a series of small tubes in the cooling tower to release heat.
Why Service a Cooling Tower?
The main reason to service a cooling tower is to get the most value out of the equipment you’ve purchased. A well-functioning cooling tower can also lower HVAC energy consumption in your commercial building. A cooling tower isn’t cheap, and it needs regular maintenance to perform to its full potential. Lack of maintenance can shave years off the life of your cooling tower and cause expensive repairs and premature replacement.
While it’s one of the most important things to maintain, cooling tower maintenance isn’t necessarily on the top of the list. Sometimes, other equipment like chillers take the attention of the maintenance team. Chillers also use much more energy than cooling towers, so some maintenance teams may spend more time working on chiller efficiency at the expense of improving cooling tower efficiency.
Effects of Poor Cooling Tower Maintenance
A poorly maintained cooling tower affects the whole system. Cooling towers get dirty. Located on the roof, they are open to dirt, pollen, insects, bird droppings, and anything else that can get swept up into the air. In addition to this, evaporating water in the tower leaves behind magnesium and calcium scale buildup. Rust, scale, and dirt can prevent cooling towers from cooling water effectively.
Dirty cooling towers also give the Legionella bacteria a home to grow. As water in the tower turns to mist, it can carry the bacteria and infect people nearby. Maintenance teams will use protective equipment to minimize health risks during cleaning. But, if you have a particularly dirty cooling tower, anyone on the roof walking close enough to the tower may be in danger of inhaling mist or spray with Legionella.
Various states and cities have requirements for water testing to limit the spread of Legionella. For example, New York requires cooling tower owners to take a general bacteriological sample every 30 days and a Legionella culture sample at least every 90 days. ASHRAE Guideline 12 provides detailed information for bacterial testing and control.
For these reasons, in addition to maintenance and inspections, we also suggest a robust water treatment plan for your cooling tower. Effective water treatment can virtually eliminate deposit build-up as well as prevent Legionella from becoming a problem. At Spaeder, we offer water testing and treatment for minerals, PH levels, as well as Legionella.
What is Cooling Tower Fill and When Should it be Replaced?
Cooling tower fill facilitates heat transfer as it allows incoming warm water to disperse and mix with cool air. The material is designed to increase the surface area and contact between air and water. It looks like a block of honeycomb material with hundreds of channels for water to run through. If you have an open cooling tower design, you can see the fill directly on the sides of the tower.
With good maintenance, you shouldn’t have to replace the fill for at least 10 to 15 years. However, scale buildup on fill is common, so you’ll need to have professionals carefully clean the fill with each annual or semi-annual maintenance. Cooling tower fill can have small or large channels depending on the application. Generally, the dirtier the water, the larger the channels to minimize buildup and clogs.
When Do You Need Cooling Tower Maintenance?
There are a few things your building maintenance crew can do each week or month. These include checking for anything out of the ordinary like loud noises or vibrations coming from the pumps and motors, checking screens for debris, checking belts for wear and tear, and treating the chemical composition of the water.
More in-depth cooling tower maintenance happens every six to twelve months depending on the condition of your water and the load on the cooling tower. It’s important to bring in a professional cooling tower maintenance team for this. Annual maintenance often requires a technician to get inside the unit through manhole access points. The power to the unit must be shut off and the water flow halted or redirected to a backup, as well.
A cooling tower maintenance team will start by removing screens, fill, and eliminators to clean them off. They will do a full cleaning of the inside of the cooling tower and remove any buildup of scale or sludge. They’ll also inspect motors for wear and grease them up. Cooling towers can collect a lot of dust and scale, so you don’t want to neglect a full clean and inspection of the cooling tower each year.
Other Ways to Improve Cooling Tower Operation
Besides regular maintenance, there are other ways you can get more life out of your cooling tower. For example, a coat of epoxy to the basin can reduce corrosion and prevent leaks. You can have this done later in the system’s lifetime and get more years out of the equipment, as well.
You can also get a filtration system that constantly circulates the water in the basin and prevents some of the buildup of grime and debris. Instead of collecting at the bottom, dust and grime would get swept off to the filtration intake and filtered out. The clean water is then pumped back into the system. Of course, adding a filtration system like this requires an additional cost.
Ensure Proper Cooling Tower Maintenance
When was the last time your cooling tower had a full service? Our technicians have years of experience in all types of commercial cooling systems in the Northeast and can help you get the most out of your equipment. Contact an industry specialist today to schedule a cooling tower inspection or cleaning.