Once outside air temperatures fall down to around 50°F, it’s time to start winterizing your commercial cooling tower and other HVAC equipment. Winterizing your cooling tower is important because it helps to prevent freezing, corrosion, scale and biological growth, as well as ensuring a smooth system start-up in the spring.
If your operation requires HVAC systems to continue running through winter, make sure that your cooling tower’s heat trays and basin heaters are working properly before cold weather hits, to prevent frozen pipes and ice formation in the cold water basins. If you’re going to shut your cooling systems down for the winter, keep reading!
If you’re looking for guidance on industrial cooling towers, check out this blog about preparing your industrial cooling systems for winter.
Before Shutdown
There are a few steps you need to take in the days before your commercial cooling tower shutdown:
Increase The Blowdown
In the last couple of days before shutdown, increase the blowdown to reduce solids in the system.
Increase The Biocide
The day before shutdown, double the amount of biocide and recirculate for at least 4 hours.
Shutdown
Follow these steps to complete your commercial cooling tower shutdown:
Clean Nozzles – Crossflow Cooling Tower
If you have a crossflow cooling tower, you will need to sweep and clean the hot water distribution basin and nozzles while the tower is operating.
Clean Nozzles – Counterflow Cooling Tower
If you have a counterflow cooling tower, you will need to remove the drift eliminators to observe the nozzle performance, while the tower is running. If the nozzles are clogged, turn off the water flow to clean the nozzles.
Drain and Clean Tower
Drain down the tower and wash out the tower fill and sump.
Clean Strainers
Remove and clean all strainers, then reinstall them.
Isolate and Shut Off Controllers
Isolate the cooling tower controllers without unplugging from the power source. DO NOT unplug the controller power source. Next, shut off the controller.
Refill Tower
Refill the tower system.
Vent Chillers
Vent all chillers to ensure that they are completely filled with water.
Close Vents
Close all the vents.
Layup Water Treatment
Add layup water treatment to the tower and re-circulate the system for a minimum of 8 hours using ALL pumps.
Drain System
Drain the system completely from the lowest point.
Clean and Flush Pumps
Clean and flush the chemical feed pumps. Place the suction line (foot valve) of each pump in water, and operate the pump to completely flush it of treatment water. Leave the foot valve out of the chemical tank for the off-season.
Open the Chiller and Brush Tubes
Open the chiller condenser end bells and brush the tubes, to avoid stagnant water building up in the chiller. Store the chiller for the off-season with the end bells removed, so that air can flow through the tubes freely.
Your winterization process is now complete! Remember the following 3 tips to keep your commercial cooling tower in top shape over the winter for a successful spring startup!
- Repair or replace any parts damaged by corrosion.
- Treat all surfaces with a biocide.
- Leave all drain and bleed valves open for the off-season.
Winter Cooling Tower Maintenance Tips
If your operation requires you to continue running your commercial cooling tower during the winter, follow these tips to keep your tower in good working condition throughout the season:
Remove Scale
Corrosion buildup can negatively affect the rate of heat transfer, so it’s good to reduce the likelihood of corrosion by removing scale buildup in the tower.
Routine Visual Inspections
When it’s colder outside, regular visual inspections of your cooling tower should be made – and more often if the weather is particularly cold.
Remove Snow and Ice Buildup
Make sure the fan blades on your cooling tower are kept free of snow and ice, as even a small imbalance caused by snow or ice buildup can be enough to reduce the efficiency of the fan. In extreme cases the blades could even break from unbalanced rotational forces.
Add Glycol
Depending on the temperatures, cooling towers should have a certain amount of glycol in them. By reducing the temperature at which the liquid in your cooling tower freezes, you can protect any parts that are constantly exposed to water. Fill material can be unfrozen relatively easily, but other parts such as spray nozzles can easily break if frozen.
Run Your Water Pump Continually at Cold Temperatures
Running your water pump continuously will draw heat from the building it’s connected to, so the water entering the tower will be warmer than the water that is already present in the tower. The heat pump itself will also generate heat, further reducing the risk of your cooling tower freezing.
Maintain a Consistent Heat Load
It’s critical to maintain a consistent heat load so that the water in your cooling tower doesn’t ice over.
Implement a Bypass for Low Heat Load
If you don’t maintain your heat load and ice begins to form, you can bypass operating water and direct it to the cold water basin. Do not let the water flow back up again until it is at the target heat load temperature.
Maintain Minimum Water Flow Rate
Maintain or exceed your cooling tower’s minimum water flow rate. It’s important to keep the water flowing uniformly so that your tower doesn’t freeze over.
Match Cells to Flow
If your water flow rate does go below the minimum, an equivalent number of cells should be diminished, so that the flow surpasses the minimum per cell.
Control Airflow
Maintain consistent airflow to keep the water temperatures above freezing throughout the fill of your cooling tower cells.
Utilize Basin Heaters
Use basin heaters to avoid freezing at the basin outlets during reduced heat load periods or long shutdowns.
Winterizing your commercial cooling tower may sound tedious, but it’s a critical process to avoid damaging your tower. This, as well as following our winter maintenance tips, will ensure a smooth startup in the spring.
Reach out to your HVAC tech today to schedule your cooling tower winterization!