Cooling Tower Layup

6 days ago

3 min read

As the temperature drops, it’s time to start thinking about fall shutdowns and off-season protection for your cooling tower system. A proper cooling tower layup helps reduce corrosion, control biological growth, prevent freeze-related damage, and support a smoother spring startup. Without the right cleaning, disinfection, and chemical treatment, issues such as biofilm, Legionella risk, corrosion products, and trapped water can create expensive problems when the system comes back online.

Why Cooling Tower Layup Matters

Cooling tower layup is the process of preparing an open-recirculating cooling tower system for an extended shutdown or low-use period, especially when freezing conditions are possible. The goal is simple: protect the equipment, preserve system integrity, and reduce the risk of unpleasant surprises when warmer weather returns.

A well-planned layup can help prevent damage to basins, piping, nozzles, valves, and fill. It also helps control stagnant-water conditions that can encourage microbiological growth and corrosion.

Not sure if your system is ready for shutdown?

We can help you review your current program and recommend a practical layup approach for your facility.

Dry Layup vs. Wet Layup

For many seasonal shutdowns, a dry layup is the preferred approach because it removes water from the system and reduces the risk of freezing. However, a dry layup still needs proper cleaning, disinfection, and corrosion protection before the final drain. Simply opening the drain valve and walking away can leave contaminants, deposits, and untreated surfaces behind.

A wet layup may be considered when a system might need to restart during the off-season or when complete draining is not practical. In that case, the system should be treated, circulated periodically, and monitored so that chemical residuals remain in control. Because every system is different, it is important to confirm the right layup method before shutdown.

Six Steps for a Safe Cooling Tower Layup

The best layup programs begin before the final day of operation. Use the shutdown window to reduce solids, clean the system, disinfect wetted surfaces, and apply the right layup chemistry. The following steps provide a practical framework for preparing your cooling tower for the off-season.

Lower cycles of concentration before shutdown. In the week before layup, adjust the conductivity set point to increase blowdown and reduce dissolved and suspended solids in the system.
Disinfect the system. Add a bio-dispersant and an oxidizing biocide to help kill bacteria, remove biofilm, and break up microbiological fouling. Circulate for 4 to 8 hours, or as directed by your water treatment professional.
Drain and physically clean the tower. Remove remaining solids from the fill, basin, sump, strainers, and other accessible areas.
Refill and circulate. Refill the system with clean water and begin circulation so that layup treatment can reach wetted surfaces.
Add layup chemistry and biocide. Apply the appropriate layup chemical and a heavy dosage of non-oxidizing biocide. Circulate for 24 to 48 hours, or according to product and site-specific guidance.
Drain completely for dry layup. Remove water from the system, including dead legs, low points, and trapped volumes. As the system dries, pretreatment chemicals can support passivation, helping create a protective oxide layer on internal surfaces.

Don’t Overlook Stagnant Zones

Dead legs, equalization piping, drain points, headers, and other trapped volumes are common problem areas during layup. Water left behind in these locations can freeze, promote corrosion, or create stagnant conditions where microbes can persist. A thorough layup plan should identify these areas in advance and confirm how they will be drained, flushed, treated, or monitored.

Plan Now for an Easier Startup Later

A clean, disinfected, and properly protected cooling tower is much easier to bring back online when cooling demand returns. By taking the time to lay up the system correctly, facility teams can reduce the risk of repairs, minimize startup delays, and help extend equipment life.

Need help preparing your cooling tower for fall shutdown? Contact us to discuss your system, review your current layup process, or schedule support before the off-season begins.