Cooling Tower Performance Check: Step-by-Step Maintenance Checklist for Maximum Efficiency

Cooling Tower Performance Check: Step-by-Step Maintenance Checklist for Maximum Efficiency

Cooling towers are critical to HVAC systems, industrial process cooling, and power plants. A routine cooling tower performance check helps maintain thermal efficiency, reduce energy costs, prevent downtime, and extend equipment life. This Blog gives a practical knowledge — including measurements, inspection items, water-treatment tips, and recommended frequencies.

Why performance checks matter

- Restore lost capacity caused by fouling, scaling, or biofilm

- Reduce energy costs by ensuring fans and pumps run efficiently

- Prevent corrosion and mechanical failure with early detection

- Improve water usage and reduce makeup water through proper cycles of concentration

Key performance metrics (what to measure)

- Range = Hot water inlet temp − Cold water outlet temp

- Approach = Cold water outlet temp − Ambient wet-bulb temp

- Effectiveness = Range ÷ (Hot water inlet temp − Wet-bulb temp)

- Cycles of concentration = Conductivity of circulating water ÷ Conductivity of makeup water (or estimate via TDS)

- Flow rate (gpm or L/s), fan speed (rpm or VFD frequency), and power consumption (kW)

Step-by-step cooling tower performance check (quick checklist)

Daily/Shift

- Visual check for leaks, unusual noise, or visible scaling

- Verify strip chart/SCADA values for temps and flow

- Check makeup water level and chemical feed alarms

Weekly

- Record inlet and outlet water temperatures and ambient wet-bulb

- Inspect drift eliminators and distribution nozzles for clogging

- Check pump operation, suction/discharge pressures, and strainers

Monthly

- Measure conductivity/TDS and adjust blowdown to maintain target cycles of concentration

- Inspect fill media for fouling or deformation; clean if necessary

- Check fan belts, bearings, motor amps, and vibration levels

Quarterly

- Perform thermal performance test: measure range, approach, and compare to baseline

- Inspect structural components (cold-water basin, casing, louvers) for corrosion or damage

- Test chemical treatment program effectiveness and biofouling control

Annual

- Drain and clean tower basin and fill, deep clean nozzles and drift eliminators

- Inspect gearbox, couplings, and motors; replace worn parts

- Consider professional thermal performance testing and balancing

How to perform a thermal performance test (practical steps)

1. Stabilize system: run the tower under normal load for at least 30–60 minutes.

2. Measure ambient wet-bulb temp with a reliable sling or electronic hygrometer.

3. Record inlet (hot) and outlet (cold) water temperatures at steady state.

4. Confirm circulating flow rate via flow meter or pump curves.

5. Calculate range, approach, and effectiveness. Compare to design or baseline.

6. If approach is too high (small difference between cold water and wet-bulb), investigate airflow, fouled fill, or reduced flow.

Common issues and fixes

- High approach (poor cooling): check airflow (fan/blades), fouled fill, restricted drift eliminators, or low water flow.

- Reduced range (less heat removed): check for scaling, biofilm, or wrong nozzle spray pattern.

- High cycles of concentration causing scaling: increase blowdown frequency or improve softening and antiscalant dosing.

- Vibration/noise: fan imbalance, bearing failure, or misaligned coupling — shut down and inspect immediately.

Water treatment basics

- Maintain target conductivity/TDS and alkalinity to control scaling

- Use biocides and periodic cleaning to control biofilm and legionella risk (follow local health regulations)

- Monitor corrosion inhibitors if system contains mixed metals

Q: How often should a cooling tower be inspected?

A: Basic visual checks daily; detailed checks monthly; full cleaning and inspection annually.

Q: What is a good approach temperature?

A: A well-performing cooling tower typically has an approach of 3–7°C (5–12°F), depending on design and wet-bulb conditions.

Q: How do you improve cooling tower efficiency?

A: Clean fill and nozzles, ensure proper airflow, maintain correct water chemistry, balance cycles of concentration, and repair mechanical faults.