Cooling towers

Warm condenser water sprays or distributes over fill. Air moves through (forced or induced draft). Some water evaporates, cooling the remaining water. Cooled water returns to the chiller condenser.

• Range — temperature drop of water through the tower (inlet minus outlet water).
• Approach — how close leaving water gets to ambient wet-bulb temperature.

Designers size towers around local wet-bulb extremes. High wet-bulb days limit how cold the tower can go — physics, not always a failed fan.

Open towers (process water contacts air) dominate HVAC condenser loops. Closed-circuit fluid coolers keep process fluid in a coil while spray water wets the outside — different maintenance, similar rejection idea. Crossflow vs counterflow describes air/water direction patterns.

Evaporation concentrates minerals. Blowdown removes concentrated water; makeup adds fresh water. Treatment (chemical or alternative programs) fights scale, corrosion, and biological growth. Neglect produces plugged fill, bad approach, and Legionella risk — treat seriously.

Towers need safe ladders, rails, and LOTO for fan work. Falling hazards and rotating equipment are real. Keep discharge air from blasting parking lots with mist when possible.

Belts, gearboxes, and VFD tuning set airflow. A tower with half its cells offline on a design day will make every chiller miserable. Stage cells intentionally.

Clogged nozzles create dry spots and poor range. Collapsed fill reduces area. Schedule inspections; document with photos for owners who only fund repairs after a hot Friday.

Below-freezing ambient needs basin heaters, bypass modes, or drained strategies per design. Ice on fans is a safety and mechanical hazard. Follow the plant’s winter sequence — do not invent one during a freeze warning.

Sudden makeup spikes can mean blowdown stuck open or a basin leak. Meter readings belong in the same binder as chiller logs.

Multi-cell towers need equalizer piping so basins share level. A dry cell sucking air while another overflows is a piping/balance problem, not a random pump curse.

### Field memory hooks

Write the key temperatures, flows, or mode checks for this topic on your job notes. Teach the helper beside you to repeat the layered order aloud before tools come out. Most callbacks shrink when the first visit follows a written order instead of a parts guess.

When OEM data exists — capacity tables, wiring diagrams, water-flow charts — photograph the rating plate and the page you used. Future you (or the next tech) should not have to rediscover the same facts under pressure.

Situation. Chiller high-pressure alarms on a 95°F / muggy afternoon. Tower fan VFD capped at 40% from a noise complaint; basin strainer clogged; approach much worse than commissioning.

What to think. Heat rejection is intentionally limited. Restore fan capacity, clean strainers/fill path, review treatment.

Conclusion. Fix the tower before rebuilding the compressor.

### Teach-back for the helper

Before leaving the topic, have the helper explain in their own words: what is normal, what is measured first, and what must never be skipped for safety. If they cannot teach it back, review the main “How it works” blocks again with a sketch on paper.

Connect this lesson to the previous one and the next one as a chain. Field skill is sequence memory — not isolated trivia. Keep OEM charts and job photos with the work order so the next visit starts smarter.

### Common measurement habits

Use the same meter locations every time so readings compare day to day. Steady the system before judging pressures or temperatures — mid-shift and mid-defrost lie. Write ambient conditions on every note page.

If a reading disagrees with the control display, believe the calibrated handheld until sensors are proven. Controls cannot fix what they cannot see accurately.

### Safety and professionalism

Apply LOTO where energy can hurt you. Wear eye protection around refrigerants, chemicals, and coil fins. On roofs and at window units, respect fall hazards. Explain findings to the owner without jargon soup — clear next steps beat impressive vocabulary.

Dispose of oil, filters, and refrigerant legally. Cutting corners on recovery or tower chemicals is not “saving the customer money”; it is transferring risk.