Cejas Cooling & Construction

Between Chillers and Startups: The Cold Truth Beneath the Switch

Starting up a chilled-water system isn’t like flipping a light switch. It’s more like waking a sleeping giant that likes its coffee iced and its pressure stable. These beasts don’t forgive carelessness, and they sure as hell don’t forget improper maintenance. You treat them right, they hum like poetry. Screw it up, and you’re looking at a very expensive metal tantrum.

General Start-Up Rituals

Every chilled-water system has its own mood, but the start-up dance has universal steps:

  • Inspect for leaks, electrical faults, and mechanical issues.
  • Ensure proper water flow and system cleanliness.
  • Check refrigerant levels and oil charge.
  • Verify sensor and control operation.
  • Power up and monitor system pressures, amperage, and temperatures.

It’s not just turning it on. It’s a full diagnostic warm-up—ironically, for a machine built to cool.

Scroll, Reciprocating, Screw, and Centrifugal: Each With Its Quirks

  • Scroll Compressors: Compact and quiet. Check for oil level, crankcase heater status, and rotation direction. Watch suction pressure during ramp-up.
  • Reciprocating Compressors: Mechanical hearts. Prime the oil pump. Watch discharge temps like a hawk.
  • Rotary Screw Compressors: High-capacity workhorses. Monitor slide valve position, oil separator pressure differential, and VFD ramp rate.
  • Centrifugal Compressors: Elegant giants. Start slow. Balance the oil system, verify pre-rotation vane settings, and keep eyes on surge zones.

Scroll and Reciprocating System Operation & Monitoring

Once running, your scroll or recip system needs:

  • Suction/discharge pressure logging.
  • Oil return verification.
  • Vibration and noise checks.
  • Discharge superheat and subcooling monitoring.
  • Condenser and evaporator approach temperature trending.

Let them run wild without oversight and you might miss the subtle signs of impending failure.

Maintenance Isn’t a Chore—It’s Survival

At least annually:

  • Electrical: Tighten terminals, check contactors and relays, test overloads and insulation resistance.
  • Mechanical: Inspect bearings, seals, and couplings. Lubricate what needs loving.

For water-cooled systems:

  • Clean strainers and Y-filters.
  • Inspect tube bundles for fouling.
  • Test and treat water chemistry religiously.
  • Check condenser water flow and temperature differential.

Large Centrifugal Chillers: Cool with Complexity

Operation here is all about stability. These chillers hate rapid changes:

  • Monitor surge conditions.
  • Maintain oil pressure differential.
  • Track condenser and evaporator approach temps.
  • Balance flow and load evenly.

Low- vs High-Pressure? Low-pressure units often use refrigerants like R-123. They demand vigilance around vacuum leaks and purging. High-pressure units are more robust, but still sensitive to superheat and flow balance.

Absorption Systems: Chemistry Over Compression

Start-up involves:

  • Ensuring proper lithium bromide concentration.
  • Purging non-condensables.
  • Charging water loops.
  • Bringing heat source online (steam, gas, or hot water).
  • Monitoring crystallization risk zones.

Maintain them by:

  • Testing solution concentrations.
  • Inspecting pumps, seals, and nozzles.
  • Cleaning internal heat exchangers.

Purge systems on these units? They’re critical. Keep them clean and operational, or you’ll end up with non-condensables choking your performance.

Troubleshooting and Safety: The Cold Reality

Chillers whisper their problems. Vibration, temperature drift, oil analysis—these are your translators. Have safety protocols in place:

  • Lockout/tagout.
  • Pressure release procedures.
  • Chemical handling standards.

Valves That Matter

Know your valves:

  • Ball Valves: Quick shutoff.
  • Butterfly Valves: For large flow control.
  • Balancing Valves: To ensure proper distribution.
  • Check Valves: To prevent reverse flow.
  • Isolation Valves: To segment system sections during service.

You can feel it—that quiet confidence when a chiller hums to life after a proper start-up. It’s mechanical grace. It’s cold perfection. And it doesn’t come from luck. It comes from understanding, from discipline. This isn’t just maintenance. It’s ritual. It’s respect. And if you’ve made it this far, you’ve earned a seat in the mechanical chapel.

Welcome to the gospel of chilled water.

Between Mist and Metal: A Closer Look at Cooling Towers

There’s something ritualistic about the steady breath of a cooling tower—a metal lung exhaling warmth from the heart of a building. Where chillers hunker behind locked mechanical doors, cooling towers stand exposed, sky-bound, open to the elements, and unapologetically industrial. They don’t pander to aesthetics. They work.

Why the Tower?

Cooling towers serve a singular purpose: they reject heat. Specifically, they remove heat from chilled-water systems by dissipating it into the atmosphere. Chillers pass heat to condenser water, and the cooling tower cools that water so it can do it all over again. Round and round, heat in, heat out.

Understanding Approach and Range

This gives you the tower’s responsibility in raw thermal exchange.

The Tower Types

  1. Crossflow: Water flows downward across air drawn in horizontally.
  2. Counterflow: Air is pulled upward against downward-flowing water—compact and efficient.
  3. Induced draft: Fans draw air up through the tower, improving flow and efficiency.

The Fill and Why It Must Stay Wet

The fill increases the contact surface between air and water. Keep it wet, keep it working. Dry fill equals lost efficiency.

Both increase evaporation, the true heat rejection hero.

Air and Water Flow: Dance Partners

Two primary flow patterns:

Each has trade-offs in size, noise, and maintenance.

What Holds It All Together?

Materials vary by budget and durability:

Behind the Blades: Gear Drives and VFDs

Cooling tower fans often use:

The Sump, Makeup, and Blowdown

Water balance is delicate. Too many solids, and the tower starts turning into a sculpture of calcified neglect.

Pumps: Centrifugal Powerhouses

Seals keep the water where it should be. Mechanical seals, lip seals—every one matters.

Vortexing and Cavitation: The Enemies Within

Mixing vs. Diverting Valves

Corrosion, Scale, and the Weird Science

Clean Water, Better Tower

Keep the system clean, and it breathes easy. Let it clog, and you’re staring down high head pressures and low efficiency.

Cooling towers aren’t flashy. They’re loud. Wet. Exposed. But they’re the lungs of chilled water systems. They don’t ask for much—just good water, a little maintenance, and the occasional pat on the side when they save your compressor from meltdown. Respect the tower. It’s the unsung hero in a world built on heat.