Chiller Maintenance Checklist
A maintenance checklist and schedule for air-cooled, water-cooled, and process chillers — covering compressor checks, condenser maintenance, refrigerant management, F-Gas compliance, and efficiency monitoring for commercial and industrial cooling systems.
What is a chiller?
A chiller produces chilled water for air conditioning, process cooling, or data centre cooling. It works by evaporating refrigerant to absorb heat from the chilled water loop, then rejecting that heat via an air-cooled or water-cooled condenser. Chillers are among the highest energy-consuming assets in a commercial building, making planned maintenance essential for both reliability and efficiency.
Air-cooled chillers reject heat directly to ambient air via fin-and-tube condenser coils and fans. They are self-contained, require no cooling tower or condenser water circuit, and are commonly installed on rooftops or in plant rooms. Well-suited to small and medium commercial buildings, they are simpler to commission and maintain than water-cooled alternatives.
Water-cooled chillers reject heat to a cooling tower via a condenser water loop, delivering better efficiency at full load. They are the typical choice for larger commercial buildings and data centres where capacity and running cost matter. They require more infrastructure — cooling tower, condenser water pump, and water treatment — but deliver lower energy costs over time. Process chillers serve industrial, pharmaceutical, and manufacturing applications with tighter temperature tolerances and often continuous operation requirements, making a structured planned chiller maintenance schedule especially critical.
Typical Chiller maintenance checklist
A practical starting point for planned preventive maintenance. Always refer to the manufacturer's O&M manual and site-specific requirements.
Visual Checks
- Inspect for refrigerant leaks — check joints, schrader caps, oil staining and brazed connections
- Inspect water-cooled condenser tubes for fouling, scaling and tube end erosion
- Check compressor oil level, colour and acidity (TAN) — log against trend
- Inspect starter panel, contactors, terminations and check star/delta or VSD operation
- Check anti-vibration mounts, pipework supports and refrigerant pipe insulation
- Inspect evaporator and condenser for tube fretting or vibration damage (water-cooled)
Functional Checks
- Check chilled water supply and return temperatures against design ΔT
- Verify condenser water temperatures (water-cooled) or ambient conditions (air-cooled)
- Record refrigerant suction and discharge pressures
- Calculate and verify superheat and subcool against manufacturer target range
- Check compressor operating current against full load amps (FLA) on each phase
- Verify chilled water flow rate against design and confirm CHW pump operation
- Review BMS trending data — flag drift in pressures, currents, ΔT and run hours
- Check expansion valve operation (TEV/EEV) and superheat stability
Cleaning & Housekeeping
- Clean air-cooled condenser coils with appropriate fin-friendly coil cleaner
Safety Checks
- Test all safety controls: HP/LP cutouts, flow switches, freeze stat and oil safety
Record Keeping
- Update the asset's F-Gas logbook with charge, top-up, leak test and engineer's cert
- Record kW input vs cooling load and calculate kW/ton or COP for the visit
Typical maintenance frequency
Suggested intervals for chiller maintenance. Actual frequencies should follow manufacturer guidance and site-specific risk assessments.
Monthly
- •Log operating parameters (pressures, temps, currents)
- •Check for leaks and oil staining
- •Clean air-cooled condenser coils where dust loading is high
Quarterly
- •Full operating check under design load
- •Test safety controls and freeze protection
- •Oil analysis on large chillers (>250 kW)
Every 6 Months
- •F-Gas leak check on systems ≥50 tonnes CO₂e
- •Inspect VSD or starter for harmonics/insulation issues
- •Review chilled water quality and inhibitor levels
Annually
- •Comprehensive chiller service
- •F-Gas leak check and logbook update (5–50 t CO₂e systems)
- •Eddy current test of condenser tubes (water-cooled)
- •Compressor oil and filter change
- •Electrical thermography of panel and motor terminations
Common faults and issues
Issues to be aware of when maintaining chiller equipment.
Safety and compliance notes
Key safety considerations for chiller maintenance. This is general guidance only — always follow OEM instructions, statutory requirements, and your organisation's safe systems of work.
Managing Chiller documentation with PM Assist
PM Assist helps FM and building operations teams search their O&M manuals and building drawings in seconds. Upload your chiller documentation and ask questions like “What is the rated cooling capacity?” or “When was the last F-Gas leak check?” — and get source-cited answers instantly.
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