Chiller air-conditioning system maintenance

Chiller systems provide large-capacity cooling for buildings and hotels. ITVC introduces the following maintenance activities for these systems.

This is a reference list for technicians. Perform only the tasks applicable to the equipment configuration, with energy sources isolated and in accordance with the manufacturer’s maintenance documentation.

1. Compressor maintenance

Compressor maintenance is essential to the reliability, service life and efficiency of a refrigeration system, particularly for large-capacity equipment.

The source highlights the commissioning period and wear of machine components as times requiring particular attention. It gives an indicative interval of 6,000 operating hours or one year, including lightly used equipment. The actual maintenance schedule must follow the specific manufacturer’s instructions and operating conditions. Equipment that has been idle for a long period should be inspected before restart.

Overhaul and inspection activities include:

• Check the condition and tightness of compressor discharge and suction valves.
• Inspect the compressor interior, oil condition and components for corrosion; clean the parts. Major and intermediate overhauls may involve dismantling, cleaning and replacement of the oil.
• Test HP, OP, WP and LP controls and the oil-supply components.
• Clean the compressor suction filter.
• Inspect the cooling-water system.

2. Condenser maintenance

The condition of the condenser significantly affects system efficiency, safety and equipment service life.

Condenser maintenance activities include:

• Clean heat-transfer surfaces.
• Remove accumulated oil where applicable.
• Service and adjust cooling pumps and fans.
• Remove non-condensable gases where the system design requires this.
• Clean the water basin and remove sediment.
• Inspect and replace spray nozzles and water eliminators where needed.
• Repair and repaint external surfaces.
• Repair or replace associated electrical equipment, safety devices and controls.

3. Evaporator maintenance

• Defrost the evaporator where applicable.
• Maintain evaporator fans where fitted.
• Clean the heat exchanger with the system stopped, using a suitable brush or water-cleaning method for the equipment.
• Clean the evaporator drain tray.
• Inspect and maintain measuring and control devices.

4. Expansion-valve maintenance

Periodically inspect the valve, refrigerant superheat, sensing-bulb contact and insulation, and capillary tube.

5. Cooling-tower maintenance

Cleaning the cooling tower helps improve condenser heat rejection. Maintenance includes:

• Check the fan, motor, pump and water-distribution assembly.
• Periodically clean the plastic fill.
• Remove sediment from the basin, clean it and replace the water.
• Check pump and fan operating current and the condition of the float valve.

6. Pump maintenance

• Check operation, bearings and water seals, and lubricate bearings as required.
• Check upstream and downstream pressure to identify filter blockage.
• Check electrical current against normal operating values.

7. Fan maintenance

• Check for abnormal noise and vibration.
• Inspect bearings and replenish oil or grease as appropriate.
• Clean the fan blades.