Cooling System Maintenance
Maintenance Information for Liquid Chillers and Heat Exchangers
Preventive maintenance procedures should be performed regularly to keep the chiller system clean and well-maintained. In air-cooled chillers, any dust or dirt that accumulates on the condenser coil will insulate the condenser and reduce the transfer of heat from the refrigerant to the air. A dirty condenser also forces the compressor to work much harder than it should, which increases energy consumption and potentially shortens the life of the condenser. Air-cooled condensers should be vacuumed clean or chemically treated on a regular basis to remove dust and dirt particulate. A filter also can be used on the condenser inlet to prevent clogging.
In water-cooled systems, tube-side scale buildup acts as an insulator, reducing the system’s ability to transfer heat and overworking the system components. Process cooling and condenser water lines should be flushed periodically to remove any rust or other dirt particulate that might have accumulated. Water-cooled condensers should also be back-flushed with a diluted concentration of boric acid to increase efficiency. Process strainer screens should be cleaned regularly to maintain flow rates and minimize power consumption.
In addition to cleaning, preventive maintenance procedures should include checking refrigerant levels. In most cooling systems, this evaluation can be performed simply by checking the system’s refrigerant sight glass window for aspiration (gas bubbles). The presence of gas bubbles indicates a leak somewhere in the refrigeration circuit that is allowing the refrigerant to escape. A certified refrigeration technician should be able to find and repair the system leak. Although refrigerant leaks are not common, the loss of refrigerant can prevent a chiller from cooling properly. Low fluid levels in the system’s reservoir tank can cause the fluid to “vortex,” or spin, which will allow air to mix with the water in the process water pump, reducing overall efficiency.
A routine check of all electrical connections within the system’s electrical box also should be performed periodically to ensure that the electrical components are operating within the manufacturer’s specifications for safe operation. Make sure to turn off and lock out the main power supply; then check all component wire terminations to ensure they are firmly seated in the terminals and are making solid contact. Repair or replace any wiring or components that look worn.
To ensure accurate temperature control, consider using an auto-tuning microprocessor controller on your chiller. The auto-tune function should be retuned whenever the chiller is moved from one process to another, particularly when the cooling load changes substantially.
You cannot control the price of energy and labor, but by taking steps to increase the efficiency and reliability of your equipment, you can minimize your energy and labor costs. Following these basic sizing, installation and maintenance guidelines can help you ensure that your cooling system will operate safely, efficiently, and reliably for many years to come.