Chiller Preventative Maintenance Plan
While some organizations use predictive maintenance — including vibration analysis, infrared thermography, and rotor bar testing — to diagnose problems in advance, a comprehensive preventive maintenance (PM) plan remains the key to ensuring the best performance and efficiency of a chiller.
There are 5 steps to Chiller and Boiler Efficiency and Operation
Step 1: Maintain a daily operating log
Chiller operators should document chiller performance daily with an accurate and detailed log, comparing this performance with design and start-up data to detect problems or inefficient control setpoints. This process allows the operator to assemble a history of operating conditions, which can be reviewed and analyzed to determine trends and provide advanced warning of potential problems.
Step 2: Keep tubes and burners clean
One large potential hindrance to desired chiller performance is heat-transfer efficiency. Chiller efficiency deteriorates as tubes become fouled, when mud, algae, sludge, scale or contaminants accumulate on the waterside of heat-transfer surfaces. The rate of fouling depends on the system type — open or closed — as well as on water quality, cleanliness and temperature. Most chiller manufacturers recommend cleaning condenser tubes annually, since they typically are part of an open system, and they recommend cleaning evaporator tubes once every three years for closed systems. But if the evaporator is part of an open system, they recommend periodic inspection and cleaning.
Step 3: Ensure a leak free Chiller
Manufacturers recommend quarterly tests of compressors for leaks. Low-pressure chillers using either CFC-11, which has been phased out, or HCFC-123 have sections of their refrigeration systems that operate at subatmospheric pressure. Although these chillers are the most common in today’s facilities, it is difficult to create a perfectly sealed machine, and leaks allow air and moisture, commonly referred to as non-condensables, to enter the unit.
Step 4: Sustain proper water treatment
Most chillers use water for heat transfer, so the water must be properly treated to prevent scale, corrosion and biological growth. A one-time chemical treatment is required for closed-water systems, which are typical of chilled-water systems connected to the chiller evaporator.
Step 5: Analyze oil and refrigerant on Chillers
Annual chemical analysis of oil and refrigerant can aid in detect chiller-contamination problems before they become serious. Testing consists of spectrometric chemical analysis to determine contaminants, including moisture, acids and metals, which hamper performance and efficiency. A qualified chemical laboratory specializing in HVAC equipment must perform the analysis. Most manufacturers provide annual oil and refrigerant analysis services.