Performing routine inspection and repairs on your recirculating chillers keeps them running efficiently and helps you avoid unplanned downtime.

This chiller reservoir shows algae growth. An inhibitor can be use to prevent algae growth in the reservoir.

Recirculating chillers provide precise temperature control as well as cooling below ambient temperature. To ensure a chiller is functioning as efficiently as possible and to minimize the risk of downtime, it is important to properly operate and maintain it. Just like a car, there are fluids that need to be checked and filters that need to be replaced. Some of these tasks should be done weekly and others can be carried out monthly or quarterly. This guide suggests when and how to conduct basic inspections and maintenance tasks.

Coolant should be added if the coolant level sight tube on the front of the chiller approaches the half-full mark.

Weekly Inspections

Because every chiller installation is unique, the conditions in a given installation should determine how often the equipment should be inspected and maintained. However, no matter the installation, a quick weekly inspection should be performed by a qualified technician.

The weekly chiller inspection typically takes less than five minutes. With the chiller powered off and unplugged, the technician can check for signs of coolant leaks; the coolant level and condition (color) in the reservoir; dust or debris accumulation on condenser coil fins; airflow; and air and coolant filter conditions, if applicable.

Leakage. If a chiller is properly maintained, leaks are rare. But, if you notice coolant on the floor near the chiller or dripping from the enclosure, turn off the chiller and disconnect the power. When leaks occur, they are usually due to use of the wrong type of fittings, connections or hoses. Any leaks should be fixed before the chiller is used again.

Coolant Level and Condition. A significant drop in the coolant level in the reservoir as compared to the level noted in the previous weekly check should be investigated. If a system leak is not visible, then the loss may be due to equipment leakage elsewhere such as within the application itself. Coolant should be added if the coolant level sight tube on the front of the chiller approaches the half-full mark.

For maximum thermal performance, the condenser coil fins should be free of dust and debris. Checking the condenser coil fins weekly is important if the system is in a dusty environment.

Condenser Coil Fins. For maximum thermal performance, the condenser coil fins should be free of dust and debris. Therefore, checking the condenser coil fins weekly is especially important if the system is in a dusty environment and is not fitted with an air filter. To check the condenser, remove the front grill by sliding it upward, pulling the bottom out and then pulling it straight down. Use a fin comb, soft paint brush or shop vacuum to remove any debris and keep the fins clean. You may also use compressed air (60 to 90 psi) to blow dust off the condenser coil fins. This will maintain the proper airflow and allow better cooling of the refrigerant. Caution should be taken when cleaning the fins as they are sharp and can bend easily.

Airflow. In addition to keeping the condenser coil fins clean, proper ventilation should be maintained around the air-cooled chiller. Inadequate ventilation will cause a decrease in cooling capacity and, in a worst-case scenario, a compressor failure. The area around the chiller must be kept clear and unobstructed in order for the chiller to work properly. The two sides and back of the chiller should have a minimum clearance of 18", and the top clearance should be at least 6" to allow proper air circulation.

It also is important to ensure that the hot air exiting the chiller does not recirculate into the inlet openings. The front of the chiller must have an ample supply of ambient-temperature air. During a weekly inspection, the clearance should be checked, as chillers can be moved (intentionally or unintentionally) if they are on casters.

A water filter (left) is an option available on most chillers. If the chiller is equipped with an air filter (right) on the condenser, the air filter should be replaced periodically.

Noise Level. Normally, chillers are quiet units. Therefore, any abnormal sound or a substantial increase in noise levels may indicate an impending pump, fan, compressor or coolant blockage problem. It is important to investigate the cause of noise and perform the necessary service to prevent system downtime.

Water Filter. Offered as an option on most chillers, the water filter can quickly accumulate foreign matter introduced during setup of a new system. This can lead to a decrease in system performance in a short period of time. If a water filter is present, inspect the cartridge one day after setting up a new system to ensure that the filter is clean and the system runs at maximum capacity. After this initial inspection, it is recommended that the water filter be checked monthly.

Deionization Package. Another option available on many chillers, a deionization cartridge’s life, like most parts, is a function of the application. The water resistivity should be checked weekly, and the cartridge should be changed if needed.

A low-level switch protects the pump in the event of accidental fluid loss. A low-level switch is an optional feature on some chillers.

Monthly or Quarterly Maintenance

If a chiller runs 24 hours per day, the following maintenance should be performed on a monthly or even more frequent basis (if needed). Otherwise, it should be performed quarterly or as needed for the application.
  • Remove the top and side covers of the chiller. If the chiller is equipped with an air filter on the condenser, replace the air filter. If the chiller does not have an air filter, vacuum or use compressed air (60 to 90 psi) to blow out the condenser coil.
  • Vacuum dust from the inside of the chiller.
  • Clean the pump strainer (if so equipped) and replace if needed.
  • Replace the water filter (if so equipped).
  • Inspect the coolant for any foreign matter by opening the cap and looking in.
The coolant should be flushed and replaced regularly based on the amount of particulate matter that has been found in the system during planned maintenance inspections. If the pump strainer and coolant are found to have little or no contamination after the first inspection, replacing the coolant and cleaning the strainer on an annual basis are recommended. When the strainer is cleaned or replaced, the electrical power must be disconnected and the system drained of all coolants. To clean the system:
  • Remove the covers and drain the coolant.
  • Replace the coolant with clean, high-quality water.
  • Run the chiller for 10 minutes; then, drain the water.
  • Replace all filters.
  • Refill the chiller with coolant and run for 3 to 5 minutes to purge air from the lines.
  • Top-off the coolant level and wipe up any spills.
  • Replace the covers.
When reconnecting the chiller to the application, it is important to keep any thread sealant outside of the liquid cooling loop. If thread sealant gets into the system, especially the pump, it can cause a clog and lead to equipment burnout.

Other monthly or quarterly maintenance tasks include checking the level controls, strainers and electrical panel.

The pump strainer removes contaminants from the coolant and changes from clean (left) to dirty (right) over time. If the chiller pump strainer becomes fouled, flow rate will decrease and the pump may wear prematurely.

Low-Level Switch. A low-level switch protects the pump in the event of accidental fluid loss, and it is an optional feature on some chillers. Because this switch is passive during normal operation, it is advisable the check it every six months. This can be done by opening the tank cover and pushing down on the switch to see if the low level alarm is activated.

Pump Motor Lubrication. A positive-displacement pump typically lasts 7,000 to 10,000 hours, or about one year of continuous use, or three to four years if used only during normal business hours. To maximize the pump life, the pump should be well lubricated at all times. The pump should never run dry, even briefly. Positive-displacement pump motors may use sleeve-type bearings with large lubricant reservoirs. If the motor does not have a port for oiling, the motor most likely is a sealed-bearing motor and does not require lubrication. Oiling instructions are posted on each motor.

Pump Strainer. If the chiller has a positive-displacement pump, it is important to periodically inspect and clean the pump strainer. If the strainer becomes fouled, flow rate will decrease and the pump may wear prematurely. Most chiller operators find that the strainer should be cleaned every three to six months. The strainer does not need to be replaced unless it is damaged.

Control Box Fuse Replacement. Lastly, if a fuse is blown on the controller board, a qualified technician can replace it. To replace the fuse, remove the top and side panels on the unit. Then, open the inline fuse holder, remove the blown fuse and replace the cover.

Whether you are considering buying a standard or custom chiller, it is important to be aware of the operation and maintenance requirements. If you already own a chiller, it is crucial to ensure that it is being properly operated and maintained. This will ensure it is operating as efficiently as possible as well as minimize the risk of equipment downtime. As with a car, you also will want to be sure you have a good mechanic. If you need spare parts, help troubleshooting or service on the equipment, contact the chiller manufacturer or distributor.