Chiller troubleshooting and its 13 common problems

Explore the most Common Problems when troubleshooting water chillers and Solutions Guide here. We can categorize three main issues:

1. Clogging problem

2. High-pressure system problem

3. Temperature system problem

A. Clogging Problem

• Failure due to oil clogging

The main cause of oil clogging is significant wear on the compressor cylinder or oversized clearance. This leads the compressor to discharge excessive oil into the condenser, which clogs the filter drier, preventing normal refrigerant circulation.

In the water chiller system, excess refrigerant oil can compromise cooling efficiency. Therefore, it's crucial to remove excess oil in the system.

Oil clogging treatment: Replace the clogged filter and use high-pressure nitrogen gas to clear accumulated oil in the condenser. Utilize a hair dryer to gently heat the condenser during this process.

Hazards of the oil film:

• Adherence of oil film to heat exchanger surfaces increases condensing temperatures and decreases evaporating temperatures, leading to higher energy consumption.
• An oil film of 0.1 mm thickness on the condenser can reduce cooling capacity by 16% and increase power consumption by 12.4%.
• A similar thickness on the evaporator might decrease evaporating temperature by 2.5°C and increase power consumption by 11%.

How to Solve Oil Film?

Using efficient oil separators greatly reduces the amount of oil entering the system. For already present oil films, nitrogen flushing can be conducted several times until the gas clears.

• Error due to ice blockage

Ice blockage occurs when a chiller retains excessive moisture, causing ice to form at the throttle outlet and completely blocking the capillary tube, halting refrigerant circulation.

Main sources of moisture:

• Residual moisture in system components due to inadequate drying.
• Moisture from refrigerant oil and refrigerants.
• Improper installation, leading to moisture entry.
• Moisture absorbed in the insulating paper of the compressor motor.

Manifestations of ice jams:

• Weakened airflow or interruptions in airflow.
• Severe blockages leading to stop in refrigerant flow through the system.
• Increased exhaust gas pressure and machine operational noise.
• Cooling effect diminishing as the frost area lessens.
• Intermittent passage and blockage of refrigerant flow through the system.

How to Solve Ice Blockage?

The ice blockage results from excess moisture, thus requiring a full drying of the refrigeration system. Treatment methods include evacuation, replacing the filter drier, and ensuring the moisture indicator shows a qualified level.

• Error due to Dirty Clogging

Dirty clogging leads to inadequate refrigerant circulation, causing consistent compressor operation while not efficiently cooling as the evaporator fails to circulate air properly.

Main causes of dirt clogging:

• Dust and debris generated during construction and installation.
• Improper sealing during pipeline welding, allowing dirt entry.
• Impurities present in refrigerant oil or low-quality desiccant materials.
• The small distance between the capillary tube and filter, leading to blockage.

Performance after dirty clogging:

• Partial cooling or air circulation when partially clogged.
• Touching filter dryer or choke surfaces that feel cool or frosty.
• No heating on compressor housing despite continual operation.

How to Solve Dirty Clogging?

Typically found in the filter drier and throttle mechanism, the filter and suction filter can be cleansed or replaced, with subsequent leak detection and vacuuming of the system.

B. High-Pressure Problem

Condensing pressure, known here as "high pressure," encompasses several potential issues:

1. Excessively high condensing pressure.

2. Excessively low condensing pressure.

3. Pressure fluctuations.

1. High Condensing Pressure Causes

High condensing pressure usually arises from:

• Presence of air or other gases in the system.
• Insufficient surface area on the condenser.
• Overcharging the refrigeration system.
• Inappropriate condensing pressure control settings.
• Fouled condenser surfaces.

How to Address High-Pressure Problems?

• Clean condenser by running the system using the recovery system until necessary operating temperatures are achieved.
• Consider replacing with a larger condenser.
• Recover refrigerant to bring the condensing pressure within normal ranges.
• Ensure pressure settings align with standard operation.
• Regularly check and clean the condenser surfaces.

For air condensers, also analyze:

• Failures in fan motor or blade dimensions.
• Obstructions restricting airflow to the condenser.
• Excessively high ambient temperatures.
• Incorrect airflow direction through the condenser.
• Potential short circuits between the pressure on the air side and suction side.

How to Remedy High-Pressure for Air Condensers?

• Replace motors or blades as necessary.
• Remove any obstructions at the air inlet or reposition the condenser.
• Ensure clean air intakes by repositioning the condenser.
• Change fan motor rotation direction to enable effective airflow.
• Install ducts to facilitate outside air flow.

For water-cooled condensers, explore these areas:

• Excessively high cooling water temperatures.
• Inadequate water flow and quantity.
• Debris in the waterline.
• Defective cooling water pump.

How to Remedy High Pressure for Water-Cooled Condensers?

• Maintain a lower cooling water temperature.
• Increase the water supply potentially with automatic valves.
• Clear any obstructions in the condenser water pipe.
• Investigate cooling water pump malfunctions and repair as necessary.

2. Low Condensing Pressure

Causes for Low Condensing Pressure:

• Condenser surface area is too large.
• Reduced load on the evaporator.
• Low inlet pressure.
• Leaky compressor valves.
• Pressure settings on the control valve are too low.
• Exposure of an uninsulated vessel.
• Low cooling air temperatures (for air-cooled).
• Excessive water amount (for water-cooled).
• Low water temperatures (for water-cooled systems).

Troubleshooting Low Condensing Pressure:

We can address these issues by analyzing each cause and rectifying them individually:

• Adjust condensing pressure settings or replace condenser.
• Regulate condensing pressures as necessary.
• Identify leaks in lines between condenser and thermal expansion valve.
• Replace compressor valve plate if necessary.
• Adjust control valve pressure settings.
• Reposition receiver or insulate appropriately.
• Decrease cooling water flow to match specifications.
• Increase cooling water temperature to optimal levels.

3. Condensing Pressure Oscillation

Causes for Condensing Pressure Oscillation:

• Pressure regulator differences during start-stop cycles.
• Vibrations from the thermal expansion valve.
• Malfunctions in condensing pressure control valves.
• Vibrations affecting suction pressure.
• Incorrect sizing or positioning of check valves.

How to Solve Pressure Oscillation?

Addressing this issue may require the following steps:

• Adjust differential settings or utilize valve settings.
• Set higher superheat levels for thermal expansion valves or change flow connections.
• Replace valves as necessary.
• Examine suction pressure operations for potential issues.
• Install properly sized check valves in the correct positions.

C. Temperature System Problem

Factors Affecting Exhaust Gas Temperature:

Exhaust gas temperature is influenced by various conditions, including the intake temperature and pressure ratio. The relevance of these variables is demonstrated by the relation of the compressor intake temperature and the overall compression ratio.

Key Factors for High Exhaust Gas Temperature:

• Increased intake temperatures elevate exhaust temperatures.
• Higher condensing temperatures lead to increased exhaust pressures.
• Defective exhaust valves can raise temperatures due to re-compression of high-pressure steam.

Further Considerations:

• Low efficiency of intercoolers or scaled surfaces.
• Air valve leaks and piston ring failures can significantly alter temperature metrics.
• Insufficient water supplies in water-cooled engines could lead to elevated temperatures.
• Irregularities in normal condensing pressure lead to abnormal outgoing exhaust gas pressures.