Poor flow is one of the most common causes of performance problems in chiller systems. If not diagnosed and resolved quickly, it can reduce efficiency, trigger alarms and lead to long-term equipment strain.
Common Symptoms of Poor Chiller Flow
Flow-related issues usually show up in a commercial chiller system’s performance long before a total failure. Recognising the signs early helps to prevent component damage and operational disruption.
- The system may struggle to reach its cooling setpoint or take longer than usual to pull down temperature.
- You might see repeated low flow alarms or receive alerts through the building management system.
- Pumps may become noisy or vibrate due to cavitation caused by low inlet pressure.
- Fluctuating temperatures across zones or branches can suggest uneven flow distribution.
- In some cases, high compressor head pressure or short-cycling occurs as the chiller tries to compensate for poor heat transfer.
Likely Causes of Flow Problems
Chilled water flow can be affected by a range of mechanical and hydraulic issues. A blocked strainer is one of the most common culprits, particularly in systems without regular flushing. Similarly, poor venting can allow air to become trapped in the system, reducing the available flow path and increasing noise or vibration.
Pump-related problems requiring emergency repair callouts are also frequent. These might include incorrect sizing, failed drive belts, or control signal errors. Valves that are partially closed or incorrectly set can also restrict movement through certain zones. In some systems, incorrect pipe layout or insulation faults lead to uneven distribution and localised cooling issues.
Glycol concentration is another important factor. If the mixture is too strong, it can become viscous and resist proper circulation, especially in colder conditions.
How Flow Is Measured and Monitored
Most modern chiller systems you can buy today are equipped with flow sensors that monitor performance in real time. These may include inline paddlewheel sensors, magnetic flow meters or pressure differential sensors, which feed data to the control system or BMS. Engineers often check flow manually using calibrated gauges or by observing pressure drops across known points. During servicing, thermal imaging can also be used to identify poor flow distribution or bypassed coils.
Diagnosing Chiller Flow Issues
Once symptoms appear, technicians follow a step-by-step approach to identify and isolate the problem. The following tasks are typical during a service visit.
- The engineer will inspect and clean strainers or filters, which are a common restriction point.
- Air will be bled from the system to remove trapped pockets that interrupt flow.
- Pump performance will be checked, including rotation, motor current and any inverter signal.
- Expansion vessel pressure will be verified to ensure it is not restricting system volume changes.
- Flow direction and valve positions will be reviewed to confirm correct balancing.
Why System Design Matters
Flow-related problems are often the result of poor system layout or mismatched components. A pipework configuration that worked when installed may no longer suit current demands, particularly in systems that have been modified or expanded over time. Proper pipe sizing, pump specification and flow balancing are all critical at the design stage. That is why Evolution Cooling designs each chiller installation to meet the specific conditions of the site.
Preventing Future Flow Problems
Preventative maintenance with professional chiller servicing not only keeps flow rates stable but also protects pumps, valves and compressors from long-term damage. Contact us to find out more.
