How To Avoid Chiller Errors
When it comes to aquaculture, few things have a bigger impact on operating costs than the efficiency of your refrigeration system. Chillers keep water at the right temperature for production, but if they’re not set up or maintained properly, they can quietly drain your budget.
Early in my career, I saw this first-hand at a land-based halibut farm. The system had two 30-hp refrigeration compressors running full tilt. Utility bills skyrocketed, but nobody thought to evaluate performance. Years later, with compressors burning out and maintenance costs piling up, it became clear that design issues were the culprit.
Why Measuring Efficiency Matters
The turning point came when performance was finally tested. The system’s coefficient of performance (COP)—a measure of efficiency—was averaging 1.6. For reference, aquaculture chillers should achieve a COP of 3.5 to 4.5.
A refrigeration contractor quickly spotted the issue: the compressors were oversized and poorly matched to the chiller barrels. By halving the compressor load and balancing the system, COP more than doubled, while energy costs dropped dramatically.
Understanding COP
The COP compares how much energy is moved versus how much electrical energy is consumed. In refrigeration, the goal is to transfer more energy than you put in.
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Typical targets in aquaculture: COP of 3.5–4.5
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Heating applications: COP above 4.0 (modern heat pumps can exceed 5.0)
If your system consistently measures below 3.5, you’re likely paying more for electricity than necessary.
Common Chiller Pitfalls
Through years of troubleshooting, four recurring issues tend to undermine chiller performance in aquaculture facilities:
1. Inadequate Water Flow
Chiller barrels are designed for specific flow rates. Too little flow reduces heat transfer efficiency and accelerates wear. To prevent this, maintain minimum flow rates and configure barrels in a loop, not in series.
2. Poor Heat Recovery
Heat exchangers are critical in reducing the load on chillers. For example, pre-cooling water from 18°C down to 8°C with a heat exchanger leaves the chiller responsible for only a fraction of the work. Without it, energy use can quadruple.
3. Mismatched Compressors
Refrigeration compressors are built for low-, medium-, or high-temperature applications. In aquaculture, systems often span multiple ranges seasonally. Contractors should match compressors and refrigerants to expected operating conditions.
4. System Imbalance
A mismatch between compressor, condenser, evaporator, and thermal expansion valves can devastate performance. In one case, an oversized compressor was paired with undersized evaporators and valves, leading to repeated failures and high costs. Checking nameplates across all components can help identify imbalance early.
Long-Term Perspective:
When properly designed and balanced, aquaculture refrigeration systems should last 10–20 years with minimal major issues. Regular preventive maintenance—such as annual electrical inspections in salty environments—helps extend equipment life.
Given the rising costs of materials like titanium, copper, and refrigerants, inefficiency is more expensive than ever. Measuring your COP is a small step that can reveal major savings opportunities.