Overall Health

Chiller 3 remains operational but shows a material whole-chiller efficiency deficit and several circuit-specific thermal deviations requiring prompt investigation.

Overall Condition: WARNING

• Whole-chiller COP is 5.38 versus expected 6.16, approximately 12.7% below expectation under the observed operating conditions.
• Average cooling effect is approximately 777 kW, with enabled input power averaging 144 kW and average loading of 34%.
• Average entering and leaving chilled-water temperatures are 11.03°C and 9.36°C, with an average leaving-water/setpoint error of 0.61°C.
• SYS2 condenser approach is the clearest high-pressure-side concern, averaging 8.6°C against 4.4°C expected.
• SYS1 presents the strongest correlated evaporator/control concern, with elevated approach and unstable suction superheat at higher loading.
• SYS3 is the most thermally balanced circuit, with evaporator and condenser approaches close to expected values.
• SYS4 has elevated evaporator approach, although its condenser performance and suction-superheat stability remain comparatively favourable.
• Invalid loading, negative cooling and impossible approach/superheat records reduce confidence in unrestricted historical averages.
• The combination of a sustained whole-chiller COP deficit, SYS2 condenser deviation and SYS1 high-load instability supports WARNING, although the data do not indicate imminent catastrophic failure.

Key Findings

The dominant Chiller 3 condition signature is SYS2 condenser underperformance combined with SYS1 high-load evaporator and refrigerant-control instability.

• SYS1: Approximately 260 kW cooling, 11 kW input, 10% loading and calculated COP 23.49. This COP is not credible as an engineering benchmark without validating system power allocation, enable-state filtering and cooling calculations.
• SYS2: Approximately 309 kW cooling, 52 kW input, 46% loading and COP 6. It carries the highest average loading and input power.
• SYS3: Approximately 304 kW cooling, 41 kW input, 40% loading and COP 7.
• SYS4: Approximately 307 kW cooling, 41 kW input, 40% loading and COP 8.
• SYS2 condenser approach is approximately 8.6°C versus 4.4°C expected, almost double its benchmark.
• SYS1 condenser approach is also elevated at approximately 4.5°C versus 2.7°C expected.
• SYS3 condenser approach is close to expected at 3.9°C versus 3.6°C, while SYS4 performs favourably at 3.9°C versus 5.7°C expected.
• Average evaporator approaches exceed expected on:
  
  • SYS1: 5.59°C versus 4.2°C
  • SYS2: 5.35°C versus 3.9°C
  • SYS4: 5.74°C versus 4.4°C
• SYS3 evaporator approach is close to expected at 4.39°C versus 4.2°C.
• At 75% loading, SYS1 evaporator approach reaches 8.28°C with 17.42°C² variance, while suction superheat simultaneously reaches 7.99 K with 10.15°C² variance. Both parameters generate alerts, providing a correlated condition signature.
• SYS2 suction superheat remains tightly controlled at approximately 6.2 K across 25–100% loading, suggesting that its primary concern is not general refrigerant starvation.
• SYS4 approach rises from 4.74°C at 25% to 7.38°C at 100% loading, while suction superheat remains comparatively stable at approximately 6.7–6.9 K.
• SYS3 provides the most useful internal thermal reference under matched operating conditions.

Historical Trends & Predictive Assessment

Historical data indicate persistent system asymmetry and recurring whole-chiller efficiency underperformance rather than one common fault affecting all four circuits.

• Whole-chiller COP remains below expected on average, making the efficiency deficit a genuine maintenance concern rather than a small statistical difference.
• Average chiller loading is only 34%, so load, operating lift, water temperatures, staging and transitional states must be normalised before diagnosing progressive degradation.
• SYS2 has substantially greater utilisation than SYS1:
  
  • SYS1: Approximately 570 operating hours and 602 starts
  • SYS2: Approximately 2,024 hours and 2,585 starts
  • SYS3: Approximately 1,818 hours and 2,536 starts
  • SYS4: Approximately 1,841 hours and 2,449 starts
• SYS2’s high condenser approach therefore coincides with the highest average loading and accumulated runtime. This increases the credibility of a developing heat-transfer or water-flow concern, but does not by itself prove fouling.
• SYS2 COP reportedly improves from approximately 3.7–4.3 during earlier operation to 4.8–6.0 during later periods. This argues against assuming simple progressive compressor deterioration.
• SYS3 and SYS4 COP behaviour is generally stable across normal loading ranges, reducing evidence of progressive degradation on these circuits.
• SYS1 has much lower utilisation, making its averages more sensitive to abnormal or invalid records.
• Copilot identifies a SYS1 input-power increase and simultaneous approach changes during July 2026. This represents a useful predictive watch point but must be confirmed at matched load and water conditions.
• Expected COP also reduces slightly during parts of 2026, suggesting that changes in operating lift may contribute to the actual COP reduction.
• A continuing SYS2 condenser-approach increase at equivalent heat rejection, condenser-water flow and entering-water temperature would strengthen evidence of developing condenser deterioration.
• A continuing SYS1 rise in approach, superheat and power at equivalent loading would strengthen evidence of an evaporator, refrigerant-control or flow problem.
• The current data do not support Copilot’s numerical prediction of a further 5–10% efficiency loss within 6–12 months. Future deterioration should be determined from measured matched-condition trends.

Unusual Behaviour & Event Trace

The following dated events should be investigated against the underlying 10-second telemetry. They should not be classified as confirmed mechanical faults until operating state and associated parameters have been validated.

• 31 October 2025 – Extreme negative calculated cooling: Cooling effect reached approximately −1,577 kW while electrical current remained non-zero.
  Classification: Telemetry/calculation anomaly.
  Trace: Verify CHW flow, ECHW/LCHW measurement order, calculation sign convention, timestamp alignment, chiller enable and compressor current.
• 24 November 2025 – Repeated negative calculated cooling: Cooling effect reached approximately −995 kW with non-zero current.
  Classification: Recurring telemetry or operating-state filtering anomaly.
  Trace: Compare with the 31 October event and determine whether both share the same flow, temperature, enable or calculation condition.
• 6–15 March 2026 – Persistent moderate-load efficiency deficit: At approximately 25–60% loading, COP remained around 5.3–5.7 versus 5.8–6.3 expected.
  Classification: Potential matched-load efficiency deviation.
  Trace: Compare condenser-water temperature, chilled-water setpoint, operating lift, SYS2 condenser approach, cooling output and input power.
• 16–17 June 2026 – High-load COP deficit: At loading above approximately 70–90%, COP remained around 5.3–5.4 versus approximately 7.0–7.4 expected.
  Classification: High-load efficiency event requiring corroboration.
  Trace: Verify whether SYS2 condenser approach, condenser-water flow, entering-water temperature or SYS1 evaporator behaviour deteriorated simultaneously.
• 22 June 2026 – Repeated high-load COP deficit: COP again remained below expected during elevated loading.
  Classification: Possible recurring matched-load efficiency deviation.
  Trace: Compare with the 16–17 June events using identical loading, water temperatures, heat rejection and active-system configuration.
• 2–7 July 2026 – SYS1 input-power increase: SYS1 input power reportedly increased by approximately 25.5% over five days, while calculated COP remained approximately 4.8–5.6.
  Classification: Possible electrical-efficiency deterioration, operating-condition change or metering drift.
  Trace: Verify system loading, compressor current, cooling output, power-meter scaling, operating lift and active compressor stages.
• 3–7 July 2026 – SYS1 evaporator and condenser approach increase: Copilot identifies an approximately 61% evaporator-approach increase and 46% condenser-approach increase over four days.
  Classification: Correlated thermal event requiring matched-condition verification.
  Trace: Determine whether the changes resulted from higher load, warmer condenser water, reduced water flow, refrigerant-control instability, sensor drift or genuine exchanger deterioration.
• 6–7 July 2026 – Repeated high-load COP deficit: High loading again coincided with COP approximately 5.3–5.4 versus around 7.0–7.4 expected.
  Classification: Recurring high-load performance deviation.
  Trace: Compare directly with the June high-load events to determine whether the same circuit and operating-condition signature recurs.
• For each event, retrieve at least 15 minutes before and after the occurrence and correlate:
  
  • Chiller enable and compressor-enable status
  • Compressor current
  • Chiller and system loading
  • ECHW, LCHW and setpoint
  • Chilled-water and condenser-water flow
  • Cooling effect and heat rejection
  • Input power and COP
  • Evaporator and condenser approach
  • Suction superheat
  • Suction and discharge pressure
• Record whether each event is isolated, intermittent or recurring, and whether it occurs during start-up, shutdown, minimum-load operation or stable loading.

Sensor & Telemetry Deviations

Core telemetry is broadly suitable for high-level performance analysis, but several invalid records must be removed before fine condition diagnostics are trusted.

• Cooling-effect excursions include approximately +1,758 kW, −1,577 kW, −817 kW and −282 kW. Negative cooling with non-zero power is physically inconsistent with normal refrigeration operation.
• SYS4 contains an invalid 696% loading state, accompanied by approximately:
  
  • −86.38°C evaporator approach
  • −92.69 K suction superheat
  • Other extreme negative or positive derived values
• These values represent scaling, mapping, calculation or invalid-state records—not physical refrigeration behaviour.
• SYS4 also contains extreme approach spikes reported above 300 K during invalid or zero-load conditions.
• Negative or extreme COP values, including SYS4 values around −8 to −18, cannot represent genuine refrigeration efficiency.
• Several system records show zero input power with substantial calculated cooling. This suggests missing power data, incorrect system-power allocation or timestamp misalignment.
• SYS1’s calculated average COP of 23.49 at only 10% loading should not be used as an efficiency benchmark until these metering issues are resolved.
• Primary water temperatures, pressures, currents and normal loading records are generally coherent, indicating that the dataset is not wholly unreliable.
• Low-resolution or zero DP/power readings during off or very-low-load periods should not be used for heat-exchanger condition assessment.
• Differences between calibration-model coefficients should not automatically be interpreted as physical sensor drift. Confirm pressure and flow sensors using field reference instruments before assigning a telemetry fault.
• Exclude compressor-off, start-up, stabilisation, insufficient-current, zero-flow and invalid-loading records from COP, approach and superheat baselines.
• Predictive alarms should require persistence under equivalent operating conditions and corroboration from multiple related parameters.

Performance Analysis

Chiller 3 shows a significant whole-machine efficiency gap, while the individual circuits have distinctly different thermal and operating characteristics.

• Whole-chiller COP is approximately 12.7% below expected:

  (6.16 − 5.38) ÷ 6.16 ≈ 12.7%

• Average system cooling capacities remain relatively balanced at:
  
  • SYS1: 260 kW
  • SYS2: 309 kW
  • SYS3: 304 kW
  • SYS4: 307 kW
• There is no evidence of a sustained gross capacity collapse on SYS2–SYS4.
• SYS1’s lower average cooling and loading reflect its much lower utilisation and prevent direct comparison with the other systems.
• SYS2 carries the greatest average load at 46% and consumes the greatest system input power at 52 kW.
• SYS3 and SYS4 each average approximately 40% loading and 41 kW input.
• Condenser performance:
  
  • SYS1: 4.5°C versus 2.7°C expected
  • SYS2: 8.6°C versus 4.4°C expected
  • SYS3: 3.9°C versus 3.6°C expected
  • SYS4: 3.9°C versus 5.7°C expected
• SYS2 condenser approach is approximately 95% above expected, making it the strongest confirmed thermal deviation.
• At comparable heat rejection, SYS2 reportedly operates with a higher condenser approach and discharge temperature than SYS3/SYS4. This supports a genuine circuit-specific deviation, subject to flow and sensor verification.
• Average evaporator performance:
  
  • SYS1: 5.59°C versus 4.2°C expected
  • SYS2: 5.35°C versus 3.9°C expected
  • SYS3: 4.39°C versus 4.2°C expected
  • SYS4: 5.74°C versus 4.4°C expected
• Loading-specific evaporator behaviour:
  
  • SYS1 reaches 8.28°C approach with 17.42°C² variance at 75% loading.
  • SYS2 progresses from 4.35°C at 25% to 6.95°C at 100%, with comparatively orderly variance.
  • SYS3 maintains the lowest approach at low-to-medium loading and remains closest to expected overall.
  • SYS4 progresses from 4.74°C at 25% to 7.38°C at 100%.
• Suction-superheat behaviour:
  
  • SYS1 reaches 7.99 K with 10.15°C² variance at 75%, with alerts at high loading.
  • SYS2 remains approximately 6.18–6.32 K with very low variance above 25% loading.
  • SYS3 remains approximately 6.14 K at 50–100% loading.
  • SYS4 remains approximately 6.72–6.86 K across normal loading stages.
• SYS4’s rising approach with stable superheat makes a water-side heat-transfer or flow limitation more credible than general refrigerant starvation, although this remains unconfirmed.
• Average chilled-water ΔT is approximately 1.67 K. At 34% loading, this could result from high flow, bypassing, low demand or averaging across operating states. It should not automatically be classified as poor heat-transfer utilisation.
• System COP comparisons must be normalised for equivalent loading, water temperatures, lift and validated electrical-power allocation.

Engineering Interpretation

Chiller 3 does not present one uniform fault mechanism. The available evidence points towards different problems affecting different circuits.

• SYS2 — Primary Condenser Concern: The persistent 8.6°C condenser approach against 4.4°C expected, combined with high loading, runtime and heat rejection, identifies a credible condenser-side performance deviation.
• Possible SYS2 causes include condenser fouling or scaling, restricted water flow, valve position, pump performance, refrigerant-side heat-transfer limitation, excessive lift or discharge/temperature measurement error.
• Normal and stable SYS2 suction superheat makes a general evaporator-feed problem less strongly supported.
• SYS1 — Evaporator/Control Concern: The simultaneous elevation of evaporator approach and superheat variance at 75% loading provides a genuine correlated high-load signature.
• Possible SYS1 causes include expansion-valve control instability, refrigerant maldistribution, liquid-line restriction, oil logging, evaporator-flow limitation or related sensor error.
• SYS1’s July 2026 power, evaporator-approach and condenser-approach changes should be examined together. If they occurred under equivalent loading and water conditions, the multi-parameter correlation would strengthen evidence of developing circuit deterioration.
• SYS3 — Best Balanced Circuit: Condenser and evaporator approaches remain closest to expected, while superheat is stable. SYS3 should be used as the internal matched-condition reference.
• SYS4 — Evaporator Watch: Average and full-load evaporator approaches are elevated, but superheat remains stable and condenser performance is favourable.
• SYS4’s normal-load behaviour supports a genuine evaporator-side watch item, while its extreme 696% loading and negative derived values represent separate telemetry faults.
• The low whole-chiller ΔT may indicate high flow or bypass operation, but flow and valve measurements are required before diagnosing hydraulic imbalance.
• Copilot’s statements that fouling, refrigerant undercharge or non-condensables are already confirmed are too strong. These remain diagnostic possibilities requiring physical and matched-condition verification.
• No present evidence confirms imminent compressor failure, major refrigerant loss or a common whole-machine mechanical fault.
• The strongest current strategy is targeted circuit investigation, telemetry correction and controlled performance testing, rather than identical maintenance across all systems.

Preventative Maintenance

Maintenance should concentrate first on SYS2 condenser performance and SYS1 high-load evaporator/control behaviour, followed by telemetry correction and SYS4 evaporator investigation.

• SYS2 condenser:
  
  • Inspect condenser tubes or plates for fouling, scale, biofilm or blockage.
  • Verify condenser-water flow, differential pressure, valve position, pump operation and water treatment.
  • Compare heat rejection, condenser approach and water-temperature rise with SYS3/SYS4 at equivalent loading.
  • Verify discharge pressure and saturated-discharge-temperature measurements.
  • Clean mechanically or chemically if inspection, flow testing or matched-condition data confirm deterioration.
• SYS1 evaporator/control:
  
  • Conduct a controlled test at 75–100% loading.
  • Correlate evaporator approach, superheat, suction pressure, cooling output, system power, water flow and expansion-valve position.
  • Check TXV/EEV actuator stroke, control tuning, refrigerant distribution, liquid-line components and oil return.
  • Verify evaporator temperature and pressure sensors before assigning a refrigerant or heat-exchanger fault.
  • Inspect or clean the exchanger if high approach persists under confirmed design flow.
• SYS1 condenser:
  
  • Investigate the July 2026 approach increase.
  • Compare against entering condenser-water temperature, flow, heat rejection and active tower configuration.
  • Inspect the circuit if the increase remains after operating-condition normalisation.
• SYS4 evaporator:
  
  • Trend approach at 75–100% loading.
  • Verify chilled-water flow, strainers, valve position, water balance and evaporator temperature measurements.
  • Separate valid normal-load data from 696% loading and extreme calculated outliers.
• SYS3:
  
  • Maintain the present water-treatment and preventative-maintenance regime.
  • Preserve stable high-load snapshots as an internal reference for SYS1, SYS2 and SYS4.
• Whole-chiller efficiency:
  
  • Perform matched-condition baseline testing at 25%, 50%, 75% and 100% loading where practicable.
  • Record COP, cooling, power, water temperatures, flow, condenser approach, evaporator approach and superheat.
• Hydronic system:
  
  • Verify chilled-water flow against design.
  • Check pump VFD control, bypass-valve position, differential-pressure control and actual water ΔT.
  • Avoid changing flow purely to increase ΔT without confirming design requirements and minimum evaporator-flow limits.
• Telemetry and calculations:
  
  • Resolve negative cooling, zero-power/non-zero-cooling, invalid COP and 696% loading records.
  • Verify system power allocation, CT polarity, scaling, timestamp alignment and operating-state filters.
  • Validate refrigerant property tables and approach/superheat calculations.
  • Range-check pressure, flow and DP transmitters under stable operating conditions.
• Sequencing:
  
  • Review lead/lag rotation because SYS1 utilisation is substantially lower than SYS2–SYS4.
  • Confirm whether the imbalance is intentional or caused by availability, control or performance limitations.
  • Review minimum runtime and anti-cycle settings to reduce unnecessary starts.
• Establish post-maintenance baselines so future changes are evaluated against equivalent operating conditions.

Maintenance Priority

Maintenance should prioritise the confirmed SYS2 condenser deviation, followed by SYS1’s correlated high-load instability and restoration of reliable diagnostic data.

• Priority 1 — SYS2 Condenser: Investigate the 8.6°C approach against 4.4°C expected, including tubes, water flow, valves, pumps, water treatment and associated sensors.
• Priority 2 — SYS1 Evaporator and Control: Investigate the combined 8.28°C evaporator approach, 17.42°C² approach variance, 7.99 K superheat and 10.15°C² superheat variance at 75% loading.
• Priority 3 — Telemetry and Calculation Integrity: Remove or diagnose negative cooling, invalid COP, zero-power/non-zero-cooling periods, 696% loading and extreme derived values.
• Priority 4 — Overall Efficiency: Determine why whole-chiller COP is 5.38 against 6.16 expected through matched-load, matched-lift testing.
• Priority 5 — SYS1 July 2026 Event: Investigate the reported simultaneous rise in input power, evaporator approach and condenser approach.
• Priority 6 — SYS4 Evaporator: Monitor and investigate its 5.74°C average approach against 4.4°C expected and 7.38°C at full load.
• Priority 7 — Hydronic and Sequencing Review: Verify chilled-water flow, bypassing, pump control and the uneven utilisation of SYS1 relative to SYS2–SYS4.
• Priority 8 — SYS3 Routine Maintenance: Maintain SYS3 as the internal reference circuit under matched conditions.

Risk Level

Overall risk remains WARNING / MODERATE, with high subsystem risk for SYS2 condenser performance and moderate-to-high risk around SYS1 high-load operation.

• Efficiency Risk: MODERATE–HIGH — whole-chiller COP is approximately 12.7% below expected, and the deficit appears during several moderate- and high-load periods.
• SYS2 Condenser Risk: HIGH — condenser approach is approximately 8.6°C versus 4.4°C expected, representing the strongest sustained thermal deviation.
• SYS1 Evaporator/Control Risk: MODERATE–HIGH — simultaneous high approach and unstable superheat provide a correlated condition signature.
• SYS1 Condenser Risk: MODERATE — average approach exceeds expected and the July 2026 increase requires investigation.
• SYS4 Evaporator Risk: MODERATE — approach exceeds expected and rises with loading, although stable superheat and favourable condenser performance reduce evidence of a severe general refrigerant problem.
• SYS3 Risk: LOW–MODERATE — current thermal performance is the most balanced and should be retained as the internal comparison reference.
• Hydronic Risk: MODERATE — low average chilled-water ΔT and recurrent setpoint excursions require flow, pump and bypass investigation.
• Telemetry Risk: MODERATE–HIGH — invalid loading, negative cooling, impossible COP and derived-value outliers can create false alarms or obscure genuine deterioration.
• Cycling and Utilisation Risk: MODERATE — SYS2–SYS4 have approximately 2,450–2,585 starts, while SYS1’s much lower utilisation indicates an uneven duty strategy requiring confirmation.
• Immediate Failure Risk: LOW–MODERATE — the dashboard does not establish imminent compressor failure or complete loss of cooling capability.
• Overall Prognosis: Chiller 3 remains operational, but the whole-chiller efficiency deficit and circuit-specific abnormalities justify WARNING status. Current evidence supports prompt, targeted condition-based investigation rather than an emergency overhaul.
• The primary action is to determine whether SYS2’s high condenser approach results from degraded heat transfer, restricted water flow, excessive operating lift or instrumentation error.
• Independently, SYS1’s high-load evaporator approach, superheat instability and July 2026 multi-parameter changes require controlled testing.
• Escalation towards CRITICAL should occur if the chiller cannot maintain LCHW setpoint under confirmed demand, SYS2 condenser approach continues increasing at equivalent conditions, discharge temperatures approach compressor limits, COP declines further, or SYS1 abnormalities become persistent while cooling capacity falls or power increases.
• Downgrading from WARNING to MONITOR should require verified improvement in whole-chiller COP, SYS2 condenser approach and SYS1 high-load stability following corrective action.
• No current evidence establishes imminent catastrophic failure, but delaying investigation may allow an efficiency penalty to develop into a capacity or reliability problem.