The tool can be used as a digital chiller log sheet for water-cooled chillers, air-cooled chillers, flooded chillers, DX chillers, plate heat exchanger chillers, screw chillers, scroll chillers and oil-free centrifugal chillers. It helps record the key readings normally taken during a chiller service, including chilled water temperatures, condenser water temperatures, suction and discharge pressures, refrigerant saturation temperatures, superheat, subcooling, evaporator approach, condenser approach, water flow and estimated cooling performance.

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The purpose of a chiller log is not just to record numbers. A good chiller log helps identify whether the machine is operating normally, whether performance is changing over time, and whether a fault is more likely to be refrigerant-side, water-side, compressor-related, heat-rejection-related or controls-related.

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What This Chiller Log Sheet Calculates

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This tool can help calculate and record common chiller service values such as:

• Chilled water delta T

• Condenser water delta T

• Evaporator saturation temperature

• Condenser saturation temperature

• Evaporator approach temperature

• Condenser approach temperature

• Suction superheat

• Liquid subcooling

• Discharge superheat

• Estimated evaporator water flow

• Estimated condenser water flow

• Estimated cooling capacity

• Compressor lift

• Compression ratio

• Estimated chiller efficiency

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These values are useful when checking chiller operation because they give a clearer picture than pressures or temperatures on their own. For example, a chiller may be maintaining leaving chilled water temperature, but still have poor evaporator approach, low water flow, excessive lift or poor heat rejection.

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Refrigerant PT Chart Support

The built-in PT chart section allows technicians to select a refrigerant and calculate saturation temperatures from entered pressures. This is useful when checking superheat, subcooling, evaporator approach and condenser approach.

For normal field use, select the refrigerant, enter the suction and discharge pressures, and leave the saturation temperature source set to Auto. The tool will calculate the PT chart saturation temperatures automatically.

Manual PT entry should only be used when the refrigerant is not listed, when comparing against a separate verified PT chart, or when intentionally overriding a reading for testing or investigation.

Always confirm the refrigerant against the chiller nameplate before relying on calculated saturation temperatures. Incorrect refrigerant selection, incorrect pressure units or incorrect sensor mapping can cause false diagnostic results.

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Using Evaporator Approach for Chiller Fault Finding

Evaporator approach is one of the most important readings in a chiller log. It compares the leaving chilled water temperature against the evaporating saturation temperature.

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On flooded and falling-film chillers, evaporator approach is especially important because it can indicate refrigerant coverage across the evaporator tubes. A rising evaporator approach can be caused by low refrigerant inventory, poor refrigerant level control, fouled tubes, low water flow, sensor error or operating conditions outside normal design.

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On DX chillers, evaporator approach is useful, but refrigerant charge checks should rely more heavily on suction superheat, liquid subcooling, sight glass condition and expansion valve behaviour.

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This is why the tool treats different chiller types differently. A flooded chiller, DX chiller, plate heat exchanger chiller and oil-free centrifugal chiller do not all use the same fault logic.

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Using Condenser Approach for Heat Rejection Checks

Condenser approach compares the condensing saturation temperature against the leaving condenser water temperature on a water-cooled machine. A high condenser approach may indicate dirty condenser tubes, low condenser water flow, cooling tower issues, non-condensables, incorrect water treatment, bypass valve problems or sensor error.

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For air-cooled chillers, condenser readings need to be interpreted differently because ambient temperature, coil condition, fan operation and refrigerant circuit design affect the result.

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For heat recovery chillers, higher condensing temperatures may be normal by design, so the tool allows for different operating conditions depending on the selected heat rejection type.

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Why Chiller Logs Should Be Compared Over Time

A single chiller log gives a snapshot of operation. Multiple chiller logs provide a trend. The most useful fault finding comes from comparing readings against previous service reports, commissioning data and manufacturer operating data.

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Useful trends to watch include:

• Evaporator approach increasing over time

• Condenser approach increasing over time

• Chilled water delta T changing from normal

• Condenser water delta T changing from normal

• Compressor lift increasing

• Superheat or subcooling moving away from normal

• Chiller efficiency reducing

• Water flow reducing compared with design

• Refrigerant level drifting away from setpoint

• Repeated compressor starts, faults or alarms

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Recording consistent readings each visit makes it easier to prove whether a machine is improving, getting worse or operating normally for the current load.

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Chiller Service Report Export

After entering the readings, the tool can generate a clean chiller service report that can be copied, saved, exported or used as a service note. The generated report is intended to help technicians present readings and findings in a clearer format.

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The report can be used for routine maintenance, fault finding, commissioning checks, follow-up visits and performance reviews. It is designed as a field reference tool and should be used alongside technician judgement, manufacturer service literature, calibrated instruments and site-specific operating history.

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Important Field Note

This chiller log sheet is a diagnostic aid, not a replacement for manufacturer procedures. Always confirm readings with calibrated instruments, verify sensor locations, check refrigerant type, confirm units and review the chiller’s operating state before making decisions about refrigerant charge, water flow, compressor operation or heat exchanger condition.

For best results, use the same logging process each time the chiller is serviced so the readings can be compared across multiple visits.