Chiller efficiency compares delivered cooling duty with electrical input: COP = Qcooling / Pelectric. Unit efficiency and total plant efficiency, including pumps, fans and towers, must use clearly defined measurement boundaries.

COP, EER and part load

COP is dimensionless when matching units are used. EER values must state their unit system. A catalogue full-load condition does not independently represent annual variable-load operation; part-load and temperature conditions also matter.

Priorities for improvement

Condenser cleanliness, suitable flow, sensor accuracy and avoiding unnecessarily low setpoints are initial checks. Variable-speed control and free cooling can be assessed for suitable projects. No fixed savings percentage applies to every unit.

Measurement and comparison

Record flow, temperature difference and electrical power at the same time. Compare before and after at similar loads and weather conditions. Include shifts, changing duty and auxiliaries in annual kWh estimates rather than declaring payback from nameplate kW alone.

Project inputs and calculation boundaries

For a quotation, specify approximate heat duty, fluid, inlet and outlet temperatures, flow, pressure loss and operating hours. Design ambient conditions, indoor or outdoor location and electrical infrastructure are also selection inputs. Flow and temperature readings must represent the same operating point. Do not transfer a catalogue capacity directly to different temperatures; confirm model performance at the required duty.

Commissioning and operating records

Check circuit cleanliness, filtration, air removal, proven flow and sensor readings. Record reference water temperatures and load conditions during commissioning. These values provide a baseline for maintenance and alarm investigations. Confirm pumps, tanks, connections and control options against the agreed quotation scope.

Frequently asked questions

Is the series capacity range sufficient for final selection?

No. Confirm the actual model at the required fluid temperature, ambient conditions, fluid properties and hydraulic duty.

Is cooling capacity the electrical consumption?

No. Cooling kW and electrical-input kW are different quantities. An energy assessment also needs actual load and operating hours.

What information is needed for a quotation?

Provide the industry or equipment, target temperature, approximate duty, flow, ambient conditions, operating hours and details of the existing system.

Technical reference

U.S. DOE — energy-efficient chiller assessment

These explanations provide general engineering guidance. Examples are not field measurements or performance guarantees for a particular model.