Chiller commissioning: what should be witnessed and recorded

Commissioning is often treated as the last hurdle before handover. It is better understood as the moment the reference data for the machine's entire operating life is created — or lost.

Before the machine runs

• Installation checked against the manufacturer's clearances, particularly air-on and air-off paths
• Pipework flushed and cleaned, with the record to prove it
• Strainers fitted, checked and cleaned after initial running
• Electrical supply verified: voltage, phase rotation, protection settings, terminations torqued
• Water system filled, vented and pressure-tested

Running a machine on a system that has not been properly flushed is one of the more expensive shortcuts available on a project.

What to record while it runs

Water flow rates and pressure drops across the evaporator and condenser. Entering and leaving water temperatures on both sides. Refrigerant pressures and the saturation temperatures they correspond to. Superheat and subcooling. Current draw per phase. Approach temperatures. Control set points as left.

These are the numbers every future diagnosis is compared against. Without them, "the machine is not performing as it used to" has no evidence behind it.

Safety devices

Every cut-out and interlock should be proved to operate, and the test recorded — not assumed because the machine has not tripped.

Handover

The record should be issued as a document, with the operating and maintenance manuals, as-built drawings, warranty terms and a named contact. A commissioning record that exists only on an engineer's tablet has, in practice, not been handed over.