Installation, Commissioning and Record Keeping
Installation and commissioning
Before charging, confirm the system is leak-tight and correctly evacuated. Pressure testing uses dry nitrogen (OFN), never the refrigerant itself, and never oxygen. Evacuation must reach a defined vacuum and hold, demonstrating both moisture removal and integrity. Charge is recorded by weight, not by guesswork, and the actual charge must be compared with the design charge.
Commissioning records are the backbone of compliance. You must be able to state what a refrigerant log contains: the identity and quantity of refrigerant, the CO2e of the charge, quantities added and recovered, the identity of the certified personnel, dates of leak checks and repairs, and the results of those checks.
Traps
- Pressure testing with refrigerant is both illegal in most contexts and a classic wrong answer; nitrogen is correct.
- Oxygen or air as a test gas is a serious safety error - never acceptable.
- Records must be retained for the prescribed period and made available on request; a question may ask who may inspect them.
- Charge size must be recorded in both kilograms and tonnes CO2e; omitting the conversion loses marks.
- Confusing commissioning records with service records - the log is continuous.
Worked example
A new split system is designed for a 3.5 kg charge of R-410A (GWP 2088). CO2e = 3.5 × 2088 = 7,308 kg ≈ 7.3 t. The commissioning entry must record 3.5 kg, 7.3 t CO2e, the date, the engineer's certification details, the evacuation result and the leak-test outcome. If the actual charge differs from design, record both and explain the variance.