Installation, testing, and commissioning
Domain 7 tests installation quality, pressure testing, evacuation, charging, airflow verification, and commissioning documentation.
Installation essentials
Follow manufacturer instructions and local code. Obtain permits and inspections where required. Maintain clearances and service access. Slope condensate drains, install a trap, and provide a secondary drain or float switch. Support line sets, protect them from abrasion, and braze with a nitrogen purge to prevent internal oxidation. Pressure-test with dry nitrogen, then evacuate with a vacuum pump and micron gauge.
Testing and commissioning
A deep vacuum is a moisture test as well as a leak test. Evacuate below 500 microns and isolate the pump; a rapid rise indicates a leak, while a slow rise suggests moisture. Charge by weigh-in or by the manufacturer's superheat/subcooling method. Verify external static pressure, airflow, temperature split, and refrigerant readings. Balance airflow room by room and record final values.
Worked example
After repairs, the system is evacuated to 400 microns and the pump is isolated. The gauge rises to 1,500 microns in 10 minutes. That is too fast for residual moisture and suggests a leak or a contaminated vacuum gauge. Re-pressurize with nitrogen, leak-test the joints and Schrader ports, repair, and repeat evacuation before charging.
Traps that cost marks
Do not skip nitrogen purging, omit the condensate trap, charge by beer-can cold, leave the system without a vacuum hold test, ignore static pressure, or fail to complete commissioning records. A unit that starts is not necessarily commissioned.