Installation, Testing, and Commissioning
Installation essentials
Correct installation starts with the manufacturer's instructions, proper clearances, a level pad or bracket, vibration isolation, and correctly sized and routed line sets. Protect the suction line, slope condensate drains with a trap where required, and keep service access clear. Electrical work must follow the NEC and local code: correct conductor ampacity, overcurrent protection, disconnect, and bonding.
Pressure testing and evacuation
After brazing with a nitrogen purge, leak-test with regulated dry nitrogen - commonly up to the low side test pressure listed on the nameplate - and hold to confirm no decay. Then evacuate to 500 microns or less and confirm with a standing vacuum test before releasing charge. Never use the compressor to pull a vacuum, and never use refrigerant to blow out lines.
Charging and start-up
Weigh-in charging is the most accurate method. If the line set exceeds the factory length, add refrigerant per the manufacturer's chart. Verify airflow first (TESP against the blower table), then set the charge by subcooling or superheat per the metering device, then check temperature split, amp draws, and operating pressures.
Commissioning documentation
Record model and serial numbers, filter sizes, static pressures, temperature split, refrigerant charge method and amount, electrical readings, and thermostat configuration. Trap: skipping the airflow check makes every later refrigerant reading meaningless. Another: leaving a system in a temporary jumper or test mode and not restoring it.
Worked example
A 40 ft line set with a factory allowance of 15 ft and an add chart of 0.6 oz per foot for 3/8 in. liquid line: (40 − 15) × 0.6 = 15 oz of additional charge by weight.