Installation, Start-up, and Commissioning
Installation quality is verified, not assumed
Good installation starts with clearances, structural support, condensate slope, service access, and routing that respects manufacturer limits on line-set length and elevation. Electrical, gas, and condensate connections must match the listing and the code.
Start-up is a documented sequence. Pressure-test with dry nitrogen, then evacuate to around 500 microns and hold a decay test; moisture left in the system forms acids and sludge that fail the compressor later. Charge by weighing in when the line set is known, or by subcooling/superheat per the manufacturer's chart when conditions allow. Verify electrical: supply voltage, amp draw against nameplate, control voltage, rotation on three-phase equipment. Verify airflow by temperature rise or static pressure, not by feel. Operate and test every safety - high limit, low-pressure switch, float switch, flame sensor - under controlled conditions.
Commissioning closes the loop: record all readings, compare to design, correct deficiencies, and hand the owner a complete package including the balancing report, controls documentation, and warranty registration.
Traps: charging by gauge pressure alone; skipping the vacuum decay test; start-up in cold weather without accommodating low ambient; leaving a condensate trap undrained or double-trapped; failing to check that the blower airflow setting matches the installed duct system.
Worked example: a system holding under 1,000 microns after a 10-minute isolation passes most specifications; a rapid rise toward atmosphere indicates a leak or moisture that must be addressed before charging.