Equipment Selection, Installation, and Start-Up
Selection Through Commissioning
Selection covers more than capacity: verify AHRI-matched combinations, minimum SEER2, EER2, and HSPF2 values required by the Florida Energy Code, nameplate MCA and maximum overcurrent protection, physical dimensions and clearances, refrigerant type, and suitability for a heat-pump-dominant climate. Installation quality then determines whether the equipment ever delivers its rated performance.
Key installation points include a level pad or curb, vibration isolation, adequate condenser clearance and unobstructed airflow, correctly sized and routed line sets, brazing with a nitrogen purge to prevent internal oxidation, evacuation to about 500 microns with a standing vacuum test, a properly sized and trapped condensate drain, a secondary drain or float switch with an auxiliary pan where required, sealed penetrations, and correct thermostat and control wiring. Start-up documentation should record voltage, amp draw, external static pressure, temperature split, refrigerant charge verification, and airflow.
Charging is a common exam theme. Fixed-orifice systems are charged to target superheat based on indoor wet bulb and outdoor dry bulb; TXV systems are charged to subcooling, typically 8 to 12 degrees Fahrenheit. Never add refrigerant to fix a low temperature split before confirming airflow.
Worked example: return air is 75 degrees dry bulb and supply air is 55 degrees, a 20-degree split, which is normal at about 50 percent relative humidity. A 12-degree split with a clean filter usually points to low airflow, such as a collapsed flex duct or undersized return, not an undercharge.