System Installation and Maintenance Flashcards

A technician is installing a new condensing unit and notices the electrical disconnect is rated for 60A, but the unit's nameplate lists a maximum overcurrent protection of 45A. Which overcurrent device should be installed?

Answer: 45A, to comply with the nameplate maximum overcurrent protection rating

The overcurrent protection device must not exceed the maximum overcurrent protection (MOP) value listed on the equipment nameplate, regardless of disconnect rating.

What is the purpose of performing an air balance on a newly installed residential forced-air system?

Answer: To ensure each room receives the correct airflow volume for design conditions

Air balancing ensures that each zone or room receives the design airflow volume, providing comfort and preventing hot or cold spots throughout the home.

When installing a new thermostat wire for a split system with a variable-speed air handler, which wire gauge is typically required for the communication wiring?

Answer: 22 AWG solid or stranded wire

Low-voltage thermostat and communication wiring for residential HVAC systems typically uses 18–22 AWG stranded or solid wire.

After completing installation of a residential split system, the technician should verify proper condenser fan motor rotation. An outdoor fan motor rotating in the WRONG direction will cause which symptom?

Answer: High discharge pressure due to reduced airflow over the condenser coil

A condenser fan rotating in the wrong direction significantly reduces airflow across the condenser coil, causing the head pressure to rise abnormally.

A homeowner reports that their new AC system is making a gurgling noise from the indoor coil. What is the MOST likely cause?

Answer: Air or non-condensables in the refrigerant circuit

A gurgling or bubbling noise from the indoor coil typically indicates air or non-condensable gases in the refrigerant circuit, which were not removed during evacuation.

When installing refrigerant line sets that will be routed through exterior walls, what additional installation step is required to prevent moisture and pest intrusion?

Answer: Seal the wall penetration with fire-rated sealant or expanding foam after routing the lines

Wall penetrations for line sets must be sealed with an appropriate sealant or expanding foam to prevent air, moisture, and pest infiltration through the building envelope.

During a maintenance visit, a technician finds the evaporator coil heavily coated with mold and biological growth. What is the recommended maintenance procedure?

Answer: Clean the coil with an EPA-registered coil cleaner and treat with an antimicrobial solution

Evaporator coils with mold growth should be cleaned with an EPA-registered coil cleaner and treated with an approved antimicrobial solution to eliminate biological contamination safely.