System Installation and Startup Flashcards
7 cards from real 313D practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 System Installation and Startup flashcards as text
When installing a split-system condenser outdoors, what is the minimum recommended clearance from the top of the unit to any overhead obstruction?
Answer: 48 inches
Most manufacturers require at least 48 inches of clearance above the condenser to allow unrestricted discharge airflow and prevent hot air recirculation.
During system startup, the technician measures suction pressure lower than expected and superheat higher than normal. What is the most likely cause?
Answer: Restricted liquid line filter-drier
A restricted liquid line filter-drier causes a pressure drop that starves the metering device, resulting in low suction pressure and high superheat.
What is the purpose of installing a crankcase heater on a scroll compressor before startup?
Answer: To boil off refrigerant that has migrated into the oil
Crankcase heaters vaporize liquid refrigerant that has migrated into the compressor oil sump, preventing slugging damage on startup.
When connecting refrigerant line sets, which brazing rod alloy is preferred to minimize oxidation scaling inside copper tubing?
Answer: Stay-Silv 15 with nitrogen purge
Stay-Silv 15 (15% silver) used with a nitrogen purge prevents oxidation scale formation inside the tubing that could contaminate the system.
A residential condensing unit is installed on a rooftop. Which installation precaution is most important for preventing vibration transmission to the structure?
Answer: Using rubber isolation pads or spring isolators under the unit
Rubber isolation pads or spring isolators absorb compressor vibration and prevent it from transmitting through the structure and causing noise complaints.
During a new installation leak check using nitrogen, at what pressure should the technician hold the system before releasing and checking for leaks?
Answer: 150 psig for 24 hours
Industry best practice calls for pressurizing with dry nitrogen to 150 psig and holding for at least 24 hours to confirm no pressure drop from leaks.
Which document must be completed and left with the homeowner after completing a new residential AC installation?
Answer: Manufacturer's warranty registration and startup checklist
Manufacturer warranty registration and the startup checklist must be completed and provided to the homeowner to validate the warranty and document system commissioning.