What is the purpose of purge non-condensables during start-up?

• A. To remove non-condensables that can hinder heat transfer and cause inefficiency.
• B. To increase system pressure.
• C. To vent refrigerant to atmosphere.
• D. To rush the start-up sequence.

Answer: (C)

The main idea is that purge non-condensables remove gases that don’t condense inside the system, such as air. These non-condensables can form pockets that insulate surfaces, hinder heat transfer in the condenser, and push the system away from its ideal operating conditions. By purging during start-up, these gases escape so the condenser can operate efficiently and the system can reach the proper pressures and temperatures more quickly. Venting refrigerant to the atmosphere would waste refrigerant and is unsafe, so that isn’t the purpose. Purging isn’t about increasing pressure or rushing the start-up; it’s about eliminating non-condensables to restore efficient heat transfer and overall performance.