In a refrigerant system, non-condensables are gases that do not condense at operating temperatures.

• A. False
• B. Sometimes
• C. True
• D. Never

Answer: (C)

Non-condensables in a refrigerant system are gases that stay in the gaseous phase and do not condense at the temperatures the condenser operates at. In practice this means air or other gases that leak into the system or remain from the initial setup, and they do not liquefy in the condenser. Their presence creates a layer of gas at the condenser surface, reducing heat transfer and causing higher head pressure and reduced efficiency. By definition, these gases do not condense under operating conditions, so the statement is true. They’re typically managed by purging or evacuation during service to restore proper performance.