What does the term "non-condensables" refer to in the context of refrigerants?

The term "non-condensables" refers to contaminants in a refrigeration system that remain in a gaseous state under the operating conditions of the system. These substances do not condense into liquid despite the temperature and pressure conditions that exist in the system. Non-condensables can include air or other gaseous impurities that may inadvertently enter the system during maintenance or leaks.

The presence of non-condensables in a refrigeration system can disrupt normal operation and efficiency by increasing the pressure in the condenser, leading to higher discharge temperatures and reduced system performance. Their characteristics and impact on refrigeration cycles make it essential for HVAC technicians to monitor and minimize their presence in a system.