Name three types of refrigerants commonly used in modern residential systems.

• A. R-22, R-123, and R-125
• B. R-410A, R-22 (legacy), and R-32
• C. R-134a, R-407C, and R-410A
• D. R-290, R-600a, and R-744

Answer: (B)

In modern residential HVAC, you’ll typically see a current standard refrigerant, a newer low-GWP option, and legacy refrigerants that remain in older equipment. R-410A is the standard for most new residential systems today because it is ozone-friendly and supports efficient cooling at higher pressures. R-32 is being adopted in newer units as a lower-GWP alternative to reduce environmental impact while maintaining similar performance. R-22 is a legacy refrigerant that was widely used in older systems; it’s being phased out for new equipment, though you may still encounter it in homes with older units awaiting replacement or repair.

Other listed refrigerants either aren’t commonly used in modern residential central systems or are used in different contexts (such as automotive or commercial refrigeration, or as niche natural-refrigerant applications). That makes the trio of R-410A, R-22 (legacy), and R-32 the best reflection of what you’re likely to find in today’s residential setups.