Name a refrigerant commonly used in modern residential systems today.

• A. R-22
• B. R-410A
• C. R-134a
• D. R-290

Answer: (B)

In modern residential cooling, the refrigerant most commonly used is R-410A. This is because it was adopted as the standard replacement for the older R-22 due to environmental regulations—R-410A has zero ozone depletion potential, so it doesn’t harm the ozone layer. Systems sold today are designed around R-410A’s higher operating pressures and its specific lubrication needs, making it the default choice for new homes and with most recent equipment.

R-134a, while common in automotive air conditioning and some appliances, isn’t typical for home central air. R-290 propane is a natural refrigerant used in some niche mini-splits or specialty units but isn’t the standard for typical residential central systems due to safety concerns and system design. R-22 is being phased out and is mostly found only in older, legacy equipment rather than new installations.