Which refrigerant is not considered an HFC?

R-22 is the correct answer because it is classified as a hydrochlorofluorocarbon (HCFC), not a hydrofluorocarbon (HFC). While HFCs have been used as replacements for ozone-depleting substances, HCFCs like R-22 were developed as transitional refrigerants. R-22 is gradually being phased out due to its ozone-depleting potential, which is in contrast to HFCs that have no ozone-depleting potential.

In contrast, R-410A, R-134a, and R-404A are all HFCs. These refrigerants have been adopted widely in modern HVAC systems due to their lower environmental impacts regarding ozone depletion. Understanding the classification of refrigerants is crucial for compliance with environmental regulations and for selecting the appropriate refrigerants for various applications.