What kind of refrigerant is prohibited in MVAC systems as of new regulations?

The correct answer focuses on the prohibition of R-22 in new MVAC systems after 2020 due to regulatory changes aimed at reducing ozone-depleting substances. R-22, also known as HCFC-22, is a hydrochlorofluorocarbon that has been identified as harmful to the ozone layer. The Environmental Protection Agency (EPA) has implemented phasedown regulations that restrict the use of R-22 in new installations and service, leading to its gradual elimination from the market. The regulations aim to protect the environment by promoting the use of more environmentally friendly refrigerants that have a lower impact on ozone depletion and climate change.

R-134a, while being phased out for some applications, was still allowed in new MVAC systems at the time the question was framed. R-410A is a commonly used refrigerant in newer systems and is not considered harmful to the ozone layer, so it is not prohibited. R-12 is an older refrigerant that has already been banned for use in MVAC systems for many years due to its significant ozone-depleting potential. Thus, the focus on R-22 specifically addresses current regulatory standards and the push towards more sustainable refrigerant options.