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Puron is a name Carrier Corp. uses for Refrigerant 410A. The correct term is Refrigerant 410A and Puron is Refrigerant 410A.
As for having to switch in 2020, all new units are now being manufactured with refrigerant 410A. R-22 units are no longer manufactured, however, you can get a dry charged unit which comes without refrigerant and R-22 can be used in them. There are replacement refrigerants on the market to replace refrigerant 22, such as R-422C. The only case you will need to use R-410A wil be when replacing a complete system and new installations, provided the EPA dosen't change the rules. I hope this answers your question. Let me know if you need additional information.