change refrigerant from R-22 to R-410A?
I am in climate zone 12, California. I have estimates to replace 30 yr old split HVAC, not including refrigerant lines. I think I remember info that R-410A cannot replace R-22, even if nitrogen to clean condensate? one bid w/ cheaper (night&day) system retains R-22 (currently the refrigerant in existing Lennox), another ($1,200 more, Trane system) includes cleaning the existing R-22 using lines. I would prefer to be environtment friendly and assure available supply of refrigerant in future. However, I am concerned R-22 might contaminate new system and that higher pressure of R-410A system would be more leak prone for old refrigerant lines. Replacing the lines would require opening wall/ceiling and extra expense. Comments or advice?