There are a number of possible HFC replacements for HCFC-22 (R-22) in existing R-22 systems that EPA has approved for passenger train end use.
They include R407A, R424A, R434A, and most recently R438A.
Does anyone have any conversion experience they would be willing to share?
We have considered R-407C, but this is a blended refrigerant with some disadvantages.
Our consultant has recommended R-410 as a better performing alternative, but it runs at a much higher pressure.
We have a pair of prototype 10 ton HVAC units being manufactured that will be tested on the CAL-1 bi-level rail cars in Northern California. The existing units (66 cars x 2 per car) have R-22.