In the U.S., R22 refrigerant will no longer be permitted in new installations beginning in January 2010. As a result, many large refrigeration systems now use R134a, which has a lower global warming potential. For systems with screw compressors, this change also provides another benefit: R134a improves the COP of the compressors by 5 to 10 percent, which increases the overall efficiency of the system. To meet this market need, Bitzer currently offers 16 CSH model compressors that are optimized for use with R134a.