Folks,
Just a few questions regarding the retrofit from R-22 to R-134a on a York YS Screw Chiller (3400KW).

1) Have any of you guys done such a job yet ??
2) Is it a worth while job to do as aposed to replacing chiller (cost effective) ??
3) What is the % loss in refrigerant efficiency ??
4) What are the alternative refrigerants to retrofit to ??

any info or stories regarding my querie would appreciated thanks.....