I need your help. I am currently working on a laboratory water chiller. The mfr is telling me that the system I am working on is an R12, 220Gram charge. This moring they said R134A or R409A would be fine to use. This afternoon they call back and leave a message that I need to use R22, 160 grams. It is a cap tube system. Original comp is danfoss PW 3.5K7. It is DX with the water and minimum temp is -20C.

I have never heard of switching out R12 with R22. What is your opinion? Wouldnt R409A be better? I am leaning to the R409a.

It is for the water baths we have been discussing in the fundamentals section.

Thank you for the help in advance