Has anyone converted a chiller back to 11 from 123 that was originally R-11? I had a customer ask me that today, but didn't want to promise him it could be done legally. His budgeting dept. has pushed back his replacement of a 1989 CVHE 500 for a couple of years. He needs more like 800t for the replacement, but thinks he can squeeze a little more out of the 500 with reverting it back to R-11. Seems straight forward. No gasket or seal compatibility issues and I can run the conversion serial # to find if the wheels were cut or orifices changed, but can it be done legally once the 11 to 123 conversion has been registered with Mother Trane?