Quote Originally Posted by sargent york View Post
York produced several YCAS units that was shipped with 407c. The only differences I remember seeing was they had a liquid line to suction line heat exchanger, The micro-processor has option built into it to run on either R22 or R407c with just a push of the button. If circumstances warranted it I wouldn't hesitant to convert to R407 including a couple of oil changes.
Why change the oil? I challenged engineers to give me a good reason and none of them could, just because somebody wrote "change the oil" on a piece of paper, doesn't mean you have to do it. R-22 is 33% miscible with mineral oil, the oil separator removes 98% of the 33% oil that travels with the refrigerant, 407c is 4%to 10% miscible with mineral oil and the oil separator removers 98% of the 4% of the oil that travels with the refrigerant,the capacity of the oil separator would be enhanced by an non-miscible refrigerant, in a package chiller the little oil that is carried away by velocity will be brought back by the same forces.