I am adding an HRU to my 3.5 ton R-22 Trane system. It involves adding about 5 feet of additional line to the superheat line coming out of the compressor.
An HVAC guy I kind of know (friend of a friend) told me that the only way to do it is to vacuum down the system, then replace all of the R-22 with new refrigerant, which will add about $ to the cost of the service. But he works out of his own small truck and I got the feeling that it's not the kind of work he usually does.
So, do I have to replace all of the R-22 refrigerant? The system is only about 6 years old and runs like a champ. I just need a second opinion before spending more