Abstract: A heat transfer system capable of being coupled to at least one temperature controlled zone, the elements of the system comprising: (i) at least one liquid refrigerant line; (ii) at least one expansion valve selected for R22 or R422D; (iii) at least one evaporator (iv) at least one compressor; (v) at least one condenser; (vi) at least one vapor refrigerant line; and wherein all of the elements have an inlet side and an outlet side and elements (i) through (vi) are in fluid communication together and contains R422D; and the system further comprising a sensing element communicatively coupled to the outlet side of at least one evaporator and at least one expansion valve and at least one sensing element contains a fluid selected to work when R22 is in the condenser-to-evaporator circuit, or R422D. Further disclosed are methods for retrofitting R22 containing heat transfer systems, including refrigerators and air conditioners. Also disclosed are refrigerators and air conditioners containing only R422D.