Substitutes for R22 in air conditioning systems and heat pumps

As the HCFC refrigerant R22 (ODP = 0.05) is accepted only as a transitional solution, a number of chlorine-free (ODP = 0) alternatives have been developed and tested extensively. They are being used for a large range of applications.

Experience shows, however, that none of these substitutes can replace the refrigerant R22 in all respects. Amongst others there are differences in the volumetric refrigerating capacity, restrictions in possible applications, special requirements in system design and considerably differing pressure levels. According to the specific operating conditions, various alternatives may be considered.

Apart from the single-component HFC refrigerant R134a, these are mainly blends (different compositions) of the components R32, R125, R134a, R143a, and R600(a). The following description mainly concerns the development and potential applications of these. The halogen-free substitutes NH3, propane and propylene as well as CO2 should also be considered, however, specific criteria must be applied for their use (Halogen free (natural) refrigerants).

In addition, R32 and HFO/HFC blends can also be used as alternatives (R32 as substitute for R22 and "Low GWP" HFOs and HFO/HFC blends).