Resulting design criteria / Converting existing R12 plants

Compressors and components can mostly remain in the system. However, when using R413A and R437A the suitability must be checked against HFC refrigerants. The actual "retrofit" measures are mainly restricted to changing the refrigerant (possibly oil) and a careful check of the superheat setting of the expansion valve. A significant temperature glide is present due to the relatively large differences in the boiling points of the individual substances, which requires an exact knowledge of the saturation conditions (can be found from vapour tables of refrigerant manufacturer and in the BITZER Refrigerant Ruler App) in order to assess the effective suction gas superheat.

In addition the application range must also be observed. Different refrigerant types are required for high and low evaporating temperatures or distinct capacity differences must be considered. This is due to the steeper capacity characteristic compared to R12.

Due to the partially high proportion of R22 especially with the low temperature blends, the discharge gas temperature with some refrigerants is significantly higher than with R12. The application limits of the compressor should therefore be checked before converting. The remaining application criteria are similar to those for the substitute substances for R502 which have already been mentioned.