Most refrigeration system manufacturers do not recommend 134a refrigerant for low temperature systems such as freezers with holding plates. Because at lower evaporator temperature the pressure ratio of 134a rises in relation to R12, and the capacity may drop off significantly. Using the Pressure-Enthalpy charts for both refrigerants shows a slight decrease in capacity and efficiency. The Danfoss BD compressors Beginning with the BD3 come equipped with 134a.

To run a test 24 hour comparison I used a standard air cooled cold machine with a BD3 compressor, first testing refrigerant R12 then 134a.

 This simple test showed no major difference. This could be explained by the method of super-cooling the liquid by the rapping of the suction line with the capillary tube.

 A word of warning - do not convert any hermetic compressors to 134a unless they are designed for 134a

BACK