replace R134A with R404

[hollandhvac]

I have two identical freezer/ cold store.

The Freezer is on R404 and the cold store is R134a.
My customer has now asked if he can change the cold store with R134a to a freezer with R404. As the information on the evaporator indicates that it can handle both refrigerants and the units are identical I want to empty and clean the system, and replace the R134 compressor condensor for an R404 compressor and condensor. But my college tells me this is not possible due to contamination? what is your opinioin?

 

[berkshire]

R 404 contains R134 as one of its components, so I do not see contamination being a problem.( R404a: hfc-125,44% hfc-143a,52% hfc-134a,4%)
R134 is considered to be more efficient than 404 except at very low temperatures, when 404 is supposed to be better.
If your cold store is running at a higher temperature leave it alone.
If you have to get the temperature down to that of the freezer, then look at making the switch. Also check to see what oils are being used.
B.E.

 

[imok2]

There is no need to change refrigerants because
R-134 can easely do at good job at -20*F sst and 105*F sct and it it has a better EER of 11% at those temperatures, uses 12% less KW/h and has a lower discharge temperature