R-407A was developed in the same era as R-507 and R-404A to replace R-502 in new installations at mid-range and low temperatures. At low temperature, R-407A is closer in cooling capacity to R-22 than to R-502, R-507 and R-404A. To convert an R-22 installation to R-407A, the mineral oil needs to be replaced by POE oil, the filter dryer changed and the safety valves and other elements calibrated to R-22 pressures.