What R-407A is and where it is used
R-407A is a zeotropic blend of R-32, R-125 and R-134a (20/40/40 by weight). It uses the same three components as R-407C in different proportions. Arkema describes it as a refrigerant for new medium- and low-temperature systems and as a retrofit for R-22 and R-404A, well suited to supermarket and food storage work. Arkema says it is not intended for air conditioning or recommended for systems with flooded evaporators.
It is ASHRAE safety group A1. Its 100-year GWP is 2107 (AR4) or 1923 (AR5), which Chemours puts at about 50% lower than R-404A.
How to read the R-407A chart
R-407A has a large glide, so the bubble (liquid) and dew (vapor) columns are far apart. At 42 psig the dew point is 19.7°F and the bubble point is 9.3°F, a glide of 10.4°F.
- Superheat: always use the dew column. A cooler suction of 42 psig is 19.7°F. Subtract that from the suction line temperature.
- Subcooling: always use the bubble column. A liquid line reading of 250 psig converts to 103.5°F. Subtract the liquid line temperature from it.
Reading suction against the bubble column overstates superheat by roughly the glide. The superheat calculator and subcooling calculator pick the right column, and bubble point, dew point and glide explains why.
Example R-407A pressures in refrigeration
The figures below are worked examples at assumed coil temperatures, not targets for any system:
- Cooler: an evaporator at a 20°F dew point runs about 42.3 psig suction.
- Freezer: an evaporator at a -20°F dew point runs about 8.5 psig.
- Head: at 105°F and 115°F condensing (bubble) temperatures, head pressure is 255.3 psig and 293.5 psig.
Arkema notes R-407A runs higher pressures than R-22, particularly in high ambient conditions, and lower pressures than R-404A. After an R-22 retrofit, cut-out settings and pressure relief devices may need changes.
Service and retrofit notes
- Charge as liquid: Arkema says R-407A should be charged as liquid to prevent fractionation, with a flash valve in the charging line where vapor is normally fed into the low side.
- Oil: POE. Arkema says R-407A does not mix with mineral oil or alkylbenzene, so retrofitting from R-22 means replacing most of the original oil. No oil change is needed when retrofitting from R-404A.
- Charge size: for an R-22 retrofit, Arkema puts the new charge at 95 to 100% of the original R-22 charge.
- Valves: Arkema says expansion valves working properly on R-22 typically do not need replacing, though slight adjustment may be needed for both R-22 and R-404A retrofits. It lists Copeland, Carlyle and Bitzer among compressor makers that approve it as a retrofit.
- Discharge temperature: noticeably lower than R-22, per Arkema.
Regulations and replacements
EPA amended its Technology Transitions rule in May 2026. New supermarket systems installed from January 1, 2027 and new remote condensing units installed from July 27, 2026 face an interim GWP limit of 1,400 until January 1, 2032, then 150 or 300 depending on charge size and configuration. New cold storage warehouses face a limit of 700 from July 27, 2026. R-407A (GWP 2,107) is above both interim limits, and EPA also names it as prohibited in some new equipment, such as high-capacity self-contained ice machines from January 1, 2027. R-448A (GWP 1,386) and R-449A (GWP 1,396) fall under the 1,400 limit but not the 700 limit. Chemours positions R-449A as a retrofit for R-407A systems, and Honeywell positions R-448A as a replacement for the R-407 series. EPA says existing systems can be serviced and repaired throughout their useful life.