What R-22 is and where you still find it
R-22 (HCFC-22, chlorodifluoromethane) is a single-component HCFC. Chemours says it was used in refrigeration, industrial cooling, air conditioning and heating for over five decades, and Arkema calls it the most widely used HCFC refrigerant. EPA lists its uses as unitary air conditioners, cold storage, retail food refrigeration, chillers and industrial process refrigeration. It is ASHRAE safety group A1 and it depletes ozone: Arkema lists an ozone depletion potential of 0.055. Its 100-year GWP is 1810 (AR4) or 1760 (AR5). Arkema says R-22 works with mineral oil, alkylbenzene or POE, and defers to the equipment maker on oil choice.
From 2010, EPA allowed newly produced or imported R-22 only for equipment made before January 1, 2010, and Arkema says it has not been permitted in new OEM equipment since then. US production and import ended on January 1, 2020. EPA says owners may keep using an existing R-22 system as long as necessary, and that recovered and reclaimed R-22, along with R-22 produced before 2020, will help meet service needs.
How to read the R-22 chart
R-22 is a single compound, so the chart has one pressure per temperature and the same column serves superheat and subcooling. Below -41.5°F it is in vacuum: at -40°F it reads only 0.6 psig.
- Superheat: a suction reading of 68 psig converts to 39.6°F. Subtract that from the suction line temperature.
- Subcooling: a liquid line reading of 260 psig converts to 120.0°F. Subtract the liquid line temperature from it.
The superheat calculator and subcooling calculator do the lookup, and how to measure superheat and subcooling covers where to put the probes.
Example R-22 pressures
The figures below are worked examples at assumed coil temperatures, not targets for any unit:
- Air conditioning suction: at a 40°F evaporator, R-22 reads about 68.6 psig.
- Air conditioning head: at 115°F and 125°F condensing temperatures, R-22 reads 242.8 psig and 278.0 psig.
- Refrigeration suction: a coil at 20°F reads about 43.1 psig; a coil at -20°F reads about 10.2 psig.
R-410A runs far higher at the same temperatures (118.8 psig at 40°F). Arkema puts R-410A operating pressures 50 to 60% above R-22 and says R-410A needs equipment and components designed for those pressures.
Service notes
- Supply: with production and import ended, service depends on recovered, reclaimed and pre-2020 R-22. EPA suggests leak checks and preventive maintenance to keep refrigerant in the system and reduce the need to buy more.
- Venting: EPA says that under Section 608 of the Clean Air Act it is illegal to knowingly vent or intentionally release refrigerant while servicing, repairing, maintaining or disposing of AC equipment.
- R-22a is not R-22: EPA warns that R-22a is a highly flammable hydrocarbon blend whose primary components include propane and butane, and that it is not an acceptable alternative for residential AC.
- Oil: use the oil the equipment maker specifies. Arkema notes that HFC retrofit refrigerants such as R-407C need POE, because they do not mix with mineral oil or alkylbenzene.
Replacing or retrofitting R-22
New equipment that replaced R-22 used R-410A, which Arkema says should never be used to retrofit an R-22 system. To keep existing equipment running, refrigerant makers offer retrofit blends. EPA says a technician retrofitting a system should recover the R-22 and follow the manufacturer's handling and installation guidelines for the new refrigerant.
- R-407C: Chemours calls it the closest performance match to R-22 in air conditioning. Retrofits need a change to POE oil and replacement of critical elastomeric seals. It has a large glide: 80.2 psig bubble and 63.2 psig dew at 40°F.
- R-422B and R-427A: Chemours positions R-422B for systems where changing to POE oil is not practical, with elastomeric seals replaced. Arkema says R-427A may not need an oil change, though POE is always recommended.
- R-407A and R-448A: Arkema lists R-407A as a replacement or retrofit for R-22 in direct expansion refrigeration, and Honeywell lists R-448A as a replacement for R-22 in low- and medium-temperature commercial refrigeration.
See R-22 vs its common replacements for pressures side by side.