R22 is a single-component HCFC (hydrochlorofluorocarbon). From the 1950s to the 2000s it was used everywhere, from split air conditioners to cold storage warehouses and from milk cooling tanks to industrial plants. Technically it is very convenient: it has no glide, its efficiency is good, it works with cheap mineral oil, it is not as sensitive to moisture as the HFCs and it is in class A1. It boils at −41 °C at atmospheric pressure; its saturation pressure is about 4 bar g at 0 °C and 14.3 bar g at 40 °C.
Its problem is the chlorine in its molecule. Its ODP (ozone depletion potential) is 0.055; although this looks low, because the quantity in use was very large it has been phased out under the Montreal Protocol. Its GWP is also 1,810. In Turkey the production and import of new R22 have been banned; systems in the field can be serviced only with reclaimed gas. This gas is both expensive and not always of reliable purity; cylinders of uncertain origin should be avoided. This is why every leak repair carries extra importance.
The owner of an R22 system has three options. If the system is leak-free and sound it is possible to go on running it. When a major fault occurs a retrofit is carried out: R407C is used in air conditioning and positive-temperature applications, R448A or R449A in cold rooms and frozen storage. Because these refrigerants do not mix with mineral oil, the oil is replaced with POE, the filter drier and seals are renewed and the expansion valve is adjusted. The third option is to replace the old, inefficient system entirely.
When deciding, look at the age of the system: a 15–20-year-old R22 condensing unit uses noticeably more electricity than today’s equipment; replacement mostly pays for itself in a few years. The gas in a dismantled system is not released to the air; it is recovered by a certified technician. If you do not know the refrigerant of your system, look at the compressor or condensing unit nameplate. The saturation pressures of R22 are given in our refrigerant pressure–temperature chart in comparison with the possible retrofit refrigerants. The nameplate states the name of the refrigerant and the charge quantity.