The "Drop In” Myth
With the phase out of R-22 and the increase of R-22 retrofit solutions, there has been some confusion in the market about replacements versus "drop-ins" regarding R-22 retrofits. The information below will try to dispell some of these myths as well as educate the contractor about the history of R-22 retrofits. Arkema recommends using Forane® 427A - The Easy R-22 RetrofitTM for your r-22 retrofit solution.
Over the years, refrigerant suppliers looking to sell product have targeted contractors looking for the easiest path for servicing equipment, and the hope of “drop in” refrigerants has become common. The term "drop in" dates back to the phase-out of chlorofluorocarbons (CFCs). Though CFCs have many properties that lead them to be considered ideal refrigerants, they are also recognized ozone depleting substances and, so, were phased-out in favor of more environmentally sustainable alternatives. During the transition away from CFCs, "interim" refrigerant blends containing hydrochlorofluorocarbons (HCFCs), such as R22, were developed to be used in existing R12 and R502 equipment. These HCFC-containing blends had a high degree of miscibility with the mineral oil used in existing CFC equipment. Retrofitting of the equipment with these interim blends could be done with fewer concerns with oil management, making the retrofits relatively easy and leading to their description as “drop ins.”
In contrast, the replacement for R12 in automotive air conditioning was R134a, which is a hydrofluorocarbon (HFC). As an HFC, R134a contains no chlorine and does not deplete the ozone layer. But unlike HCFCs, which contain chlorine and are recognized ozone depleting substances, R134a is immiscible with mineral oil. Retrofitting of R12 equipment to R134a requires that the mineral oil also be removed and replaced with a miscible, synthetic lubricant, which for automotive AC is typically a PAG (polyalkylene glycol) oil. This need to change the oil complicates the retrofit procedure.
The term “drop in” has now migrated to the present day R22 phase-out. And, like with the automotive R12 phase-out, the EPA approved refrigerant choices for retrofitting an R22 system (that are not themselves subject to phase-out) are HFC refrigerant blends. Presently, there are over 20 such HFC-based R22 retrofit refrigerants. However, HFCs are not miscible with mineral oil, and instead typically require use of a synthetic lubricant, such as PAG, POE (polyol ester), or PVE (polyvinyl ether) lubricants.
To attempt to improve oil return in R22 systems using an HFC retrofit without changing the oil, some refrigerant suppliers have developed blends containing a small amount of hydrocarbon (HC), including propane, butane, isobutane, or a pentane. HCs are highly miscible in mineral oil but also highly flammable, limiting the amount that can be used in the retrofit blends to only a few weight percent. These HC-containing HFC blends remain immiscible with mineral oil and so are not capable of duplicating the performance of R22/mineral oil. Furthermore, the R22 retrofits are all blended refrigerants, which will not behave the same in all cases as a single component refrigerant like R22.
Regardless of this, some refrigerant suppliers have taken to describing these HC-containing HFC blends as “drop in” retrofits for R22, even where they still recommend that the oil be changed to POE. Arkema Inc. does not advocate the use of the term "drop in" as we believe the term implies a technician can just “drop” the refrigerant into an R22 system without doing any other work. Or even worse, interpreting "drop in" as to mean being able to top off an existing R-22 charge with a retrofit refrigerant. A proper retrofit should involve the following: Evaluating the system to determine whether the layout itself will prove difficult for oil return (eg. long line sets, vertical risers with evaporators that were not trapped correctly, etc...); conducting an oil analysis to confirm oil quality; installing a new filter dryer; installing new Schrader valves; leak checking the system and repairing any leaks. Once these steps are completed the technician can recharge the evacuated R-22 system with the retrofit gas. We do not believe this is considered "dropping it in." When it comes to drop ins, the truth is that there are none.