If your system is running on R22 most likely is using mineral oil to lubricate the compressor. If you mix R407C with R22 inside your system the molecule of the
R-407C should be used only in systems that currently use R-22. It should not be mixed with R-22 or any other refrigerant. 5. The capacity of the existing R-22 thermal expansion valve (TEV) will be approximately the same when using R-407C.
R-22 systems are typically about 300 psi maximum. If you add R-22 to an R-134a system, you will not get close to the rated cooling capacity of the A/C system. In conclusion, do not mix R-22 with R-134a refrigerants, you will ruin the charge, and possibly seriously damage or destroy your A/C system.
Replacing R-22 with Freon™ 407C in these systems requires switching to polyolester (POE) oil. For a no-oil change R-22 replacement, see Freon™ MO99.
R-407A is a close match to R-22's capacities and flow rates, making it well suited as a retrofit for R-22 in supermarket and food storage applications. Additionally, R-407A is one of the more energy efficient R-22 retrofit options available for refrigeration applications.
When retrofitting an HVAC system, drain all existing refrigerant from the system before adding a new refrigerant. Never mix refrigerants, or "top off" a system running on R-22 with a 400-Series blend.
Air handlers with R-22 coils and thermal expansion valves will operate with R-407c at approximately 6% lower capacity than the published R-22 performance.
R-407C has thermodynamic properties that make it a "look alike" replacement for R-22, with compressor capacities and system pressures and temperatures that are similar. The major difference of R-407C is that it has a temperature glide of about 6°C (1 0.8°F) for typical air~ conditioning evaporating temperatures.
The best replacement for R-22 Freon is usually R-407c. It has a very low loss in capacity (0 – 5%) relative to R-22 and is less expensive than many other R-22 replacement refrigerants. If a system has R22 in it already you cannot use a replacement refrigerant to simply add to the R22.
The commonly used synthetic refrigerants such as R134a, R407C and R410A have a GWP value higher than 2,500. As a result, their production is being phased out.
If you use R-22 in the same system as R-410a, the compressor is going to be trying to work two different fluids through the same coils as both refrigerants respond differently to different mechanical situations. As you might imagine, this isn't going to go well for your air conditioner or heat pump.
What Happens to Your AC System if You Mix Refrigerants? Mixed refrigerants can cause increased system pressures and temperatures changing them for the worse. This can result in ineffective compressor cooling and possible compressor damage, ineffective cooling, and metering device malfunction.
As of January 1, 2020, production and import of R22 refrigerant will be illegal in the United States. Of course, continued use of your air conditioner (AC) or heat pump system using R22 refrigerant is allowed.
At the very least, leaks will occur. Mixing refrigerants is not an option either. This will contaminate the system, and the R22 will not evaporate under the higher suction pressure that R410A requires.
407C REQUIRES AN OIL CHANGE TO POE OIL WHEN RETROFITTING A R22 SYSTEM! All HFC refrigerants are made to be used with and are only truly miscible with polyolester oil (POE).
R-407C can be used to retrofit existing R-22 systems in positive displacement, direct expansion refrigeration, and air conditioning equipment. R-407C should not be used in centrifugal chillers or other equipment that uses a flooded evaporator, due to its high temperature glide.
Mixing R22 with R407C
According to the 609 EPA rule, mixing refrigerants is illegal and anybody caught doing so will be heavily fined.
Freon™ 407A (R-407A) refrigerant is a reliable, stable, and nonflammable option for low- and medium-temperature refrigeration systems. This non-ozone depleting, hydrofluorocarbon (HFC) refrigerant is a replacement for R-22 and provides a lower global warming potential (GWP) alternative to R-404A and R-507.
So… what refrigerant can be mixed with R-22? None. You can't mix refrigerants.
The Figure shows that R-407C had a heating capacity that was 5% higher than R-22 at the high temperature test condition and was 12% higher than R-22 at the low temperature test condition. The heating capacity of R-41 OA ranged from 1% to 2% lower than R-22.
Recovery of R-407C requires a cylinder with a service pressure of 300 psig minimum. National Refrigerants, Inc.
Opteon™ XP20 (R-449C) refrigerant is a hydrofluoroolefin (HFO) option that replaces R-22 and R-407C in residential and commercial air conditioners, as well as direct expansion chillers. It has similar performance and properties to R-22 and R-407C and can be used in both retrofit and new equipment.
Contact the lubricant manufacturer for the recommended test method. Freon™ 407C provides similar energy efficiency and capacity to R-22 with a lower discharge temperature and slightly higher discharge pressure.
What happens if R-22 gets mixed into an installation of Freon™ MO99 that is not properly labeled? Mixing refrigerants is never recommended. However, based on the similar operating conditions of Freon™ MO99 and R-22, system damange would not be expected.
Conclusion. R407C can continue to be used in existing systems, provided they remain in good technical condition and are regularly maintained. However, operators should consider transitioning to more environmentally friendly alternatives such as natural refrigerants in the long term.