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.
You cannot mix R22 and 410A. IF you are going to switch to 410 then you need to replace everything.
The pressure can become high enough for parts of the system to rupture. 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.
You cannot just switch refrigerants because R410-A and R-22 have different chemical properties. R410-A operates at a higher pressure. If you put R410-A into an R-22 system, the parts will rupture due to the increased force. You can convert your current system to one that runs on R-410A, but the cost will be high.
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.
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.
I think it is important to remember that R22 and r410a are made of the same chemicals just in different ratios. Though the oils are different, Mineral and Polyester are not going to contaminate each other. They will not mix but that does not cause a problem.
In fact, R410A can cool a room slightly faster with less energy. Efficient performance is a significant benefit of R410A. However, it works the same way as R22 in absorbing heat to provide cooling. But R410A doesn't make a room any colder than its predecessor.
A small amount of R 22 left in a 410A system will not sludge the oil. This is because most POE oils are mixable (meaning they mix well) with any refrigerant even R 22.
When you replace an air conditioner or heat pump and upgrade from R-22 to R-410A, the ideal solution is to replace your refrigerant lines. This is because the mineral oil used in R-22 systems is not compatible with the new R-410A refrigerant and oil.
Never mix R-22 and R-410a.
To retrofit an R-22 system with R-410A system your line set must not be more than 25-50 feet in total distance. If the line set is longer than this, you will have to replace the line set with larger lines.
How much will an R-22 to R-410A conversion cost? The actual cost will depend on many things, including where you live, but most of the time R-22 conversions start at around $2,000 and go up from there. The higher end of that range is somewhere around $4,500 to $4,600.
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.
The operational pressure of the refrigerant R410A becomes higher compared to R22. In the worst case, a lack of compressive strength may lead to piping explosion.
R-22 uses simple mineral oil, non-toxic, safe, stable, etc. while R-410a uses a somewhat exotic Poly o Ester (POE) oil typically found in jet turbine engines. The refrigerant used MUST match the oil present in the system, which is one reason why you can't replace the R-22 with R410a in a system.
Explanation: It is important not to mix R-22 and R-410A refrigerants in the same container because they use different oils. Mixing refrigerants that require different oils can lead to equipment malfunction due to incompatibility between the oils and the refrigerants.
The refrigerants have very different heat-transfer properties and use chemically incompatible lubricating oils, so they aren't interchangeable and can't be mixed. Transitioning one unit to the next could require replacing the compressor, evaporator and condenser, along with potentially replacing their copper lines.
So… what refrigerant can be mixed with R-22? None. You can't mix refrigerants.
Tube-side materials in R-410A coils need to be thicker due to the higher operating pressures associated with R-410A relative to R-22. We're not arguing that there's not a difference in operating pressure between the two. There is – roughly 130 PSI for R-410A evaporators compared to about 70 for R-22.
Understanding the Current HVAC Refrigerant Guidelines
Most HVAC brands have started to swap out their older AC and heat pump units over the year, preparing for the 2025 deadline, when they will have to completely stop the production of systems with R-410A.
R22 is being phased out because it harms the ozone and causes global warming. This means less production and use, eventually banning it in new equipment. Switching to alternatives with lower global warming potential can greatly reduce cooling systems' carbon footprint. Old A/C systems often use R22 refrigerant (Freon).
So what the manufacturer recommends, the best option, is if you're going to go from an R22 unit to an R410 unit, that you should have your line set replaced at the same time. So everything is new. There's no contamination, there's no possibility of contamination.
"Hey Dan, do I need to change the TXV valve when switching the outdoor condenser from R-22 refrigerant to R410A?" Yes, you are going to have to change out the TXV. Why? Well, R410A works at a different temperature and a different pressure than R-22. If you don't change it then it's not going to boil off correctly.
Systems that use R-410A also use synthetic oil for lubrication, rather than mineral oil like in R-22 systems. The synthetic oil is more soluble, making the whole system more efficient. Therefore, R-410A works better than R-22 and has more efficient systems.