Refrigerant regulations are changing quickly at the state and federal levels, in order to facilitate a smooth transition away from R-410A to lower-GWP refrigerants. Finding a replacement for R-410A has been challenging, but several alternatives have emerged as top contenders. One of those is the mildly flammable (A2L) refrigerant, R-454B, which is manufactured by Chemours. It has been selected by Carrier to be the primary lower-GWP solution to replace R-410A in all of its ducted residential and light commercial packaged solutions sold in North America.

There are many questions surrounding the safe use of mildly flammable refrigerants, which is why The ACHR NEWS asked Stephen Spletzer, a principal engineer at Chemours, and Jeff Warther, a training and business development manager at Chemours, to discuss some of the technical details of R-454B.

ACHR NEWS: In terms of properties and performance, how does R-454B compare to R-410A (e.g., efficiency, capacity, pressures, discharge temperatures)?

Spletzer: From a properties and performance standpoint, R-454B is a very close match to R-410A. That was the goal when this refrigerant blend was designed — a product that mirrors the performance of R-410A while simultaneously reducing its GWP. R-454B happens to have the lowest GWP of the leading R-410A alternatives. Given recent activities related to the AIM Act, and an upcoming HFC phasedown in the U.S., this is becoming an important aspect for replacement refrigerant selection. With R-454B, OEMs can select a product that minimizes design changes, while potentially offering a longer-term solution than other R-410A alternatives.

From a thermodynamics standpoint, R-454B has similar capacity to R-410A with better efficiency. What that means in layman’s terms is that less energy will be used for an occupant’s cooling needs and the equipment will be similar in size. In in-house testing we conducted of R-454B in an R-410A residential split heat pump system, we saw similar capacity to R-410A in both cooling and heating modes. We also saw better efficiencies than both R-410A and R-32. Increases in COP, or efficiency, were up to 5% higher than the R-410A baseline. And this was in equipment designed for R-410A. So, better performance might still be seen in equipment that’s optimized for R-454B. This becomes very important for new air conditioner equipment designs that are required to meet higher efficiency levels in 2023.

Technicians can also expect to see slightly lower evaporator and condenser pressures with R-454B, which means their existing R-410A gauge sets can handle the new refrigerant. Discharge temperatures of R-454B are usually slightly higher, but much closer than those of R 32. So, R-454B systems shouldn’t require active discharge temperature controls to maintain the same operating range.

ACHR NEWS: As a mildly flammable refrigerant, R-454B can’t be retrofitted into existing R-22 and R-410A systems. What changes will be made to the components and accessories used in R-454B systems, such as compressors, metering devices, filter-driers, etc., in order to utilize a mildly flammable refrigerant? Will technicians notice any difference?

Warther: Given that R-454B is such a close match to R-410A, this helps limit the level of system or component redesign required. To the service technician, the look and feel of many R-454B systems will be similar to that of R-410A. Components like compressors and filter-driers will have to be rated and sized for R-454B, just like with any other refrigerant, but overall, we expect differences to be relatively minor. In fact, some components today are rated for both refrigerants.

Now, R-454B systems will have additional labels, required by safety standards, to indicate the use of a flammable refrigerant. Some units will also include integrated refrigerant leak detection and control systems for fan operation. And larger equipment may also have electrical components installed in protective enclosures.

ACHR NEWS: Can refrigerant line sets from R-22 and R-410A systems be re-used with R-454B? Or should they be replaced when a new system is installed? What type of oil is used in R-454B systems?

Warther: The short answer for line sets is yes, they can be reused, if the lines are in good shape and properly sized for the system. As with any new installation, technicians should inspect the lines and follow local codes and manufacturer instructions, for things like evacuation and pressure testing. And it’s always good practice to flush the lines to remove any carbon deposits or leftover oil.

As far the compressor oil is concerned, R-454B can be used with the same types of oil that are used today with R-410A. And unlike R-32, R-454B has similar miscibility and viscosity to R-410A with standard POE oils. It’s important to note, though, that there are some new oils being developed for use with the A2L refrigerants in certain applications.

ACHR NEWS: How does the charge size of an R-454B system compare to R-410A? What do technicians need to know about charging a system with R-454B — how does it differ from R-410A?

Spletzer: The density of R-454B is a little lower, so system charge sizes could be about 5 to 10 percent less than that of a comparable R-410A installation. Now both R-410A and R-454B are lower glide blends, so the same charging techniques can be used for both refrigerants. Technicians should always charge the blend as a liquid and make sure they either use a flash valve or crack the gauges when charging on the low side of a system. And as with R-410A, the system charge with R-454B can also be topped off after repairs to a leaking system have been made.

ACHR NEWS: Will technicians need any new tools, test instruments, recovery machines, etc., in order to work with R-454B? If so, please describe. Is the recovery process the same as that of R-410A?

Warther: Many of the existing tools in use today with R-410A will be suitable for use with R-454B. Gauge sets used with R-410A should be okay to use with R-454B, although technicians may need to update their digital manifolds to include the newer refrigerants. Standard hand tools like wrenches and tube cutters should be the same. However, technicians will need to verify with the manufacturers that their vacuum pumps, leak detectors, and recovery machines are compatible with A2L refrigerants. There are a number of existing models in use today that are compatible, so if they need to replace or upgrade any of these items, selecting an A2L compatible unit is probably a good idea.

When it comes to refrigerant recovery, the process is essentially the same. However, there are a couple of things to keep in mind. One, it’s always a good idea to monitor for leaks during the recovery process. When recovering refrigerant indoors, it’s also recommended to use a fan to help ventilate the area. And the recovery cylinders used with A2L refrigerants will have left-handed threads and a red-colored band or top on the cylinder to indicate a flammable refrigerant, so technicians may need to pick up some adapters for use with A2L cylinders.

ACHR NEWS: Is the installation and service of an R-454B system much different than that of an R-410A system? Are there safety precautions that need to be observed, particularly if soldering and brazing are required?

Spletzer: Overall, installation and service procedures are similar for both products. As with any refrigerant, technicians should review the Safety Data Sheet to understand its hazards and select the appropriate personal protective equipment (PPE). Controlling the work area is also a good practice. Technicians should also never use an open flame for leak checking with either of these refrigerants. Use an electronic sniffer designed for A2Ls or soap bubbles to find leaks on R-454B systems.

The same types of best practices in use today with R-410A — practices that ultimately save time and money by reducing callbacks — should also be used with R-454B:

1. Properly recover the refrigerant from a system before making repairs;
2. Use a nitrogen purge to help remove any residual refrigerant and evacuate the system before opening it to the atmosphere;
3. Flow nitrogen through the lines while brazing to prevent carbon deposits; and
4. Pressure and vacuum test refrigerant lines to ensure that the system is tight and dry.

OEMs will provide installation and service instructions with their equipment. As with previous refrigerant transitions, these instructions will help highlight any specific differences in procedures that technicians need to be aware of.

ACHR NEWS: Do you expect different procedures or requirements with transporting R-454B in a service truck or storing it in a warehouse when compared to R-410A?

Warther: Transporting refrigerant cylinders in a technician service van is covered under materials of trade, so whether it’s R-410A or R-454B, it’s business as usual for most people. For wholesalers and distributors who warehouse refrigerant cylinders, things are a little different. Today, storage of flammable refrigerants is limited to 150 to 600 pounds per control area, depending on the use of sprinkler systems and storage cabinets. However, there’s been a lot of work done around lower flammability gases, like A2Ls, and there are proposals to change the building codes to increase storage levels to 20,000 to 40,000 pounds per control area, depending on the use of sprinkler systems, which would be more in line with the needs of our industry.

ACHR NEWS: Some technicians may be a little anxious about installing or servicing a unit that uses a mildly flammable refrigerant. What advice would you give them that might allay those fears?

Spletzer: It’s only natural that some people are concerned about these changes. The good news is that our industry has a long history of successfully dealing with these types of transitions. And the fact is, there are already many millions of A2L systems in use in the US, in car air conditioners, window units, and other applications, with many more millions in use around the world with an excellent track record.

Warther: I’d also just add that while some things will be different with A2Ls, many things will be the same. Best practices that we’ve used for years will still be used with A2Ls. And technicians who embrace these changes will be using the latest technologies to help tackle some of society’s biggest challenges. That’s why training and certification are so important. If technicians haven’t attended A2L training yet, we highly recommend it, as it will put a lot of those fears to rest. Chemours is proud to be a part of this transition. We’re here to help with training and answers to any questions.