This kind of reminds me of a time, not so long ago, when R22 ruled the world, and a new up and coming contender was looking to take a shot at the title, R410A. The HVAC world was frozen stiff. Shocked and in dis-belief, many ran for the hills or hung up their spurs all together. 

After all was done and said, we realized, it wasn't a big deal after all. 

Much of the same now as R32 and R454B make their way into our industry. Its not that big of a deal. Here is some knowledge on what's to come, somethings you need to know and how to deal with it.

Pressures: Meh, pretty much the same as R410a, give or take a PSI or two. Pressure of the refrigerant is just a reference point to determine temperature ( which we really should be more focused on), so as long as you have a PT chart and any type of pressure gauge that will read up to 600 psi or so, you're good. 

Tools: Most of the same tools you use today will still be good for tomorrow. The A2L connections will be "left hand thread" so you may need to purchase an adapter. Spark-less tools are recommended, so as long as your Gauge manifold, micron gauge, vacuum pump, recovery machine, core tool, nut driver, aren't know for the occasional 4th of July party, you're good. Local code MAY (highly unlikely) want to see a "R32 compatible" sticker or label in your tool instructions. Most tool manufactures in our trade are considered spark-less already. 

Brazing: Brazing is not spark-less, you are correct. However, there is not much to worry about here. Brazing is still legal and acceptable, so long as the service valves are closed and there is not an A2L refrigerant leak near by. The Truth about A2L refrigerants is that they are MILDLY flammable. You will need a SIGNIFICANT amount of refrigerant and a SIGNIFICANT ignition source, even then, it is still rather difficult to ignite and sustain. No more dangerous than rubbing alcohol or nail polish remover. Hence the classification as MILDLY Flammable. 

Retrofits: Most manufactures that we are aware of, are making their new A2L furnaces, condensers and heat pumps "Backwards compatible". Yes they will work with the old stuff, kinda. You may have to add a kit (super easy to do) or program the equipment during install. Not hard at all. Evaporator coils for A2L refrigerants will NOT be suitable for R410A or R22. 

Line-sets: Yep, re-use them, as long as they are the right size, length, free of contaminants and old refrigerant. A2L systems use POE oil just like R410A but its always a good idea to get the old oil out of an existing line-set.   

Super-heat, Sub-cooling and Charge amounts: Much of the same here as well. Still the same old methods and requirements. Charging by weight is best practice, still .6oz per foot of line-set after 15ft. Remove if under 15ft. 

Refrigerant leaks: R32 is a single component, so "topping off" would be ok. R454B is a blend, so if you suspect a leak, best practice would be to remove and recharge by weight. You shouldn't need to pull a vaccum as long as the system does not go to atmospheric pressure, or if you know you're free of non-condensibles. 

No heat, No cool lockouts: If a leak is detected by the leak system, the equipment will go into a "lockout". Basically the furnace or AC is shutdown for a period of time (15min), the blower will run and the system will auto reset if no leak is detected. 

If you have any questions or concerns, feel free to ask anyone of us and we will get you the answers you need. 

In Summary:

Key Points

• Pressures: Similar to R410A with minor differences. A PT chart and standard gauges that read up to 600 psi will suffice.

• Tools: Most current tools are compatible. A2L connections use left-hand threads, so an adapter may be required. Spark-less tools are recommended, but most HVAC tools already meet this standard.

• Brazing: Still acceptable if service valves are closed and no A2L refrigerant leak is nearby. A2L refrigerants are mildly flammable, comparable to rubbing alcohol.

• Retrofits: New A2L systems are mostly backward compatible, though some may require kits or programming. A2L evaporator coils are not compatible with R410A or R22.

• Line Sets: Existing lines can be reused if they meet size, length, and cleanliness standards. Flushing out old POE oil is recommended.

• Charging Methods: Similar to R410A — charge by weight, adding 0.6 oz per foot of line set beyond 15 ft.

• Leaks:

  • R32 is a single-component refrigerant, so topping off is acceptable.

  • R454B is a blend, so it's best practice to evacuate and recharge by weight if a leak occurs.

• System Lockouts: Equipment may enter a 15-minute lockout if a leak is detected. The blower will continue to run, and the system will auto-reset if no further leak is detected.

Conclusion: The R32/R454B transition is far less daunting than past refrigerant changes. With minimal adjustments and proper preparation, the switch should be smooth.