ponytug
Super Member
What refrigerant are new units using?
I believe 410a is going away but I see lots of 410a installs.
Anyone have a preference between R32 or R454b?
@Sigarms is more knowledgeable than me, but I don't think it is simple. There are advantages and disadvantages to both. R32 is slightly flammable, but more efficient, higher capacity, with low GWP, R454b is less efficient, but not flammable, and lower GWP. R454b was designed as a drop in replacement for R410, and R32 may work in some R410 systems.

An HVAC Technician’s Guide To R-32
Change is coming once again to the HVACR industry, as there is a growing movement to transition from R-410A to lower-GWP refrigerants.

The Battle of Refrigerants: R-32 vs. R-454B
As the world strives to reduce its carbon footprint, the HVAC industry has actively sought alternative refrigerants to replace hydrofluorocarbons (HFCs), which have a high global warming potential (GWP). The US Environmental Protection Agency (EPA) began the HFC phase-out plan in 2022, intending...

Then there is R-744. More complicated to manage and install, but with lots of advantages.

Demystifying CO2 Refrigeration - HVAC Insider
An introduction to the characteristics, nuances and applications of an emerging natural refrigerant By Andre Patenaude, Director, Solutions Strategy, Emerson The use of CO2 as a refrigerant (R-744) in commercial refrigeration is expected to rise significantly in the U.S. over the next several...

Cheat sheet;

All the best,
Peter