A2L Refrigerant Transition
R-32 vs R-454B
The two A2L refrigerants replacing R-410A, side by side. The load-bearing difference is not GWP or pressure, it is that R-32 is a pure single-component refrigerant with zero glide while R-454B is a zeotropic blend with a bubble/dew split. That changes how you read the PT chart and charge.
R-32 vs R-454B Comparison Chart
| Property | R-32 | R-454B |
|---|---|---|
| Safety class (ASHRAE 34) | A2L (mildly flammable) | A2L (mildly flammable) |
| Composition | Pure single-component (HFC-32) | R-32 / R-1234yf (68.9 / 31.1%) |
| Temperature glide | Zero (single-component) | ~2°F (zeotropic, bubble/dew) |
| PT chart columns | One saturation temp | Bubble (subcooling) + dew (superheat) |
| Vapor-charge fractionation | None (nothing to fractionate) | Charge as liquid to avoid it |
| GWP (100-yr, AR4) | 675 | 465 |
| Suction pressure at 40°F | ~121 psig | ~112 psig |
| Head pressure at 100°F | ~326 psig | ~301 psig |
| Oil | POE | POE |
| Typical equipment | Ductless mini splits, some unitary | New ducted split systems / heat pumps |
GWP on the AR4 basis EPA uses. Pressures are saturated values from the PT tables (R-454B read on its bubble column). R-32 glide is zero; R-454B glide is about 2°F, bubble to dew.
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Single-Component vs Zeotrope: What Changes
- PT chart shape. R-32 has one saturation temperature at each pressure. R-454B has two: the bubble point (read it for subcooling on the liquid line) and the dew point (read it for superheat on the suction line). Reading R-454B off a single-temperature scale skews both numbers.
- Vapor charging. On R-32 there is nothing to fractionate, so topping off from the vapor port does not shift the mix. R-454B is a blend, so it should be charged as a liquid to keep the composition correct.
- Pressure and GWP. R-32 runs a few psig higher across the range (~25 psig more head at 100°F). R-454B carries the lower GWP (465 vs 675) because it swaps part of the R-32 for very-low-GWP R-1234yf.
- Where you meet them. R-32 dominates ductless mini splits (critically charged, weigh-in is the method); R-454B leads new ducted splits and heat pumps. In both, superheat and subcooling verify the charge against the manufacturer chart, they do not set it.
Frequently Asked Questions
What is the main difference between R-32 and R-454B?
R-32 is a pure single-component refrigerant (difluoromethane), so it has zero temperature glide: it boils and condenses at one temperature for a given pressure. R-454B is a zeotropic blend of R-32 and R-1234yf with about 2F of glide, so it has two saturation temperatures at each pressure, a bubble point and a dew point. Both are A2L (mildly flammable) replacements for R-410A, but that single-component versus blend distinction changes how you read the PT chart and charge the system.
Does R-454B have glide and R-32 does not?
Yes. R-454B is a zeotrope with roughly 2F of temperature glide, so its PT chart lists a bubble temperature (used for subcooling) and a dew temperature (used for superheat) at each pressure. R-32 is a pure compound with zero glide, so a single saturation temperature serves both superheat and subcooling. That is why R-32 pages show one PT column and R-454B pages show a bubble and a dew column.
Can I charge R-32 as a vapor but not R-454B?
R-32 cannot fractionate because it is a single compound, so vapor charging does not shift its composition (liquid charging is still faster and usually specified). R-454B is a blend, so charging or topping off from the vapor port can preferentially remove one component and shift the mix; it should be charged as a liquid, throttled into the suction side. Either way, follow the equipment manual and A2L handling practice.
Which has the lower GWP, R-32 or R-454B?
R-454B is lower. R-454B has a GWP of 465 versus 675 for R-32 on the AR4 basis EPA uses, because R-454B replaces part of the R-32 with very-low-GWP R-1234yf. Both are far below R-410A's 2,088 and both clear the EPA 700-GWP cap for new residential and light-commercial equipment.
Do R-32 and R-454B run at different pressures?
Close, but R-32 runs a little higher. At a 40F coil R-32 is about 121 psig versus 112 psig for R-454B (bubble), and at 100F condensing R-32 is about 326 psig versus 301 psig, roughly 25 psig higher head. Always read each on its own PT scale, and remember R-454B's ~2F glide when interpreting superheat and subcooling.
Where is R-32 used versus R-454B?
R-32 leads in ductless mini splits and some Daikin and Goodman unitary equipment. R-454B (Carrier Puron Advance) leads in new ducted split systems and heat pumps from Carrier, Trane, and York. Both arrived as the A2L answer to the R-410A phase-down for equipment built from 2025, so which one you service depends on the equipment type and brand, not the application.
Related HVAC Tools
R-32 Superheat Calculator
Check charge on R-32 with the full PT chart and zero-glide handling.
R-454B Superheat Calculator
Superheat and subcooling with the R-454B bubble/dew PT chart, glide accounted for.
R-32 vs R-410A
How the pure A2L compares with the outgoing R-410A standard.
R-454B vs R-410A
The zeotropic A2L against R-410A for new ducted systems.