Is R-454B pressure higher or lower than R-410A?

Lower, by roughly 8 to 10 percent across the normal operating range. At 40 degrees F saturated vapor, R-410A is about 118.4 psig and R-454B is about 107.5 psig — about 11 psi lower. At 110 degrees F the gap widens to about 29 psi, 365.4 psig versus 336.3 psig. Read the other direction, the same gauge pressure corresponds to a saturation temperature about 5 degrees F higher on R-454B than on R-410A.

Can R-454B be used in an R-410A system?

No. R-454B is not a drop-in replacement for R-410A. It is an A2L classified refrigerant, which means equipment must be designed and listed for it, including refrigerant detection and mitigation where required. Beyond the safety listing, the oil, the metering device sizing and the charge quantity are not interchangeable. R-410A remains available for servicing existing R-410A equipment.

What is refrigerant glide and does R-454B have it?

Glide is the temperature difference between the dew point and the bubble point at a fixed pressure, and it exists in zeotropic blends because the components boil at different temperatures. R-454B has about 2.7 degrees F of glide at 40 degrees F. That is small compared with R-407C at about 11 degrees F, but it is more than R-410A, which is near-azeotropic at about 0.2 degrees F and can be treated as a single number.

Which pressure column do I use for superheat on R-454B?

Superheat is measured in the vapor line, so use the dew point column. Subcooling is measured in the liquid line, so use the bubble point column. On R-410A the two columns are within a fraction of a degree and nobody had to think about it. On R-454B they differ by about 2.7 degrees F, and on a blend such as R-454A they differ by more than 12 degrees F, so using the wrong column is a real measurement error.

What happens if a technician uses an R-410A chart on an R-454B system?

The saturation temperature will read roughly 5 degrees F low, which makes the calculated superheat roughly 5 degrees F high. A system with correct superheat will appear undercharged, and the likely response is to add refrigerant that the system does not need. Overcharging raises head pressure, reduces capacity and shortens compressor life.

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Home › Calculators › R-454B vs R-410A

R-454B vs R-410A: pressure, glide and what changes at the gauge

Kyle Lorinos, PE — August 2026 · Pressures computed from the Helmholtz equations of state in CoolProp 8.0

R-454B runs about 8 to 10 percent below R-410A. That is close enough to feel familiar and far enough to matter — the same gauge reading is roughly five degrees off, and five degrees of saturation temperature is five degrees of superheat.

The short version

R-454B pressures are lower than R-410A at every temperature — about 11 psi lower at 40 °F, about 29 psi lower at 110 °F.
Read backwards, that means higher saturation temperatures. A gauge showing 118 psig is 39.8 °F on R-410A and 44.8 °F on R-454B.
R-454B has about 2.7 °F of glide. Use the dew column for superheat, the bubble column for subcooling. On R-410A that distinction did not exist in practice.
It is not a drop-in. R-454B is an A2L, and equipment has to be listed for it.

Pressure comparison

Saturated vapor (dew point) pressures, in psig, from −60 to 145 °F at 1 °F resolution in the full PT chart. R-32 is included because several manufacturers use it, and it sits on the other side of R-410A.

Sat. temp	R-410A	R-454B	R-452B	R-32
20 °F	78.4	70.6	72.0	80.0
40 °F	118.4	107.5	109.4	121.0
45 °F	130.1	118.3	120.5	133.0
110 °F	365.4	336.3	341.5	374.9
120 °F	418.3	385.5	391.4	429.3

Pressures in psig, saturated vapor.

The pattern is consistent: R-454B and R-452B sit below R-410A, R-32 sits slightly above it. R-452B is the closer match to R-410A of the two A2L blends, which is why it appears in equipment lines where the manufacturer wanted minimal change to the rest of the system. R-454B, which is the more widely adopted of the two, sits further away.

The same reading, a different temperature

This is the table that actually matters in the field, because it is the direction a technician reads a gauge.

Gauge reads	R-410A	R-454B	R-452B	R-32
70 psig	15.0 °F	19.6 °F	18.7 °F	14.1 °F
118 psig	39.8 °F	44.8 °F	43.9 °F	38.7 °F
200 psig	69.7 °F	75.2 °F	74.1 °F	68.3 °F
300 psig	96.1 °F	101.9 °F	100.8 °F	94.3 °F
400 psig	116.7 °F	122.8 °F	121.6 °F	114.7 °F

Saturation temperature at a given gauge pressure, saturated vapor.

Why five degrees is not a rounding error Superheat is measured suction temperature minus saturation temperature. If saturation reads 5 °F low, superheat reads 5 °F high. A system sitting at a correct 10 °F superheat looks like 15 °F — which reads as undercharged, and the reflex is to add refrigerant to a system that did not need any.

The error compounds in the direction that does damage. Adding charge to a correctly charged system raises head pressure, floods the condenser, reduces capacity and puts the compressor under load it was not selected for. The failure is slow, so it does not get connected back to the gauge reading that caused it.

Glide, and which column to use

R-410A is near-azeotropic. Its dew point and bubble point differ by about 0.2 °F, which is to say they do not differ. Twenty years of practice built on that, and PT charts for R-410A print one column because a second one would be identical.

Zeotropic blends behave differently. Their components boil at different temperatures, so at any fixed pressure the refrigerant starts evaporating at the bubble point and finishes at the dew point. The spread between them is glide.

Refrigerant	Glide at 40 °F	Practical effect
R-410A	0.19 °F	One column is fine
R-404A	0.89 °F	Effectively one column
R-452B	2.20 °F	Two columns matter
R-454B	2.66 °F	Two columns matter
R-449A	10.08 °F	Wrong column is a large error
R-407C	11.10 °F	Wrong column is a large error
R-454A	12.23 °F	Wrong column is a large error

Dew point minus bubble point at 40 °F saturation.

The rule, in one line Superheat uses the dew (vapor) column. Subcooling uses the bubble (liquid) column. Superheat is measured in the suction line where the refrigerant has finished evaporating — that is the dew point. Subcooling is measured in the liquid line where it has finished condensing — that is the bubble point.

On R-454B, using the wrong one costs about 2.7 °F. That is tolerable but not free. On R-454A it costs more than 12 °F, which is enough to make a correctly charged system unrecognizable. The habit is worth building now on the refrigerant where the penalty is small, because the same habit is what protects you on the refrigerant where it is not.

PT chart with separate dew and bubble columns

Fourteen refrigerants including R-454B, R-452B, R-454A, R-32 and R-410A, at 1 °F resolution from −60 to 145 °F, with a superheat and subcooling calculator. Free, no signup.

Open the PT chart →

Why the change happened

Under the AIM Act, the EPA is phasing down high global-warming-potential refrigerants. R-410A has a GWP around 2,088; R-454B is around 466 and R-32 around 675. Manufacture and import of R-410A equipment ended at the start of 2025, with a sell-through period allowing existing inventory to be installed into 2026.

Nothing about that phase-down obligates anyone to replace working equipment. R-410A remains available for servicing systems already in the field, and will be for a long time. What changed is what ships new.

What A2L means, precisely

A2L is an ASHRAE 34 safety classification: lower toxicity, lower flammability. The flammability is real but narrow — these refrigerants need a sustained, high-energy ignition source and a specific concentration range to burn. They are considerably harder to ignite than the natural gas already piped into most buildings.

What it changes in practice is procedural rather than dramatic: equipment is listed with refrigerant detection and mitigation, recovery equipment and gauges must be rated for A2L service, storage and transport rules differ, and brazing procedures account for it. None of that is exotic, but none of it is optional either.

Practical checks

Read the nameplate before the gauge. The refrigerant is on the data plate. Equipment now in the field is a mix, and assuming R-410A because it always was is exactly the failure mode.
Confirm what your gauge set is scaled for. A digital manifold with an R-454B curve loaded is doing the conversion for you. One without is not, and an analog scale ring for R-410A is simply wrong on this equipment.
Use the dew column for superheat, bubble for subcooling. Every time, on every blend.
Be more suspicious of small charge corrections than large ones. A 5 °F superheat discrepancy is exactly the size that a wrong-refrigerant chart produces, and exactly the size that looks like a legitimate reason to add a little refrigerant.

PT chart and superheat calculator — the full tables these numbers came from.
The refrigerant transition, for building owners — the same subject written for the person paying for the equipment rather than servicing it.
AC size chart — if you are replacing rather than servicing, sizing matters more than refrigerant.

Method and sources

All pressures and saturation temperatures were computed from the Helmholtz-energy equations of state implemented in CoolProp 8.0. Blends were evaluated as HEOS mixtures at their nominal mass fractions — R-454B as 68.9% R-32 / 31.1% R-1234yf, R-452B as 67% R-32 / 7% R-125 / 26% R-1234yf. Dew point corresponds to vapor quality 1 and bubble point to quality 0.

As a check on the mixture construction, R-410A was rebuilt as a 50/50 mass mixture of R-32 and R-125 and compared against CoolProp's predefined R410A fluid. The two agreed to 0.00 psi at 20, 40 and 60 °F.

Refrigerant classification follows ASHRAE Standard 34. Phase-down dates follow the EPA's AIM Act technology transitions rule. Manufacturer service literature governs on any specific piece of equipment and takes precedence over any general chart, including this one.