R-454B (Puron Advance)
R-454B Superheat & Subcooling Calculator
Check charge on R-454B systems with the calculator preloaded for the A2L refrigerant that replaced R-410A in new ducted equipment. Full PT chart, TXV and fixed orifice targets, and the A2L handling notes that actually change how you charge.
R-454B Pressure-Temperature Chart
| Pressure (psig) | Bubble °F (subcooling) | Dew °F (superheat) | Publisher spread (°F) |
|---|---|---|---|
| 24.3 | -20°F | -18.3°F | 0.67 |
| 33.9 | -10°F | -7.9°F | 0.67 |
| 45.3 | 0°F | 1.9°F | 0.64 |
| 58.5 | 10°F | 12.2°F | 0.69 |
| 73.9 | 20°F | 22°F | 0.67 |
| 91.7 | 30°F | 32.3°F | 0.63 |
| 112 | 40°F | 42.1°F | 0.60 |
| 135 | 50°F | 52.4°F | 0.65 |
| 161.1 | 60°F | 62.1°F | 0.65 |
| 190.5 | 70°F | 72.4°F | 0.65 |
| 223.4 | 80°F | 82.2°F | 0.64 |
| 260 | 90°F | 92.4°F | 0.65 |
| 300.8 | 100°F | 102.1°F | 0.65 |
| 345.9 | 110°F | 112.3°F | 0.65 |
| 395.7 | 120°F | 122.1°F | 0.66 |
| 450.5 | 130°F | 132.2°F | 0.66 |
About the spread column. It is the widest gap in saturation temperature between the published tables we hold, at that pressure, on the bubble column. Across this chart the widest is 0.69°F, at 58.5 psig. Our table and 3 other published tables are compared here: 1 is a separate publisher, and 2 resolve to the same equation of state as our base, so those are consistency checks rather than independent confirmation. A narrow spread means the charts agree, which is not the same as the charts being right: they are all computed from equations of state fitted to lab data, and no field measurement settles it.
- Checked against Arkema Forane 454B, within 0.1 psig [same model]
- Checked against Chemours Opteon XL41, within 0.05 psig [same model]
- Checked against Honeywell Solstice 454B, within 2 psig [separate publisher]
- Checked against Weitron, reprinted as Daikin/Goodman PM-A2LPTC-USA_04-24, bubble line about 0.64 F away [separate publisher]
Arkema and Chemours make this blend, and both state their tables were generated from NIST REFPROP, the same equation-of-state lineage our own base resolves to. Their agreement is close and it is not independent confirmation. Weitron is the one table that disagrees: its bubble line sits about 0.64 F from ours across the whole range, a constant offset rather than noise, and no further chart can settle which is right. The calculator says so on any reading close enough to a band edge for that difference to change the call.
A separate publisher can catch a transcription, edition or rounding error. A cross-check marked same model resolves to the same equation of state as the base table, so it is a consistency check rather than independent confirmation. One marked same printing prints numbers identical to another table listed here, so the two are one witness and we do not count them twice. Sources last re-verified 2026-08-05.
For quick sanity checks: a typical R-454B system on a mild day runs a 40–45°F evaporator, which puts suction pressure around 110–121 psig. Condensing at 100–110°F puts liquid pressure around 301–346 psig. If your gauges are far outside those windows with the system running steady, verify the reading before touching the charge.
R-454B Normal Operating Pressures
On a properly charged R-454B air conditioner, the low-side (suction) pressure stays fairly steady because the evaporator temperature is set by the load and metering device, while the high-side (liquid) pressure climbs with outdoor temperature as the condenser has to reject heat into hotter air. Typical running pressures, read from the PT chart above:
| Outdoor Conditions | Suction (Low) | Liquid (High) |
|---|---|---|
| Mild day, ~75°F | ~110 psig | ~297 psig |
| Warm day, ~85–90°F | ~114–121 psig | ~320–342 psig |
| Hot day, ~95°F+ | ~114–121 psig | ~365–395 psig |
Suction assumes a 40–45°F evaporator saturation; liquid assumes condensing about 15–25°F above ambient. Pressures shift with indoor load, airflow, and humidity, so confirm the charge with superheat and subcooling, not pressure alone. R-454B runs slightly lower than R-410A (within about 5%, roughly 15–20 psig on the high side). An R-410A manifold reads the pressure fine, but use an R-454B PT scale for saturation temperature.
R-454B Target Superheat & Subcooling
| Metering device | Target superheat | Target subcooling | Charging method |
|---|---|---|---|
| TXV | 8–15°F | 8–14°F | Charge by subcooling; the TXV holds superheat |
| Fixed orifice (piston) | 5–20°F | 4–10°F | Charge by superheat from the manufacturer charging chart |
What Is R-454B?
R-454B is the A2L refrigerant that replaced R-410A in new ducted residential and light commercial equipment. Under the AIM Act, new AC and heat pump systems manufactured in the US moved to lower-GWP refrigerants starting January 1, 2025, and most major ducted equipment lines (Carrier, Bryant, Trane, American Standard, Lennox and others) chose R-454B. Carrier markets it as Puron Advance. It is a blend of R-32 and R-1234yf with a GWP of 465, versus 2,088 for R-410A.
The good news for charging: R-454B behaves very much like R-410A on the gauges. It runs slightly lower pressures at the same saturation temperature (42°F is about 114 psig on R-454B versus roughly 123 psig on R-410A), and the superheat and subcooling targets are the same 8–15°F and 8–14°F with a TXV. The diagnostic logic you know from R-410A carries over directly: high superheat with low subcooling still means low charge, low superheat with high subcooling still means overcharge.
A2L Charging Notes for R-454B
What changes is handling, not thermodynamics. R-454B is mildly flammable (A2L), which drives four practical rules. First, charge liquid only: R-454B is a zeotropic blend, and vapor charging fractionates it, pulling off a different composition than what stays in the cylinder. Second, use A2L-rated recovery machines, hoses, and leak detectors; standard R-410A recovery equipment is not listed for flammable refrigerants. Third, no brazing or open flame on a circuit holding charge; recover first, then purge with nitrogen while brazing. Fourth, respect the equipment leak-detection system: many R-454B air handlers carry refrigerant sensors that drive the blower on a detected leak per UL 60335-2-40, and that circuit must stay functional after service.
R-454B has about 2°F of temperature glide. That is small, but this calculator still handles it correctly: it reads the dew point off the suction pressure for superheat and the bubble point off the liquid pressure for subcooling, the same bubble/dew treatment used for R-407C. On a critically charged system where you are splitting hairs at the edge of a target range, remember the glide adds roughly a degree of uncertainty; charge to the middle of the manufacturer target rather than the edge.
One thing R-454B is not: a retrofit refrigerant. R-410A equipment is not listed for A2Ls and cannot legally or safely take R-454B. Service existing R-410A systems with R-410A, and install R-454B only in equipment designed for it.
Worked Example: New R-454B Heat Pump with TXV
A 2026-installed R-454B heat pump in cooling mode, TXV metering. Field readings: suction pressure 110 psig, suction line temperature 50°F, liquid pressure 300 psig, liquid line temperature 91°F.
Saturated suction temp at 110 psig (dew point) = 41.1°F
Superheat = 50°F − 41.1°F = 8.9°F
Saturated liquid temp at 300 psig (bubble point) = 99.8°F
Subcooling = 99.8°F − 91°F = 8.8°F
Diagnosis: Superheat 8.9°F sits inside the 8–15°F TXV target and subcooling 8.8°F sits inside 8–14°F. The system is properly charged. Log both numbers on the startup sheet: baseline readings on a new A2L install are worth their weight when the same unit gets a warranty call two summers later.
superheat_subcooling tool live, handing back the verdict with its cited source instead of a guess. Then keep the reading as one job in the Intry app.R-454B Charging FAQs
What are normal operating pressures for R-454B?
A properly charged R-454B air conditioner typically runs about 110 to 121 psig on the suction (low) side, matching a 40 to 45F evaporator saturation, and 297 to 395 psig on the liquid (high) side depending on how hot it is outside. On a mild 75F day expect roughly 110 psig / 297 psig; on a hot 95F-plus day the high side climbs to about 365 to 395 psig while the suction stays near 114 to 121 psig. R-454B runs slightly lower than R-410A (within about 5%), so an R-410A manifold reads the pressure fine, but you must use an R-454B pressure-temperature scale to read saturation temperature correctly.
What are R-454B running pressures on a 90 degree day?
On about a 90F day, a healthy R-454B system in cooling runs roughly 114 to 121 psig suction (40 to 45F evaporator) and 320 to 342 psig liquid (condensing around 105 to 110F, or 15 to 20F above ambient). Those are ballpark values: the exact high side depends on outdoor temperature, condenser airflow, and indoor load, so verify the charge with superheat and subcooling rather than pressure alone.
What should R-454B suction and head pressure be?
Suction (low side) should sit near the saturation pressure for your evaporator temperature, about 110 to 121 psig for a 40 to 45F coil. Head (liquid, high side) should sit near the saturation pressure for a condensing temperature 15 to 25F above the outdoor air, which lands around 297 psig at 100F condensing up to about 395 psig at 120F condensing. If the head is much higher, check condenser airflow and for overcharge; if it is much lower, check for low charge or a low outdoor temperature.
What should superheat be for R-454B?
On a TXV system, target 8 to 15F of superheat at the evaporator for R-454B (many techs settle in the 8 to 12F middle of that band), the same window you would use for R-410A, because R-454B is an A2L near-drop-in with nearly identical pressure-temperature behavior. Pair that with 8 to 14F of subcooling at the liquid line, and always charge R-454B as a liquid from an inverted cylinder, since it is a zeotropic blend and vapor charging shifts its composition. Its temperature glide is low (about 2F), so the bubble-point/dew-point split is small, though this calculator still applies it (dew point for superheat, bubble point for subcooling). On a fixed-orifice or piston system, set the charge by the manufacturer's charging chart against indoor wet-bulb and outdoor dry-bulb instead of a fixed superheat number.
What should my subcooling be on 454B?
Target subcooling for R-454B with a TXV is 8-14°F, measured at the liquid line near the condenser outlet. Subcooling is the primary charging indicator on TXV systems. Many manufacturers print a specific subcooling target on the unit nameplate; the nameplate value always wins over generic ranges.
What is normal superheat for R-454B?
With a TXV, normal superheat for R-454B is 8-15°F at the suction line near the outdoor unit. With a fixed orifice, target superheat depends on outdoor ambient and indoor wet bulb, typically 5-20°F, so use the manufacturer charging chart. Superheat below 5°F risks liquid floodback to the compressor.
Can I use my R-410A gauges on R-454B?
Your manifold body handles the pressures fine because R-454B runs slightly lower than R-410A, but the R-410A temperature scale on an analog gauge will give wrong saturation temperatures. Use an R-454B PT scale, digital probes with R-454B selected, or this calculator. Hoses, recovery machines, and vacuum pumps used on R-454B should be A2L rated per the manufacturer.
Do I charge R-454B as liquid or vapor?
Charge R-454B as liquid from the cylinder. It is a blend of R-32 and R-1234yf, so vapor charging can fractionate the blend and shift its composition. Invert the cylinder (or use a liquid port) and throttle liquid into the suction side slowly through a charging valve or metering device so slugs never reach the compressor.
Is R-454B dangerous to work with?
R-454B is classified A2L: low toxicity and mildly flammable. It is much harder to ignite than propane (A3) and needs a strong ignition source plus a concentrated leak, but it changes work practices: no open flames or brazing on a charged circuit, A2L-rated recovery equipment, ventilation in enclosed spaces, and leak detection per UL 60335-2-40 on the equipment side.
Can I retrofit my R-410A system to R-454B?
No. R-454B is not a drop-in replacement for R-410A. Existing R-410A equipment is not listed for A2L refrigerants and lacks the required leak detection, airflow mitigation, and electrical design. Existing R-410A systems keep getting serviced with R-410A; R-454B goes only into equipment designed and listed for it.
Does R-454B have temperature glide?
Yes, but it is small, roughly 2°F. R-454B is a zeotropic blend, so bubble point and dew point differ slightly at the same pressure. This calculator handles that split the honest way: it converts suction pressure to the dew point for superheat and liquid pressure to the bubble point for subcooling, so the glide is already built in. In field practice that glide is close to gauge accuracy. R-407C, by comparison, has 9-11°F of glide, where using the wrong point misdiagnoses the system outright.
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Target Superheat Calculator
Charging a fixed-orifice (piston) system? Set the charge by target superheat from indoor wet-bulb and outdoor dry-bulb, compared to your measured superheat.
Normal Superheat & Subcooling Values
The target numbers by refrigerant and metering device, with what a high or low reading means. R-410A, R-454B, R-32, R-22, R-134a, and R-407C in one reference.
How to Calculate Superheat & Subcooling
The formulas, the step-by-step field method, and worked examples for R-410A and R-22. The math behind the calculator.
Printable Superheat & Subcooling Chart
Target ranges by refrigerant plus PT charts for R-410A, R-454B, and R-22, formatted to print or save as a PDF for the truck.
Subcooling on a Heat Pump
Why heat pumps have no subcooling target in heating mode, how to charge by weigh-in, and when the cooling-mode subcooling number still applies.
A2L Charge Limit Calculator
Maximum A2L charge for a room, or minimum room area for a charge, per UL 60335-2-40 and ASHRAE 15.2. Covers R-454B, R-32, and 6 more refrigerants.
EPA Refrigerant Leak Rate Calculator
Topping off a covered 15+ lb appliance triggers a leak rate calculation under 40 CFR 84.106 as of January 1, 2026. Residential and light commercial air conditioning and heat pumps are excluded by 84.106(a)(3)(ii), so on most split systems the rate is informational. Run the EPA math and check the thresholds.
BTU / HVAC Load Calculator
Size the system by climate zone, insulation, windows, and duct location with automatic tonnage recommendations.
Charging a brand-new A2L install? Check the sizing too.
New R-454B equipment means a fresh chance to catch an oversized replacement. Run the load by climate zone, insulation, and windows before you trust the old tonnage.