HVAC PT Charts

R454B vs R454C: Same Components, Different Applications

Updated October 3, 2026

R-454B and R-454C are both A2L blends of the same two components — R-32 (difluoromethane) and R-1234yf (2,3,3,3-tetrafluoropropene) — but in wildly different mass fractions. R-454B is 68.9/31.1 R-32/R-1234yf (residential AC replacement for R-410A, GWP 465, glide 2.3°F); R-454C is 21.5/78.5 (low-temperature commercial refrigeration, GWP 146, glide 13.9°F). Same ASHRAE 34 400-series designation family, same components, opposite ends of the R-32 / R-1234yf spectrum, opposite application classes.

R-454B AHRI Guideline N service cylinderIllustration of a refrigerant cylinder painted light green gray (RAL 7044), the color AHRI Guideline N-2017 calls for on all new refrigerant containers from 2020. Label: R454B, safety class A2L, GWP 465. Red band on the shoulder: AHRI Guideline N-2017 calls for one on containers of flammable refrigerants.R454BA2LGWP 465
R-454C AHRI Guideline N service cylinderIllustration of a refrigerant cylinder painted light green gray (RAL 7044), the color AHRI Guideline N-2017 calls for on all new refrigerant containers from 2020. Label: R454C, safety class A2L, GWP 146. Red band on the shoulder: AHRI Guideline N-2017 calls for one on containers of flammable refrigerants.R454CA2LGWP 146
R-454B (A2L, red flammability band) versus R-454C (A2L, red flammability band). Both ship in the AHRI Guideline N light gray-green service cylinder (RAL 7044) industry-uniform since 2020; ASHRAE 34 safety class alone drives the shoulder-band difference.
R-454B
HFC/HFO blendA2L Lower toxicity, lower flammability
GWP (100-yr)
465
Lubricant
POE
Glide @ 0°C
2.3°F
R-454C
HFC/HFO blendA2L Lower toxicity, lower flammability
GWP (100-yr)
146
Lubricant
POE
Glide @ 0°C
13.9°F

PT curves, overlaid

Solid line = bubble, dashed = dew where the refrigerant has significant temperature glide.

Pressure comparison at service temperatures

Side-by-side pressure values at common service temperatures, computed from CoolProp 7.2.0. Useful for retrofit feasibility — pressure deltas within ±20% typically allow retrofit-compatible service equipment; larger deltas require component pressure-rating review.

Saturation pressure (PSIG) at common service temperatures
TemperatureR-454BR-454CΔ vs R-454B
−20°F24 PSIG16 PSIG−35.5%
0°F45 PSIG32 PSIG−29.8%
40°F112 PSIG82 PSIG−26.4%
70°F191 PSIG141 PSIG−25.9%
95°F280 PSIG207 PSIG−26.0%
120°F396 PSIG292 PSIG−26.3%
Pressure delta: R-454C vs R-454B (% deviation)0%−39%−19%+19%+39%−20°F−35.5%0°F−29.8%40°F−26.4%70°F−25.9%95°F−26.0%120°F−26.3%

Pressure delta visualization: positive = R-454C runs higher than R-454B; negative = lower. Service equipment pressure rating matters when delta exceeds ±20% on the discharge side. For R-454B (zeotropic blend) bubble pressure is shown; for R-454C same rule applies.

Property differences side by side

Key differences at a glance
  • GWP impact: R-454B = 465, R-454C = 146 (−69% vs R-454B). Switching reduces direct climate impact substantially.
  • Lubricant: R-454B: POE; R-454C: POE. Same lubricant family — no oil change needed.
  • Glide change: R-454B glide = 2.3°F; R-454C glide = 13.9°F. Service measurement (superheat / subcooling) needs dew/bubble curve awareness for the higher-glide blend.

Properties side by side

PropertyR-454BR-454C
TypeHFC/HFO blendHFC/HFO blend
ASHRAE classA2LA2L
Composition68.9% R-32 / 31.1% R-1234yf21.5% R-32 / 78.5% R-1234yf
GWP (100-yr)465146
ODP00
LubricantPOEPOE
Boiling point @ 1 atm−50.5°C−45.6°C
Critical pointBlend (locus, not point)Blend (locus, not point)
Temp glide2.32°F13.89°F
AIM Act affectedNoNo

Choose R-454B if…

New residential and light-commercial AC equipment as the R-410A replacement. R-454B has near-azeotropic behavior (2.3°F glide), pressure envelope within a few percent of R-410A across the residential AC operating range, and GWP 465 (well under the 700 threshold for new residential AC equipment). Carrier markets R-454B equipment under its Puron Advance branding. Requires A2L-certified equipment per UL 60335-2-40 and IEC 60335-2-40 — A2L-listed equipment, charge limits per room volume, A2L-rated leak detection on larger installations.

Choose R-454C if…

New low-temperature commercial refrigeration equipment as the R-404A / R-448A / R-449A next-generation replacement. R-454C's much higher R-1234yf content brings GWP down to 146 (below 150, the limit in 517/2014 Annex III rows 11 and 13, and below every 40 CFR 84.54 limit — the lowest is 150), at the cost of substantial temperature glide (13.9°F). The zeotropic behavior requires TXV/EEV metering with careful superheat measurement on the dew curve — bubble-curve SH calculation would err by the full glide magnitude.

When neither is ideal

For medium-temperature commercial refrigeration where the R-454C glide is too large for the equipment class, R-455A (R-32/CO₂/R-1234yf, GWP 146, similar glide profile) or R-448A/R-449A (higher GWP but more manageable ~11°F glide, A1 safety class) are the alternatives. For residential AC where A2L classification isn't yet acceptable (some jurisdictions phasing in A2L certification), continued R-410A service on reclaimed supply is the interim option — but the AIM Act phase-down makes this a shrinking window.

Retrofit and transition

R-454B and R-454C are not retrofit candidates for each other in either direction. The pressure envelope gap is substantial — R-454B at 40°F evaporator saturation is 112.0 PSIG (bubble) / 107.0 PSIG (dew); R-454C at the same temperature is 82.4 PSIG (bubble) / 61.5 PSIG (dew). Neither ratio is close enough for a common metering-device orifice to handle both, and the compressor displacement sizing differs materially.

More fundamentally, they're designed for different application classes. R-454B replaces R-410A in residential AC where evaporator saturation runs around 40°F (roughly 45°F return-air with 5–15°F superheat) and condenser saturation runs 115–130°F. R-454C replaces R-404A in low-temperature commercial refrigeration where evaporator saturation runs −20 to 0°F for frozen-goods walk-ins. Different pressure envelopes, different capacity requirements, different equipment topologies.

Both refrigerants use POE lubricant and require A2L-certified equipment, but to different product standards — R-454B per UL/IEC 60335-2-40 (residential AC), R-454C per IEC 60335-2-89 (low-temperature commercial refrigeration). The A2L class and POE lubricant are the shared properties. Everything else about the equipment design flows from the different evaporator and condenser operating points.

If the question is "which A2L blend replaces R-410A in residential AC?", the answer is R-454B (or R-32 in some OEM lines). If the question is "which A2L blend replaces R-404A in LT commercial refrigeration?", the answer is R-454C or R-455A. The two never compete for the same equipment slot.

Regulatory and transition context

Both refrigerants sit in an active regulatory transition driven by climate-impact rules. The transitions affect availability, pricing, and new-equipment specification.

  • AIM Act (40 CFR Part 84): US HFC production / import phase-down. Cap declines from 90% allocation (2022) to 15% by 2036. Neither refrigerant is directly affected.
  • EU: Regulation (EU) No 517/2014, replaced by (EU) 2024/573 (applying from March 11, 2024); 2024/573 uses AR4 GWPs for HFCs and AR6 for other fluorinated gases (recital 8).
  • Kigali Amendment to Montreal Protocol (2016): international HFC phase-down framework. The Montreal Protocol has 198 parties; 174 have ratified the Kigali Amendment (as of August 10, 2026). The AIM Act and EU F-Gas are regional implementations. Schedules differ by country group.
  • ASHRAE 34-2022: safety classification (A1, A2L, A3, B1, B2L). For A2L refrigerants like R-32, R-454B, R-454C, R-455A: equipment must be A2L-certified, charge limits per IEC 60335-2-40 apply.

Why R-454B → R-454C isn't a direct retrofit

R-454B → R-454C is a full equipment-replacement decision, not a service-time swap. The barriers below are structural — equipment certification, oil chemistry, pressure ratings — so no field checklist can bridge them. The realistic path is to continue servicing existing R-454B equipment through its useful life, then install new R-454C-rated equipment at end-of-life.

Specific barriers for this pair
  • Saturation pressure delta −26% at 95°F. Compressor, TXV, condenser, and service-valve ratings are engineered around R-454B's envelope (280 PSIG at 95°F); running R-454C (207 PSIG) at this delta exceeds the design margins on multiple components. Retrofitting means re-rating hardware, not just changing charge.

Lifecycle and operational context

Beyond the per-service-call decision, the R-454B ↔ R-454C choice sits inside a broader regulatory and lifecycle context. The transition direction (which is the predecessor, which is the successor) is driven by climate policy and the AIM Act phase-down, not technical preference alone.

Lifecycle and regulatory snapshot
  • GWP profile: R-454B = 465 GWP; R-454C = 146 GWP. Switching from R-454B to R-454C reduces direct refrigerant climate impact by 69%.
  • AIM Act exposure: Neither refrigerant is directly affected by the AIM Act phase-down. Other regional regulations (EU F-Gas, Kigali signatory implementations) may still apply.
  • EU (Regulation (EU) No 517/2014, replaced by (EU) 2024/573): R-454B (GWP 465) meets 2 Annex III placing-on-the-market prohibitions; the earliest is Refrigerators and freezers for commercial use (hermetically sealed equipment) (GWP ≥ 150) from January 1, 2022. R-454C (GWP 146) is below every Regulation (EU) No 517/2014 Annex III GWP threshold.
  • Service supply outlook: Neither refrigerant faces near-term supply constraints from AIM Act phase-down. Pricing follows normal commodity dynamics.
  • TEWI / LCCP framing: Total Equivalent Warming Impact accounts for both direct refrigerant emissions (leakage, end-of-life) and indirect emissions from equipment energy consumption. For HVAC equipment with ≤5% annual leak rate, indirect emissions typically dominate TEWI by 80-90% — meaning equipment efficiency matters more than refrigerant GWP for total climate impact. For commercial refrigeration with higher leak rates, the balance can tip toward favoring low-GWP refrigerants.

Regulatory sources: AIM Act (40 CFR Part 84), EU F-Gas Regulation 517/2014 and update 2024/573, Kigali Amendment to the Montreal Protocol (2016). GWP values on the US EPA basis (40 CFR 84 / IPCC AR4).

Service implications — R-454B → R-454C

What a service technician needs to know when transitioning from R-454B to R-454C (or comparing them for new equipment specification). Two real-world scenarios show how the difference plays out in practice.

1
Service problemR-454B ↔ R-454C

Pressure envelope check for R-454B → R-454C

Scenario · Field tech needs to know: do R-454B service tools handle R-454C, or does the pressure delta require new equipment? PT chart comparison at service temperatures gives the answer.

Comparison
TempR-454BR-454CΔ
40°F112 PSIG82 PSIG−26.4%
70°F191 PSIG141 PSIG−25.9%
95°F280 PSIG207 PSIG−26.0%
Action required · Large pressure delta — equipment changes required
Pressure delta exceeds typical retrofit-acceptable margin. Component pressure ratings need engineering review; full equipment replacement is often the right answer rather than retrofit.
Fix
Component pressure ratings must be verified for the higher-pressure refrigerant. R-410A-rated service equipment (800 PSI gauges) handles many newer refrigerants, but R-744 (transcritical) requires 3000+ PSI components.
2
Service problemR-454B ↔ R-454C

Service-side implications: lubricant and safety

Scenario · Beyond pressure envelope, the switch from R-454B to R-454C affects lubricant, safety class, and operating procedure.

Comparison
ConcernR-454BR-454CAction
LubricantPOEPOENo change
Safety classA2LA2LNo change
Glide2.3°F13.9°FCurve awareness
OK · No major service-side changes
Service procedures essentially the same. Retrofit is mostly a refrigerant swap without equipment changes.

When to use which tool for this comparison

Frequently asked

›Why are R-454B and R-454C so different if they share the same components?

The 21.5/78.5 R-32/R-1234yf ratio in R-454C compared to R-454B's 68.9/31.1 flips the dominant component. R-32 (pure) is a moderate-glide-free HFC with GWP 675, high vapor pressure, and no glide. R-1234yf is a HFO with GWP < 1, low vapor pressure, and no glide by itself. When blended in near-equal proportions there's little glide; when one component dominates by 68% or 78% mass, the mixture behaves close to that component with the small fraction of the other producing the glide seen in the blend. R-454B is R-32-dominant (behaves like R-32 with some R-1234yf character); R-454C is R-1234yf-dominant (behaves like R-1234yf with some R-32 character). Different components dominating produces different pressure envelopes and glide.

›Are R-454B and R-454C interchangeable?

No. Different pressure envelopes (roughly 35% pressure difference at 40°F evaporator saturation), different glide characteristics (2.3°F vs 13.9°F), different equipment designs, different application classes. Equipment designed for one cannot operate on the other. This is a common misunderstanding driven by the shared '454' designation family — the family indicates ASHRAE 34 zeotropic-blend numbering, not any interchangeability.

›Which has lower GWP?

R-454C at 146 — below 150, the limit in 517/2014 Annex III rows 11 and 13, and below every 40 CFR 84.54 limit (the lowest is 150). R-454B at 465 is well under the residential AC threshold (700) but doesn't meet the tighter thresholds applicable to commercial refrigeration. This split matches their application-class targets: residential AC has a higher GWP allowance than LT commercial refrigeration.

›Do both refrigerants require A2L-certified equipment?

Yes, both are ASHRAE class A2L (lower toxicity, mildly flammable) under Standard 34. R-454B equipment complies with UL/IEC 60335-2-40 (residential AC); R-454C low-temperature commercial equipment complies with IEC 60335-2-89. Either way: charge limits computed from installation room volume, appropriate ventilation, and (on larger charges) A2L-rated leak detection. Field retrofit of A1-only equipment to either A2L blend is generally not possible — the safety certification requires factory-level engineering of the refrigerant circuit and electrical components.

›Why not just use R-32 alone for residential AC?

Pure R-32 is used in residential AC in some markets. R-454B exists as an alternative for OEMs (particularly Carrier) that wanted lower GWP than pure R-32 (465 vs 675) with a similar pressure envelope. The choice between R-32 and R-454B for residential AC is now largely OEM preference; both refrigerants are AIM Act-compliant for new residential AC production.

›How does R-454C compare to R-455A for LT commercial refrigeration?

Both are A2L blends targeting the same LT commercial refrigeration market with GWP well under 150. R-454C is R-32/R-1234yf (21.5/78.5, glide 13.9°F); R-455A is R-32/CO₂/R-1234yf (21.5/3/75.5, glide ~22°F, with CO₂ as the low-boiling glide-inducer). See our r-454c-vs-r-455a comparison for the direct head-to-head — the choice comes down to whether the CO₂ content and larger glide are acceptable for the specific equipment design.

Related

R-454B PT chart

Full reference: PT chart, properties, retrofit guidance.

R-454C PT chart

Full reference: PT chart, properties, retrofit guidance.

R-454B operating pressures

Suction/discharge ranges by ambient + diagnostic procedure.

R-454C operating pressures

Suction/discharge ranges by ambient + diagnostic procedure.

Sources & provenance

  • Saturation pressures from CoolProp 7.2.0 (Bell, Wronski, Quoilin, Lemort 2014, doi:10.1021/ie4033999)
  • Safety classifications per ANSI/ASHRAE Standard 34-2022
  • GWP values on the US EPA basis (40 CFR 84 / IPCC AR4), with IPCC AR4/AR5/AR6 shown where listed
  • Regulatory context: AIM Act (40 CFR Part 84), EU F-Gas Regulation 517/2014 + 2024/573, Kigali Amendment to Montreal Protocol
  • Service-cylinder color convention: AHRI Guideline N-2017 (RAL 7044 industry-uniform since 2020)
  • R-454B: CoolProp 7.2.0 mixture model: R-32/R-1234yf, 68.9/31.1% by mass
  • R-454C: CoolProp 7.2.0 mixture model: R-32/R-1234yf, 21.5/78.5% by mass