R-450A
Near-azeotropic R-134a/R-1234ze(E) blend (42/58 mass) marketed as Honeywell Solstice N13 — A1 safety, GWP 605 (~58% lower than R-134a), very small glide. The Honeywell alternative to Chemours R-513A for R-134a chiller drop-in retrofit.
Lower toxicity (Occupational Exposure Limit ≥ 400 ppm). No flame propagation in air at standard atmospheric pressure and 60°C. R-134a, R-22, R-410A, R-404A, R-744 (CO2) are A1.
- Flammability
- None (no flame propagation)
- Toxicity
- Lower (OEL ≥ 400 ppm)
Classification per ANSI/ASHRAE Standard 34-2022. See full reference.
Saturation pressure-temperature curve
No PT chart in this build — see manufacturer datasheet. R-450Ahas a published PT chart in its manufacturer's technical datasheet (linked below). The chart has not been transcribed into this site's dataset. For service work, use the manufacturer's published PT chart directly — link below.
- manufacturer-datasheetThe Chemours Company, Opteon XP10 (R-450A) Technical Information / Product Data Sheet.PT chart and properties for R-450A (R-134a/R-1234ze(E) 42/58 mass% zeotropic blend).https://www.opteon.com/en/products/stationary-refrigerants/xp10
- standardsAHRI Standard 700-2019 — R-450A specification.
At a glance
Chemistry
Lubricant compatibility
POE required. Lower-GWP R-134a alternative for medium-temp commercial refrigeration, chillers, and heat pumps. Low glide (~0.5 K).
Blend composition
- R-134a42.0%
- R-1234ze(E)58.0%
Trade names
- Opteon XP10Chemours
Common applications
- Medium-temperature commercial refrigeration
- Centrifugal and screw chillers
- R-134a retrofit
Properties
- Boiling point (1 atm)-23.4°C / -10.1°F
- Critical point220.1°F at 532 PSIG
- Molar mass108.70 g/mol
- Temperature glideNegligible (0.90°F)
- ODP0
- GWP (AR5, 100-yr)605
- GWP (AR6, 100-yr)645
What is R-450A?
R-450A is a near-azeotropic binary blend of 42% R-134a (HFC) and 58% R-1234ze(E) (HFO) by mass [ashrae34]. The near-azeotropic composition produces very small temperature glide (~0.6°F) — service-equivalent to a pure refrigerant for practical measurement purposes.
R-450A was developed by Honeywell as a near-drop-in retrofit for R-134a centrifugal chillers and commercial refrigeration. The R-1234ze(E) component (GWP 7) is different from R-513A's R-1234yf component (GWP 4) but serves the same role: diluting the blend's overall GWP while preserving A1 safety classification and operational compatibility with R-134a equipment.
Where R-450A is used
- R-134a centrifugal chiller retrofit
- R-134a screw chiller retrofit
- Commercial refrigeration retrofit (display cases, beverage coolers)
- New chiller equipment installations where A1 classification is preferred
Regulatory & phase-down status
R-450A's GWP of 605 is below the EPA AIM Act 700-GWP threshold for residential AC. For chiller and commercial refrigeration applications, R-450A provides moderate GWP reduction with A1 safety preservation [aimact][eufgas].
Like R-513A, R-450A is a transitional refrigerant for R-134a equipment retrofit. New chiller equipment increasingly specifies R-515B (A1, GWP 287) or R-1234ze(E) (A2L, GWP 7) for lower long-term GWP positioning.
Service notes
POE oil required — same lubricant family as R-134a, so R-134a retrofit to R-450A typically does NOT require oil change [ahri700]. The near-azeotropic composition (~0.6°F glide) is small enough that service measurement procedures from R-134a practice apply without modification.
R-450A operating pressures are very close to R-134a across the chiller operating range. Standard 500 PSI manifold gauges handle the envelope. A1 classification means no A2L procedures required.
Phase-down timeline
No phase-down milestones documented for R-450A in this build. This may mean: (a) no regulatory phase-down currently published; (b) the refrigerant has local regulatory schedules not yet transcribed into the site dataset; or (c) it is a specialty refrigerant outside the main regulatory frameworks. For authoritative current status, consult the EPA AIM Act allocations (40 CFR Part 84), EU F-Gas Regulation 517/2014 + 2024/573, and the relevant national implementations of the Kigali Amendment.
Global warming potential, in context
Commercial refrigeration — medium temperature
Retrofit and replacement paths
R-450A replaces
Replacements for R-450A
Reading the R-450A PT chart — near-azeotropic, single curve adequate
R-450A is near-azeotropic with very small glide (~0.6°F). The PT chart can show bubble and dew curves but the spread is small enough that a single curve approximation is operationally adequate for most service measurements.
For superheat measurement at the suction line, use the dew curve (or single approximation curve). For subcooling at the liquid line, use the bubble curve (or single approximation curve). The 0.6°F glide creates measurement uncertainty much smaller than typical superheat/subcooling targets.
R-450A's near-azeotropic behavior means R-134a service procedures apply without procedural change. Technicians transitioning from R-134a to R-450A face no operational training adjustment — same lubricant, same pressure envelope (within 8%), same effectively-single-curve measurement.
The 42/58 R-134a/R-1234ze(E) composition with R-450A vs R-513A differentiation
R-450A combines R-134a (42%, GWP 1430, A1) and R-1234ze(E) (58%, GWP 7, A2L) in near-azeotropic proportions. The mass-weighted GWP: 0.42 × 1430 + 0.58 × 7 = 600 + 4 = 605 [ipccar5].
The R-1234ze(E) component differentiates R-450A from R-513A. R-1234ze(E) has slightly higher GWP than R-1234yf (7 vs 4 per IPCC AR5) but lower vapor pressure, producing a blend with slightly lower operating pressure than R-513A. The composition trade-offs:
- R-450A pressure envelope sits slightly below R-134a's
- R-513A pressure envelope sits slightly above R-134a's
For chiller applications where centrifugal compressor efficiency depends on the operating envelope, the small pressure differences between R-450A and R-513A can matter. Equipment OEMs typically evaluate both retrofits and may have a slight preference based on their specific compressor designs.
Pressure envelope ~8% below R-134a
R-450A's pressure envelope is slightly below R-134a across the operating range. At 70°F R-450A saturation is 65 PSIG vs R-134a's 71 PSIG (CoolProp 7.2.0) — approximately 8% below. At 95°F, R-450A is approximately 112 PSIG vs R-134a's 124 PSIG.
The lower pressure profile is mildly beneficial for chiller centrifugal compressor designs that operate near the upper end of their efficient pressure-ratio range with R-134a. Some chiller OEMs may show slightly better efficiency with R-450A than with R-513A in specific equipment lines; others may show the opposite. The differences are small (typically within 1-2% COP) and are equipment-specific.
GWP 605 — slightly lower than R-513A, same regulatory positioning
R-450A's GWP of 605 is approximately 4% below R-513A's 631 and 58% below R-134a's 1430 [ipccar5]. The GWP reduction is marginally better than R-513A but operationally insignificant for regulatory compliance — both clear EPA AIM Act 700-GWP threshold and face similar EU F-Gas Regulation positioning.
For very-low-GWP chiller applications, R-515B (A1, GWP 287) and R-1234ze(E) (A2L, GWP 7) are the destinations beyond R-450A and R-513A. R-450A is a transitional refrigerant for R-134a equipment retrofit through the late 2020s.
R-450A at chiller operating temperatures
R-450A saturation values across typical chiller operating conditions:
- 35°F (chilled water evaporator) — R-450A saturation approximately 25 PSIG.
- 45°F (chilled water reference) — R-450A saturation approximately 35 PSIG.
- 70°F (bench reference) — R-450A saturation 65 PSIG.
- 85°F (cooling tower water supply) — R-450A saturation approximately 88 PSIG.
- 95°F (warm cooling water condenser) — R-450A saturation approximately 112 PSIG.
- 105°F (extreme condenser operation) — R-450A saturation approximately 130 PSIG.
For typical chiller operation: expect 30-40 PSIG suction and 110-140 PSIG discharge. Very similar to R-134a operating ranges in the same equipment.
Service procedures identical to R-513A and R-134a
R-450A service is operationally indistinguishable from R-513A and R-134a for typical chiller and commercial refrigeration work. Same safety class (A1), same lubricant (POE), near-equivalent pressure envelope, near-azeotropic behavior.
| Equipment / procedure | R-134a | R-450A | R-513A | | --- | --- | --- | --- | | Manifold gauge rating | 500 PSI | 500 PSI | 500 PSI | | Recovery cylinder | Standard | Standard | Standard | | Lubricant | POE | POE (no change) | POE (no change) | | Curve selection | Single curve (pure) | Effectively single (0.6°F glide) | Single curve (azeotrope) | | Safety class | A1 | A1 | A1 | | Charge by weight | Required | Required | Required | | Vacuum target | 500 microns held 30+ min | 500 microns held 30+ min | 500 microns held 30+ min |
Field service can be standardized across R-134a, R-450A, and R-513A. Technicians familiar with any one of the three can work on the others without procedural retraining.
Honeywell vs Chemours — same retrofit market, different chemistry path
R-450A (Honeywell Solstice N13) and R-513A (Chemours Opteon XP10) compete for the R-134a chiller retrofit market with operationally equivalent products built around different HFO components. The competition parallels the R-448A vs R-449A rivalry in commercial refrigeration retrofit — same regulatory niche, similar performance, different manufacturer brand.
Choice typically driven by: equipment OEM specification preferences, refrigerant distributor relationships, established manufacturer-customer agreements. Both Honeywell and Chemours offer extensive technical support for retrofit specification and execution; either retrofit path produces successful R-134a → low-GWP transition in chiller equipment.
For end-user operators with established Honeywell or Chemours relationships across their refrigerant portfolio (R-410A replacement, R-404A retrofit, R-134a retrofit), brand consistency may simplify procurement and training. For new operator decisions, R-450A and R-513A are essentially interchangeable.
How to think about R-450A in 2026 and beyond
R-450A occupies the R-134a chiller retrofit niche alongside R-513A. For existing R-134a centrifugal chillers and commercial refrigeration equipment with substantial remaining service life, R-450A provides ~58% GWP reduction with A1 safety preservation, POE oil compatibility, and operational simplicity.
For new chiller equipment, the trajectory is toward lower-GWP alternatives. R-515B (A1, GWP 287) for A1 new equipment with substantial GWP reduction; R-1234ze(E) (A2L, GWP 7) for very-low-GWP applications with A2L-rated equipment.
For service technicians, R-450A work is operationally interchangeable with R-134a and R-513A work. Field practice can be standardized across all three refrigerants. The retrofit transition is the easiest of any major HFC retrofit category.
Frequently asked
›What is the normal operating pressure of R-450A?
Very close to R-134a. At 70°F R-450A saturation is approximately 65 PSIG (CoolProp 7.2.0). Compare to R-134a at 70°F (71 PSIG) — R-450A is about 8% lower.
For typical chiller operation, the pressure delta is small enough that R-134a-rated equipment handles R-450A within design tolerances. Compressor and expansion-valve adjustments are typically not required.
›What's the difference between R-450A and R-513A?
Both are A1 near-azeotropic HFC/HFO blends marketed as R-134a chiller retrofits. R-450A (Honeywell Solstice N13) uses R-134a/R-1234ze(E) 42/58, GWP 605, ~0.6°F glide. R-513A (Chemours Opteon XP10) uses R-134a/R-1234yf 44/56, GWP 631, azeotropic (~0°F glide).
R-450A has slightly lower GWP (605 vs 631) and uses R-1234ze(E) (slightly higher GWP individually than R-1234yf but lower vapor pressure). R-513A has slightly higher pressure envelope match to R-134a. The choice between them is typically driven by manufacturer relationship.
›Can I retrofit R-134a to R-450A without oil change?
Yes — both refrigerants use POE oil. Standard retrofit procedure: recover R-134a, replace filter-drier, evacuate to 500 microns, recharge R-450A by weight to OEM nameplate.
›What does R-450A's GWP of 605 mean?
A 1 kg release of R-450A traps approximately 605 times more heat over 100 years than 1 kg of CO₂ (IPCC AR5, mass-weighted from 42% R-134a × 1430 + 58% R-1234ze(E) × 7) [ipccar5]. The 605 figure represents a ~58% reduction from R-134a's 1430.
›Does R-450A have temperature glide?
Very small — approximately 0.6°F at typical operating pressures (CoolProp 7.2.0). The near-azeotropic composition means service measurement procedures from R-134a practice apply without modification. Single-curve approximation is acceptable for routine superheat and subcooling calculations.
›What lubricant does R-450A use?
Polyolester (POE) oil — same lubricant family as R-134a [ahri700]. No oil change required for R-134a retrofit.
›Is R-450A safe to handle?
ASHRAE class A1 — non-toxic and non-flammable [ashrae34]. Standard HFC service procedures apply. No A2L-specific requirements.
›Why does R-450A use R-1234ze(E) instead of R-1234yf?
Different HFO has different vapor pressure profile. R-1234ze(E) has lower vapor pressure than R-1234yf (NBP −2°F vs −21°F), producing a different blend pressure envelope. R-450A's pressure envelope sits slightly below R-134a's; R-513A's sits slightly above.
For chiller applications specifically, the slightly lower pressure of R-450A may be marginally preferred for some centrifugal compressor designs. Honeywell selected R-1234ze(E) for the Solstice N13 product; Chemours selected R-1234yf for the Opteon XP10 product. Both serve the same retrofit application.
Sources & citations
- [1]ASHRAE Standard 34-2022
- [2]IPCC AR5 (2014) Working Group I, Chapter 8, Table 8.A.1
- [3]EPA AIM Act — 40 CFR Part 84 Subpart BFinal Rule Oct 2021https://www.epa.gov/climate-hfcs-reduction
- [4]EU F-Gas Regulation 517/2014 (revised 2024)
- [5]EPA SNAP — R-450A acceptable for chiller retrofit
- [6]CoolProp 7.2.0
- [7]AHRI Standard 700-2019
- [8]Honeywell Solstice N13 (R-450A) Technical Information