HVAC PT ChartsVerified saturation data · 61 refrigerants
RefrigerantASHRAE R-1234ze(E)

R-1234ze

A2LMildly flammableHFO (pure)
CHF=CHCF3

Pure HFO (E-isomer of 1,3,3,3-tetrafluoropropene, CHF=CHCF₃) — chiller and heat pump refrigerant. AR4-basis GWP 7 (the figure EPA SNAP and Honeywell datasheets cite); strict IPCC AR5/AR6 ≈ 1. A2L safety class. Honeywell Solstice ze. Lower pressure envelope than R-134a; well-suited to centrifugal chiller designs.

Saturation @ 70°F
49.5PSIG
GWP (IPCC AR5)
—
Temperature glide
≈0°F
Boiling point
-2.1°F
Sourced facts
ASHRAE safety class
A2L[src]
Chemical formula
CHF=CHCF₃ (E)[src]
GWP (100-yr)
7IPCC AR4 / EPA SNAP basis[src]
ODP
0[src]
Normal boiling point
−2.2°F (−19°C)[src]
Temperature glide
0°F[src]
Required lubricant
POE / PVE[src]
Trade name
Solstice ze[src]
R-1234ze PT calculator Superheat
A2L
Mildly flammable

Lower toxicity. Flame propagates in air at 60°C, but with a low burning velocity (≤ 10 cm/s) and a heat of combustion < 19,000 kJ/kg. Requires A2L-rated equipment, leak detection, and charge limits per UL 60335-2-40 and ASHRAE 15. R-32, R-454B, R-1234yf, R-1234ze(E), R-452B, R-454C, R-455A, R-516A are A2L.

Flammability
Low (burning velocity ≤ 10 cm/s)
Toxicity
Lower (OEL ≥ 400 ppm)

Classification per ANSI/ASHRAE Standard 34-2022. See full reference.

01

Saturation pressure-temperature curve

Pressure
Temperature
°F
70°F: 49.5 PSIG
Quick lookup — R-1234ze
49.5PSIG(341 kPa)
Range: -40 to 150°FOpen full PT calculator →
Common service temperatures
32°F
17PSIG
Freezing
45°F
26PSIG
Heat-pump heat
70°F
49PSIG
Standard
75°F
55PSIG
Test ref
80°F
61PSIG
Warm
95°F
82PSIG
Summer peak

Saturation values from CoolProp 7.2.0 R1234ze(E). Operating pressure on a running system differs — see the operating-pressure references for in-use values.

02

R-1234ze PT chart PDF — printable saturation table

Looking for the R-1234ze PT chart PDF for shop reference? The complete pressure-temperature saturation table is below — every 1° increment from −40°F to 150°F (or to the refrigerant's critical temperature). Use the Print / Save as PDF button in the table header to download a clean, table-only PDF (the rest of the page is hidden from the print output). Important service temperatures (normal boiling point, freezing point of water, residential AC evap and condenser targets) are tinted and tagged in the table for at-a-glance shop reference.

R-1234ze PT Chart — Pressure-Temperature Saturation Table

1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com

R-1234ze · 1° increments · °F / PSIG
Tinted rows: NBP atmospheric crossover · 32°F H₂O freeze · 40°F Chiller evap LCHW · 100°F Cond saturation · 130°F High-side limit
R-1234ze pressure-temperature saturation table in Fahrenheit and PSIG
Temp (°F)Pressure (PSIG)
-40°F-9.4
-39°F-9.2
-38°F-9.0
-37°F-8.9
-36°F-8.7
-35°F-8.5
-34°F-8.3
-33°F-8.2
-32°F-8.0
-31°F-7.8
-30°F-7.6
-29°F-7.4
-28°F-7.2
-27°F-7.0
-26°F-6.8
-25°F-6.5
-24°F-6.3
-23°F-6.1
-22°F-5.8
-21°F-5.6
-20°F-5.3
-19°F-5.1
-18°F-4.8
-17°F-4.6
-16°F-4.3
-15°F-4.0
-14°F-3.8
-13°F-3.5
-12°F-3.2
-11°F-2.9
-10°F-2.6
-9°F-2.3
-8°F-2.0
-7°F-1.6
-6°F-1.3
-5°F-1.0
-4°F-0.7
-3°F-0.3
-2°FNBP (atmospheric)0.1
-1°F0.4
0°F0.8
1°F1.1
2°F1.5
3°F1.9
4°F2.3
5°F2.7
6°F3.1
7°F3.5
8°F4.0
9°F4.4
10°F4.8
11°F5.3
12°F5.8
13°F6.2
14°F6.7
15°F7.2
16°F7.7
17°F8.2
18°F8.7
19°F9.2
20°F9.7
21°F10.2
22°F10.8
23°F11.3
24°F11.9
25°F12.5
26°F13.0
27°F13.6
28°F14.2
29°F14.8
30°F15.4
31°F16.1
32°FH₂O freeze16.7
33°F17.4
34°F18.0
35°F18.7
36°F19.4
37°F20.1
38°F20.8
39°F21.5
40°FChiller evap LCHW22.2
41°F22.9
42°F23.7
43°F24.4
44°F25.2
45°F26.0
46°F26.8
47°F27.6
48°F28.4
49°F29.2
50°F30.0
51°F30.9
52°F31.7
53°F32.6
54°F33.5
55°F34.4
56°F35.3
57°F36.2
58°F37.2
59°F38.1
60°F39.1
61°F40.1
62°F41.0
63°F42.1
64°F43.1
65°F44.1
66°F45.1
67°F46.2
68°F47.3
69°F48.4
70°F49.5
71°F50.6
72°F51.7
73°F52.9
74°F54.0
75°F55.2
76°F56.4
77°F57.6
78°F58.8
79°F60.1
80°F61.3
81°F62.6
82°F63.9
83°F65.2
84°F66.5
85°F67.8
86°F69.2
87°F70.5
88°F71.9
89°F73.3
90°F74.8
91°F76.2
92°F77.6
93°F79.1
94°F80.6
95°F82.1
96°F83.6
97°F85.2
98°F86.7
99°F88.3
100°FCond saturation89.9
101°F91.5
102°F93.2
103°F94.8
104°F96.5
105°F98.2
106°F99.9
107°F101.6
108°F103.3
109°F105.1
110°F106.9
111°F108.7
112°F110.5
113°F112.4
114°F114.3
115°F116.1
116°F118.0
117°F120.0
118°F121.9
119°F123.9
120°F125.9
121°F127.9
122°F129.9
123°F132.0
124°F134.1
125°F136.2
126°F138.3
127°F140.4
128°F142.6
129°F144.8
130°FHigh-side limit147.0
131°F149.3
132°F151.5
133°F153.8
134°F156.1
135°F158.4
136°F160.8
137°F163.2
138°F165.6
139°F168.0
140°F170.4
141°F172.9
142°F175.4
143°F178.0
144°F180.5
145°F183.1
146°F185.7
147°F188.3
148°F191.0
149°F193.6
150°F196.3
CoolProp 7.2.0 · PSIG/kPa = gauge · PSIA = PSIG + 14.696 · kPa(abs) = kPa(gauge) + 101.325

Full saturation values at 1° increments — toggle between °F / PSIG and °C / kPa. Use Print / Save as PDF for laminated shop reference, or download the CSV / JSON below for use in other tools. R-1234ze PT chart data: CoolProp 7.2.0 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.

03

At a glance

Chemistry

CHF=CHCF3
1,3,3,3-Tetrafluoropropene (the E isomer is the default unless Z specified)

Lubricant compatibility

POEPVEMO

Long-term low-GWP replacement for R-134a in chillers, heat pumps, and commercial refrigeration. Same molecule as the explicit E-isomer page; this slug preserves a legacy URL.

Trade names

  • Solstice zeHoneywell
  • Opteon 1100Chemours (some references)

Common applications

  • Centrifugal chillers (low-pressure / large-tonnage)
  • Heat pumps (commercial)
  • Foam blowing agent
  • Aerosol propellant
04

Properties

  • Boiling point (1 atm)
    -19.0°C / -2.1°F
  • Critical point
    228.9°F at 513 PSIG
  • Molar mass
    114.04 g/mol
  • Temperature glide
    Negligible (0.00°F)
  • ODP
    0
  • GWP (AR5, 100-yr)
    —
  • GWP (AR6, 100-yr)
    1.37
  • Atmospheric lifetime
    0.045 years
05

What is R-1234ze?

R-1234ze is pure 1,3,3,3-tetrafluoropropene in the E (trans) isomer configuration — a single-molecule HFO with very low GWP and a pressure envelope well-suited to centrifugal chiller compressor designs [ashrae34]. R-1234ze is one of the dominant HFO refrigerants for new chiller equipment in EU and increasingly US markets.

The defining characteristic vs R-134a is the lower operating pressure — R-1234ze saturation at 70°F is 49 PSIG vs R-134a's 71 PSIG. The lower pressure makes R-1234ze a better match for centrifugal chiller impeller designs operating at moderate pressure ratios.

Where R-1234ze is used

  • Centrifugal chillers — new equipment installations (Carrier AquaForce 30XV-VFD, others)
  • High-temperature heat pumps — industrial process heating
  • Component in R-454B, R-450A, R-515A, R-515B blends
  • Aerosol propellant in some specialty applications
  • Foam blowing agent in polyurethane insulation

Regulatory & phase-down status

R-1234ze faces no phase-down pressure — under any reasonable GWP basis (7 per AR4 / EPA SNAP, ≈1 per AR5/AR6) the value sits below every regulatory threshold including the EU F-Gas 150-GWP cap [aimact][eufgas]. R-1234ze is structurally a long-term destination refrigerant.

Market position is dominant in new centrifugal chiller installations in EU markets and growing in US chiller market. R-1234ze is increasingly the chiller industry's choice for very-low-GWP new-equipment specification.

Service notes

POE or PVE (polyvinyl ether) oil required depending on equipment OEM [ahri700]. Mineral oil is not compatible. The A2L safety class requires sealed motors, A2L-rated leak detection in some installations, and nitrogen-purged brazing during service [ul60335].

R-1234ze operating pressures are lower than R-134a across the chiller operating range — standard 500 PSI manifold gauges have ample margin. Pure single-component refrigerant; no glide handling needed.

07

Operating cycle

CompressorRaises pressureCondenserRejects heat to outdoorsExpansion deviceDrops pressureEvaporatorAbsorbs heat from indoorsDischarge: 107 PSIG, 180°FLiquid: 107 PSIG, 100°FEvap inlet: 22 PSIG, 40°F (two-phase)Suction: 22 PSIG, 50°FTypical residential cooling cycle for R-1234ze (40°F evap, 110°F condenser, 10°F superheat, 10°F subcooling)
08

Phase-down timeline

R-1234ze is not currently regulated by AIM Act or EU F-Gas phase-down. Its very low GWP (<1) places it below regulatory thresholds. No published phase-down milestones exist for this refrigerant — it is a forward-compatible option for the current low-GWP transition rather than a refrigerant being phased out.

Properties: GWP not published · ODP 0 · Not AIM Act-affected · type: hfo-pure
09

Global warming potential, in context

Medium-pressure centrifugal & screw chillers

R-515B293R-515A392R-450A605R-513A631R-134a1.4kEU F-Gas (150)EPA AIM Act (700)
10

Retrofit and replacement paths

R-1234ze replaces

Reading the R-1234ze PT chart

R-1234ze's PT chart is a single saturation curve — R-1234ze is pure single-component HFO with no temperature glide [ashrae34]. Service measurement uses standard single-curve procedures: superheat = suction line temp − saturation temp; subcooling = saturation temp − liquid line temp.

The pressure envelope is substantially lower than R-134a. At 70°F R-1234ze saturation is approximately 49 PSIG vs R-134a's 71 PSIG (CoolProp 7.2.0) — about 30% lower. This is the engineering reason R-1234ze is well-suited to centrifugal chiller designs but not to R-134a retrofit (the pressure delta is too large for direct refrigerant swap).

HFO chemistry — E-isomer of 1,3,3,3-tetrafluoropropene

R-1234ze (E-isomer) is one of two tetrafluoropropene isomers used as refrigerants. The E (trans) isomer is the standard refrigerant; the Z (cis) isomer (R-1234ze-Z) has different physical properties and is used in different applications.

The "E" designation refers to the geometric configuration around the carbon-carbon double bond — trans-positioned substituents. The isomer choice affects boiling point, vapor pressure, and other thermodynamic properties; the E isomer produces the lower pressure envelope used in chiller applications.

The carbon-carbon double bond (the "ene" in HFO) is the chemistry feature that gives R-1234ze its very low GWP — atmospheric OH radicals attack the double bond rapidly, producing 16-day atmospheric lifetime.

Lower pressure envelope than R-134a — chiller-optimized

R-1234ze operates at substantially lower pressures than R-134a — approximately 30% below across the typical chiller operating range. The lower pressure envelope is the engineering reason R-1234ze became the chiller industry's preferred low-GWP choice rather than R-1234yf (which has R-134a-comparable pressure better matched to mobile AC).

Centrifugal chiller compressors operate most efficiently at moderate pressure ratios. R-1234ze's lower pressure envelope produces a different impeller speed and stage count than R-134a equipment; chillers designed for R-1234ze use chiller architectures specifically optimized for the lower-pressure envelope.

For service technicians, R-1234ze pressures stay comfortably within standard 500 PSI manifold gauge ratings across the chiller operating envelope.

GWP — very low, long-term regulatory positioning is strong

R-1234ze's GWP is reported as 7 under the IPCC AR4 100-yr basis (the figure EPA SNAP, the AIM Act exchange-value table, and Honeywell Solstice ze literature cite) and near 1 under strict IPCC AR5 / AR6 because the ~16-day atmospheric lifetime is far below the integration window. Either way, R-1234ze sits in the lowest-impact tier alongside R-1234yf (AR4 GWP 4), R-290 propane (AR5 GWP 3), and R-744 CO₂ (GWP 1). The very-low GWP eliminates phase-down risk under EPA AIM Act, EU F-Gas Regulation, and Kigali Amendment.

For chiller industry positioning, R-1234ze is the long-term low-GWP destination for new equipment installations. EU chiller installations increasingly specify R-1234ze for compliance with tightening F-Gas thresholds; US chiller installations are following the same trajectory through the 2020s.

A2L equipment requirements for R-1234ze chillers

R-1234ze chiller equipment is designed for A2L safety per UL 60335-2-40 / IEC 60335-2-40 — sealed compressor motors, charge limits scaled to equipment-room volume, A2L-rated leak detection where appropriate, ignition-source isolation in the refrigerant circuit.

Service procedures: nitrogen-purged brazing (standard HFC practice anyway, mandatory for A2L), A2L-rated leak detection sensors, charge by weight from sealed cylinders, recovery to A2L-rated cylinders (yellow with red top stripe).

Lubricant is POE or PVE depending on equipment OEM. Both lubricant chemistries are hygroscopic — vacuum to 500 microns and hold ≥30 minutes before charging.

How to think about R-1234ze in 2026 and beyond

R-1234ze is the long-term low-GWP destination for centrifugal chiller equipment. New chiller installations increasingly specify R-1234ze for very-low-GWP regulatory positioning; the A2L safety class is accepted in chiller machine-room installations where engineered controls are standard.

For technicians, R-1234ze chiller work is operationally similar to other A2L chiller refrigerants. The standalone refrigerant has a substantial price premium over R-134a (reflecting smaller production scale and patent positioning), but lifecycle economics favor R-1234ze for installations expected to operate 20-30 years through tightening GWP regulatory environments.

For existing R-134a chillers, R-1234ze is NOT typically the retrofit path — the pressure envelope difference is too large. Retrofit to R-513A or R-450A (A1, GWP 605-631) preserves the pressure envelope; R-1234ze is the choice for new chiller equipment specification.

11

Frequently asked

›What is R-1234ze used for?

Centrifugal chillers in commercial cooling applications, and as a component in lower-GWP HFC/HFO blends (R-454B, R-450A, R-515A, R-515B). Honeywell markets the standalone refrigerant as Solstice ze [honeywellsolstice]. New chiller installations in EU markets increasingly specify R-1234ze; US adoption is growing.

›What's the difference between R-1234yf and R-1234ze?

Both are pure HFOs with very low GWP — commonly cited as 4 (R-1234yf) and 7 (R-1234ze) under the IPCC AR4 / EPA SNAP exchange basis, and below 1 to about 1 respectively under strict IPCC AR5/AR6. R-1234yf (2,3,3,3-tetrafluoropropene) is used dominantly in mobile AC with pressure envelope similar to R-134a. R-1234ze (1,3,3,3-tetrafluoropropene, E-isomer) is used in chillers with lower pressure envelope better matched to centrifugal compressor designs.

Isomer differences in molecular structure produce different pressure profiles despite similar chemical compositions.

›Is R-1234ze flammable?

Yes — ASHRAE class A2L (mildly flammable with low burning velocity). A2L equipment design requirements apply per UL 60335-2-40 — sealed compressor motors, A2L-rated leak detection in some installations, ignition-source isolation in the refrigerant circuit [ul60335].

›What's the GWP of R-1234ze?

The widely-cited figure is **7** — the IPCC AR4 100-yr GWP, which is also the AIM Act / EPA SNAP exchange figure and what Honeywell Solstice ze literature cites [ipccar5]. The strict IPCC AR5 / AR6 100-yr GWP is **around 1** because R-1234ze's ~16-day atmospheric lifetime is far below the integration window IPCC's later assessments use for a precise figure. For compliance and reporting, cite 7. For the underlying climate impact, the figure is essentially negligible. R-1234ze sits in the same lowest-impact tier as R-1234yf, R-290 propane, and R-744 CO₂.

›What lubricant does R-1234ze use?

POE oil typically, with some equipment OEMs specifying PVE (polyvinyl ether) instead [ahri700]. Verify against equipment OEM service literature. Mineral oil is not compatible.

›What is Solstice ze?

Honeywell's trade name for R-1234ze [honeywellsolstice]. Honeywell is the primary commercial manufacturer of standalone R-1234ze; the refrigerant is also used as a component in Chemours and other manufacturer blends.

›Can R-1234ze replace R-134a in chillers?

For new chiller equipment: yes — R-1234ze is increasingly the chiller industry's choice for very-low-GWP new installations. For retrofit of existing R-134a chillers: not directly — R-1234ze has a substantially lower pressure envelope that requires compressor redesign. The typical R-134a chiller retrofit path is R-513A or R-450A (A1 HFC/HFO blends preserving the R-134a pressure envelope).

Download this dataset

Full PT chart for R-1234ze · CC BY 4.0 · attribute the source

CSV JSON
13

Sources & citations

  1. [1]
    ASHRAE Standard 34-2022
    2022https://www.ashrae.org/technical-resources/standards-and-guidelines
  2. [2]
    IPCC AR5 (2014) Working Group I, Chapter 8, Table 8.A.1
    2014https://www.ipcc.ch/report/ar5/wg1/
  3. [3]
    CoolProp 7.2.0
    2014 (continually updated)http://www.coolprop.org/doi:10.1021/ie4033999
  4. [4]
    EPA AIM Act — 40 CFR Part 84 Subpart B
    Final Rule Oct 2021https://www.epa.gov/climate-hfcs-reduction
  5. [5]
    EU F-Gas Regulation 517/2014 (revised 2024)
    https://climate.ec.europa.eu/eu-action/fluorinated-greenhouse-gases_en
  6. [6]
    UL 60335-2-40 / IEC 60335-2-40 — A2L safety standard for AC equipment
    https://www.ul.com/services/ul-60335-standards
  7. [7]
    AHRI Standard 700-2019
    2019https://www.ahrinet.org/search-standards
  8. [8]
    Honeywell Solstice ze (R-1234ze) Technical Information
    https://www.honeywell-refrigerants.com/americas/

Data sources & provenance

PT chart
CoolProp 7.2.0 R1234ze(E)
Cross-checked against
CoolProp 7.2.0 (R1234ze(E)); Honeywell Solstice ze datasheet
Properties
CoolProp 7.2.0 + Honeywell Solstice ze technical datasheet
GWP
IPCC AR5 Table 8.A.1
Generated
2026-06-12

Reference material. Always verify pressure values against the equipment data plate and manufacturer service literature before charging or troubleshooting a specific system. Saturation pressure differs from operating pressure — see superheat & subcooling fundamentals.