R-1234ze(Z)
Pure HFO — the cis (Z) isomer of 1,3,3,3-tetrafluoropropene (CHF=CHCF₃). Distinct from the more common E-isomer (R-1234ze(E)) — different physical properties, different applications. Normal boiling point +9.7°C (E-isomer is -19°C). A2L. Used in high-temperature heat pumps and organic Rankine cycle systems.
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.
Saturation pressure-temperature curve
Saturation values from CoolProp 7.2.0 R1234ze(Z). Operating pressure on a running system differs — see the operating-pressure references for in-use values.
R-1234ze(Z) PT chart PDF — printable saturation table
Looking for the R-1234ze(Z) 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(Z) PT Chart — Pressure-Temperature Saturation Table
1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com
| Temp (°F) | Pressure (PSIG) |
|---|---|
| 32°FH₂O freeze | -4.8 |
| 33°F | -4.6 |
| 34°F | -4.3 |
| 35°F | -4.1 |
| 36°F | -3.8 |
| 37°F | -3.6 |
| 38°F | -3.3 |
| 39°F | -3.1 |
| 40°F | -2.8 |
| 41°F | -2.5 |
| 42°F | -2.2 |
| 43°F | -2.0 |
| 44°F | -1.7 |
| 45°F | -1.4 |
| 46°F | -1.1 |
| 47°F | -0.8 |
| 48°F | -0.5 |
| 49°F | -0.2 |
| 50°FNBP (atmospheric) | 0.2 |
| 51°F | 0.5 |
| 52°F | 0.8 |
| 53°F | 1.1 |
| 54°F | 1.5 |
| 55°F | 1.8 |
| 56°F | 2.2 |
| 57°F | 2.5 |
| 58°F | 2.9 |
| 59°F | 3.3 |
| 60°F | 3.6 |
| 61°F | 4.0 |
| 62°F | 4.4 |
| 63°F | 4.8 |
| 64°F | 5.2 |
| 65°F | 5.6 |
| 66°F | 6.0 |
| 67°F | 6.5 |
| 68°F | 6.9 |
| 69°F | 7.3 |
| 70°F | 7.8 |
| 71°F | 8.2 |
| 72°F | 8.7 |
| 73°F | 9.1 |
| 74°F | 9.6 |
| 75°F | 10.1 |
| 76°F | 10.6 |
| 77°F | 11.1 |
| 78°F | 11.5 |
| 79°F | 12.1 |
| 80°F | 12.6 |
| 81°F | 13.1 |
| 82°F | 13.6 |
| 83°F | 14.2 |
| 84°F | 14.7 |
| 85°F | 15.2 |
| 86°F | 15.8 |
| 87°F | 16.4 |
| 88°F | 16.9 |
| 89°F | 17.5 |
| 90°F | 18.1 |
| 91°F | 18.7 |
| 92°F | 19.3 |
| 93°F | 20.0 |
| 94°F | 20.6 |
| 95°F | 21.2 |
| 96°F | 21.9 |
| 97°F | 22.5 |
| 98°F | 23.2 |
| 99°F | 23.9 |
| 100°F | 24.5 |
| 101°F | 25.2 |
| 102°F | 25.9 |
| 103°F | 26.6 |
| 104°F | 27.4 |
| 105°F | 28.1 |
| 106°F | 28.8 |
| 107°F | 29.6 |
| 108°F | 30.3 |
| 109°F | 31.1 |
| 110°F | 31.9 |
| 111°F | 32.6 |
| 112°F | 33.5 |
| 113°F | 34.3 |
| 114°F | 35.1 |
| 115°F | 35.9 |
| 116°F | 36.7 |
| 117°F | 37.6 |
| 118°F | 38.5 |
| 119°F | 39.3 |
| 120°F | 40.2 |
| 121°F | 41.1 |
| 122°F | 42.0 |
| 123°F | 42.9 |
| 124°F | 43.9 |
| 125°F | 44.8 |
| 126°F | 45.7 |
| 127°F | 46.7 |
| 128°F | 47.7 |
| 129°F | 48.6 |
| 130°F | 49.6 |
| 131°F | 50.7 |
| 132°F | 51.7 |
| 133°F | 52.7 |
| 134°F | 53.8 |
| 135°F | 54.8 |
| 136°F | 55.9 |
| 137°F | 57.0 |
| 138°F | 58.0 |
| 139°F | 59.2 |
| 140°F | 60.3 |
| 141°F | 61.4 |
| 142°F | 62.6 |
| 143°F | 63.7 |
| 144°F | 64.9 |
| 145°F | 66.1 |
| 146°F | 67.3 |
| 147°F | 68.5 |
| 148°F | 69.7 |
| 149°F | 70.9 |
| 150°F | 72.2 |
| Temp (°C) | Pressure (kPa) |
|---|---|
| 0°CH₂O freeze | -33 |
| 1°C | -30 |
| 2°C | -27 |
| 3°C | -24 |
| 4°C | -21 |
| 5°C | -17 |
| 6°C | -14 |
| 7°C | -10 |
| 8°C | -7 |
| 9°C | -3 |
| 10°CNBP (atmospheric) | 1 |
| 11°C | 5 |
| 12°C | 9 |
| 13°C | 14 |
| 14°C | 18 |
| 15°C | 23 |
| 16°C | 27 |
| 17°C | 32 |
| 18°C | 37 |
| 19°C | 42 |
| 20°C | 48 |
| 21°C | 53 |
| 22°C | 58 |
| 23°C | 64 |
| 24°C | 70 |
| 25°C | 76 |
| 26°C | 82 |
| 27°C | 89 |
| 28°C | 95 |
| 29°C | 102 |
| 30°C | 109 |
| 31°C | 116 |
| 32°C | 123 |
| 33°C | 131 |
| 34°C | 138 |
| 35°C | 146 |
| 36°C | 154 |
| 37°C | 163 |
| 38°C | 171 |
| 39°C | 180 |
| 40°C | 189 |
| 41°C | 198 |
| 42°C | 207 |
| 43°C | 216 |
| 44°C | 226 |
| 45°C | 236 |
| 46°C | 246 |
| 47°C | 257 |
| 48°C | 268 |
| 49°C | 278 |
| 50°C | 290 |
| 51°C | 301 |
| 52°C | 313 |
| 53°C | 325 |
| 54°C | 337 |
| 55°C | 349 |
| 56°C | 362 |
| 57°C | 375 |
| 58°C | 388 |
| 59°C | 402 |
| 60°C | 416 |
| 61°C | 430 |
| 62°C | 444 |
| 63°C | 459 |
| 64°C | 474 |
| 65°C | 489 |
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(Z) PT chart data: CoolProp 7.2.0 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.
At a glance
Chemistry
Lubricant compatibility
Z-isomer with higher boiling point than R-1234ze(E). Used in high-temperature heat pumps and organic Rankine cycle applications.
Trade names
- Solstice zdHoneywell (related lines)
Common applications
- High-temperature heat pumps (industrial)
- Organic Rankine cycle working fluid
Properties
- Boiling point (1 atm)9.7°C / 49.5°F
- Critical point302.2°F at 497 PSIG
- Molar mass114.04 g/mol
- Temperature glideNegligible (0.00°F)
- ODP0
- GWP (AR5, 100-yr)—
What is R-1234ze(Z)?
R-1234ze(Z) is the cis (Z) isomer of 1,3,3,3-tetrafluoropropene. Same molecular formula and same atoms as R-1234ze(E), but with the carbon-carbon double bond in cis configuration rather than trans. The geometric difference produces substantially different physical properties — the Z-isomer has a normal boiling point of +9.7°C (49.5°F) versus the E-isomer's -19°C (-2.2°F).
The higher boiling point makes R-1234ze(Z) unsuitable for typical air-conditioning or chiller applications — its saturation pressure at ambient temperatures is too low (sub-atmospheric on the evaporator side for cooling work). Where it shines is in high-temperature heat pumps and organic Rankine cycle (ORC) systems where the refrigerant's condensing temperature is well above ambient (60-120°C in some industrial process-heating applications). For those applications, the E-isomer's pressure profile is too low; the Z-isomer's profile is appropriate.
Where R-1234ze(Z) is used
- High-temperature industrial heat pumps (process heating 60-130°C condensing)
- Organic Rankine cycle (ORC) working fluid for waste-heat recovery
- Research applications in academic and pre-commercial settings
- Not used in conventional HVAC chiller or AC service
Regulatory & phase-down status
R-1234ze(Z) is not subject to phase-down — its GWP is in the same low-single-digit range as R-1234ze(E) (estimated ~6 per IPCC AR5; dataset value pending peer-reviewed publication). No regulatory pressure exists. The constraints on adoption are commercial availability (specialty manufacturer Honeywell), application narrowness (only high-temperature systems), and equipment scarcity (industrial heat pumps and ORC systems are niche markets).
Industrial decarbonization initiatives (EU Heat Pump 2030 targets, US Inflation Reduction Act industrial heat pump incentives) are growing the high-temperature heat pump market significantly through 2030 — R-1234ze(Z) demand is expected to grow correspondingly, though from a small base.
Service notes
POE oil is standard; PVE oil is approved in some applications. Mineral oil is not used.
A2L safety class applies though with reduced practical concern due to the relatively high boiling point — the refrigerant is liquid at ambient temperatures, reducing the vapor-cloud risk that's the primary A2L concern. Standard A2L service procedures (no open flames, A2L-rated leak detection, sealed motor equipment) still apply.
Industrial heat-pump and ORC equipment is OEM-specific; consult equipment service literature for refrigerant handling. Generic HVAC procedures don't fully cover these specialty applications.
Operating cycle
Phase-down timeline
R-1234ze(Z) 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.
Global warming potential, in context
No peer-comparison group is defined for R-1234ze(Z). The refrigerant's GWP is not published in this dataset.
Peer-comparison groups are defined for refrigerants that compete in the same application sector (residential AC, commercial MT/LT, chillers, mobile AC). Specialty or research-grade refrigerants without a clear peer set don't appear in any group; their GWP is shown above in absolute terms instead.
Frequently asked
›Why is R-1234ze(Z) different from R-1234ze(E) if it's the same chemical formula?
Geometric isomers — same atoms, different spatial arrangement around the carbon-carbon double bond. In R-1234ze(E) (trans, "entgegen") the two larger substituents on the double bond are on opposite sides; in R-1234ze(Z) (cis, "zusammen") they're on the same side. This changes the molecule's dipole moment, intermolecular packing, and ultimately its boiling point (Z: +9.7°C vs E: -19°C). The boiling-point difference makes them suitable for completely different temperature ranges of HVAC operation.
›Can R-1234ze(Z) be used as a drop-in for R-1234ze(E)?
No. The 28°C difference in normal boiling point means R-1234ze(Z) operates at much lower pressures across any given temperature range — an R-1234ze(E) chiller compressor would not develop adequate mass flow with R-1234ze(Z). The two refrigerants are application-distinct: R-1234ze(E) for conventional chillers and HVAC, R-1234ze(Z) for high-temperature heat pumps and ORC. They share a chemical name; they are not interchangeable.
›What's an organic Rankine cycle?
A power-generation cycle that uses an organic working fluid (refrigerant-class molecule) instead of water in a Rankine cycle. Waste heat (from industrial processes, biomass, geothermal, or solar thermal) vaporizes the working fluid, the vapor expands through a turbine to produce mechanical/electrical power, then condenses for return to the boiler. ORC is used where the heat-source temperature is too low for steam (typically 80-300°C) — water Rankine cycles need much higher temperatures. R-1234ze(Z) and R-245fa are common ORC working fluids in the medium-temperature range; R-1336mzz(Z) for higher temperatures.
›Where are industrial high-temperature heat pumps used?
Process heating applications where waste heat (40-60°C) is upgraded to useful heat (80-150°C) — district heating networks, dairy and food processing pasteurization, paper drying, chemical batch heating. The economics work where natural gas prices are high or carbon-pricing makes electrified heating competitive. The EU has targeted industrial heat pump growth as part of REPowerEU; the IRA includes industrial heat pump tax credits. R-1234ze(Z) and R-1336mzz(Z) are the typical working fluids for this range.
›Is R-1234ze(Z) more or less stable than R-1234ze(E)?
Slightly less stable at the upper end of typical operating temperatures. The cis configuration is the higher-energy isomer; under prolonged high-temperature operation R-1234ze(Z) can isomerize to R-1234ze(E). This is generally not significant within rated operating envelopes (condensing <130°C) and proper lubrication, but does mean compressor discharge temperatures should stay within OEM-rated limits.