R-1224yd(Z)
Pure HCFO (hydrochlorofluoroolefin) — cis-1-chloro-2,3,3,3-tetrafluoro-1-propene. AGC Chemicals AMOLEA 1224yd. ASHRAE A1, GWP 1, ODP 0.00012. Designed as a near-drop-in replacement for R-123 in low-pressure centrifugal chillers.
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 — published primary source exists. A published Helmholtz equation of state exists for R-1224yd(Z)(cited below), but is not implemented in this site's CoolProp 7.2.0 WASM build. The site never fabricates values to fill gaps; values would need to be computed by transcribing the published Wagner-form ancillary equation coefficients into the dataset. For service work, refer directly to the cited primary source.
- peer-reviewed-eosAkasaka, R. and Lemmon, E.W. (2023), "A Helmholtz Energy Equation of State for cis-1-Chloro-2,3,3,3-tetrafluoro-1-propene [R-1224yd(Z)]", International Journal of Thermophysics 44, 166.Fundamental EOS valid from triple-point T (157.8 K) to 473 K, pressures up to 35 MPa. Includes vapor-pressure ancillary equation suitable for PT chart generation.https://link.springer.com/article/10.1007/s10765-023-03266-3
- measurementSotani, T. et al. (2022), "Saturation vapour pressure measurements of refrigerant R1224yd(Z) from 274 K to 338 K", International Journal of Refrigeration.Static-method vapor pressure measurements at INRIM, 274-338 K, precision capacitance manometer (full scale 0.5 MPa). Used to validate Akasaka & Lemmon (2023) EOS.https://www.sciencedirect.com/science/article/abs/pii/S0140700722003450
- manufacturer-datasheetAGC Chemicals, "AMOLEA 1224yd Technical Information" (PDF).Manufacturer-published PT table and P-h diagram covering the operating range. Free download from AGC Chemicals website.https://www.agc-chemicals.com/file/AMOLEAyd_Tech_English_D.PDF
At a glance
Chemistry
Lubricant compatibility
Designed as a low-GWP replacement for R-123 in low-pressure centrifugal chillers.
Trade names
- AMOLEA 1224ydAGC Chemicals
Common applications
- Low-pressure centrifugal chillers (high-tonnage commercial)
- Industrial cooling
Properties
- Boiling point (1 atm)14.5°C / 58.1°F
- Critical point311.9°F at 463 PSIG
- Molar mass148.49 g/mol
- Temperature glideNegligible (0.00°F)
- ODP0.00012
- GWP (AR5, 100-yr)1
- Atmospheric lifetime0.06 years
What is R-1224yd(Z)?
R-1224yd(Z) is a hydrochlorofluoroolefin (HCFO) — the chlorine-containing analog of an HFO. The single chlorine atom gives it a small but measurable ozone-depletion potential (ODP 0.00012, several orders of magnitude lower than R-123's 0.02 or R-22's 0.055). Despite the technically-non-zero ODP, R-1224yd(Z) is acceptable under Montreal Protocol carve-outs for very-low-ODP working fluids that replace higher-ODP HCFCs in transitional applications.
Commercially developed by AGC Chemicals as AMOLEA 1224yd, R-1224yd(Z) is targeted specifically at low-pressure centrifugal chiller applications where R-123 has been the historical refrigerant. The R-123 phase-out (US production ban January 1, 2020 under HCFC schedule) created an immediate replacement need for an estimated 30,000+ remaining R-123 chillers worldwide. R-1224yd(Z) is one of three commercial replacements (with R-1233zd(E) and R-514A) competing for that market.
Where R-1224yd(Z) is used
- Low-pressure centrifugal chillers (commercial cooling, district cooling, large institutional buildings)
- R-123 replacement in existing low-pressure centrifugal chillers
- Some new low-pressure chiller installations
- Limited deployment outside the centrifugal chiller niche
Regulatory & phase-down status
R-1224yd(Z) is not on any active phase-down list. Its ODP of 0.00012 is below the Montreal Protocol's de-minimis threshold (treated as zero for regulatory purposes in most jurisdictions). Its GWP of 1 is below every climate phase-down threshold.
The competitive landscape in the centrifugal chiller R-123 replacement space: R-1233zd(E) (Honeywell Solstice zd, A1, GWP 1, established market presence), R-514A (Chemours Opteon XP30, B1 toxicity class, GWP 2), and R-1224yd(Z) (AGC AMOLEA, A1, GWP 1). R-1233zd(E) currently leads in market share; R-1224yd(Z) competes on slightly different properties (lower pressure, modestly different efficiency).
Service notes
POE and PVE oils are compatible. Mineral oil is not used. A1 safety classification simplifies service — no special A2L procedures required. R-1224yd(Z) is a low-pressure refrigerant; system saturation pressures on the evaporator side can be sub-atmospheric at typical chiller operating temperatures, which is normal for this refrigerant class but requires attention to leak-tightness (atmospheric air ingress is the failure mode rather than refrigerant escape).
EPA Section 608 covers R-1224yd(Z) handling. Recovery is required.
Phase-down timeline
R-1224yd(Z) is not subject to AIM Act or EU F-Gas phase-down regulation. With a 100-year GWP of 1 (HFO) and low ozone-depletion potential, it sits below both the EU F-Gas 150 GWP cap and the EPA AIM Act 700 GWP cap. No phase-down schedule applies — it is one of the refrigerants chosen for the transition away from high-GWP HFCs.
Global warming potential, in context
Low-pressure centrifugal chillers
Retrofit and replacement paths
R-1224yd(Z) replaces
Frequently asked
›What's the difference between R-1224yd(Z) and R-1233zd(E) as R-123 replacements?
Both are A1 (non-flammable) low-pressure refrigerants with GWP 1 and effectively-zero ODP, both targeting R-123 replacement in centrifugal chillers. Differences: (1) R-1224yd(Z) has slightly lower vapor pressure than R-1233zd(E) — chillers may need slight compressor adjustment for the lower-pressure operating envelope; (2) chemistry — R-1224yd(Z) has one chlorine atom, R-1233zd(E) has one chlorine and slightly different fluorination pattern; (3) market presence — R-1233zd(E) (Solstice zd) has wider OEM adoption; R-1224yd(Z) (AMOLEA) is newer and growing. Both work; choice often depends on chiller OEM preference and regional supplier availability.
›Is the small ODP of R-1224yd(Z) a regulatory problem?
No. The ODP of 0.00012 is below the Montreal Protocol's de-minimis threshold and is treated as zero for HCFC phase-down compliance purposes. R-1224yd(Z) is SNAP-listed acceptable for the centrifugal chiller substitute use. Modern regulatory frameworks recognize that requiring strictly zero ODP would exclude useful low-GWP refrigerants for negligible environmental benefit.
›Can I retrofit an R-123 chiller to R-1224yd(Z)?
Yes, with manufacturer guidance — R-1224yd(Z) is designed as a near-drop-in for R-123 chillers. The procedure involves: recovery of R-123; oil change from mineral oil (R-123's standard) to POE; replacement of seals incompatible with HFO chemistry; pull vacuum to 500 microns; charge R-1224yd(Z) by weight to OEM-specified amount. Compressor and expansion device typically don't change. Verify capacity match — R-1224yd(Z) delivers within 5-8% of R-123 capacity in most installations, with slightly lower efficiency that may or may not be material for the application.
›What is the GWP of R-1224yd(Z)?
1 per IPCC AR5. This is effectively zero direct global warming impact — R-1224yd(Z) decomposes in the atmosphere within days via OH radical attack, with minimal warming contribution. Compare to R-123 (GWP 79, also very low) and R-134a (GWP 1430, much higher).
›Why use R-1224yd(Z) instead of just continuing with R-123?
R-123 production was banned in the US on January 1, 2020 under the HCFC schedule (despite its very low GWP). The remaining R-123 chiller fleet is supplied by reclaimed R-123 from equipment removals, which is a finite and shrinking pool. Most chiller owners face a 5-15 year window of practical service availability before retrofit or replacement becomes the only option. R-1224yd(Z), R-1233zd(E), and R-514A provide that retrofit / replacement path.