R407C Refrigerant23/25/52 HFC blend · R22-era transition refrigerant · Meaningful temperature glide
R407C is a zeotropic HFC blend containing approximately 23% R32, 25% R125 and 52% R134a by mass. It became a major non-ozone-depleting alternative to R22 in air conditioning, heat pumps and positive-displacement refrigeration. Its A1 safety class avoids A2L/A3 flammability requirements, but its GWP of 1,774 and significant temperature glide make both regulation and correct service practice important.
What is R407C refrigerant?
R407C is a three-component zeotropic HFC blend designed to provide R22-like performance in many air-conditioning and refrigeration systems. Because it is not a pure refrigerant, bubble point, dew point, temperature glide, liquid charging and possible fractionation after leakage must all be understood during design and service.
R407C refrigerant properties
Use these values for research and screening. Equipment design and compliance should use the property source, SDS, standard or regulation required for the specific application. Where GWP values differ between assessments, this page states the basis rather than hiding the difference.
| Property | Reference | Engineering / source note |
|---|---|---|
| Designation | R407C | Zeotropic HFC blend |
| Nominal composition | R32 / R125 / R134a = 23 / 25 / 52 mass % | EPA / manufacturer blend composition |
| Average molecular weight | ≈ 86.2 g/mol | Honeywell technical data |
| Boiling behavior | Bubble and dew temperatures differ | Use an R407C-specific pressure-temperature chart |
| Critical temperature | ≈ 86.0°C | Honeywell technical data |
| Critical pressure | ≈ 46.3 bar | Honeywell technical data |
| Temperature glide | Several kelvin; value changes with condition and definition | Use supplier PT / cycle data |
| ODP | 0 | No ozone depletion |
| 100-year GWP | 1,774 | EPA Technology Transitions calculated value |
| Safety classification | A1 | Lower toxicity / no flame propagation |
| Typical lubricant | POE | R22 retrofit may require oil-management procedure |
| Charging phase | Liquid charging commonly specified | Helps preserve blend composition |
Scientific assessment reports, equations of state, supplier datasets and regulatory programs may use different reference years or methods. The most important practice is to identify which value the governing regulation or equipment document requires.
Where is R407C used?
Application suitability depends on system architecture, refrigerant charge, compressor design, heat exchanger, safety classification, climate and local rules. These are established use contexts, not blanket retrofit authorization.
Air-conditioning retrofits
Historically one of the major non-ozone-depleting R22 retrofit routes where the equipment manufacturer supports conversion.
Heat pumps
Used in legacy and installed heat-pump equipment with R22-like pressure / capacity intent.
Positive-displacement refrigeration
Applicable to scroll, reciprocating and screw systems within the approved operating envelope.
Medium-temperature commercial refrigeration
R407C can provide a reasonable performance match to R22 in selected commercial systems.
Not ideal for every flooded system
Manufacturer literature cautions that glide and composition behavior complicate some flooded-evaporator / centrifugal applications.
Large installed service base
Technicians continue to encounter R407C even as new-system policy moves toward lower-GWP options.
For broader selection research, explore the Refrigerant Database, Refrigerant Replacements and Low-GWP Refrigerants guides.
R407C temperature glide: bubble point vs dew point
R407C does not evaporate or condense at one temperature when pressure is constant. The saturated-liquid temperature is the bubble point; the saturated-vapor temperature is the dew point. The difference is the temperature glide.
Published cycle examples can show around 4–5 K of glide, while pressure-temperature data under other conditions can show larger values. The correct engineering practice is to use the exact supplier PT data rather than treating one glide number as universal.
Superheat and subcooling calculations must use the correct saturation endpoint for the method and instrument. A technician who uses a single “saturation temperature” can misdiagnose system charge or heat-exchanger performance.
Why R407C is normally charged as liquid
Because R407C is zeotropic, its vapor phase and liquid phase can have different compositions. Charging only vapor from a cylinder can change the blend delivered to the system.
Manufacturer guidance therefore commonly specifies liquid transfer. When final charging into a running system, the liquid may need to be throttled safely according to the equipment and refrigerant supplier procedure.
A major leak can also change the composition of the refrigerant left in the system depending on where and how the leak occurred. Blind topping-off should not be treated as universally correct.
R407C as an R22 retrofit: what actually changes
R407C was designed as a strong R22 performance match, but “retrofit” does not mean “drop-in.” Compressor approval, lubricant, seals, expansion device, filter-drier, charge mass and control settings all need review.
Legacy R22 systems often used mineral oil, while R407C systems commonly use POE. A conversion can therefore require an oil-management procedure to meet the manufacturer’s residual-mineral-oil target.
After conversion, superheat, subcooling, charge and protection settings should be commissioned with R407C data rather than R22 gauges or rules of thumb.
Why R407C has become a transition refrigerant itself
R407C solved the ozone-depletion problem associated with R22, but all three blend components are HFCs and the EPA GWP is 1,774.
Current U.S. Technology Transitions limits of 700 for important residential and light-commercial AC / heat-pump products and systems therefore place R407C outside those new-equipment pathways.
Installed systems can continue to create service, leak-repair and recovery demand, while new designs increasingly move toward R32, R454B, hydrocarbons or other application-specific lower-GWP options.
R407C vs R410A
This comparison highlights major engineering differences; it does not imply interchangeability.
| Characteristic | R407C | R410A |
|---|---|---|
| Blend composition | R32/R125/R134a = 23/25/52 | R32/R125 = 50/50 |
| EPA GWP | 1,774 | 2,088 |
| Safety class | A1 | A1 |
| Temperature glide | Meaningful / several K | Very small |
| Historical role | R22 retrofit / replacement | New higher-pressure R22-era platform |
| Typical pressure relationship | Closer to R22 | Substantially higher than R22 |
| Current new-equipment role | Restricted by high GWP in key sectors | Restricted by high GWP in key sectors |
R407C safety: A1 classification does not remove blend, pressure or decomposition hazards
R407C is A1, so flammability is not the defining risk. However, large releases can displace oxygen, liquid refrigerant can cause cold burns, and hot work can form hazardous decomposition products. The zeotropic blend also requires correct charging and recovery so performance is not compromised by composition shift or contamination.
Confined-space release
Large refrigerant inventories can create oxygen-deficiency risk.
Blend integrity
Service practice must account for liquid / vapor composition and fractionation.
Hot work
Recover refrigerant and control the work area before brazing or flame exposure.
Actual risk depends on refrigerant charge, pressure, release rate, room volume, ventilation, ignition sources, temperature, equipment construction, alarm logic, servicing condition and applicable codes.
See the site-wide Refrigerant Safety Guide for A1, A2L, A3 and B2L classification context.
R407C refrigerant leak detection
Define the monitoring function before choosing the sensor
R407C-compatible infrared, heated-diode / semiconductor and other electronic leak detectors are commonly used. Fixed monitoring should be validated for the finished R407C blend rather than assuming calibration to R32, R125 or R134a alone is equivalent. A refrigerant analyzer can be useful when fractionation, mixed gas or contaminated recovery cylinders are suspected.
A portable leak locator, fixed machinery-room monitor, equipment mitigation sensor, oxygen monitor and refrigerant identifier perform different functions. Required concentration range and alarm action should be defined first.
Regulatory position of R407C in 2026
United States
EPA historically listed R407C as acceptable in several SNAP air-conditioning and refrigeration end uses, but the current Technology Transitions reference GWP is 1,774. That exceeds the 700-GWP limit now applied to important new stationary residential/light-commercial AC and heat-pump products/systems, so R407C’s new-equipment role is contracting.
European Union
R407C is an HFC blend subject to EU F-gas quota reduction and application-specific restrictions. Its GWP makes it increasingly unattractive for new equipment even where service of existing installations remains possible under applicable rules.
Is R407C being phased out?
R407C does not have one worldwide “ban date,” but high GWP is steadily shrinking its new-equipment role. The installed base will continue to require service, leak repair, recovery and planned replacement.
A refrigerant can be permitted in one application, restricted in another and treated differently for new manufacture, installation, service and reclaimed material. Verify the exact equipment category and compliance date.
Use the Refrigerant Regulations Hub for region-level research.
What should be compared with R407C?
Useful alternatives depend on the real decision: new equipment, retrofit, long-term regulation, safety class, energy efficiency, charge, climate and service capability.
Practical misconceptions about R407C
“R407C has one saturation temperature at each pressure.”
It is zeotropic; bubble and dew temperatures are different.
“You can charge R407C vapor without affecting composition.”
Normal service guidance calls for liquid charging to preserve blend composition.
“R407C is a drop-in R22 gas.”
Retrofit can require POE oil, component checks, charge changes and recommissioning.
“A1 means leaks only waste refrigerant.”
Large releases can cause oxygen displacement and cold injury; hot work can create decomposition hazards.
R407C refrigerant FAQ
Concise answers to common technical, service and regulatory questions about R407C.
What is R407C refrigerant?
What is the GWP of R407C?
Is R407C flammable?
What is the temperature glide of R407C?
What is the difference between bubble point and dew point?
Should R407C be charged as liquid?
Can R407C replace R22?
Can I top up R407C after a leak?
Is R407C being phased out?
How is an R407C leak detected?
R407C sources and further reading
This profile was researched against current government, standards, scientific, manufacturer and validated refrigerant-detection references. Re-check the latest edition before design, service or compliance decisions.
Working with R407C or planning a refrigerant transition?
Compare refrigerant properties, safety class, regulatory position and leak-detection requirements before choosing an equipment pathway.
Technical Notice: This page is for refrigerant research and general technical reference. Refrigerant suitability, permitted charge, equipment approval, leak mitigation, servicing procedures and regulatory compliance depend on the exact equipment, installation and jurisdiction. Always verify current manufacturer documentation, SDS, applicable standards and local regulations before selecting, replacing, charging or servicing a refrigerant.