# R-410A
**R-410A** is a near-azeotropic blend of two hydrofluorocarbons, difluoromethane (R-32) and pentafluoroethane (R-125), mixed 50/50 by mass, used as a refrigerant in residential and light commercial air conditioning and heat pumps.[1](https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations) Introduced in the late 1990s as an environmentally preferable replacement for the ozone-depleting refrigerant R-22, it became the primary refrigerant for light-to-medium commercial and residential cooling after federal rules banned R-22 in new equipment starting in 2010.[2](https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/glossary/r410a-refrigerant.html) Its own high global warming potential has since made it the target of phaseout rules in the United States and elsewhere, with lower-GWP blends such as R-454B taking its place in new equipment.[3](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table)
| Key fact | Detail |
|---|---|
| Composition | R-32/R-125, 50.0/50.0 by mass (ANSI/ASHRAE 34-2022 designation 410A)[1](https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations) |
| Safety classification | ASHRAE Standard 34 group A1: lower toxicity, no flame propagation[4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) |
| Environmental profile | Ozone depletion potential 0; 100-year GWP 2,088 (AR4), 1,924 (AR5), 2,256 (AR6)[4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) • [5](https://handbook.ashrae.org/Handbooks/R26/IP/r26_ch01/r26_ch01_ip.aspx) |
| Physical data | Molecular mass 72.6 g/mol; normal boiling point −51.7 °C; critical temperature 71.4 °C[4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) |
| Pressure vs R-22 | Approximately 60% (1.6 times) greater than R-22[6](https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/installation-instructions/pdf-92-20522-75-wp14.pdf) |
| Lubricant | Polyol ester (POE) oil; mineral oil is incompatible[7](https://academy.workzen.io/en/academy/hvac/universal-r-410a-safety-certification-usa/course/06-compatible-oils-and-materials/) |
| US phaseout | Manufacture and import of R-410A residential and light commercial AC equipment prohibited January 1, 2025; pre-2025 inventory may be installed with no deadline under the May 2026 reconsideration rule[8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons) • [9](https://www.govinfo.gov/content/pkg/FR-2026-05-26/pdf/2026-10387.pdf) |
## Composition and properties
R-410A is designated under ANSI/ASHRAE Standard 34 as a zeotropic blend of R-32 and R-125 in equal mass fractions, though it behaves in a near-azeotropic manner in service.[1](https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations) • [4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) The two components divide the work of the blend: R-32 offers higher thermodynamic performance than R-125 for air conditioning conditions, while the R-125 component offsets R-32's limited flammability, and R-410A has a lower critical temperature than R-22.[10](https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860951)
Because it contains no chlorine, R-410A has zero ozone depletion potential.[2](https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/glossary/r410a-refrigerant.html) Its climate impact is substantial: the EPA's Technology Transitions reference table assigns it a 100-year GWP of 2,088, and the AP has described it as 2,088 times more damaging to the climate than carbon dioxide.[3](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table) • [11](https://apnews.com/article/afa5bef0fd1b9c3600be2549103b59d7) Under ASHRAE Standard 34 it is classified A1, meaning lower toxicity and no flame propagation at the standard test conditions.[4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/)
## Performance compared with R-22
R-410A operates at substantially higher pressures than R-22: manufacturer service literature puts its pressure at approximately 60% (1.6 times) greater, and York's manual describes operating pressures 50 to 70 percent higher.[6](https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/installation-instructions/pdf-92-20522-75-wp14.pdf) • [12](https://homeappliance.manualsonline.com/manuals/mfg/york_a_johnson_controls_company/r410a_16.html?p=36) The higher pressure and higher volumetric capacity allowed manufacturers to design more compact, highly efficient equipment than was possible with R-22.[2](https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/glossary/r410a-refrigerant.html)
Measured head-to-head performance depends on conditions. In a NIST study by Piotr A. Domanski and William V. Payne, researchers at the [National Institute of Standards and Technology](https://www.edgepedia.org/national-institute-of-standards-and-technology), split air conditioners charged with R-22 and R-410A were tested at outdoor temperatures from 82 °F to 135 °F. The R-410A system's capacity stayed within 8% of the R-22 system's, but its energy efficiency ratio (EER) fell relative to R-22 as outdoor temperature rose: the EER ratio of the R-410A system to the R-22 system varied from 1.05 to approximately 0.8 across the range. Additional tests at ambient temperatures up to 155 °F drove the R-410A system into transcritical operation, with no noticeable change in noise level or operation.[13](https://www.nist.gov/publications/properties-and-cycle-performance-refrigerant-blends-operating-near-and-above)
## Servicing requirements
The higher pressures shape service practice. R-22 service equipment and components must not be used on R-410A equipment; hoses, gauges, recovery machines, and other tools must be specifically rated for R-410A, and valves, filters, pressure controls, and accessories must be checked for compatibility with R-410A pressures.[6](https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/installation-instructions/pdf-92-20522-75-wp14.pdf) • [14](https://manualmachine.com/trane/rauj/2055577-installation-and-maintenance-manual/)
R-410A systems use polyol ester (POE) lubricant. [Mineral oil](https://www.edgepedia.org/mineral-oil) is incompatible: it separates from the refrigerant and pools in low spots such as the evaporator and suction-line traps, starving the compressor of lubrication.[7](https://academy.workzen.io/en/academy/hvac/universal-r-410a-safety-certification-usa/course/06-compatible-oils-and-materials/) POE oil is also hygroscopic, which drives moisture-control practices during service.[7](https://academy.workzen.io/en/academy/hvac/universal-r-410a-safety-certification-usa/course/06-compatible-oils-and-materials/)
R-410A is strictly a replacement for new applications and is not a retrofit: using it in R-22 equipment may result in poor performance, system damage, and unsafe conditions.[15](https://forane.arkema.com/en/resources/faqs/) In the United States, installing an R-410A mini-split, including adding or removing refrigerant and connecting hoses or pre-charged lines, requires Section 608 technician certification.[16](https://www.epa.gov/section608/epas-refrigerant-management-program-questions-and-answers-section-608-certified)
## Regulatory phaseout in the United States
Under the American Innovation and Manufacturing Act, the EPA's Technology Transitions Rule set a GWP limit of 700 for the residential and light commercial air conditioning and heat pump subsector, with manufacture and import compliance on January 1, 2025.[17](https://www.epa.gov/hfcs/technology-transitions-hfc-restrictions-sector) Because R-410A's GWP of 2,088 exceeds that limit, the manufacture of residential and light commercial air conditioning products using R-410A is prohibited from that date, whether charged with virgin or reclaimed refrigerant; packaged terminal air conditioners using R-410A may be sold, distributed, or exported until January 1, 2028.[8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons) Components such as condensing units may continue to be manufactured and imported after January 1, 2025, but only for servicing existing R-410A systems, and they must be labeled "for servicing existing equipment only."[8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons) Homeowners may maintain and repair R-410A systems throughout the equipment's useful life, replacing faulty components with similar R-410A parts.[8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons)
The installation rules have shifted. A December 2023 interim final rule allowed higher-GWP equipment manufactured or imported before January 1, 2025, to be installed until January 1, 2026.[8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons) After supply chain problems in 2025, including shortages, price spikes, and stockpiling of the replacement refrigerant R-454B, the EPA proposed removing the installation compliance date, and a final rule issued May 26, 2026 removed the deadline entirely: pre-2025 R-410A inventory may be installed until supply runs out.[18](https://www.epa.gov/system/files/documents/2025-09/sept-2025-technology-transitions-reconsideration-proposal-fact-sheet.pdf) • [9](https://www.govinfo.gov/content/pkg/FR-2026-05-26/pdf/2026-10387.pdf) R-410A is also listed among the prohibited substances, with a January 1, 2027 compliance date, for retail food refrigerated processing and dispensing equipment above 500 g of refrigerant.[17](https://www.epa.gov/hfcs/technology-transitions-hfc-restrictions-sector)
## Replacements
The leading replacement in residential and light commercial equipment is R-454B, an A2L (mildly flammable) HFO blend with a GWP of 465, well under the 700 limit.[3](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table) • [4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) R-32 alone, with a GWP of 675, also falls below the limit and can continue to be used in the subsector.[3](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table) • [8](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons) Both introduce flammability considerations that R-410A's A1 classification avoided, which affects equipment design and installation practice.[4](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/) A Department of Energy report comparing R-22, R-410A, CO₂, and R-32 against an ideal refrigerant notes the tradeoff pattern: R-410A's key deficiency is its high GWP, while lower-GWP candidates bring flammability, pressure, or efficiency tradeoffs of their own.[19](https://www.energy.gov/sites/prod/files/2016/07/f33/The%20Future%20of%20AC%20Report%20-%20Full%20Report_0.pdf)
## References
1. [ASHRAE Refrigerant Designations, ANSI/ASHRAE 34-2022](https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations)
2. [What Is R-410A Refrigerant? Trane Commercial HVAC](https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/glossary/r410a-refrigerant.html)
3. [Technology Transitions GWP Reference Table, US EPA](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table)
4. [Forane 410A (R-410A) product page, Arkema](https://www.arkema.com/usa/en/product/fluorochemicals/forane410a/)
5. [ASHRAE Handbook, Chapter 1: Halocarbon and Hydrocarbon Refrigeration Systems](https://handbook.ashrae.org/Handbooks/R26/IP/r26_ch01/r26_ch01_ip.aspx)
6. [Fujitsu General installation instructions 92-20522-75 (R-410A)](https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/installation-instructions/pdf-92-20522-75-wp14.pdf)
7. [Compatible Oils & Materials, WorkZen Academy R-410A safety certification course](https://academy.workzen.io/en/academy/hvac/universal-r-410a-safety-certification-usa/course/06-compatible-oils-and-materials/)
8. [Frequent Questions on the Phasedown of Hydrofluorocarbons, US EPA](https://www.epa.gov/hfcs/frequent-questions-phasedown-hydrofluorocarbons)
9. [Phasedown of Hydrofluorocarbons: Reconsideration of Certain Regulatory Requirements, Final Rule, Federal Register Vol. 91 No. 100 (May 26, 2026)](https://www.govinfo.gov/content/pkg/FR-2026-05-26/pdf/2026-10387.pdf)
10. [R-22 Replacement Status, NIST](https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860951)
11. [Refrigeration chemicals are a nightmare for the climate, AP News](https://apnews.com/article/afa5bef0fd1b9c3600be2549103b59d7)
12. [York R-410A Manual](https://homeappliance.manualsonline.com/manuals/mfg/york_a_johnson_controls_company/r410a_16.html?p=36)
13. [Domanski, P. and Payne, W. (2002). Properties and Cycle Performance of Refrigerant Blends Operating Near and Above the Refrigerant Critical Point, NIST](https://www.nist.gov/publications/properties-and-cycle-performance-refrigerant-blends-operating-near-and-above)
14. [Trane RAUJ R-410A Installation and Maintenance Manual](https://manualmachine.com/trane/rauj/2055577-installation-and-maintenance-manual/)
15. [Forane Refrigerants Frequently Asked Questions, Arkema](https://forane.arkema.com/en/resources/faqs/)
16. [EPA's Refrigerant Management Program: Questions and Answers for Section 608 Certified Technicians](https://www.epa.gov/section608/epas-refrigerant-management-program-questions-and-answers-section-608-certified)
17. [Technology Transitions HFC Restrictions by Sector, US EPA](https://www.epa.gov/hfcs/technology-transitions-hfc-restrictions-sector)
18. [September 2025 Technology Transitions Reconsideration Proposal Fact Sheet, US EPA](https://www.epa.gov/system/files/documents/2025-09/sept-2025-technology-transitions-reconsideration-proposal-fact-sheet.pdf)
19. [The Future of Air Conditioning for Buildings, US Department of Energy](https://www.energy.gov/sites/prod/files/2016/07/f33/The%20Future%20of%20AC%20Report%20-%20Full%20Report_0.pdf)
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*Topic: Encyclopedia › Technology and the built world › Engineering and manufacturing › Chemical, biochemical, and biomedical engineering › Titles Mo to V*
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