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Question: What is A2L, and what are the implications of changes beginning in 2025 with refrigerant R-454B to DX coils for use in Catalog and Semi-Catalog AHUs and shipping coils?
Answer: The A2L-compliant equipment will have dedicated changes to the unit, such as leak detection sensor and labeling. Shipping coils will require field installed leak detection to be compliant with regulatory requirements for A2L.
A2L is a refrigerant safety classification that indicates a refrigerant has low toxicity and low flammability. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) uses a letter and number system to classify refrigerants, with the first letter indicating toxicity and the second and third digits indicating flammability.
Here's what the A2L classification means:
- A: Indicates lower toxicity
- 2: Indicates lower flammability
- L: Indicates low burning velocity
A2L refrigerants are considered the second safest refrigerant category. They have a lower global warming potential (GWP) than other refrigerants and are more energy efficient than R-410A and transcritical CO₂ systems. A2L refrigerants are also safer than ammonia and hydrocarbon refrigerants.
A2L refrigerants are being used to replace older, high-impact refrigerants in air conditioning and commercial refrigeration systems. They are helping businesses meet the goals of the Montreal Protocol, the Kigali Amendment, the U.S. AIM Act, Canada's ODSHAR, and the EU Green Deal.
Introduction
Scientific research has shown that certain man-made chemicals can affect the earth’s naturally occurring stratospheric ozone layer when released into the atmosphere. In particular, several identified chemicals that may affect the ozone layer are refrigerants containing Chlorine, Fluorine, and Carbon (CFCs) and those containing Hydrogen, Chlorine, Fluorine, and Carbon (HCFCs). Not all refrigerants containing these compounds have the same potential impact on the environment. Trane advocates for the responsible handling of all refrigerants.
Important Responsible Refrigerant Practices
Trane believes that responsible refrigerant practices are crucial for the environment, our customers, and the air conditioning industry. All technicians who handle refrigerants must be certified according to local rules. In the USA, the Federal Clean Air Act (Section 608) sets forth the requirements for handling, reclaiming, recovering, and recycling certain refrigerants and the equipment used in these service procedures. Additionally, some states or municipalities may have additional requirements that must also be adhered to for responsible management of refrigerants. It is essential to know and follow the applicable laws.
R-454B Flammable A2L Refrigerant
Warning: Failure to use proper equipment or components as described below could result in equipment failure, and possibly fire, which could result in death, serious injury, or equipment damage.
The equipment described in this manual uses R-454B refrigerant, which is flammable (A2L). Use ONLY R-454 B rated service equipment and components. For specific handling concerns with R-454B, contact your local representative.
A2L Refrigerants and Split Systems
Additional Resources
https://hub.tranetechnologies.com/docs/DOC-220651
https://hub.tranetechnologies.com/videos/38092
https://hub.tranetechnologies.com/docs/DOC-222070
Safety Standards for Dual-Rating Split System Indoor Components
Safety codes and standards have been written to enhance safety when using A2L refrigerants. To meet this objective, the certification of indoor products to both A1 and A2L refrigerants is not allowed. Existing A1 indoor products do not have the necessary controls, labels, or markings required by the EPA and UL safety codes for use with A2L applications. Dual-rating for different refrigerant classes would increase the possibility of improper installation and/or servicing. This would imply that changing refrigerant safety classes is allowed on existing equipment, which is not the case.
Dual-rating equipment is an abdication of the manufacturer’s responsibility to appropriately warn users of hazards. The responsibility of applying the necessary warning labels and other markings belongs to the contractors installing the equipment. As a result, indoor products rated to be installed with an A1 or A2L refrigerant violate the safety standards and federal rules for using A2L refrigerants.
Supporting Content from UL 60335–2–40, EPA SNAP 23, and EPA Technical Transitions Rule
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UL Safety Standard (UL 60335 2–40)
- Clause 7.1: If a flammable refrigerant is used, an additional warning symbol shall be placed on the nameplate of the unit near the declaration of the refrigerant type and charge information. Nameplates are never left to be installed after leaving the factory.
- Clause 7.1DV.3 DR: Refrigerants of different safety classes are not allowed. A means shall be provided to permanently identify the refrigerant installed. Appliances using flammable refrigerants shall not be marked with alternative refrigerants of different safety classifications.
- Clause 22.135DV D1: If an appliance is marked for use with alternative refrigerants, the appliance shall comply with all requirements of this standard for each refrigerant. The refrigerants shall be the same safety class.
- A formal interpretation from the UL Standards Technical Panel reinforced that allowing different safety classes is not allowed by an overwhelming majority.
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EPA SNAP 23 Requirements
- These refrigerants may be used only in new equipment specifically designed and clearly identified for the refrigerants (e.g., none of these substitutes may be used as a conversion or "retrofit" refrigerant for existing equipment designed for other refrigerants).
- The following markings must be attached at the locations provided and must be permanent. This refers to warnings, installation restrictions, and nameplates.
- The equipment must have red-marked service ports, pipes, hoses, or other devices through which the refrigerant passes, to indicate the use of a flammable refrigerant.
- These substitutes may only be used in air conditioning equipment that meets all requirements in the UL Safety Standard.
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EPA Technology Transitions Rule
- Components using R-410A fabricated after 01/01/2025 must be marked for service only and cannot be installed as part of a complete system installation. Therefore, these are not allowed to be dual-rated components. They are not allowed to be installed in R-410A systems during the 2025-2026 sell-through period because they were not manufactured before 1-1-25 and may only be used as an R-410A service component as they are marked "for service only" as required.
Reusing Components from Existing R-410A Split Systems
Only the line sets of refrigerant piping can be reused from an existing R-410A system when replacing it with an A2L system. These line sets must also comply with more rigorous vacuum and pressure testing requirements when applied with an A2L system per ASHRAE® 15 or ASHRAE® 15.2.
Special Precautions for Installing an A2L Split System
If all equipment and controls in the system comply with the UL Safety Standard and the equipment controls have compatible inputs and outputs for the Leak Detection System (LDS), the safety requirements are met.
Options for Existing R-22 and R-410A Split Systems After 12/13/24
There are two options for existing R-22 and R-410A systems:
- Repair and replacement of R-22 and R-410A failed components are allowed throughout the life of the equipment if the components are available.
- Replacement of the entire system with an A2L split system.
Definition of a Specified Component
"Specified component" for purposes of equipment in the refrigeration, air conditioning, and heat pump sector means condensing units, condensers, compressors, evaporator units, and evaporators.
Triggering GWP Limits for New Systems
Replacing 75% or more of the evaporators (by number) and 100% of the compressor racks, condensers, and connected evaporator loads of an existing system would trigger the requirements of new systems.
Important Reminder
You can never use R-454B in a component or system designed for R-410A. Rating indoor air handlers in a split-system application for two different refrigerant classes would violate the UL Safety Standard. Subsequently, this would prevent compliance with the EPA SNAP 23 rule and limit compliance with the EPA Technology Transitions rule.
For further information or specific handling concerns, please contact your local representative.
Equipment Labels
Leak detection system label
Refrigerant label