Residential and light commercial air conditioners and heat pumps manufactured after Jan. 1, 2025, must use the new refrigerant. The equipment manufactured prior to this date has a one-year grace period to be installed — a Jan. 1, 2026, installation deadline.

For products that do not require field assembly, such as window air conditioning units, the rules establish the final date of sale as three years after the manufacture compliance date — a Jan. 1, 2028, sale deadline — without a compliance date for installation.

The EPA is evaluating an extension of transition dates by one year only for Variable Refrigerant Flow (VRF) systems with capacities of 65,000 BTU/h (19 kW) or more.

Existing air conditioning and heat pump equipment is not subject to EPA regulations and can continue to be used through equipment end-of-life. Components used for servicing and repair also are not subject to EPA regulation. The supply of R-410A, R-134a, and other refrigerants to meet servicing needs will remain available for the foreseeable future even as overall production and imports decline through the middle of the next decade, as was the case in prior refrigerant transitions in the 1990s and early 2000s.

How A2Ls are Different

All refrigerants are required to be classified by toxicity and flammability. A2Ls retain the same toxicity designation — non-toxic — as their predecessor (R-410A). However, the flammability has been reclassified as Class 2L (lower flammability), compared to Class 1 (no flame propagation) for R-410A.

A2L refrigerants require a redesign of the HVAC equipment. It is important that home builders actively begin to plan for the transition and engage with their suppliers and installers to ensure an adequate pipeline of equipment in the upcoming months and to avoid potential bottlenecks, delays, and last-minute change orders. Each equipment manufacturer will have their own roll-out strategy and timeline, but these changes are imminent and will happen over the coming months.

To address the slight increase in flammability, equipment manufacturers are adding safety features to equipment, revising transportation and handling procedures, and updating installation instructions.

Primary mitigation measures for the building include:

1. Minimizing the risk of refrigerant leaks by requiring enhanced testing of refrigerant lines using both pressure and vacuum methods, requiring specific joint types, and requiring nail plates at framing members where lines run through, and
2. Controlling the refrigerant concentration in the building in a potential leakage scenario to levels below the flammability limit.

In many cases, equipment manufacturers will add a leak detection sensor installed in the air handler unit and programmed to activate the main fan to quickly circulate the air throughout the home to reduce refrigerant concentration. Other safety strategies can include the use of shut-off valves also activated by leak sensors and designed to limit the quantity of refrigerant that can leak out. For systems without leak detection sensors, the quantity of the refrigerant in the system, including the lines, will need to be sized more carefully such that a refrigerant leak into the smallest space (e.g., bathroom) directly served by the system would not exceed the established concentration limit.

Additional documentation requirements include a permanent label on the equipment listing the company that installed the system and the weight of the installed refrigerant.

Although there are several A2L refrigerants approved for use, the primary two refrigerants that you should expect in the market are R-32 and R-454B. Each equipment manufacturer will specify which refrigerant is used for their equipment.

Multifamily Buildings

For multifamily buildings where refrigerant lines penetrate fire-rated floor assemblies, the building code may require that the refrigerant lines be placed in a fire-rated shaft or other fire safety measures be implemented. Developers should coordinate designs with their MEP firms. The shaft requirements can impact plan layouts and architectural designs.

Centrally Ducted System vs. Mini-Splits

Different mitigation strategies will be specified for centrally ducted systems vs. mini splits. Again, builders should reach out to their vendors for information and follow installation instructions to make sure all required safety measures are implemented so that concentration limits are not exceeded in case of a refrigerant leak.

Design Software

Software programs for sizing equipment and energy modeling should use updated specifications for the new equipment with A2L refrigerants.

What Should Home Builders Do Right Now

Have a transition plan in place that achieves the following goals:

• Coordinate a switch-over timeline with vendors and installers
• Ensure a sufficient pipeline of existing equipment before the switch-over and new equipment after the switch-over (old and new equipment will not be compatible unless specifically stated by the manufacturer)
• Coordinate with your mechanical system designer (for multifamily buildings, evaluate if a fire-rated shaft is required)
• Make sure your HVAC contractor is knowledgeable on the new installation requirements and safety measures for the specific equipment that will be installed in your homes
• Ensure that installation instructions are available from the manufacturer for the specific units to be installed in your homes
• Coordinate between all involved parties throughout the process and establish a direct feedback loop

Building Code Updates

Information about the status of building codes regarding A2L refrigerants in each state can be found using this interactive map from the Air-Conditioning, Heating, and Refrigeration Institute (AHRI).

Additional Resources from EPA, AHRI, and ICC

• Technology Transitions HFC Restrictions by Sector | US EPA
• Frequent Questions on the Phasedown of Hydrofluorocarbons | US EPA
• Safe Refrigerant Transition | AHRI (ahrinet.org)
• A2L Refrigerants Transition | ICC (iccsafe.org)