Insights on the HVAC Industry Transition to A2L Refrigerants
Code Considerations for Building Officials and Inspectors
As the HVAC industry continues its transition from HFC refrigerants to A2L refrigerants, many questions and concerns have come up related to the permitting process and inspection expectations. Rest assured, the transition to A2L refrigerants is moving forward smoothly.
The keys to success reside in the following areas:
- Selection of HVAC equipment that is listed and labeled to current product safety standards
- Understanding all federal, state and local A2L refrigerant restrictions and the regulations for changing and mixing refrigerants
- The installation and operation of equipment following the HVAC equipment manufacturer’s instructions manuals
- The proper labeling of all equipment and piping systems
Selection of Equipment
Chapter 11 of the 2024 International Mechanical Code® (IMC) regulates the design, installation, construction and repair of refrigeration systems. It references the appropriate standards to which factory-built equipment must comply and indicates the specific UL standards that apply to equipment that uses A2L refrigerants.
The code requires A2L equipment to comply with UL 484—2014, UL/CSA 60335-2-40—2022, or UL/CSA 60335-2-89—2021, as applicable. Building officials and inspectors verify that A2L equipment is listed and labeled to these standards during the permitting process and during all subsequent mechanical inspections performed during construction.
Refrigerant Restrictions
The IMC limits the quantities of refrigerants in systems because of the risks refrigerants present to building occupants. The maximum allowable quantities of refrigerants are based on the characteristics and risks associated with each individual refrigerant, the building occupancy classification and the type of refrigeration system. The permissible quantities allowed by the code are based on ASHRAE 15 which establishes calculations for the maximum refrigerant charge in a system based on the building occupation, the equipment and the specific refrigerant used. There is no one size that fits all for systems using A2L refrigerants.
Calculations must be made for each installation and building type to determine code compliance. Since the calculations are also equipment and refrigerant specific, the UL listing requires that detailed instructions for completing these calculations be included in the manufacturer’s instructions manual. It is important that system designers, contractors and technicians use the manual specific to the equipment installed to ensure installation is code compliant.
It is good practice to provide a copy of the calculations and applicable installation manuals with the documentation provided for the permitting process. Building officials need this information to verify HVAC system code compliance.
Changing of Refrigerant
The changing of refrigerant in an HVAC system has become a critical issue with the transition to A2L refrigerants. When changing or replacing refrigerants in an existing system to another refrigerant, the 2024 IMC requires contractors and technicians to notify the owner or their agent prior to any change of refrigerant. This gives them the opportunity to object to the changes prior to replacement. Additionally, the code provides three pathways for compliance in replacing a refrigerant:
- Following the instructions from the original equipment manufacturer
- Utilizing an evaluation by a registered design professional or by an approved agency
- Approval by the code official
These requirements address safety concerns related to changing refrigerants from one safety group to another as well as changing from one refrigerant to another within the same safety group. Note that some HVAC equipment on the market can operate on either R454-B or R32 refrigerant; however, many cannot. Additionally, it is not currently possible to convert HFC equipment to use A2L refrigerants or vice versa.
Mixing of Refrigerants
The mixing of refrigerants in an HVAC system is another critical issue that has arisen with the transition to A2L refrigerants. Typically, refrigerants of different designations cannot be mixed in a system because the chemical combinations may have different and unpredictable or possibly hazardous properties.
The 2024 IMC allows mixing of refrigerants only when it is permitted by the equipment manufacturer and when the resulting mixture does not change the refrigerant safety group. Without following the manufacturer’s instructions, the mixing of refrigerants remains prohibited by the code.
Installation of Equipment
Strict adherence to the equipment manufacturer’s installation manual, the product listing and federal regulations must be maintained for HVAC systems using A2L refrigerants. The IMC requires installation to comply with the equipment manufacturer’s installation manuals along with product listing and labeling.
These resources are what building officials and inspectors rely on to determine compliance with code. The manufacturer’s installation manual must always remain on-site during construction, and the equipment rating plates must be readily accessible.
Pipe and Equipment Labeling
Labeling of refrigerant piping helps to prevent serious accidents where piping is damaged or opened by mistake. This has become more important with the transition to A2L refrigerants.
The 2024 IMC requires additional markings for A2L refrigerants. The identification on refrigerant lines must include the statement, “WARNING—Risk of Fire. Flammable Refrigerant.” In addition to these labeling requirements for piping, equipment manufacturers are required by the product listing to include warning labels on their equipment alerting owners, contractors and technicians that the equipment, as well as the refrigerant piping, contains flammable refrigerant.
Considerations for Building Officials and Inspectors
Some jurisdictions across the U.S. have not yet adopted the 2024 IMC but have chosen to amend their existing building codes, or otherwise, to include provisions related to A2L refrigerants and equipment.
Nearly all states and local jurisdictions have taken steps to allow the use of A2L refrigerants in residential and light commercial construction. Regardless of how your jurisdiction is addressing A2L refrigerants, focusing on the four keys to success presented will help to ensure that the permitting and inspection processes run smoothly.
For additional information on this topic, please reach out to Jim Cika via email at jcika@iccsafe.org.
For more information on preparing for A2L refrigerants, please click here.
Visit the websites referenced below for additional information.
To learn more about water-related issues and how codes and standards can help, view the ICC’s PMG Webpage
To stay updated on the latest PMG industry news, subscribe to ICC’s PMG newsletter here.
EPA website links:
EPA Office of Enforcement and Compliance Assurance Enforcement Guidance Memo.
Regulatory Actions for Technology Transitions
EPA Technology Transitions Program
HFCs and the AIM Act Protecting Our Climate by Reducing Use of HFCs.
Federal Register Links:
About the Author
Jim Cika, director, PMG technical resources for the International Code Council, where he serves as a subject matter expert to the plumbing, mechanical, and fuel gas codes. He represents ICC in federal and state coalitions, task forces, committees, and councils where expertise in I-Code subjects is required. Cika has more than 20 years of experience in the manufacturing and construction industry where he has served as chief technical expert for regulatory, product standards, building code and product engineering matters.
