The regulations regarding A2L refrigerant are found in a tapestry of Guides, Standards, and Codes which often refer to each other. Here is a list of the most consequential.
ICC International Mechanical Code 2024, IAPMO Uniform Mechanical Code 2024
These recently revised codes allow the use of A2L refrigerants in traditional HVAC systems. They specify conditions for use of A2L refrigerant and refer to ASHRAE Standard 15/34 2022 and UL 60335-2-40, 2022.
Amendments to ICC International Mechanical Code 2021, IAPMO Uniform Mechanical Code 2021
Some states have passed amendments to their existing 2021 codes to allow the use of A2L refrigerants in traditional HVAC systems and specifies conditions for use of A2L refrigerant. They refer to ASHRAE Standards 15/34 2019 and UL Standard 60335-2-40, 2022.
UL 60335-2-40, 2022
This is the latest standard from UL for HVAC systems. It is similar to the international IEC standard with the same name and number. The provisions in the IEC standard have already been in place in many other places around the world; including, Europe, Japan, and Australia. UL 60335-2-40 spells out in detail how A2L refrigerant may be safely applied. It refers to ASHRAE Standards 15/34 2022.
ASHRAE Standards 15 2022 “Safety Standard for Refrigeration Systems”
This standard describes how refrigeration systems may be safely installed and operated. The 2022 edition includes specific conditions for A2L refrigeration systems.
ASHRAE Standard 15.2 “Safety Standard for Refrigeration Systems in Residential Applications” Standard 15 addresses larger buildings while 15.2 describes how refrigeration systems may be safely installed and operated in residential low-rise applications, including specific conditions for A2L refrigeration systems.
ASHRAE Standard 34 – 2022 “Designation and Classification of Refrigerants” Standard 34 lists refrigerant safety ratings and important safety data for a long list of refrigerants, including several A2L refrigerants. Data listed in Standard 34 is used to determine specific system requirements detailed in Standards 15 and 15.2. Taken together, Standards 15 and 34 provide very clear guidance for application of A2L refrigerant.
EPA Final SNAP Ruling 23
This ruling specifically allows the use of A2L refrigerants R-32, R-452B, R-454A, R-454B, R-454C, and R-457A in new residential and light commercial air conditioners and heat pumps. The rule incorporates UL 60335-2-40 by reference.
EPA AIM Act Final Ruling, Sept 2021
This ruling establishes the HFC allocations for the phasedown of HFC refrigerants under the AIM Act. One unexpected significant component of this ruling is a ban on disposable refrigerant cylinders beginning in 2025.
AHRI Guideline M 2020 “Unique Fittings and Service Ports for Flammable Refrigerant Use”
AHRI Guideline M specifies that service connections for systems with flammable refrigerant. For cylinders holding less than 50 lbs. of A2L refrigerant, it specifies CGA 164 fittings which are 1/4 inch flare with left-hand threads. For equipment using A2L refrigerant it specifies 1/4 inch flare with right-hand threads, exactly the same as those used on systems with A1 refrigerant. Same size and same threads.
CGA Standard V-1 2019 “Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections” The CGA V-1 standard describes the connections on compressed gas cylinders. Standard CGA V-1 2019 introduces the CGA 164 connection specifically for A2L refrigerant cylinders. It describes the CGA 164 connection as a 1/4 inch flare with left hand threads. The latest edition of this standard is now CGA V-1 2021.