IAPMO UMC 1-2024

The 2024 edition of the Uniform Mechanical Code (UMC®) represents the most current approaches in the mechanical field. It is the eighth edition developed under the ANSI Consensus process is designated as an American National Standards by the American National Standards Institute (ANSI). Contributions to the content of this code were made by every segment of the built industry, including such diverse interests as consumers, enforcing authorities, installers/maintainers, labor, manufacturers, research/standards/ testing laboratories, special experts and users.
The UMC provides complete requirements for the installation and maintenance of heating, ventilating, cooling and refrigeration systems, while at the same time allowing latitude for innovations and new technologies. Key changes to the 2024 UMC include:

Significant changes to the UMC include:

New minimum air filtration requirements for occupied spaces of mechanically ventilated buildings
Revised outdoor air intake requirements for transient occupancies
New air balancing requirements for ventilation systems
New exceptions for materials exposed with ducts or plenums
New provisions for high-probability systems using Group A2L refrigerants for human comfort applications
New refrigerant safety group classifications based on flammability and toxicity
New requirements for refrigeration machinery rooms where A2L and B2L refrigerants are used
New materials standards for refrigerant piping, tubing, and fittings
New design requirements for geothermal district systems ambient temperature loops (ATL)
New Appendix H providing minimum qualifications for installers, inspectors, or employers for systems covered by the UMC
New Appendix I addressing mechanical system requirements indoor horticultural facilities
New Appendix J addressing CO2 monitoring and clean air delivery for adequate ventilation in occupied spaces