2024 Uniform Mechanical Code Loose-Leaf

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:

• 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