2018 Uniform Mechanical Code

2018 Uniform Mechanical Code (UMC)

The 2018 Uniform Mechanical Code (UMC®) provides comprehensive requirements for the installation and maintenance of heating, ventilation, cooling, and refrigeration systems. Developed through the ANSI Consensus Process and designated as an American National Standard by the American National Standards Institute (ANSI), the 2018 UMC reflects modern practices and technologies in the mechanical industry.

The 2018 edition represents an important milestone in mechanical and HVAC standards, introducing specific provisions for low-flammability A2L and B2L refrigerants. These refrigerants are associated with lower Global Warming Potential (GWP), making the 2018 UMC an important reference for professionals working with evolving refrigeration technologies.

The code was developed with contributions from a broad range of industry stakeholders, including consumers, code officials, installers, maintenance professionals, manufacturers, laboratories, experts, and other users.

Key Updates in the 2018 Uniform Mechanical Code

The 2018 UMC includes significant updates and new requirements covering mechanical, HVAC, refrigeration, duct, hydronic, and fuel gas systems.

Mechanical Systems & Exhaust

• New clearance requirements for solid-fuel-burning appliances
• Updated requirements for ducts serving Type I hood exhaust systems
• New provisions for product-conveying ducts
• New requirements for Type I and Type II exhaust systems

Duct Systems & Air Distribution

• New duct system sizing provisions
• Updated duct leakage testing requirements
• Revised installation and closure requirements for flexible air ducts
• New provisions for air dispersion systems

Furnaces & Pressure Regulators

• New requirements for pressure regulators
• Updated requirements for electric furnaces

Refrigeration Systems

• New requirements for A2L and B2L low-flammability refrigerants
• Updated refrigeration machinery room requirements
• Requirements addressing machinery room access, openings, detectors, and ventilation systems
• New provisions for pressure-limiting devices for compressors

Hydronic Piping Systems

• New pressure testing requirements for piping and components
• Updated requirements for expansion tanks
• New requirements covering materials used in hydronic systems

Fuel Gas Piping Systems

• Updated requirements for piping materials
• New and revised overpressure protection provisions
• Updated requirements for gas piping installation