Intro to HVAC Mechanical Code Regulations : Duct Systems

 IMC Section 601: General Air Movement

• Scope: Addresses the general movement of air within duct systems.
• Topics:
  • Air movement in egress elements
  • Corridor sealing
  • Usage for airflow exit enclosures
  • Contamination prevention
  • Return air openings

IMC Section 602: Plenums

• Definition: Plenums are air distribution boxes attached to the supply outlet of HVAC equipment, connecting to ductwork.
• Categories: Supply, return, exhaust, relief, and ventilation.
• Topics:
  • Plenum enclosure construction
  • Plenum materials
  • Plenum wiring
  • Stud cavity and joist space plenums
  • Plenum usage in flood hazard locations

IMC Section 603: Duct Construction and Installation

• Scope: Regulations for constructing and installing ductwork systems.
• Topics:
  • Duct sizing and classification
  • Usage of metallic and non-metallic ducts
  • Flexible air ducts and connectors
  • Rigid duct penetrations
  • Underground ducts
  • Joints, seams, connections, and support
  • Condensation prevention
  • Flood hazard area installation
  • Protective measures
  • Air dispersion systems
  • Registers, grills, and diffusers

IMC Section 604: Insulation

• Purpose: Protects ductwork depending on location and type of airflow.
• Types: Fiberglass wraps, aluminum membranes, tapes.
• Topics:
  • Thermal insulation requirements
  • Coverings and linings
  • Duct covering assembly penetration restrictions
  • External duct insulation identification
  • Lining installation
  • Service openings
  • Internal insulation

IMC Section 605: Air Filters

• Purpose: Ensure that all return air, outdoor air, and makeup air is filtered upstream from any heat exchanger or coil.
• Topics:
  • Air filter installation
  • Air filter labeling
  • Air filter approval
  • Airflow over the filter

IMC Section 606: Smoke Detection Systems Control

• Purpose: Ensure systems only operate with appropriate airflow and protect against smoke contamination.
• Topics:
  • Locations where smoke detector controls are required
  • Smoke detector installation
  • Smoke detector controls operation capabilities

IMC Section 607: Duct and Transfer Openings

• Purpose: Protect duct penetrations through structures and air transfer openings in assemblies.
• Pertinence: Especially important for ductwork passing through fire-rated assemblies.
• Topics:
  • Damper installation
  • Smoke control systems
  • Damper testing ratings and actuation
  • Damper access and identification
  • Damper location requirements
  • Fire partitions and smoke barriers
  • Shaft enclosure penetration