HVAC DUCT SYSTEMS

Duct System Design

1. Design all ducts that serve heating, cooling, and ventilation appliances using Air Conditioning Council of America (ACCA) Manual D or another approved method.

Flexible Duct Installation

General Installation Requirements
1. Install flexible ducts according to manufacturer’s installation instructions. The installation instructions that follow are from the Air Diffusion Council and may be downloaded at www.flexibleduct.org.
2. Use flexible ducts that are labeled at least (≥) every 36 inches with information such as the manufacturer’s name and the R-value of the duct insulation. Read the full Topic

Framing Cavity Return Ducts

Return Ducts in Framing Cavities Installation Requirements
1. You may use framing cavities in interior areas, such as cavities in interior stud wall and between solid floor joists, as return ducts or plenums. Do not use framing cavities for supply ducts or plenums. Consult your local building official to reconcile this provision with IRC provision N1102.2.10. Read the full Topic

Outdoor and Retuen Air Location and Installation

Appliances Governed by these Code Provisions
1. Apply these code provisions to forced-air furnaces, and to air conditioning systems, and to heat pumps. Read the full Topic

Underground Ducts

Ducts Installed Underground or in Concrete
1. Use approved concrete, clay, metal, or plastic for HVAC ducts that are installed underground or in concrete.
2. Protect metal ducts from corrosion or completely surround them with concrete at least (≥) 2 inches thick. Read the full Topic