This article is about HVAC Air Terminal Devices (Diffusers, Grills and Registers) Installation as per International Codes and standards.
HVAC Air Terminal Devices (Diffusers, Grills and Registers) & Flexible Connector Installation
- Air Terminal Devices shall be mounted at locations shown on approved Construction Drawings
- Air terminal devices shall not be installed directly on the main ducts
- Air terminal devices shall be connected to main ducts with branch ducts having a minimum length of two duct sizes.
- Troffer light diffusers, perimeter slot diffusers or similar shall not be located on the same duct branch with standard type diffusers
- Flexible ducts used for connecting air diffusing devices to ducting shall be Pre-Insulated double wall Type.
- Flexible ducts used for connecting the ducting to air diffusing devices shall not exceed 5 feet in overall length and shall not have bends greater than 45 degrees
- Air Connectors (flexible connector) shall not pass through any wall, partitions, or enclosure of a vertical shaft that is required to have a fire resistance rating 1 hour or more (NFPA 90-A Para 4.3.2.1.4)
- Air Connector shall not pass through floor (NFPA 90-A 4.3.2.1.5)
- The end of ducts shall be trimmed square before installation (SMACNA Para S3.29).
- Collars to which flexible duct is attached shall be a minimum of 2″ in length. (SMACNA Para S 3.30)
- Collars shall be inserted of into flexible duct (connector) a minimum of 1″ before fastening. (SMACNA Para S 3.31)
- Non metallic flexible connector shall be secured to the sleeve or collar with a draw band. If the duct exceeds 12″” in diameter the draw band must be positioned behind a bead on the metal collar (SMACNA Para S 3.30).
Standards Codes and References for HVAC Air Terminal Devices (Diffusers, Grills and Registers) Installation
1- SAES-K-001 — Heating, Ventilating, and Air Conditioning, 25 November 2006.
2- SMACNA, HVAC Duct Construction Standards, Metal & Flexible, 1995.
3- NFPA 90-A — Installation of Air-Conditioning and Ventilating Systems, 2002.
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