SMACNA Standards

SMACNA Duct Construction Standards

Ductwork must be supported by trapeze hangers or straps, not wire. Wire hangers can cut into insulation and don't provide adequate support.

SMACNA Duct Liner Standard

Duct insulation in occupied plenums must have a proper jacket/facing. Exposed fiberglass releases fibers into the airstream causing IAQ issues.

SMACNA HVAC Controls Guidelines — Pneumatic Tubing Installation

Pneumatic tubing must use proper bend fittings or gradual sweeps at direction changes. A kinked 90-degree bend restricts airflow through the tubing, causing sluggish actuator response or complete loss of pneumatic signal. The actuator may not reach full stroke, resulting in poor temperature control and comfort complaints.

SMACNA HVAC Controls Guidelines / Manufacturer Installation Instructions

EP transducers must be mounted below or at the same level as the pneumatic actuator they serve. Mounting above causes condensation from compressed air to drain down into the actuator valve body, causing corrosion, sticking, and eventual valve failure. Condensate should drain back toward the air supply where it is caught by drip legs and filters.

SMACNA HVAC Duct Construction Standards

Rectangular duct aspect ratio should not exceed 4:1 for efficiency. Higher ratios increase friction loss and are difficult to seal properly.

SMACNA HVAC Duct Construction Standards / IMC 603.5

Duct liner is not permitted inside kitchen supply ductwork per the Crestline specifications. Fiberglass duct liner in kitchen areas can trap grease particles and food odors, creating a fire hazard and unsanitary condition. The porous surface of duct liner is impossible to clean once contaminated with cooking grease. Noise attenuation in kitchen supply ducts must be achieved through external duct wrap, silencers, or sound-attenuating duct transitions — not internal liner. IMC 603.5 requires duct materials to be suitable for the application and environment.

SMACNA TAB Procedural Guide

SMACNA TAB procedures require a pitot tube traverse (multiple readings across the duct cross-section) to determine average velocity. A single center-point reading overestimates airflow by 10-25% because velocity is highest at the center of the duct.

SMACNA TAB Procedural Guide / AABC Standards

All balancing dampers must be locked in their final position after TAB is complete. Unlocked dampers are easily bumped or moved by other trades, invalidating the entire balance.