Ductwork

Ductwork is the system of enclosed conduits that distributes conditioned air from heating, ventilation, and air conditioning (HVAC) equipment to and from occupied spaces. It includes supply ducts that deliver air, return ducts that remove air, and exhaust ducts that vent air to the outside, along with fittings, dampers, diffusers, grilles, and access doors. Ducts are commonly rectangular or round in cross-section and are made from materials such as galvanized steel, aluminum, or PVC, with insulation as needed. Flexible ducts are used for certain transitions or tight spaces, though they are more prone to leakage and pressure loss if not properly installed.

Design and construction considerations focus on delivering the required airflow with minimal energy loss. Ducts should be routed to shorten paths, avoid unnecessary bends, and maintain appropriate clearances. Joints are sealed with mastic, UL-listed tapes, or mechanical fasteners to minimize leakage. Insulation reduces heat transfer and prevents condensation, particularly for ducts that pass through unconditioned spaces. Access doors and cleanouts are provided for inspection and maintenance. Duct systems are sized and routed in accordance with relevant standards and building codes.

Installation practices emphasize airtight sealing, proper support, and vibration isolation. Performance is often verified through leakage testing and balancing to ensure the intended airflow to each space is achieved. Maintenance includes inspecting seals and joints, cleaning, and replacing filters. Standards and guidelines from organizations such as SMACNA and ASHRAE, along with local codes, address design criteria, fabrication, installation, and safety considerations for ductwork.