HVAC Ducting Work

        HVAC Ducting Work

📘 Article 1 — What is an HVAC Ducting System?

• An HVAC ducting system is the air distribution network that delivers conditioned air from air handling equipment to occupied spaces and returns air to the system.
• Ducts are installed above false ceilings, inside shafts, or exposed in mechanical areas. Their performance depends on the correct selection of materials, proper installation, sealing quality, and insulation.

1. Main functions:
2.  Supply air distribution
3. Return air collection
4. Exhaust air removal
5.  Fresh air intake       

                            📘 Article 2 — Types of HVAC Duct Materials.

• HVAC ducts are manufactured from different materials depending on the application:

1. Galvanized Steel Duct

         The most common type used in HVAC. Zinc coating protects against corrosion. Suitable for commercial and residential systems.

       2. Black Steel Duct

      Used in high-temperature applications such as kitchen exhaust and smoke extraction.                                Usually welded.

        3. Stainless Steel Duct.

            Used in laboratories and hygienic areas. Resistant to corrosion, chemicals, and bacterial growth.

        4. Aluminum Duct

           Used as external cladding protection for ducts and pipes in exposed areas.

          5. Pre-Insulated Duct.

             These factory-insulated panels are easy to handle and quick to install. External

              Insulation is unnecessary.

           6.Fabric (Textile) Duct.

              Used in open areas like malls and halls. Lightweight and good for air distribution 

               but not for concealed ceilings

📘 Article 3 — Duct Shapes and Where to Use Them.

• Ducts are manufactured in three main shapes:

1. Rectangular Duct.

          Most widely used above false ceilings and inside shafts. Easy to fabricate 

           and adjust height.

      2. Round Duct.

          Common in exposed ceilings and decorative installations. Good for fan connections and small ventilation lines.

        3. Oval Duct
            Used where appearance matters. Combines airflow efficiency with a better visual look.

📘 Article 5 — Duct Supports and Installation Levels.

•  Duct supports must follow standard spacing tables (such as SMACNA). Rectangular                   ducts are supported using trapeze hangers with threaded rods.

• Key installation rules:

1.  Follow the bottom of the duct level (BOD) from the drawings
2.  Coordinate with pipes, cable trays, and structure
3. Do not allow the duct to touch the walls
4.  Provide access to dampers and equipment

📘 Article 6 — Flexible Connections, Plenum Boxes, Sleeves.

• Flexible connectors are installed between equipment and ducts to isolate vibration.

          Plenum boxes are installed above diffusers to distribute air evenly.

          Wall sleeves must be coordinated before construction. Gaps are sealed with foam or fire-rated sealant for fire walls.

📘 Article 7 — Duct Insulation Types.

• Duct insulation improves energy efficiency and prevents condensation.

        Common types:

1. Fiberglass insulation
2. Rockwool insulation (high temperature exhaust)
3.  Armaflex rubber insulation
4. Polyolefin foam insulation

     Thickness and density depend on location and application.