Air Distribution Design: How to Size Grilles, Diffusers and Ducts

Air distribution design turns a room's load into airflow, then sizes the terminals, ducts and dampers that carry it. A step-by-step sequence for MEP consultants and contractors.

HVAC Ductwork Accessories: Plenum Boxes, Flex Duct, Access Doors, Exhaust Valves & VAV Devices

Plenum boxes, flexible duct, access doors, exhaust valves, and VAV devices round out an HVAC air distribution system beyond the visible grilles and diffusers. Specs, applications, and how to specify each.

What Is an Aluminium Collar Damper? Specs and How to Specify One

An aluminium collar damper is a lightweight, corrosion-resistant single-blade damper built into a round duct collar, suited to standard comfort HVAC branch connections. Specs, applications, and how to specify one.

What Is a Flowbar (Hidden Type Slot Diffuser)? Specs and How to Specify One

A flowbar (hidden type slot diffuser) is built to disappear into a ceiling shadow gap or reveal detail, supplying air with almost no visible fixture. Specs, applications, and how to specify one.

What Is a Trimless Slot Diffuser? Specs and How to Specify One

A trimless slot diffuser has no visible metal frame — it plasters directly into the ceiling finish, unlike a flowbar which sits in a reveal detail. Specs, applications, and how to specify one.

What Is a Backdraft Damper? Specs and How to Specify One

A backdraft damper opens with airflow and closes automatically under gravity or spring tension to stop reverse flow, without needing power or a control signal. Specs, applications, and how to specify one.

What Is an Industrial Control Damper? Specs and How to Specify One

An industrial control damper is built for heavier-duty process airflow regulation than standard comfort HVAC dampers, handling wider temperature and pressure ranges. Specs, applications, and how to specify one.

What Is a Butterfly Collar Damper? Specs and How to Specify One

A butterfly collar damper uses a single flat disc pivoting on a central shaft, built into a round duct collar for compact airflow regulation at branch takeoffs and diffuser necks. Specs, applications, and how to specify one.

What Is a Double Skin Eyeball Type Jet Nozzle? Specs and How to Specify One

A double skin eyeball type jet nozzle has a movable outer shroud that swivels like an eyeball, letting the throw direction be adjusted after installation. Specs, applications, and how to specify one.

What Is a Single Skin Spot Type Jet Nozzle? Specs and How to Specify One

A single skin spot type jet nozzle uses a fixed, simple-shell design to direct a concentrated jet of air at a specific spot, rather than a wide sweep. Specs, applications, and how to specify one.

What Is a Pan Diffuser? Specs and How to Specify One

A pan diffuser uses a shallow pan-shaped face to spread supply air in a wide, gentle pattern, suited to lower ceiling heights and lower air volumes. Specs, applications, and how to specify one.

What Is a Swirl Diffuser? Specs and How to Specify One

A swirl diffuser uses angled fixed vanes to induce a spinning airflow pattern, pulling in room air for fast mixing rather than a straight throw. Specs, applications, and how to specify one.

What Is a Circular Diffuser? Specs and How to Specify One

A circular diffuser distributes supply air in a symmetrical radial pattern from a round duct connection, without needing a square-to-round transition. Specs, applications, and how to specify one.

What Is a Round Plaque Diffuser? Specs and How to Specify One

A round plaque diffuser combines the plaque diffuser's flush, no-pattern face with a circular shape instead of square. Specs, applications, and how to specify one.

What Is a Plaque Diffuser? Specs and How to Specify One

A plaque diffuser uses a flat, solid face plate rather than a grid or cone pattern, for a minimal, architectural ceiling look. Specs, applications, and how to specify one.