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.
A circular diffuser is an HVAC air terminal with a round face that distributes supply air in a symmetrical radial pattern, connecting directly to round duct without a square-to-round transition fitting. Goodwind manufactures the Circular Diffuser (model GT-CD) in aluminum, with powder-coated, anodized, or custom color finishes, matching the material and finish options used across its wider diffuser range.
Circular Diffuser Specifications
| Spec | Detail |
|---|---|
| Model | GT-CD |
| Material | Aluminum |
| Finish | Powder coated, anodized, or custom colors |
| Mounting | Ceiling, direct connection to round duct |
| Applications | Commercial and residential ceiling installations with round ductwork |
Circular Diffuser vs. Square Diffuser
Both distribute supply air radially from the ceiling, but the circular diffuser connects directly to round duct, similar to how a round grille avoids a transition fitting on the grille side. A square diffuser is the better fit where the ductwork is already rectangular, since forcing a round diffuser onto square duct just moves the transition problem rather than solving it.
How to Specify a Circular Diffuser
For MEP Consultants at the Design Stage
Specify a circular diffuser where the duct run is already round or spiral, so the connection is direct. Confirm the neck diameter matches the connecting duct size, and check the throw pattern suits a centrally-located ceiling position, since circular diffusers typically distribute air in all directions equally.
For Contractors at Procurement Stage
Confirm the neck diameter against the actual duct size on site before ordering, and confirm finish against the drawing. Since these are manufactured to size rather than stocked in fixed dimensions, field-verify duct diameter where possible rather than relying solely on drawn dimensions.
FAQ
What is a circular diffuser used for?
It's used where the supply air connection is round or spiral duct, distributing air radially from a centrally-located ceiling position.
Does a circular diffuser need a transition fitting?
No, it connects directly to round or spiral duct without a square-to-round transition.
Can it be custom sized and finished?
Yes, in a range of sizes and finishes including powder coating and anodizing.
What material is it made from?
Aluminum.
Running round duct to a ceiling diffuser? Contact Goodwind for technical input, or see our round grille guide for the same direct-fit principle on grilles.