A return-air grille provides an opening through which room air enters a return or extract path. It does not actively create airflow. The fan, duct system and grille resistance together determine what is delivered.
Separate three sizes
- Nominal size
- The ordering designation, which must be interpreted according to the supplier's drawing.
- Neck or opening size
- The interface to the duct, plenum or building opening.
- Overall face size
- The visible outer frame and any flange covering the opening edge.
A replacement ordered by outside dimensions alone may fail to fit the existing opening. Record mounting holes, flange depth and available space behind the face.
Compare airflow through the usable area
Blade pattern, mesh and frame reduce the open area. Two grilles with the same nominal size can therefore have different resistance and noise at the same flow. Use the relevant performance data rather than a blanket assumption that all egg-crate or louvred faces behave alike.
The connected plenum and duct also matter. An obstruction directly behind part of the grille can create uneven flow and noise that a new face alone will not cure.
Choose a location that supports the room
Return position influences the overall air path. Avoid casually relocating a return to a convenient empty wall without considering supply outlets, equipment and the room's pressure strategy.
TROX's grille information identifies application and configuration details for a specific grille family. Obtain equivalent data for the offered return grille at its intended duty.
Specify removable access, finish and cleaning requirements. If a filter is required, use a suitable filter-access assembly rather than wedging loose media behind an ordinary face.
Send the opening measurements and airflow to shengtongJH for return-grille configurations that fit the existing or planned system.