A register normally includes a way to adjust airflow; a grille normally does not. Both cover an HVAC opening, and in everyday shopping the words vent, vent cover, register and grille are often used loosely. The practical difference is whether the cover also controls the air passing through it.
What is an HVAC register?
A register is a cover for an air opening that traditionally includes an adjustable damper or similar airflow-control mechanism. Registers are commonly used on supply openings, where conditioned air enters the room.
What is an HVAC grille?
A grille covers an HVAC opening but traditionally has no built-in airflow-control damper. Grilles are common on return-air openings, although the exact setup varies by HVAC system and product design.
What is a vent cover?
Vent cover is the broadest consumer term. It can describe a register, grille, diffuser or decorative cover used over an air opening in a floor, wall or ceiling. That is why product searches often mix terms such as floor vent cover, floor register and register cover.
Register vs. grille at a glance
| Feature | Register | Grille |
|---|---|---|
| Covers an HVAC opening | Yes | Yes |
| Built-in airflow adjustment | Typically yes | Typically no |
| Common on supply openings | Yes | Sometimes |
| Common on return openings | Sometimes | Yes |
Which one should you buy?
First identify whether the opening is a supply or return, then measure the duct opening. If you are replacing an existing product, also note whether you need airflow adjustment. Do not choose only by appearance or by the outside dimensions of the old cover.
Next: Supply Vent vs. Return Vent or How to Measure Vent Covers.