What supply register means
A supply register is the grille where conditioned air enters a room, usually with louvers or a damper to aim or adjust the flow.
Also called register, supply vent, diffuser.
Where it matters on a HVAC job
Closing registers to push air elsewhere raises static pressure and rarely works. When a room is hot or cold, check the branch duct and the register size before blaming the equipment.
What the model code says
- Supply air is air delivered to a conditioned space through ducts or plenums from the heating, cooling or ventilating system. (IRC 2021, Chapter 2)
Check which code edition your building department enforces for supply register before you quote.
What it costs
Jobs that involve supply register are priced in the ductwork replacement cost guide: about $1,250 typical, usually $450 to $2,200. The guide shows its sources and what moves the price. The duct size calculator prices a job line by line.
Work it out
- Free calculator: Duct size calculator
- Cost guide: Ductwork replacement cost
- Licensing: HVAC license rules by state
- Tools, templates and guides: Free HVAC resources
Sources: 2021 International Residential Code, Chapter 2, Definitions (ICC). Checked October 9, 2026.