Equipment, Flex & Terminal Connections ยท Equipment & Terminals
VAV inlet duct connection
Terminal unit inlet
ConnectionSlip/gasketed inlet
SupportIndependent VAV support
Before you start
- Confirm the VAV model, inlet size, manufacturer-required straight inlet condition, flow-sensor location, airflow direction, and control access.
- Inspect the inlet, sensor tubes, controls, casing, and support points.
- Verify the VAV is independently supported and level before the inlet duct is connected.
- Do not place an elbow or abrupt transition at the inlet unless the approved design permits it.
Tools and materials
VAV box, round inlet duct, approved slip or gasketed components, fasteners, sealant, independent supports, level, tape, marker, and manufacturer installation instructions.
Lay it out
- Establish the VAV inlet centerline.
- Reserve the required straight inlet length.
- Keep controls, sensor tubes, and access panels clear.
Set and support it
- Support the VAV independently and level.
- Support the inlet duct separately.
- Keep the inlet connection concentric.
Make the connection
- 1
Verify the VAV airflow direction and inlet size.
- 2
Set the VAV level.
- 3
Bring the straight inlet duct to the collar.
- 4
Seat and mechanically secure the connection.
- 5
Seal the inlet joint.
- 6
Check that the flow sensor is unobstructed.
- 7
Verify controls and access remain clear.
Check the install
- The VAV is level.
- The inlet is straight and concentric.
- The flow sensor is unobstructed.
- The inlet duct does not load the casing.
- Controls and service access remain open.
Common mistakes
- Putting an elbow directly at the inlet.
- Letting the inlet duct pull the VAV out of level.
- Blocking sensor tubes.
- Burying controls behind ductwork.
Stop and ask
Stop if the inlet arrangement conflicts with manufacturer guidance, the VAV cannot be supported level, or the flow sensor and controls cannot remain accessible.