Static field route #18811

What do I do when an elbow is installed directly on a VAV inlet?

Equipment Connections: RTU, AHU, VAV, Fans & Louvers📐 PERFORMANCE / COORDINATION CHECKV188 answer-gap expansion

📖 Verified core answer

A hard elbow at the VAV inlet can make the airflow sensor read dirty, uneven air. Check the VAV manufacturer/install detail and bring options like a straight spool, box shift, or approved inlet fitting before TAB/startup.

Open in Field Rescue Open category

Field verification checklist

Confirm VAV tag, airflow direction, inlet size, sensor orientation, and manufacturer installation requirements.
Check how much straight duct is actually available before the inlet.
Look for an elbow, transition, flex, damper, or offset right at the sensor.
Check ceiling/access constraints before moving the box.
Document the condition before TAB/startup so the issue is not blamed on controls only.

Ask foreman

VAV [tag] has a hard elbow right at the inlet. I checked the tag and available straight length. Do you want me to add a straight spool, shift the box, use an approved inlet fitting, or hold for detailer/TAB direction?

Text to foreman

Route options

AMake the small field correction only if it is within your assignment and the approved method.

BHold and document the condition if the fix affects airflow, access, life safety, pressure class, rated assemblies, equipment, or another trade.

CBring the foreman/detailer the location, what you checked, and what decision you need before cover, startup, or rework.

Do not do this

Do not assume the VAV is fine because air is moving. Bad inlet conditions can make CFM readings unstable.

Why this matters

A bad inlet condition can make balancing difficult, cause hunting controls, and create comfort complaints even when the duct is physically connected.

Verification basis

Approved drawings/specs, project coordination drawings, manufacturer instructions/submittals, shop standards, foreman/detailer direction, employer policy, and AHJ/code requirements.