Static field route #19605

What do I do when a 45-degree branch enters directly into a VAV inlet and causes bad readings?

Equipment Connections: RTU, AHU, VAV, Fans & Louvers⚠️ CHECK BEFORE YOU FIXField answer expansion

📖 Verified core answer

A VAV inlet needs stable air entering the sensor area. An angled short entry can spin the air and make the box read wrong.

Open in Field Rescue Open category

Field verification checklist

Check if an elbow or 45 enters directly at the VAV collar.
Look for short flex or offset right at the inlet.
Confirm airflow arrow and sensor tubing are correct.
Ask TAB/foreman if readings are unstable.
Provide straight rigid inlet run where the project/detail requires it.

Ask foreman

VAV [number] has a 45-degree entry right at the inlet and TAB readings may be unstable. I checked the inlet path. Do you want a straight rigid spool added before the box?

Text to foreman

Route options

A Correct it only if the fix is within your assignment and approved method.

B Hold and document if it affects pressure class, listed assembly, material spec, support load path, fire barrier, equipment, TAB, or another trade.

C Bring the foreman/detailer the location, what you checked, and what decision you need before sealing, testing, cover, or startup.

Do not do this

Do not slam an angled fitting directly onto a VAV inlet and expect stable CFM readings.

Why this matters

Bad inlet geometry can make the VAV hunt, read wrong, or fail air balance.

Final verification

Use this as field training guidance. Final direction still comes from the foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, pressure/material schedule, and AHJ/code requirements.

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