Apprentice answer

Why is a 45-degree entry bad right at a VAV inlet

3rd YearVAVs, Fan Coils & Equipment ConnectionsCheck first

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

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Plain-English answer

A VAV box reads airflow through an internal sensor array. If the air enters at a hard angle or immediately after a short offset, the sensor can see swirl instead of a stable velocity profile.

Check the inlet connection, straight run, flex/round transition, and obstructions. The recovery is usually a straighter rigid inlet spool, revised offset before the straight section, or detailer/TAB-approved connection.

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?

Verify before acting

Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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