Apprentice answer

Do I need to internally line the first 10 feet of duct leaving the VAV box

2nd YearVAVs, Fan Coils & Equipment ConnectionsCheck first

Yes, if specified by the engineer. This is standard practice in commercial design to deaden the acoustic air velocity noise and the metallic sound of the VAV damper blades opening and closing before the air reaches the occupied office spaces.

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Plain-English answer

Field checklist

Yes, if specified by the engineer. This is standard practice in commercial design to deaden the acoustic air velocity noise and the metallic sound of the VAV damper blades opening and...

Ask Foreman

Hey boss, I’m checking vavs & fan coils: Do I need to internally line the first 10 feet of duct leaving the VAV box? I found the likely issue and want to verify the next step before I lock it in. Do you want me to adjust it now or check the drawing/detail first?

Verify before acting

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

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