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Apprentice answer

How do I transition from rectangular duct to the round inlet of a VAV

2nd YearVAVs, Fan Coils & Equipment ConnectionsCheck first

Use a factory-built or shop-fabricated square-to-round transition fitting. * Ensure the angle of the transition slope does not exceed 30^\circ (per SMACNA guidelines) to prevent excessive static pressure drops and turbulent air noise right before it hits the box sensor.

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Plain-English answer

Use a factory-built or shop-fabricated square-to-round transition fitting. * Ensure the angle of the transition slope does not exceed 30^\circ (per SMACNA guidelines) to prevent excessive static pressure drops and turbulent air noise right before it hits the box sensor.

Field checklist

Ask Foreman

Hey boss, I’m checking vavs & fan coils: How do I transition from rectangular duct to the round inlet of a VAV? 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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