TinnerFlow™3rd YearAirflow / TABYELLOW · Check First
A large first tap can rob the trunk if the branch is uncontrolled or the system was not balanced. Verify the print, branch damper/access, downstream starvation, and TAB direction before cutting in changes.
If the first branch near the unit pulls hard, the far end of the main can starve even when the duct is installed cleanly. The issue may be design, missing damper, damper left open, wrong tap, wrong VAV/branch, or TAB not complete.
Do not randomly choke a branch because it “seems like too much air.” First confirm the print, branch size, damper location, access, airflow complaint, and whether TAB/controls are involved. Likely recovery is adding or correcting an accessible balancing damper or getting TAB/detailer direction.
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.