Bypass Theory

As Zone Dampers open and close, static pressure in the supply trunk can vary tremendously. Increasing static pressure increases air velocity and high velocity air can create objectionable air noise. Bypass is a technique used to maintain static pressure within acceptable limits. A trunk with a control damper is added between the supply and return. This provides an alternate path for some of the air if several supply dampers are closed.

Bypasses should be designed to be as small as possible. Bypassed air is already conditioned therefore it interferes with heat transfer.

Bypass Damper Solutions

Young Regulator offers two bypass damper solutions:

    • The Barometric Counter-Balanced Damper –  provides a weighted arm to balance static pressure. When zone dampers close and pressure increases to the point where it can overcome the weight of the counterweight, the damper will start to open. Barometric dampers are typically effective up to about 0.25″ wc supply pressure.


  • The Electronic Bypass Damper – provides a finer level of control over a wider range of pressures. There is an on-board pressure switch to monitor static pressure. This modulates a damper to maintain particular set-point. Round dampers feature an elliptical blade that provides a more proportional response.


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