The RA damper D-3 modulates to maintain a pressure difference across which component?

The RA damper D-3 modulates to maintain a pressure difference across which component?

• A. D-4.
• B. D-2.
• C. D-5.
• D. The outdoor air damper.

Answer: (A)

Maintaining a controlled pressure difference across a downstream damper is a common way to stabilize airflow through that damper. The return-air damper modulates to set the back pressure so that the pressure drop across the damper downstream of it stays at a set point. This keeps the flow through that downstream damper predictable and prevents bypass or excess leakage as other pressures in the system change (such as outdoor air fraction or supply pressure). So the RA damper is used to hold the differential across the downstream damper, ensuring stable operation of that downstream component.

Maintaining a controlled pressure difference across a downstream damper is a common way to stabilize airflow through that damper. The return-air damper modulates to set the back pressure so that the pressure drop across the damper downstream of it stays at a set point. This keeps the flow through that downstream damper predictable and prevents bypass or excess leakage as other pressures in the system change (such as outdoor air fraction or supply pressure).

So the RA damper is used to hold the differential across the downstream damper, ensuring stable operation of that downstream component.