At what pressure should ducts be attached to prevent negative air pressure?

• A. Positive air pressure
• B. Neutral air pressure
• C. Negative air pressure
• D. Static pressure

Answer: (A)

Attaching ducts at positive air pressure is essential for maintaining proper airflow and preventing the issues associated with negative air pressure. When ducts operate under positive pressure, it helps ensure that air is effectively pushed through the system rather than being pulled in from the surrounding environment. This is particularly important for preventing backdrafts, which can introduce contaminants and reduce the efficiency of the HVAC system.

Positive air pressure within the ductwork enhances the distribution of conditioned air throughout the building, maintaining comfortable indoor environments. It also prevents moisture ingress, which can lead to mold and other air quality issues.

While neutral air pressure and static pressure may sound relevant, they do not provide the necessary force to maintain airflow and ensure that the system operates efficiently. Negative air pressure would inversely draw air from outside the ductwork, risking energy losses and compromising indoor air quality. Thus, maintaining ducts at a positive pressure is key to effective HVAC operations.