In a forced-air system, velocity pressure is the ________________.

In a forced-air system, velocity pressure is defined as the difference between the total pressure and the static pressure. This relationship is crucial in understanding how air moves through the system. Total pressure encompasses both the static pressure (the pressure of the air at rest) and the dynamic pressure (or velocity pressure), which is created by the movement of air in the ductwork.

To elaborate, when air is forced through ducts by a fan or blower, it creates a pressure that can be measured. The total pressure includes the pressure exerted by the air at its current velocity, while the static pressure represents the pressure exerted equally in all directions at a specific point in the duct. By subtracting static pressure from total pressure, you isolate the velocity pressure, which indicates how much pressure is associated with the movement of the air.

Understanding this concept helps HVAC professionals accurately analyze and design air distribution systems, ensuring sufficient airflow for heating, cooling, and ventilation needs. Velocity pressure is an essential component in calculations related to the system's efficiency and performance.