What is used to measure total resistance to airflow in a ductwork system?

The measurement of total resistance to airflow in a ductwork system is best determined by assessing the external static pressure at the air handler. This measurement provides insight into the pressure differential created by the airflow as it moves through the ducts. External static pressure represents the resistance that air encounters as it travels through the system, including losses caused by friction, bends in the duct, fittings, and any restrictions that might be present.

Understanding the external static pressure is critical for evaluating the performance of the HVAC system and ensuring that it is operating efficiently. If this pressure is too high, it indicates that air is having to work harder to move through the system, which could lead to decreased system performance and increased operational costs.

While other factors, such as internal static pressure or flow rate, are important in a comprehensive assessment of duct performance, external static pressure at the air handler specifically indicates the total external resistance faced by the system, making it the crucial measurement for this particular context.