In duct calculations, what is the first step when measuring cross-sectional area?

When measuring cross-sectional area in duct calculations, the first step is to multiply the dimensions of the duct. This involves taking the width and height measurements of a rectangular duct or measuring the diameter for a circular duct. The product of these dimensions will give you the area in square units, which is essential for determining airflow and ensuring appropriate system design.

Multiplying the dimensions is crucial because it provides the fundamental area measurement needed for further calculations, such as airflow rate and velocity. Once the area is known, it can be used in various formulas to assess system performance and to make adjustments as necessary.

Converting to square feet, calculating air velocity, and aerodynamic testing follow after calculating the cross-sectional area and serve different purposes in the overall design and analysis process. These steps generally rely on the area measurement to provide accurate and efficient results in HVAC calculations.