A 90-degree venting has an equivalent length of what?

In HVAC design and ductwork, the concept of equivalent length is used to account for the resistance that various fittings and turns impose on airflow. A 90-degree venting turn, for instance, causes turbulence and a loss of pressure that must be calculated into the overall duct length for proper sizing.

The standard equivalent length for a 90-degree elbow in ductwork is generally accepted to be around 10 feet. This figure can vary slightly based on the duct size and material, but 10 feet is a commonly used reference based on industry standards. This means that when calculating total duct length and airflow, the installation of a 90-degree elbow would equate to adding an additional 10 feet of straight duct to the system.

Understanding this concept is crucial for HVAC professionals to ensure that systems are designed efficiently and operate effectively, providing adequate airflow while maintaining system balance.