How many 6" branch ducts can an air handler moving 800 CFM at 0.1" accommodate?

To determine how many 6" branch ducts an air handler moving 800 CFM at a pressure drop of 0.1" can accommodate, it's essential to understand the characteristics of 6" ductwork and how airflow interacts with it.

A 6" duct typically has a free area that can facilitate a certain amount of airflow. According to airflow tables for duct sizes, a 6" round duct can carry approximately 100 CFM at 0.1" pressure drop under ideal conditions. This estimation can vary slightly based on factors such as the length of the duct and the number of bends, but 100 CFM is a commonly accepted approximation used for size calculations in HVAC design.

To find out how many such ducts can handle the total airflow from the air handler:

1. Divide the total airflow (800 CFM) by the individual capacity of a 6" duct (approximately 100 CFM).

2. Performing the calculation: 800 CFM / 100 CFM per duct = 8 ducts.

However, considering practical limitations and adjustments in real-world installations, the flow might not be exactly 100 CFM per duct due to additional factors, leading to adjustments that suggest the number should be rounded down.