If you’re in the process of planning a ducted heating or cooling system for your home, you may be wondering how to determine the right size for your needs. One key factor is CFM, or cubic feet per minute. This measures the volume of air that can be moved by a fan through a ductwork system in one minute. In general, the larger the space to be heated or cooled, the higher the CFM rating you’ll need.
For example, a small room like a bathroom might only require around 50 CFM, while a large living room could need 400 CFM or more. When it comes to 4 inch ducts specifically, they can typically move anywhere from 80 to 300 CFM of air. The exact amount will depend on factors like the length and layout of your ductwork as well as the power of your blower motor.
To find out precisely how much airflow you need for your home, it’s best to consult with a professional HVAC contractor who can help design a system that meets your specific needs.