Q & A

Welcome to the Planet Natural Garden Forum! Whether you’re new to gardening or have been at it for some time, here you can search existing messages for answers to your questions or post a new message for others to reply to. If this is your first visit, please read over our forum instructions carefully before posting. Enjoy!

This topic contains 1 reply, has 2 voices, and was last updated by  E. Vinje 2 years ago.

  • Fan efficiency (CFM loss) due to ducting

    Created by Bill on August 15, 2016 at 7:01 am

    Hello,

    I’m trying to size my ventilation system using inline fans such as the Vortex. Is there a table or rule of thumb for CFM loss through ducting? I would be interested in these values for 4″, 6″ and 8″ duct diameter. I may have longer runs, so this will be important.

    Thanks for your help.

  • Author
    Posts
  • August 15, 2016 at 8:28 am #207549 Reply

    E. Vinje
    Keymaster

    Hi Bill –

    Great question. When setting up a ventilation system we typically figure a 7% loss in CFM for every 25 ft. when using flexible ducting (a 3% loss if using metal duct pipe). You should also factor a 3% loss for every 90 degree bend in your ductwork. Keep in mind that these are ballpark numbers — each system is unique and actual numbers may vary.

    The following post should also help:

    In-line fan, filter & vented reflector

    Good luck!

  • Author
    Posts

You must be logged in to reply to this topic.