Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Power Lost on Restriction in Ductwork

  1. May 5, 2010 #1

    I need a formula to calculate how much power is wasted on different types of air filters. A typical application is a residential central air ductwork. A typical pressure drop is 0.1-0.2 inch wg. Typical volume passing through filters is 700-2000 cfm. A typical filter size is 2-3 sq. ft.

    Your help is much appreciated in advance.


    This is not a homework. :smile:
    Last edited: May 5, 2010
  2. jcsd
  3. May 5, 2010 #2


    User Avatar

    Staff: Mentor

    Welcome to PF. The equation is:


    That's flow in CFM, dP in inches w.g. and efficiency of the fan. A typical good HVAC fan is about 65% efficient, so for example, 2000 CFM at 0.2" is 2000*.2/6356/.65=0.097hp
  4. May 5, 2010 #3

    Awesome. Thanks a lot.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook