Replies

1. 
   jonblakemore | Feb 13, 2009 09:14am | #1

   You will restrict the flow. That may or may not be a problem.

    

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   RappahannockINC.com Fredericksburg, VA

1. 
   calvin | Feb 13, 2009 02:15pm | #2

   Jon, with the same c.i.'s is there a reduction?

   I've seen several installs where they run up a 2x4 wall using the oval 6.A Great Place for Information, Comraderie, and a Sucker Punch.

   Remodeling Contractor just outside the Glass City.

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1. 
   danski0224 | Feb 13, 2009 03:48pm | #3

   The oval and round duct may have the same area, but the oval duct has a higher friction rate due to the aspect ratio.

   Round duct is the best for airflow, square is next.

   Your 6" oval is roughly 7.5" x 3.5", which yields an aspect ratio (length/width) of 2.14 : 1 (round or square is 1 : 1).

   The 6" oval pipe will flow the equivalent of a 5" round duct in the standard residential environment... less if the crimps go against the direction of flow. Don't forget about the tape on the joints. Oval fittings add more restriction.

   Oval duct is used in walls because that is the only thing that fits, not because it is the best choice.

1. 
   HammerHarry | Feb 13, 2009 05:19pm | #4

   A 6" oval will not have the same area as a 6" round, but it's not likely much of an issue...depending on how flat the oval is, of course.

2. 
   Piffin | Feb 13, 2009 06:51pm | #5

   flow of a 8" oval is closer to same flow as a 6" round

    

    

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3. 
   Tim | Feb 17, 2009 10:11pm | #6

   That depends on how much air needs to pass through it. 6" oval is equivalent to a 4" round.

   If you need the full capacity of the 6" round, a 3-1/4 x 10 is a true equivalent in resistence to air flow.

1. 
   pete123 | Feb 18, 2009 05:54pm | #7

   Thanks all