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duct work

ricK_10 Member Posts: 23
I am looking for some info on sizing ductwork .Raised ranch with mutiple additions with partial duct work and electric heat .I am going to install duct work in the basement with ac . Any good websites for info on sizing.


  • JimGPE_3
    JimGPE_3 Member Posts: 240
    Key component left out

    Once you know the airflow you will have in each trunk and branch, the sizing is easy. You just need something called a duct-o-lator, available from Carrier, Trane or ASHRAE. Put the "0.08"/100 ft" mark on the cfm and the slide rule thingy gives you the family of ducts that will carry that airflow at that pressure drop rate.

    The trick is knowing what airflows will be in each duct.... For that you need to know how to run a heat gain load and how to convert BTUH's to CFM's. If that sentence doesn't make sense to you, its time to hire a professional.
  • John Shea
    John Shea Member Posts: 247

    Do not forget that the return duct is always larger then the supply.
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