Page 1 of 2 12 LastLast
Results 1 to 13 of 14

Thread: Duct Size

  1. #1
    Join Date
    Feb 2006
    Posts
    4
    Well I'm back again kicking arround more ideas. The issue that I am trying address is that the house I am purchasing has the furnace in the center of the house and the duct work running across the floor joist is large enough that it makes the ceiling too low to get from one side of the basement to the other. I am looking for ideas on how to reduct the basement without loosing ceiling height. How do I figure out how big my ducts need to be, and are there any helpful hints that anyone has to offer?

    Thanks

  2. #2
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    18,050
    Your looking at it all wrong. Its not that the duct is too big..its because the floor is too high.
    To put the world in order, we must first put the nation in order; to put the nation in order, we must put the family in order; to put the family in order, we must cultivate our personal life; and to cultivate our personal life, we must first set our hearts right.
    -- Confucius

  3. #3
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    9' walls.

    Without them, you get low ducts. Period.

  4. #4
    Join Date
    Jan 2006
    Posts
    214
    you can always purchase a ductulator and an hvac contractor to reconfigure your duct system. thanks

  5. #5
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    18,050
    There is only one way to do it. You need to know how much cfm you need in each room and design your duct accordingly useing a .1 friction rate.
    To put the world in order, we must first put the nation in order; to put the nation in order, we must put the family in order; to put the family in order, we must cultivate our personal life; and to cultivate our personal life, we must first set our hearts right.
    -- Confucius

  6. #6
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    make the duct shorter and wider. you'll need a ductulator and someone who knows how to use it.
    FILL OUT YOUR PROFILE!!

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    Tear out the ducts, and furnace, and install a boiler.

    The copper is alot smaller then duct work.


    Ok, how much heigth are you trying to gain.

    You might not be able to make your duct as short as you would like.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Feb 2006
    Posts
    4
    There are two sections of the duct where I am trying to gain about 6 inches. The current main ducts are 18"by30". The areas I am trying to raise are at either end of the main duct. As I understand it, I need at least 6" ducts to feed each vent. I was wondering if I could simply cut the main ducts shorter, and break to individual runs earler? I realize that this will unbalance the system some, and that I'll have to control it at the vents. Does this sound like a reasonable solution?

    Thanks

  9. #9
    Join Date
    Jul 2005
    Posts
    717
    wow! ...30 x 18 mains.
    why not just close off the other 40 rooms and live in a small part of the basement

  10. #10
    Join Date
    Jan 2006
    Posts
    214
    what size furnace do you have down there?that supply trunk is way oversized for a residential application.call in an hvac contractor and have your duct properly sized and reconfigured.

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,311
    It may or may not work, as you increase the length of those 6" runs, you may decrease the flow.

    Can you take pics of the duct work, and post them. Also the brand an model of your furnace.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by coolwhip
    There is only one way to do it. You need to know how much cfm you need in each room and design your duct accordingly useing a .1 friction rate.

    .1 is just a rule of thumb,Have a Manual D( from http://www.acca.org ) ,duct sizing Calculation done to find the correct friction rate.

  13. #13
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    To reduce the 18" to 12",the 30" must increase to 50".


    Taking the branch runs off closer to the pleunum,would allow the trunk to be educed,may requie the 6' rounds to be 7 or 8"s.Really need that Manual D calculation.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event