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  1. #1
    Join Date
    Feb 2001
    Posts
    445

    Question

    Is it true that an extended plenum can only run about 24' before it loses pressure? Is the same true for a reducing plenum?

  2. #2
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    one must consider the whole system! just like __ ton/sf! or hp/passenger
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  3. #3
    Join Date
    Sep 2004
    Location
    Memphis
    Posts
    2,502
    Originally posted by charles2
    Is it true that an extended plenum can only run about 24' before it loses pressure? Is the same true for a reducing plenum?
    I'm not sure what your really meaning by extended plenum. Are you wanting to add to your existing plenum? Plenums are usually around 2 ft if the furnace is in a basement or a attic, but a lot of furnaces around here are in closets in the hallway. These setups usually require a 5 ft plenum to get it above the ceiling joices enough to tie your duct on to. I dont think adding 2 ft to a plenum would ever be noticed.
    Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.

  4. #4
    Join Date
    Nov 2005
    Location
    USA
    Posts
    529
    I think this is what he is referring to.
    http://www.rhvactools.com/techinfo/t...tendplenum.htm
    The posts and comments made by me are in no way affiliated with any company or organization. They are simply my personal opinions.

  5. #5
    Join Date
    Jul 2005
    Posts
    717
    "extended plenums" have been around for perhaps than 40 years or more ( it was the method of choice in installing duct systems back in the 60's.)
    As far as the 24 Ft being the limit, any extra distance can be obtained by installation of a 'tapered' fitting in order to maintain cfm/fpm.
    See manual D

  6. #6
    Join Date
    Feb 2001
    Posts
    445

    Smile

    OK, thanks. You guys figured out what I was trying to ask.

  7. #7
    Join Date
    Sep 2004
    Location
    Memphis
    Posts
    2,502
    Ahhhh after seeing the pic that the estimator had a link to I see whatcha mean. We call the plenum whats going up right there. We always call the square duct coming off of it a "trunk line".
    Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.

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