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  1. #1
    Join Date
    May 2005
    Posts
    2
    I have one room that is getting very little air off the main unit. It currently has a 6" flexible duct. I would like to increase the flow by reducting with rigid duct. The question is: Would I be any better off, or should I change the size of the duct? Increasing to an 8" would seem to help move more volume, or should it be smaller to increase the pressure of the air flow? I am also going to insert a blower fan that triggers off the main unit fan relay. Any suggestions?

  2. #2
    Join Date
    Dec 2002
    Posts
    174

    is there...

    ...a damper on the start collar that is closed? Is there a means for return air frome the room? Where is the 6" tied in, on a wye or triangle?
    need more info

  3. #3
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    How long of 6" duct?
    Where is it tied to wye/or plenum.
    What size room? Windows/number.
    Is there a return air close to this room?


    Don't really like duct boosters they never work well.
    Return would help in the problem room..

    Air Conditioning ,the removal of heat/humidity from a conditioned space with air changes per/hour.
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  4. #4
    Join Date
    May 2005
    Posts
    2
    The room is a 12x12 bedroom with one 30" window. The duct comes directly off the main unit and runs about 27 feet. There is no return air in that room and the closest return is in the hallway outside the room 25 feet away.

  5. #5
    Join Date
    Nov 2004
    Location
    Naples, Fla.
    Posts
    1,403
    Installing a larger duct wo'nt solve all your problems, you've got to remember your system will only supply X air volume @ a given pressure. Installing a lager duct will only rob air from other areas unless the the main trunk / plenum is under too high of pressure right now.

    FYI - even the mfgs of flex duct advise when you increase duct run 20+ ft you have to go up to next size duct due to friction loss.

    Adding returns is usually the key to better air circulation. Please have a lic. contractor inspect your system. Improper duct static and or poor design can prematurly destroy your system. A tech can evalaute blower spd, TTL static presure & give you good advice, yes, you'll pay for a service call & his time.

    Pls consider upgrading your air filtration system at the same time - ask for the Aprilaire 2200

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    It's likely that increasing it to an 8" flex will solve the problem.

    First check to see if it's a return air promblem.If the room cools fine with the door left open then the 6" is large enough,and you a "means" of letting air out of the room and back to the return.This can be a return duct,thru the wall,under the door,or jumper duct.


    If it doesn't cool with the door open ,the supply is too smalll or is restricted in some way.The entire duct system may be undersized,causing high static pressure(resistance) ,if so the longest run usually suffers the most air loss.

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