Cold Air Return....

Discussion in 'HVAC Heating & Cooling' started by mcnauge, Jan 20, 2010.

  1. mcnauge

    mcnauge New Member

    Jan 9, 2010
    Ontario, Canada
    Hello all,

    Here is my problem.

    I have a 2 story house and half of it (yes the in-sun side) get warm very quickly and stays warm and the 2 rooms on the other side are always much cooler (the doors on those rooms are usually closed). So i checked out all the ducts and traced how they got from the furnace to the vent and found that in each room (1 cold air return each) that the one 5" duct was very long and when the fan is on you can feel a little but or air movement, and the other isn't connected to a duct at all, just down through the wall and then an opening in the basement...soooo the questions are:

    1) Can i just connect ductwork to the hole in the basement and then to the return trunk line (this will be very hard to do as the hole it right above one of the I-beams)
    2) Can i cut a new vent into the wall (the 2 rooms would then be using the same duct line just on opposite sides of the wall) and then drywall over the old vent. (i don't know if a 5" duct can handle the air required for those 2 rooms). PS: i don't mind puting an inline fan booster in that duct to compensate.

    Any other suggustions would also be greatly appreciated.

    Thanks in advance

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    What size are the ducts feeding into those rooms?

    Unless the ducts are very leaky, the vent that terminates in the basement isn't doing much. If there is a return duct in the hallway and there's room underneath the closed doorway, some will go that route.

    If you have any dampers on the supply ducts, you could try slightly closing the feed to the rooms that are hot and making sure those to the cold rooms are fully opened.

    Having a common wall return duct will work somewhat, but not as effective as individual ones. It will also enable a passageway for sound from one room to the other.
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  4. mcnauge

    mcnauge New Member

    Jan 9, 2010
    Ontario, Canada
    The supply duct for the 2 rooms in question are 5" round duct once they come off of the trunk line. I am going to be taping all the connections, but before i do that I think a couple of them need to be moved as 1 of the duct lines is seems very long and take a wierd route. I do have dampners on the supply ducts to the other rooms and they have been partially closed along with the registers too. One of the problems is that that door needs to be shut most of the time because thats the pet room when i'm at work, so i need to keep it shut and fit the problem.

    The only 2 options i have are to either connect the in-wall path to the return lines or to connect it to the other rooms. I think i would rather just "activate" the existing vent. Also there are no other returns that go near that room... so the question is now is:

    Can i connect this "hole" into a new section of 5" duct and then use a Y connection to attach it to the system, or should i connect the new 5" duct directly to the main retangular return duct.

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