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  1. #1
    Join Date
    Dec 2005
    Posts
    4
    I'm looking for some help on cold air returns. I have an older home that has the cold air returns on the outside walls. The house has 1 bdrm down and 2 up. There is a C.A.R in each bedroom, one very large one in living room and one under kitchen cabinets. I haven't seen outside C.A.R.'s before and they seem to allow a lot of cold air into the rooms....when the furnace runs it feels like cool air is actually blowing out......and when furnace isn't running they feel very drafty.

    Is there anything I can do with these?? Seeing cold air drops, can I put an elbow type diffuser over these...will that even do anything? Looking for any advise.

    Thanks

  2. #2
    Join Date
    Apr 2004
    Posts
    7,680
    In the 50's, some pretty wacky stuff was done. I almost bought a home with a forced air furnace that had no supply or returns, the air blew through the walls, returned through the ceiling cavity and back down the iside walls.

    First off returns shouldnt be blowing anything so let us clarify. By return in this business, we talk about the air that is pulled in from the room and "returned" back to the furnace a Supply would be one that supplies conditioned air to the space. If we ae on the same page then there should be no air coming from a return.

    Also, if you are still talking returns, I would get rid of the one in the kitchen.

  3. #3
    Join Date
    Dec 2005
    Posts
    4

    Outside Wall Cold Air Returns

    Thank you for your reply....

    I realize the returns should not be 'blowing' any air, that the purpose of them is so the air forced into the room has a way to return to the furnace and get filtered.

    I now know the air is flowing in.....I held paper close by and it sucked to the grill.....I guess it just seemed to be coming out because I could feel 'coldness' and movement.

    I will block the kitchen return. But, is there anything that can be done with the others? It seems they are a good source of cool air entering the room as the floor is cold by them.

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,309
    Other then having your duct system replaced, no.

    My house is set up the same way. The floor will always be cold at the returns. And when the blower shuts off it will feel like a draft is going through the room. I tested my place and its not a draft, its just that the outside walls are cold.

    It bites just as much in the summer for A/C.

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  5. #5
    Join Date
    Sep 2003
    Posts
    1,311
    Have the ducts redone. C.A.R.s on the perimeter was for the old gravity furnaces.

  6. #6
    Join Date
    Apr 2004
    Posts
    7,680
    There is a an effect that most of us overcome by installing the supplies on the outside walls. I dont know what the term is off hand but maybe convection would be close.

    Warm room air contacts the cold wall and becomes cooler and heavy, dropping from the ceiling pretty rapidly to the floor level along the wall. This may be the draft you feel. By installing the supplies at the outside wall, we can effectively wash that wall. Without cooling the air below room temperature the air will not cool off and fall at the same rate which will eliminate that drafty feel.


  7. #7
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    besides, having conditioned air wash the exterior wall helps prevent unwanted heat transfer --

    sounds like someone did not want to pay to have the correct duct system installed with a new furnace --

    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  8. #8
    Join Date
    Sep 2002
    Posts
    4,970
    If you have the money to spend to change all the ductwork thats fine but the guys saying that it would be all that differant by going through everything as far as changing the heat runs to outside walls and gettig the returns to inside walls might want to try it themselves. I Know thats the way it is done nowdays but it didnt worl all that bad before. I dont care wether the runs are on outside wall or inside wall, it still stacks from the ceiling down. Yes I know its nice to be able to wash the walls with air but being these new units do so much better a job of keeping even temperatures then the old oversized units that were put in I dont buy that they will see that big of differance by changing all the ductwork as long as its the right size. You look at how everything on the new units has changed as far as as how hot the air coming out is and the amount of time the units run and you find you have way more even temperatures withe the new furnaces. Main thing I would make sure is that if you have returns on outside walls, that they have insullation on the wall where the return is so that its sucking the cold air off a bare wall. Ok you guys can flame me for my opinion but unless its an easy fix as far as it being a house with an unfinished basement where its easy to change or the owners thinking of majorly remodeling the whole house anyway I would even suggest changing the supply and return locations unless it need more.

  9. #9
    Join Date
    Dec 2005
    Posts
    4
    Thanks to all that replied. The house had a new furnace w/ central air added in '99. All the ductwork was also redone at that time, they just left the supply and returns in the same locations. it's just frustrating.....it's an older house and a pain to heat, it's always cold in here. Windows are caulked on the outside and rope caulk on the inside. 22 outside temp right now and the way the furnace runs you'd think it was -22.

    Thanks again for all the replies

  10. #10
    Join Date
    Sep 2002
    Posts
    4,970
    How deeply have you looked into how well insullated it is? do you know how well insullated the walls and ceiling are? If not better check.

  11. #11
    Join Date
    Dec 2005
    Posts
    4
    I haven't. Walls are plaster, not even sure how to check something like that. House is 1 1/2 story, so there are triangular 'crawlspaces' upstairs running the length of the house......there is no insulation in the ceiling joists there, but on the back walls of the bedrooms there is. One side has a small room I use a walk in closet and there are two openings to these crawlspaces.....I use the other side (full length) for storage. These areas get very cold and I bought insul. to put between joists...I'm hoping that helps. There is also Insulation in the attic...but it could use more....lots of old exposed wires up there (knob and tube I believe they call it) so I'm not too eager to go up there.

  12. #12
    Join Date
    Sep 2002
    Posts
    4,970
    Ya I would think you might want to have that knob a tube replaced befor you re-insulate the attic. Sounds like thats more a problem then the mechanical system.

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