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  1. #1
    Join Date
    Mar 2010
    Posts
    2

    Default heating return cut open

    My home is a tri-level ranch with cold air returns in various spots around the house. The furnace is in an unfinished basement section under the main living space. I just noticed the top of the return venting is completely opened in one joist opening. I can only think someone thought there was an issue with how much air was being returned to the furnace. I'm wondering if this negatively impacts how the system runs and is something I need to address. Any and all thoughts are much appreciated.

  2. #2
    Join Date
    Aug 2007
    Posts
    7,592

    Default Re: heating return cut open

    You want the conditioned air from the living space returning to the furnace, not unheated and probably rank air (unfinished basement ) from under the structure.

    Will it negatively effect? Well, the furnace and AC will have to work harder to heat/cool the house because it's not recycling living space air. You'll lose more of your conditioned air when doors are opened because the house is pressurized due to less air being drawn out of the house than blown in. I would recommend repairing the damaged section.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
    Join Date
    Jan 2010
    Posts
    163

    Default Re: heating return cut open

    Quote Originally Posted by darrmill View Post
    My home is a tri-level ranch with cold air returns in various spots around the house. The furnace is in an unfinished basement section under the main living space. I just noticed the top of the return venting is completely opened in one joist opening. I can only think someone thought there was an issue with how much air was being returned to the furnace. I'm wondering if this negatively impacts how the system runs and is something I need to address. Any and all thoughts are much appreciated.
    Before you close it off, look along the joist bay that it opens into. Look both ways along the joist bay, and see if there is an opening cut up thru the floor deck to allow return air to pass from a room above.

    If this is the case, the intention of the installer was to use the joist bay as a return air chase, or path, that would later be covered with drywall when the basement ceiling is finished, and you should not close off the hole in the top of the return duct.

    Until such time as the basement is finished, the return air from the room(s) above will simply float into the duct opening, and is an important part of the return air system.

  4. #4
    Join Date
    Mar 2010
    Posts
    2

    Default Re: heating return cut open

    Thanks for the feedback! The basement will remain unfinished. That opening may have been an intended or past return. It's a couple of feet from one that serves the same room it is under. Should I close it if it will never become a return? I don't like the idea, as the first responder mentioned, of burdening the furnace with dirtier air of a cooler temperature than the living spaces. But, I also don't want to suddenly suffocate the furnace. Thanks!

  5. #5
    Join Date
    Jan 2010
    Posts
    163

    Default Re: heating return cut open

    Quote Originally Posted by darrmill View Post
    Thanks for the feedback! The basement will remain unfinished. That opening may have been an intended or past return. It's a couple of feet from one that serves the same room it is under. Should I close it if it will never become a return? I don't like the idea, as the first responder mentioned, of burdening the furnace with dirtier air of a cooler temperature than the living spaces. But, I also don't want to suddenly suffocate the furnace. Thanks!
    That opening in the top of the duct is needed to return the air from the room above.

    If you want, you can enclose the space between the joists by covering the bottom with light gage sheet metal, and heading off the ends with more sheet metal or wood blocks. These heads would enclose the portion of the joist space between the opening from above to the back side of the return air duct that has the opening in the top.

  6. #6
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: heating return cut open

    If the return that's a couple feet away is ducted to the main return trunk and, has nothing to do with the opening that is on top of your return you may be able to close it off. But only if you have at least as much return air as supply, if you don't have enough return air your furnace will not be able to move enough heated air. This can cause your furnace to go off on high limit, it will also cause your blower motor to work harder than it should be and could over amp. Over amping can eventually burn out the blower motor. Do you have an A/C coil installed at the furnace, not moving enough air across the coil will cause the head pressure at your condenser to be to high. In the long run this will also put more wear and tear on your compressor as well as your Blower motor and will give you to high of a Delta T.

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