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  1. #1
    Join Date
    Apr 2009
    Posts
    19

    Default Supply and Return in older home

    My neighbor has an older home (1920s). The supply ducts are located on the inside walls, and returns on the outside walls. From my inspections, there is one return and one supply in each room, including the kitchen. Each is a 9" metal duct.

    My question is, would it be possible to reverse the supply and returns, and would this improve heating? Also, there are no dampers. It would be possible to add dampers to each supply in order to balance the system a little better.

    Any advice would be appreciated.

    Brian

  2. #2
    Join Date
    May 2011
    Posts
    251

    Default Re: Supply and Return in older home

    Just flip the furnace upside down. j/k

    If nothing else, having shorter return runs is better than supply runs if all the ductwork is the same size. You need more return duct in terms of total area, than supply.

    In cold climates it's beneficial to supply heat at the perimeter of the home where the heat loss and gain occurs. It reduces the feeling of drafts and better mixes the air at the point where the air is coldest.

    Now, is it worth spending the money to modify the ductwork? I think on a old home, you could put in on a list of things to improve, but it wouldn't be near the top.

    Probably something worth changing when the unit gets replaced or upgraded.


    The next question is whether or not the ductwork sized adequately and before that, if the furnace is sized correctly.

    For example, before 1930, it was common to leave a few windows cracked partly open all winter for fresh air. Following the Flu pandemic, it was believed that fresh air in winter could help prevent getting sick. The boilers or furnaces at the time were sized accordingly.
    1925 Two-Story Stucco Beaux Arts Neoclassical

  3. #3
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Supply and Return in older home

    Supplies should always be put on the cold wall (for heat) so they are backwards and yes you can install dampers. Always damper the supplies, never on the return. All joking aside if the ductwork is the same on supplies as returns and you have a multi positional furnace or A/C, it may be feasable or even easier to reverse the furnace , as motoguy states

  4. #4
    Join Date
    May 2011
    Posts
    251

    Default Re: Supply and Return in older home

    That's a good point... on some furnaces it is possbile to mount to blower in several positions, so you could reverse the airflow. However, you'd have to relocate the evap. coil as well.
    1925 Two-Story Stucco Beaux Arts Neoclassical

  5. #5
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Supply and Return in older home

    No, not change the blower pos, change the furnace pos, if it is multi positional

  6. #6
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Supply and Return in older home

    Quote Originally Posted by motoguy128 View Post
    That's a good point... on some furnaces it is possbile to mount to blower in several positions, so you could reverse the airflow. However, you'd have to relocate the evap. coil as well.
    You can't reverse the airflow on the furnace.

    It was very common in older homes to have the return vent located under the window -- the supply vents on interior walls.
    As the years went by , closer studies from building scientists found the opposite arrangement was more benifical for comfort and efficiency.
    "" an ounce of perception -- a pound of obscure "
    - Rush

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