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  1. #1

    No Return Duct for Basement Finish?

    I am in the process of finishing my basment, and have decided that the HVAC (among a few other things) is one of the tasks that I want to leave to those with the proper tools and know-how. However, the one contractor that showed up to quote the work told me that a return duct was not necessary in the basement. I'm hesitant to believe him - the first and second stories in my house each have them, and it would only make sense to me that balancing the pressure from the three additional vents that I'm adding would be necessary by adding at least one additional return. Who's right?

    The basement is approximately 500 sf and will have one bedroom (~120 sf), one bath (~80 sf), and an open game room (~300 sf).

  2. #2
    Join Date
    Feb 2004
    Posts
    2,597
    Can your existing system handle the airflow loss you will create by adding three supply's? If it was originally sized and designed for what is there now, you will be stealing air from your existing supply's reducing comfort overall.

    As for a basement return, I would recommend it (with a damper) to remove moisture settling there.

  3. #3
    Join Date
    Dec 2007
    Location
    Afton, VA / Khorat, Thailand
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    2,469
    Quote Originally Posted by billva View Post
    Can your existing system handle the airflow loss you will create by adding three supply's? If it was originally sized and designed for what is there now, you will be stealing air from your existing supply's reducing comfort overall.

    As for a basement return, I would recommend it (with a damper) to remove moisture settling there.
    Yes, agreed.
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  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,085
    most likely your short of return already. So yes you want a return.
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  5. #5
    Thank you for your input. Without doing a load balance, I can't say that the existing system will be able to handle the loss of three supplies that will be added. The contractor said that as long as the doors leading upstairs are undercut sufficiently, it would be fine, but that just doesn't make sense to me.

    Considering that it's in a basement, would you think that it's better to put the return register closer to the floor or the ceiling? Ceiling would be easier, but I'd rather have it done right!

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,085
    If your using standard supply registers in the basement ceilng, then I prefer to have a low return for the winter.
    Cooling a basement is easy. Dehumidifing it, and heating it are the hard part.
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  7. #7
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    Where are you located? When we size a house with a basement we always include the basement. It dosn't add much to the load at all and many around here finish them withen the first few years. Make sure the contractor checks the ductwork for sizing.

    You would always want to put at least 1 return or more in the basement. Even with a return the basement will always be a little cooler in the winter. If you want the same temperature as upstairs you may look into zoning it.
    Its a good Life!

  8. #8
    I'm in the Denver area. The house is only about 4 years old, and I was told that the HVAC system was sized for the entire house, including the basement. The 1st and 2nd levels are approximately 2000 sf, and the basement is about 500 sf. The A/C was put in later and is a 3 1/2 ton unit, which I was told should be sufficient for that size, without doing a test to make sure.

    As for the temperature variation between basement and upstairs, I figured it would be cooler downstairs - I've already got an individual room heater in anticipation of that!

  9. #9
    Join Date
    Jun 2008
    Location
    Buffalo ny
    Posts
    8
    You always want to equalize the supply and returns. If you don't have return air from the basement you will do two things. The 1st floor will probably have more return than supply, removing too much air. Then the 2nd floor probably not have enough return air. What goes in must come out. If you have a chance to do it correctly the first time, do it. Make sure they put in volume dampers to balance the returns.

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