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  1. #1
    Join Date
    Jun 2007
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    Adding Basement Ducting to Finish Daylight Basement

    Hello HVAC Experts-
    I'm currently finishing a Unfinished daylight basement and have access to the Main Trunk line for the Main Floor. I'm The Layout of the house is this way

    Top Level- 1000SF 1 Return
    Main Level - 710 SF 1 Return
    Basement - 670 SF 10 foot ceilings Unfinished No Return No Ducts.

    The house is ran with Flex Duct on that branch off the main trunk line. The size feeding the upstairs in 6 Inch with R8. I know the furnace was sized to heat the whole house because the city made them size it for the unfinised space.

    Questions -

    1.Should I Add a Return in the basement what are the pro/cons

    2. Can I follow the exact heating that they did on the main level 3 4x10 registers and run the flex line to match. Will i have any isuses here?

    4. Can i just cut a collar in and run them a few feet and go with it? How do you mount the register upside down on the joist?

    Last but not least I had a HVAC guy out and he wanted to cut the registers into the side of the trunk line that I'm going to Soffit. I rather not and run them to the end of the celing and have the register be on the ceiling. What are your thoughts.

    Thanks for all of your help;-)


  2. #2
    Join Date
    Jun 2004
    4H: Hot, Humid Houston H.O.
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    Quite a little time has gone by with no response from any pros. I think it would not hurt the board, to have a homeowner-to-homeowner reply. Especially as I try to consistently point out that the pros in the industry are the ones who have special knowledge and abilities which will be important to get the job right. Especially as in the past what I have said is intended to align with what the obviously talented pros say.

    But I won't say much, and it really would be wrong for me to give you the impression that I speak for any HVAC pro. There is a manual called "ACCA Manual D" for $XX which is pretty much the only way to get a duct design right. Without getting it right, you are likely to have inferior air distribution which will result in your being unsatisfied with heating and cooling.

    What this basement-free Texan would say, is you have a custom engineering job on your hands, and IMO you need to seek out one of the HVAC pros who is better than maybe 75% of them out there. I hope you appreciate the variety of things that can go wrong if you either DIY, or get a less qualified AC tech. Perhaps the complexity of your situation is a reason your question has not attracted more professional attention.

    Best of luck -- Pstu

  3. #3
    Join Date
    Sep 2005
    Atlanta GA area
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    My suggestion is zoning: That is, zone for main level and basement level. Otherwise, you will most likely end up with something called stratification; which basically means it will always be warm upstairs and cold downstairs, and you will not enjoy the basement space as much as you planned to.

    Now if this is a 2 story with a basement that is ALL on one system, then you will need to zone for 3 levels (up, main, and basement). This becomes even more important now. A note about zoning: When it is done correctly, the sizing of the A/C actually goes down a little.

    Now since I suggested zoning, I agree with the Houston HO that says to get a pro! Zoning is not something that many HVAC guys/gals understand. And if it is done incorrectly, it will shorten the life of the equipment as well as provide inferior results.

    The information about the ACCA books is also important!

    The gentleman said you have an 'engineering problem'. I agree, and suggest you get someone that can resolve this problem. The person does not need a degree and a PE certificate to do this, but they DO need to understand air flow and zoning.

    Best to you, and let us know how it works out!

    Your comfort, Your way, Everyday!

  4. #4
    Join Date
    Mar 2007
    West Palm Beach
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    Assuming your duct and unit are sized to cool/heat the basement, sidewall grills are a very good choice, by running duct in the ceiling you are limited to the room you have between it and the floor joists, however you can run up in between the joists aswell.
    The previous post regarding getting a pro to set you up correctly is your best bet because there are a lot of different ways to do this but not a lot of them are correct for your situation.

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