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  1. #1
    Join Date
    Dec 2019
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    HVAC for basement

    Hello, I am about to finish my unfinished basement and had a few questions regarding the HVAC situation. Before finishing and sheetrocking the basement, I plan to zone the first floor and second floor with honeywell zone dampers, bypass and etc. So when I finish the basement, can I add a few supply ducts, return ducts, and dampers and now make it a 3 zone, or does that throw off the balance? My friend who just recently finished his basement got a ductless mini split system but Im not a big fan. Thank you

  2. #2
    Join Date
    Jun 2014
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    Dover, DE
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    Minisplit.
    Basements are a much different environment then the rest of the home.
    And you can’t just slap dampers one existing duct and call it zoned. The duct must be designed for such a system.
    Minisplit can easily handle a basement space. If your not a fan of the wall mount mini get a ducted model.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

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  3. #3
    Join Date
    May 2018
    Location
    Elizabethtown, PA
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    Why are you not a fan of the minisplit? That is my suggestion as well.

    If the existing conditioned area is reasonably balanced, I wouldn't consider zoning. I am not a fan of bypasses. I would never design a system using one.

    Do a ducted minisplit if the appearance of the head is the issue.

  4. #4
    Join Date
    Jun 2003
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    Madison, WI/Cape Coral, FL
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    Most deep basements in green grass climates need a good dehumidifier more than an a/c.
    What is your climate. Basements are a little on the cool side unless you have high activity.
    I would duct in a small whole house dehumidifier with the fresh air ventilation option. With all of the walls sealed, plan a fresh air change in 4-5 hours to purge indoor pollutants and renew oxygen. The dehu will also maintain <50%RH plus add a few degrees of heat.
    KEEP us posted and the location.
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    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
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  5. #5
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Get a Dehumidifier and the smallest Mini needed!

    Zoning the existing equipment is not a good idea.

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  7. #6
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
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    OP,you plan on zoning(2)a pre-existing ducted 1 zone system? And you thought about adding a 3rd zone? Within reason here,how many compressors are you planing to replace?

  8. #7
    Join Date
    Dec 2019
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    Thread Starter
    Thank you for all the reply. The reason why I originally wanted to zone the house is because my main level and second level temperature can vary greatly, so I figured I could fix this by zoning and installing a bypass. The several reasons why I wanted to add ducts and dampers was because I thought the installation of adding ducts was easier than installing a mini duct plus since Im putting a bathroom, i can add a duct in that room whereas a mini split is only one unit for the entire basement.

  9. #8
    Join Date
    May 2018
    Location
    Elizabethtown, PA
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    Bypasses increase airflow across the coil but at a much reduced temperature. It's not a good way to go. Zoning can be done but dampers and a bypass is not the way to do it.

    A ducted minisplit can be used to service multiple rooms. Care must just be taken in the duct design to meet static pressure requirements.

  10. #9
    Join Date
    Jan 2004
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    PA
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    Moved to AOP.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  11. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Depending upon ducts, you still can short cycle the equipment on limits with 1 zone calling. WORSE if a 3 zone and 1 zone is calling. Bypass lowers the air noise when 1 zone is calling but dumps hot or cold air in the return which does nothing to avoid the short cycling. Every decent zone panel has a limit and you want that limit to protect the equipment. The limit in the furnace can often stick open if it overheats very often. That won't happen with the zone panels limit but still you could have very short run times. In the summer, same thing. The zone panel's limit protects against freezing of the coil but if you have so little air moving that it gets too cold, the panel shuts it off.

    One solution is a panel by Jackson Systems, AKA IO Controls that have dampers that will throttle the non calling zone open a bit to relieve the excess air into the house, not the return air. Really slick system. Avoids the short cycling though does put air into a zone that is not asking for it. We have 3 out there so far and no problems. One was replacement of a 4 zone system, one was 2 zone remodel and one was zoning an existing house.

    https://jacksonsystems.com/products/...-required.html

    Mini splits are nice for heating & cooling an area like basement or sunroom but we tend to get complaints in the summer about poor dehumidification.

  12. #11
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Quote Originally Posted by BaldLoonie View Post

    Mini splits are nice for heating & cooling an area like basement or sunroom but we tend to get complaints in the summer about poor dehumidification.
    That's the need for a dehumidifier and the smallest mini!

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