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  1. #1
    Join Date
    Sep 2007
    Location
    State College, PA
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    Where is my air?

    Have a customer with a 4 ton LP & A/C. Complaint was not enough air flow in basement. Furnace in basement blower set to high. 3300 square feet equal between firs fllor and basement built in 2005. One story and basement. Filter is new (4" Merv 8) and cleaned blower wheel which was not too bad but getting desperate on what is going on. Even pulled the filter and left cover off with almost no change. He had the ducts cleaned hoping that would solve the problem. I am the third contractor to look at this. No one else had a solution.

    There are some high ceilings, mostly 9' and some cathedral ceilings that go up to maybe 15'. All flex duct is 6" and there are 17 supply ducts and lots of returns in all rooms, including basement.

    Return static: .35 in w/c
    Supply static: .15 in w/c

    Any ideas on what to look for next?
    Can someone please explain to me -
    Why is there never enough time to do it right the first time, but plenty of time to do it twice?


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  2. #2
    Join Date
    Jun 2017
    Location
    Missouri
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    195
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    Quote Originally Posted by joemach View Post
    Have a customer with a 4 ton LP & A/C. Complaint was not enough air flow in basement. Furnace in basement blower set to high. 3300 square feet equal between firs fllor and basement built in 2005. One story and basement. Filter is new (4" Merv 8) and cleaned blower wheel which was not too bad but getting desperate on what is going on. Even pulled the filter and left cover off with almost no change. He had the ducts cleaned hoping that would solve the problem. I am the third contractor to look at this. No one else had a solution.

    There are some high ceilings, mostly 9' and some cathedral ceilings that go up to maybe 15'. All flex duct is 6" and there are 17 supply ducts and lots of returns in all rooms, including basement.

    Return static: .35 in w/c
    Supply static: .15 in w/c

    Any ideas on what to look for next?
    Has it ever worked correctly?

  3. Likes DavidDeBord, TrevD liked this post.
  4. #3
    Join Date
    Dec 2004
    Location
    Chicago area
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    The basement was probably a remodel/afterthought.

    And likely the hvac was never really properly reworked for the basement.

    Either redesign the ductwork, which may have ill effects on the main floor, or put in a dedicated for the basement system of some kind.


    Sent from my iPhone using Tapatalk

  5. #4
    Join Date
    Dec 2004
    Location
    Chicago area
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    Where were the static pressures taken? Be precise.


    Sent from my iPhone using Tapatalk

  6. Likes DavidDeBord liked this post.
  7. #5
    Join Date
    Jun 2012
    Location
    Northern NV
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    Open ceiling or drywalled in?

    Did the folks that finished the basement disconnect the ductwork or pinch it off with framing? I've seen that before.

  8. Likes DavidDeBord liked this post.
  9. #6
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    My bet the air is lost to filter static. I have never seen a residential unit with a 4" filter that wasn't short of air. Before you ask I have tested hundreds and probably over a thousand.

  10. Likes DavidDeBord liked this post.
  11. #7
    Join Date
    Jul 2012
    Location
    WA
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    Do you have access to a flow hood? Then you’d know where the air’s going and you can get pointed in the right direction.

  12. Likes DavidDeBord liked this post.
  13. #8
    Join Date
    Dec 2004
    Location
    Chicago area
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    Quote Originally Posted by WAYNE3298 View Post
    My bet the air is lost to filter static. I have never seen a residential unit with a 4" filter that wasn't short of air. Before you ask I have tested hundreds and probably over a thousand.
    You’ve probably never seen one sized or installed right either.


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  14. #9
    Join Date
    Mar 2018
    Location
    Maryland
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    I’d start by making sure there’s flow through each supply. No matter how little it may be. Like dollar bill test or even toilet paper test if it’s bad enough. That’ll tell you if something was disconnected in the drywall, or if the airtight damper is just restricting it.
    Also you said the fan is set to “high” do you have any kind of cfm for that? If “high” is somewhere around 1600 that would be (roughly) 94 cfm per line with ~ .1 static on helix wire flex. Your right in that range. I’m with heatingman. Your probably gonna have to damper down the main floor to get more air to that basement. See if there’s a bathroom you can close off. No one likes to be cold while there in the shower or on the toilet anyways.
    Also if it is LEAKAGE and NOT a disconnected line or just poor flex installation I’ve used Aeroseal with ALOT of success. I’ve dropped leakage from 450cfm to 15cfm in less than a 30 minutes sealing event. And seen (a few times) rooms that never heated or cooled all the sudden get the air they were designed for.

  15. #10
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    I have a theory. But before I spew what some call BS I have one question about the flex - do you have lots of long runs? (over 25 feet)

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  17. #11
    Join Date
    Jan 2012
    Location
    Broomall, PA
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    All 6" flex? Wasn't upsized?
    If I do a job in 30 minutes it's because I spent 30 years learning how to do that in 30 minutes. You owe me for the years, not the minutes.

  18. Likes HVAC_Marc, DavidDeBord, joemach liked this post.
  19. #12
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    I think Steve is going where I am, also

  20. #13
    Join Date
    Mar 2013
    Location
    Treasure coast, FL
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    Quote Originally Posted by HVAC_Marc View Post
    I have a theory. But before I spew what some call BS I have one question about the flex - do you have lots of long runs? (over 25 feet)
    I would like to hear your spewage.

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