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  1. #1
    Join Date
    Dec 2007
    Location
    chicago
    Posts
    249

    residential air flow

    Can anyone tell me how many cu in. I can get out of a 6" duct. The reason I'm asking is, I have a lack of airflow on the opposite end of my house. I have a 4 ton drive serving a two story at approx. 2800 sq. ft. thanks

  2. #2
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    no
    not enuf info
    how long?
    how many fittings? where are they?
    what type of fittings?
    joints & cracks sealed?
    what size trunk?
    what size plennum?
    how many other ducts?
    what size, etc?
    what size blower?
    etc, etc.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  3. #3
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    110 cfm if duct is sized right.
    "Go big or Go Home"

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    6" duct ,could be from 40 to 120 cfms,depends on the rest of the duct system.

    If space is available the duct system can be remediated,to correct any issues.Follow Man. D.

  5. #5
    Join Date
    Jan 2007
    Location
    in my lumpy chair
    Posts
    1,949
    calla pro to calculate and identify your problem
    I dont warranty Tinkeritus

  6. #6
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,274
    next AHU changeout .. go to a Variable Speed ( if not already done so)
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  7. #7
    Join Date
    Jan 2004
    Posts
    48
    Not a tough question, just too many variables..kind of like asking how much water can i get out of my 1/2" garden hose?
    Class of 70

  8. #8
    Join Date
    Dec 2007
    Location
    houston, texas
    Posts
    3,787
    2800sq ft with 4 tons of air , doesn't compute in Texas. Not enough information.

  9. #9
    Join Date
    Dec 2007
    Location
    MA
    Posts
    58
    Quote Originally Posted by Black Adder View Post
    110 cfm if duct is sized right.
    depending on the static pressure

  10. #10
    Join Date
    Sep 2002
    Location
    Boise Idaho
    Posts
    1,032
    Quote Originally Posted by Bruck View Post
    2800sq ft with 4 tons of air , doesn't compute in Texas. Not enough information.


    my house in boise, 2755 sq ft, 2-story with a 4-ton. Variable speed with 2 -stage (5-ton drive set at 350 cfm). Winter temp 0 and summer high 108. Strugles about three weeks a year upstairs and runs all day. Have a new 432 true zone on the work bench, just need the time to do it.


    matt

  11. #11
    Join Date
    Dec 2006
    Location
    Arkansas
    Posts
    292
    Quote Originally Posted by Bruck View Post
    2800sq ft with 4 tons of air , doesn't compute in Texas. Not enough information.
    You're correct, but only because you can't determine what size unit is needed for a given house size unless you have all of the information about the house. That goes for Texas or Alaska. I know of houses in Texas with 500-600 sf per ton and houses with 1000-1200 sf per ton. There are too many variables, but in most cases if the number turns out to be 500 sf/ton, it is probably too large. A load calculation is not sf/500. It involves a little more work.

  12. #12
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Just did a home that was 1300 sf per ton. I did the load 4 times before submitting to customer.

    Home had a 12-foot wrap around porch. No window load.
    Perhaps you should have read the instructions before calling.

  13. #13
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,274

    Cool

    Quote Originally Posted by tuckerin View Post
    Not a tough question, just too many variables..kind of like asking how much water can i get out of my 1/2" garden hose?
    3.46 GPM







    on an average day
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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