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How do you do U-Values???

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  • 18-03-2010 10:37pm
    #1
    user12
    Registered Users Posts: 115 ✭✭


    Any help at all??


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    #2
    Crow92
    Registered Users Posts: 1,017 ✭✭✭Crow92


    You need to find the resistance of each material,(sometimes it is given)

    You will need these two formulas,

    Conductivity/Thickness = Resistance, K/T=R

    and

    Thickness x Resistivity = Resistance, Txr=R

    *Don't forget to add in the resistance of the surface area of internal/exteral

    Add together all the resistance and then This formula gets you the U-Value


    1/Total resistance= U-Value.


    *If it's for a new housing within regulations the U-Value is supposed to be under 0.27 but that's not always right.

    Hope it helps


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    #3
    user12
    Registered Users Posts: 115 ✭✭user12


    Crow92 wrote: »
    You need to find the resistance of each material,(sometimes it is given)

    You will need these two formulas,

    Conductivity/Thickness = Resistance, K/T=R

    and

    Thickness x Resistivity = Resistance, Txr=R

    *Don't forget to add in the resistance of the surface area of internal/exteral

    Add together all the resistance and then This formula gets you the U-Value


    1/Total resistance= U-Value.


    *If it's for a new housing within regulations the U-Value is supposed to be under 0.27 but that's not always right.

    Hope it helps

    Im sorry but am lost!!...whats up with the small and big letters?


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    #4
    Crow92
    Registered Users Posts: 1,017 ✭✭✭Crow92


    K=Conductivity

    Small r = Resistivity

    T = Thickness

    big R = resistance

    Your gotta make a box with all the materials and all thoses above^^^^ as headings.

    Dunno how else to exlain it but thats how you do it,


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    #5
    user12
    Registered Users Posts: 115 ✭✭user12


    Crow92 wrote: »
    K=Conductivity

    Small r = Resistivity

    T = Thickness

    big R = resistance

    Your gotta make a box with all the materials and all thoses above^^^^ as headings.

    Dunno how else to exlain it but thats how you do it,

    Ok im kinda getting it now thanks!!!...see the formulas,dya multiply or divide>>
    lost there


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    #6
    Smcgie
    Registered Users Posts: 1,379 ✭✭✭Smcgie


    Info here:

    Linky


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    #7
    Crow92
    Registered Users Posts: 1,017 ✭✭✭Crow92


    where i wrote 'x' you multiply
    where i wrote '/' you divide

    the goal is to use one of the formula's to get the resistance of Everything and then to divide

    1/ total resistance,

    hope that helps


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    #8
    Crow92
    Registered Users Posts: 1,017 ✭✭✭Crow92


    Smcgie wrote: »
    Info here:

    Linky

    The info is too broad and so much extra than what you need to deal with :rolleyes:


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    #9
    user12
    Registered Users Posts: 115 ✭✭user12


    Crow92 wrote: »
    where i wrote 'x' you multiply
    where i wrote '/' you divide

    the goal is to use one of the formula's to get the resistance of Everything and then to divide

    1/ total resistance,

    hope that helps

    ok say the conductivity was 1.430 and the thickness was 0.012.and i divide 1.430 by .012 and get 119.16666667
    but the answer is .00839??
    what am i doin wrong


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