“reverting” HVAC references (back to human readable)

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    Jonathan Chertok (Edited )

    i’ll kick it off.
    #6 is Total Heat Loss (through material):
    q [BTU/Hr] = U [BTU/Hr-ft^2 deg F] x A [ft^2] x Td [deg F]

    q = total heat loss

    U = overall coefficient of heat transmission

    A = area

    Td = temperature differential (inside to outside etcetera)

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    Jonathan Chertok (Edited )

    #5 is definition of “1 ton” of AC (which is basically a metric thing i think).

    #7. Definition of U Value (?) for a Wall Section (?)
    U [BTU/Hr-ft^2-degF] = 1 / Rt [BTU/Hr-ft^2-degF]
    Rt = resistance total

     

    AKA: U = 1 / Sum of R Values

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    Jonathan Chertok (Edited )

    what do i call #3? Rate of Sensible Heat or Gain due to Infiltration or Ventilation (?):
    q(u) [BTU/Hr] = V [CFM] x 1.08 x delta T [degF]
    q(u) or “q sub u” = heat loss
    V = volumetric flow rate of air (in cubic feet per minute). this is empirically rested and is provided as a given value.
    1.08 = is a constant

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    Jonathan Chertok

    # 8: Coefficient of Heat Transmission
    Uo [BTU/Hr-Ft^2-degF] = (Uw x Aw) + (Uop x Aop) / Ao
    all U are in BTU/Hr-Ft^2-degF and all A are in Ft^2
    Uo = overall coefficient of heat transmission (overall)
    Uw/Aw = coefficient of heat transmission or area for window
    Uo/Aop = coefficient of heat transmission or area for “opaque wall” (?)
    Ao = area of total wall

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    Jonathan Chertok

    #9:
    same as 8 but for an (opaque) roof and a skylight?
    Uo [BTU/Hr-Ft^2-degF] = (Ur x At) + (Us x As) / Ao
    definitions as above except r = roof and s = skylight

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    Jonathan Chertok (Edited )

    #4 Definiton of Kilowatt-Hour (metric thing):
    1 kWh = 3,400 BTU/Hr

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    Jonathan Chertok

    #10. Definition of R Value (or Resistance) (?)
    R [Hr-Ft^2-degF/BTU] = x [inches] / k [constant]
    R = Resistance or the hours needed for 1 BTU to pass a given thickness at a temp change of 1 degree Fahrenheit.
    x = material thickness
    note that “C” is Comsuctsnce which is basically k but for a specific material (leaving out the thickness. so R = 1/C and C = 1/R

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    Jonathan Chertok

    anyone able to proof that and help with #’s 1, 2, and 11...?!

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    Jonathan Chertok

    looks like i just need help with three before i can summarize this for everyone. any takers for 1, 2 and 11? 

    THANKS



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    Robin Tannenbaum

    Jonathan,

    These are helpful explanations.  Did you find any specific example problems to practice using these?

    Thanks,

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