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Edge Loss

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John T_2
John T_2 Member Posts: 54
in THE MAIN WALL
edge loss of a slab. Slab is above grade so edge loss will be significant. How would I go about putting a number to it?
Looking in manual J there are values for slab on grade and a slab containing perimeter warm air ducts. The td as indicated in the manual J table would be the indoor air - outdoor air td. How would I figure a radiant heated slab? The slab is 12" and exposed along the entire perimiter of the structure with no insulation. The exterior walls are masonry, and of course are in contact with the slab. I need to estimate how many btu's will be lost to the exterior.

Any help will be greatly appreciated.

John

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  • John T_2
    John T_2 Member Posts: 54
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    Found the formula

  • John T_2
    John T_2 Member Posts: 54
    Options
    Found the formula

    but of course I need to know the exposed surface in square feet. The 12" deep slab which extends directly to the exterior will also conduct to the walls above and below in which it's in contact with. Use just the 12" of depth x the perimiter, or should I be including a portion of the wall above and below it? These walls have been included in a complete heat loss but I'm trying to calculate the loss of the much warmer and more exposed radiant slab. Any thoughts? Am I over-complicating this?
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