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Adding Slab to existing concrete basement floor

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by I Stand Alone, Apr 1, 2010.

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  1. I Stand Alone

    I Stand Alone New Member

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    I am looking into storage options and thought for efficiency of space that a slab on top of my existing concrete floor may be an option. Ceiling height is not a problem and the basement is completely unfinished, ran out of money once the house was completely remodeled!

    Any suggestions on design. The floor is 28' x 36'

    Thanks

    I Stand Alone

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  2. webie

    webie Minister of Fire

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    I am confused ? What does adding a slab have to do with storage ?
  3. I Stand Alone

    I Stand Alone New Member

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    The concrete slab as storage. Using radiant tubing in the slab I could use it for storage. I have a econuburn 150 and need storage to stop the idling time
  4. webie

    webie Minister of Fire

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    The concept might be good but it wont work as you think it will . First I think my concrete guys said the max injection temperature I believe is 130 degrees , but the max I think I read that you should do is a 40 degree difference in slab actual temp verses water temp . My heating guy says for me to max out my mixer at 110 to be on the safe side . Using mass for storage really doesn't work as you have no control over it . Once it is hot you have no control over the heat dissipating from it . As far as radiant in slab it works because of the large surface area and continual heat out put . Your basement still will only require so many BTU's to heat all the slab does is buffer out the highs and the lows . Its not really designed for mass storage.
    If you have a large open basement why don't you put in a insulated storage tank so as to store excess heat for use later .
  5. Floydian

    Floydian Feeling the Heat

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    I agree with webie.

    Here are some quick numbers to think about:

    specific heat of concrete= .2 btus/lb/degree F

    28'x36'x4" slab=12 yds of concrete=48,000 lbs.
    48000x.2=9600 btus/degree F
    Assuming you'd be comfortable with a 10 degree F temp swing in the slab, that's 96,000 btus stored.

    specific heat of water=1 btu/lb/degree F

    250 gal. of water=2085 lbs or 2085 btus/degree F
    Assuming a 50 degree F delta T in the tank (180*-130*)=104,250 btus stored.

    NOTE: all numbers subject to error.

    A storage tank should come in far below the cost of a slab. If you could squeeze in 500 or more gallons of storage you could gain some convenience that the slab just cant really give you.

    Good luck,
    Noah
  6. Frozen Canuck

    Frozen Canuck Minister of Fire

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    North central Alberta, Canada
    Agree with the above advise. Think of a slab like a train, very slow to gain speed (heat) very slow to cool down. Storage will give you far more comfort & satisfaction at far less cost. It will also solve your idling issues provided you install enough.
  7. Reggie Dunlap

    Reggie Dunlap Feeling the Heat

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    Northern Vermont
    You said headroom isn't an issue, but you'll need at least 2 inches of foam under the slab for a total of 6 inches. At the very least you'll have to re-frame the stairs, and if there are any windows they are going to be pretty low.
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