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  1. #1
    Join Date
    Dec 2007
    Posts
    1

    Default Fire Rating On Drywall

    I recently installed a wood burning stove in my home. I mounted the unit twice the minimum distance as specified by the manufacturer. I am concerned because the stove works so well that the drywall behind the stove just above the stack connector gets very hot to the touch. I can put my hand on the wall but it is very hot. What is the flash point on 1/2" drywall? Anyone know?

    crazyhamm

  2. #2
    Join Date
    Nov 2007
    Posts
    28

    Default Re: Fire Rating On Drywall

    The flash point for paper is 451*F. (Remember the Ray Bradbury book, Farenheit 451?) This exact temperature will be affected by the composition of the paper.

    A more general question is how hot are you running your stove? Do you have a magnetic temperature gauge on your stack or stove? Like this one?
    (http://www.northerntool.com/webapp/w...&ci_sku=173619)

    The idea is to not have too much heat going up the stack since it is wasted fuel and will make you have to load the stove sooner. You may have to back off the combustion air a little so it promotes a more complete burn inside the firebox. My stove usually runs a stack temp between 200* - 300* at about 18" above the exhaust port on the stove. I could have it much much hotter if I have the air feed open way too much, but that would be wasting fuel.

    What is the make/model of your woodstove and does the manual give any recommendations for combustion air settings?
    Last edited by titleist; 12-31-2007 at 08:28 AM. Reason: spelink errers

  3. #3
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Fire Rating On Drywall

    in drywall Two molecules of water are chemically bound to the calcium crystal during the formation of gypsum. As a result, gypsum is about 21 percent chemically combined water. One of the many unique properties of gypsum is its ability to give up these water molecules as steam when heated, in a process known as calcination, making gypsum board ideally fire-resistant.
    the problem occurs when they gypsum has given up all its water molecules. obviously when it is 21 percent water it looses almost one quarter of its mass by the time that it fails. this would be quite obvious since. anyone who has been in a house that has burned has actually seen this in its different stages where they see drywall that is still attached to its back paper (which is thicker and heavier then the face paper.) so the face papaer really won't "flash" at the same temp as other paper because of the moleculer composition of the drywall. if the drywall face isn't getting blackened you are still ok, if it is getting blackened and and starting to crack then the temp is too high and will slowly dry out the board and then it will fail.

    part of this post was a quote from the below linked web site.

    http://www.architecturalrecord.const...10gypsum-1.asp

  4. #4
    Join Date
    Nov 2007
    Posts
    980

    Default Re: Fire Rating On Drywall

    just also a note burning at too low a temp allows for creasote buildup, burning it hotter closer to the 400 and upper 300 helps keep it from solidifying in the chimney.

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