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  1. #1
    Join Date
    Dec 2008
    Location
    Erwin, TN
    Posts
    330

    Default New House TPRV not 6" from Floor

    Does anyone see anything wrong with this NEW house install ? Going by the 2018 IRC standards. 1. TPRV not within 6" of floor, I'm seeing this about every week on new construction.

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  2. #2
    Join Date
    Mar 2007
    Location
    Fletcher, NC
    Posts
    28,032

    Default Re: New House TPRV not 6" from Floor

    Once hot water starts blowing out the end of that unsupported and unsecured PEX ... the end may very well be 6" above the pan (the 'floor' the discharge pipe drains to).

    This is what the typical Watts T&P relief valve safety warning tag states:
    https://www.watts.com/dfsmedia/0533d...source/tag-100

    Read the right side (back) of the tag, not quite half-way down in the top paragraph:
    "The discharge line must pitch downward from the valve and terminate with a 6" (152mm) air gap from an approved location or building drain."

    Watts, and the code, does not want any restriction or any obstruction which might somehow cause a backpressure and reduce or restrict the discharge from the end of the discharge pipe.

    And the code specifies the maximum spacing of supports for the various types of pipe and various sizes of plastic pipe (which is not as rigid as metal pipe).

    What temperature water come out of that pipe? For starters, the valve releases at 210 degrees F ... do you want to be on the receiving end of water spraying out of that pipe?

    Let's say, just for discussion, that the temperature drops 60 degree F by the time it discharges from the pipe (I agree with your chuckle, I doubt that the water will cool 60 degrees F) - if the water did cool 60 degrees F, the water would be 160 degrees F coming out.

    Here is a table showing time vs temperature to scald/burn:
    https://aosmithme.com/wp-content/upl...Manual_FCG.pdf
    (scroll down to page 13/38)

    The table shows 154 degree F water causes 1st degree burns instantaneously, and 1 second creates permanent 2nd and 3rd degree burns.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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