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bury pex heating lines?

MaxMax Member Posts: 4
Hi. Part of our house is on a slab and currently doesn't have enough heat. I was thinking of running some new pex heating lines underground to the addition. One issue is that I'd rather continue to use straight water in the system. So, if I insulate the pex, does it need to be below the frost line?




  • Larry WeingartenLarry Weingarten Member Posts: 1,099
    A suggestion slightly off topic... that you put your well-insulated water lines in conduit.  Earth is essentially always wet and is a wonderful heat sink!  The moisture, even with insulated lines, will carry off loads of heat.  If you keep the lines in conduit, you'll prevent that loss and be able to get to the lines if needed.   Others will have to comment on depth of burial and frost line, though if the water flow stops, it must become the same temperature as the surrounding soil in a few hours or less.

    Yours,  Larry
  • Jamie HallJamie Hall Member Posts: 6,017
    Indeed you should

    bury the lines below frost.  Why?  Because if you are running straight water in them, and the flow stops long enough, they will freeze.  And unfreezing a buried PEX line is no fun.

    Larry' suggestion to put them in conduit is a very good one, too.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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