Tapping into PEX in crawl space - questions about freezing

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by sandskout, Jul 3, 2014.

  1. sandskout

    sandskout New Member

    Jul 2, 2014
    North Carolina
    Hello experts!

    I live in NC where it is not uncommon to have consecutive days of sustained temperatures below freezing. I have two questions about that:

    Question 1) The PEX tubing inside my crawl space is not insulated. So what keeps it from freezing? I've never had a problem with that.

    Question 2) If I tap in an irrigation line where the main PEX line comes into the crawl space from the street, am I going to have a problem with a freeze break in the line or a fitting somewhere between the center leg of the tee and the front half of the cutoff valve? If so, is simply wrapping those fittings with a piece of insulation enough to prevent that?

  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Unless the crawl space is real breezy, that's not a problem.
    I don't consider insualtion on pipes to be any use to prevent freezing if its going through a below freezing space. Code requires the insulation now, but it doesn't really do anything except keep the hot water a bit warmer while it's flowing. Once the water stops, it all cools down to ambient temperatures.

    Some Winters I do a lot of freeze repairs. It's commone to repair breaks in garages on outside walls or on the front hosebib in the garage, garages over the unheated attic space, inside the home on outside walls.
    Near kitchens is a big one.

    In a crawl space? Like never really.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    There's often enough heat from the living space above to keep the pipe/tubing from freezing unless there's an air leak in your climate...then, all bets are off. Pipe insulation by itself won't keep the pipe from freezing, but if you do add batt type insulation, keep the pipe/tubing towards the living space, and that can help a lot.

    Pex itself can expand enough to not be damaged if it is frozen, but that is NOT true of any fittings, which are rigid. Moving water brings above freezing water into the pipes, but stop the flow, and it can get to whatever the temp of the surrounding area is. If there's insulation below it, that would help trap any from the living space, and help keep it above freezing.

    If you use a frost-free hose bib, pay very careful attention to the slope of that floppy tubing and the valve so that things drain properly - the tubing won't anchor the inside end at all without some effort.
  5. sandskout

    sandskout New Member

    Jul 2, 2014
    North Carolina
    Thanks, gents, for the input. I hear you, Terry, but with your stories of freeze repairs I was still concerned knowing there will be still water in the tee and front half of the shutoff ball valve all winter. I was able to work it out so the tee and valve are tucked right up against the underside of the living space decking, sandwiched between the deck above and the insulation batts below. Better peace of mind for me, anyway, that it should be cozy warm (enough) during the freezing months.
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