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I live in an apartment in the US midwest, and during the winter my pipes freeze unless I trickle my faucet. I think that the point at which it freezes is in a difficult-to-access exterior wall on the second floor, significantly downstream of my water shutoff.

So I was wondering: If I shut off my running water when I'm not using it (and if I'm correct about the above), could I possibly prevent the pipe from freezing? Are there obvious negative consequences that this could have (other than convenience)?

Obviously I would need to double-check that this wouldn't cut off anyone else's water.

Edit: If I want to do this, I believe that I need to be very certain that there will not be a freeze upstream of my shutoff, because this could exacerbate the damage caused by the upstream freeze.

(Related question here)

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    I'll note that here in Minnesota "summer cottages" commonly have the water shut off and the pipes drained in the winter. But this must be done with care, and it usually involves "blowing out" the pipes with compressed air to make sure that all the water is gone. – Hot Licks Dec 5 '20 at 22:41
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Clarification of terms: Your tap is the downstream end. The City water supply is the upstream end.

My understanding of your situation:

  • City
  • Waterline
  • Building shutoff vale
  • Local distribution valve
  • Cold wall
  • Tap you trickle.

I don't know that your building valve and local distribution valve are or are not the same.

You want to know if it's safe to use what I'm calling your local distribution value to keep your water from freezing.


If I've understood correctly this will NOT work. For it to work you would have to drain the line in the wall's cold spot. Since the valve is below you, you can't open your local tap and drain the water in the cold spot.


It could work if there is a valve that can be used as a drain valve below the cold spot. E.g. If there was a sink on first floor at an elevation below your cold spot, then shutting off the valve an opening up the sink tap would drain all the water above that tap, assuming you opened all the upstairs taps.


One way to reduce your trickling: Use a digital thermometer, and record the cold water temperature. You're looking for the minimum temp. You're looking for that slug of water in the cold spot. Record the outside temperature too. After a while you will see how cold the outside temp has to be in order to freeze the pipe.

E.g.

Water Temp    Outside
40            20
38            17
36            16
34            14
32            12

It won't be this clear. It will depend on wind, on sun if that wall gets sun, but you should be able to figure out that when the outside temp is going to be below 15, you better run a trickle.

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Why not simply install trace htg to the problematic pipe? Of course that's assuming you can access it! Insulation, of itself, does not stop freezing but simply slows down the heat loss.

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    Welcome to Sustainable Living! Could you please explain what "trace htg" is? – THelper Nov 28 '20 at 9:42
  • Trace heating is where you install an electrical element which heats up when its on running alongside the pipe & covered by insulation. The idea, which works brilliantly in practice, is to replace the heat that the cold is taking away. If you replace the heat then the water doesn't freeze. – YorkshireDave Nov 29 '20 at 13:49
  • @YorkshireDave Thanks! That's a good idea. It's tough for me to get to most of it but I can get to some of it. Do you think it's possible that accessing maybe 10% of the exposed length would do anything? – capet Nov 29 '20 at 19:40
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    TBH I feel 10% is too little. While heat will travel along the copper & water, you'll be left with 90% of the area losing heat. I feel that battle could never be won. If you could switch that round, it'd be a diff ball game. – YorkshireDave Nov 30 '20 at 20:05

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