Preventing frozen pipes
December 12, 2008 8:34 PM   Subscribe

Preventing my house's pipes from freezing while a few timezones away?

Suppose I live in a city where it rarely freezes (say, Portland, Oregon), yet it's predicted that we'll soon have three+ days of subfreezing temps (as in, not even rising above 32). Yet I'm out of town now, and will be for all the drama.

I'm worried about the pipes in our 100-year-old house. We have lots of stuff in the basement. I have a friend with a key. Should I ask her to:

1.) leave a slow drip from all the faucets & the shower? The two outdoor faucets too?


2.) shut off our water valve completely, and run out as much water as possible from all our faucets?

Or something else?

We left the thermostat at 50, for what that's worth.

Thanks in advance!
posted by lisa g to Home & Garden (13 answers total)
If you left the thermostat at 50, what makes you think there would be a problem with frozen pipes? The inside pipes should be fine. For the two outdoor faucets, it might be a good idea to shut off the water to them and run out as much as possible. (Although I bet the outside ones will be fine too as long as the interior is heated, and it doesn't get *very* cold out.)
posted by paulg at 9:01 PM on December 12, 2008

if you're house is at 50, and any pipes related to the outside are dealt with ... i'd be happy.
posted by Frasermoo at 9:09 PM on December 12, 2008

If you're seriously concerned just have the person with a key turn the heat up to 68 F.
posted by 517 at 9:25 PM on December 12, 2008

Response by poster: Well, there is a non-zero chance that our heating oil will run out while we're gone ... It would have been fine for two weeks if the outdoor temp was 45, but it'll use a lot more when it's 15 degrees. I can order more oil without being there, but no way is an oil truck coming in the next few days. Portland TOTALLY shuts down in icy situations like this (last 2004). Very few plows, etc.

So imagine my heat goes off. Should we drip?
posted by lisa g at 9:31 PM on December 12, 2008

Response by poster: And my friend may be stuck at her place Sunday-Tuesday (seriously, 3/4 of the roads will likely be unusable), so anything she does will have to be on Saturday.

(Portland: "Plows? Rocksalt? What?")

Thanks for all answers so far; forgive my new-homeowner paranoia.
posted by lisa g at 9:44 PM on December 12, 2008

The outdoor taps, if attached to the house, would normally have a long rod attached to a shutoff valve that is inside the house wall, so they shouldn't freeze either. If they are not attached to the house, you should have a main irrigation water shutoff well below ground level somewhere. If you shut off the water main for the house, be sure to turn off your water heater as well, so it cannot boil dry.
posted by weapons-grade pandemonium at 10:43 PM on December 12, 2008

Could you get your friend to lower the thermostat to decrease the chance that your heats shuts off?
posted by soma lkzx at 11:22 PM on December 12, 2008

The drip is probably best unless your friend is a plumber. Also, (2) may not save your basement -- you would have to have the city turn off the street valve.

This is a 100-year-old house, so the basement has a much higher chance of getting too cold if the house upstairs is at 50 than with modern construction. One thing your friend could do is look for a basement vent along one of the ducts and just open it. But that, too, would use more fuel.

You can also get pipe heaters at a well-equipped hardware store. It's basically a long extension cord that you can wrap around a pipe and plug in to a ceiling fixture (Y adapters are available if needed). This should be done particularly for any pipes that run close to an outside wall where there is no insulation.

Also, your friend can elevate the more valuable stuff in the basement, or bring really important stuff upstairs.

I will say that in my experience (in Wisconsin) it takes much colder temps than "high below 32" to really get to worrying about pipes, and Portland may not get as cold as Wisconsin but it probably wasn't being built much differently than Wisconsin 100 years ago. Still, caution is worth exercising.
posted by dhartung at 12:43 AM on December 13, 2008

If it's a real basement (not a crawlspace) I'd be very surprised if even a week of, say, 25ºF temps would cause the basement itself to go below freezing, even in an unheated house. The basement is the best-insulated part of the home, and the ground temperature just a short distance below the surface will be above freezing.
posted by zippy at 12:58 AM on December 13, 2008

In 3 days, unless it's sub-zero temperatures or you leave all the windows open, your inside pipes wont get cold enough to freeze.
Isolate the outside taps and then leave them open.
posted by whoda at 6:22 AM on December 13, 2008

Best answer: All the people who say "Oh! The house is above freezing! You'll be fine" know nothing about heat transfer. My first experience with freezing pipes was at my great-grandma's house. She kept the place warm (she was old!) but it was 10F outside for a solid week straight. Her kitchen sink was on an ouside wall. The pipes came from the basement *through the floor*, not in the wall, but radiative heat transfer from that c-c-cold outside wall finally froze the pipes.

50/50 chance, on an old house, that your outside spigots have been retrofitted to freeze-proof design. Either way, you should have your friend disconnect any hoses (and drain them) . The water in front of the actual shutoff (which should be on the inside of the house) will dribble out if it's freezeproof. If not, well, step two.

Do you have a washing machine in the basement? Shut off the valves above the hoses. Shut off the house valve (where the water service comes in). Disconnect the washer hoses from the washer, port them to a floor drain, and open the washer valves. THis should do a pretty good job of draining most of your system, excepting the water in the water heater, which is...staying warm.
posted by notsnot at 9:13 AM on December 13, 2008

One other thing.. have your friend open the cupboards underneath any sinks (kitchen/bathroom, etc) so that the heated air can circulate better in those areas. Unless it gets ridiculously cold and your heating oil runs out, this is probably overkill, but it's easy to do.
posted by everybody polka at 1:06 PM on December 13, 2008

Response by poster: Thanks to everyone who responded. I was able to get a delivery of heating oil before Arctic Blast '08, and had my friend make the pipes drip. Then another contractor-type friend volunteered to go over and totally turn the water mains off -- as well as the hot water heater, so it wouldn't boil down. (I couldn't remember ever seeing separate shutoff valves for the two outdoor spigots, but he can likely find them if they're there.) So hopefully we're fine.
posted by lisa g at 11:50 AM on December 17, 2008

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