How best to prevent freezing pipes?
charles3
| Posted in General Questions on
I’m working on a (mostly) vacant house near Atlanta. It’s on a vented crawlspace and has only electric resistance (baseboard) heat. What combination of heat and dripping water is the least environmentally damaging way to prevent water pipes from freezing this winter?
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Replies
Charles,
Here in Vermont, everyone knows that pipes in a vented crawl space will freeze. That's why Vermonters with crawl spaces make sure that their crawl spaces are sealed. For more information on sealed crawl spaces, see this article: Building an Unvented Crawl Space.
A vented crawl space is outside of your home's thermal envelope, so it's no surprise when pipes outside of your home's thermal envelope freeze. Ideally, all plumbing pipes should be located inside your home's thermal envelope.
If you are forced by circumstances to live in a house with outdoor pipes, you can leave a faucet running on cold nights -- ideally, the faucet farthest from the location where the pipes enter your crawl space. The stream of water should be the diameter of a pencil lead. That wastes water, of course. Another stopgap measure (until you can improve your crawl space) is to wrap your pipes with electric heat tape (which is thermostatically controlled), and then wrap the whole shebang with pipe insulation.
These are imperfect solutions. One wastes water (and depends on the presence of an alert occupant who reads the thermometer regularly), and the other wastes energy. Take your pick.
A vented crawlspace in Atlanta has no advantages, only disadvantages, and it allows more moisture into the house than it purges, increasing the latent cooling load, AND the sensible heating load.
A heavy vapor barrier over the dirt (or rat-slab) combined with air sealing insulating the crawlspace walls is the best solution, if it's in the budget.
If your situation allows it, it would be least environmentally damaging to turn off the heat and water and purge the pipes with compressed air.
Thanks for the replies, all. Jon, we need intermittent water, so purging is not an option. Martin, you wrote, "Take your pick." Do you have any insight into which or what combination is least environmentally damaging? We don't really have access to the crawl to install heat tape or insulation. By pencil lead, do you mean a standard #2 pencil or a mechanical pencil?
Charles,
If you don't have access to the crawl space, then obviously you have only one option -- leaving the water running on cold nights. (I'm guessing that a cold night in Atlanta means a night when the temperature is below 25 degrees or so, but the pipes probably won't freeze until the temperature is in the teens.) Don't get too wigged out about the definition of "the diameter of a pencil lead."
Needless to say, closing the vents from the outside obviously makes sense. If you have no money or time, you will close the vents with (a) polyethylene and a staple gun, or (b) a few bales of hay. A winter with deep snow would help, but I guess you don't have that good fortune in Atlanta.
How does one drip water in toilets and clothes washing machines?
Charles,
If you are worried about pipes freezing on one particularly cold night in one vulnerable bathroom, leaving the tap dripping works (by keeping water running through the pipe leading to the vulnerable room).
If you plan to be away from the house for a week, you're right: the supply pipes running to a toilet or a washing machine can easily freeze. Ideally, if you want to avoid this problem, all plumbing is inside the conditioned space of your house, and you can leave the heating system turned on during the winter.
Good design saves headaches.