There's a handy article on the Liberty Mutual Solutions site with tips on how to prevent your pipes from freezing when the temperature outside drops. Here are a couple of highlights:
-If water supply lines are in your garage, keep garage doors closed.
-If you're going away during cold weather, leave the heat on in your home, set to a temperature no lower than 55ºF
You can find some more crucial prevention tips in the full article included in the related links below.
There is no single best way to keep pipes from freezing. Insulating (wrapping) pipes is a common method. Leaving the cold water faucet open just enough for a slow drip is another method to prevent freezing.
Fill with anti freeze solution or keep the water running.
At least one degree above freezing?
Undersoil heating involves the placement of warm water pipes underneath the field. Warm water is circulated through the pipes to keep the field from freezing or from icing over.
Copper pipes are used for plumbing. They are usually in interior walls or the basement. Typically, at least here in the North east, you would try to keep them out of exterior walls to keep them from freezing.
Water EXPANDS as it freezes, hello.
Result is broken pipes, so symptoms are: 1) no Water at faucet 2) leaking water elsewhere.
Heat tape is just for keeping the pipes from freezing, it does not heat the water. That's what the hot water heater is for.
insulation in the wall
Yes, they can
water expands when frozen.
Assuming you don't mean water heating systems, and just mean normal fresh (drinking) water systems, then they freeze at 0 degrees Centigrade like all water. But in the case of for example a home, the plumbing protected from freezing in a few different ways. Firstly most homes that are lived in have some form of heating, so this keeps the ambient temperature of the water in the pipes above freezing. Pipes that are in places more likely to be exposed to freezing, such as lofts, and roof cavities will be insulated with pipe lagging to protect them from freezing. Plus remember those pipes in roof cavities will benefit from heat rising from the home/building, helping to keep those pipes above freezing. If the subject of your question is in relation to 'burst' pipes caused by frozen water in the pipes expanding and literally tearing the pipes apart, then this will start to happen at about 20 Degrees Fahrenheit or -6 degrees Centigrade. Remember that a little freezing is not a major problem, as plumbers sometimes use special freezing kits, that will freeze a short section of pipe to block it off temporarily, while they work on the pipes.