So, imagine the water line going into your house instead of this steel container. (Unless you collect rainwater or make water from hydrogen and oxygen, you probably have one.) If it gets too cold, the water can freeze and literally burst your pipe. This is a bad thing. Now for some questions and answers.
Why doesn’t this happen more often in the south?
Residential water lines are almost always underground — and that’s a good thing. Although air temperature can vary greatly from summer to winter, ground temperature is much more stable. In southern states, this ground temperature is unlikely to go below freezing – so the water in the pipes will also be above freezing (and staying liquid).
But there are some exceptions. In some places with hot climates, not all parts of the water pipe system will be underground, and will pass through the air areas. (Heck, I have water pipes in my attic, and I live in a hot spot). Although there is a small temperature difference between cold water (say 1 ° C) and hot ice (0 C), there is a very large energy difference. It takes a bit of energy to convert water from its solid phase to a liquid. This is what we call latent heat of fusion. For water, its value is 344 joules per gram. This can be difficult to understand, so how about an example?
Suppose you have one liter of ice (with a mass of about 1,000 grams). If you want to take this ice at 0 C and turn it into water at 1 C, it will take 344,000 joules of energy (plus a little more energy to raise the temperature of the water). How much energy is there? Okay, let’s say you have a 3,000-mAh battery (milli-hour) smartphone. This is equivalent to 41,000 joules. So, you may have enough energy to run your phone for a full day, but you will need eight or nine of these phones to melt all this snow.
This is actually a good thing. This means that you can use melting ice to cool your drink-And you don’t really need that much ice. This also means that you need to extract a lot of heat energy from your pipes to freeze them. A cold night probably won’t be enough for your pipe to burst.
Does it help to leave the tap?
Yes. Okay, imagine that you are inside a water pipe. (Yes, you are super small now.) If the water is stagnant, you may get stuck in a section of pipe exposed to cold air. You could actually freeze, and then you would have to break the pipe. But now suppose that this water is running, which is caused by a tap that is dripping slightly. You are still a small person inside a pipe, but now you are also moving forward. You go through the section of the cold pipe and you get cold – but you don’t freeze. Instead, you simply move to other parts of the house.
Oh, but more water from the main underground line is coming into that colder part of the pipe. Will it freeze? it is unlikely. Remember, the water pipe is at ground temperature, which is almost certainly not below freezing. So, the incoming water is not super cold, and hopefully it will not freeze.
What about insulation?
Insulation helps. If you wrap some foam insulation around any exposed pipe, it works similarly to your cooler or insulated beverage cup. Insulation reduces the rate that energy is transferred from hot cheeses to cold cheeses through thermal interactions. If you place a cold drink on a table, the energy is transferred to the drink as the temperature increases. On the other hand, pouring the drink into the cooler increases insulation and decreases the rate of energy transfer, which makes the drink take longer to heat up.