Q. During winter, why do hot-water pipes freeze and burst more frequently than cold-water pipes?
A. Foster Lyons, an engineer and building-science consultant, responds: The short answer is because hot-water pipes aren’t attached to toilets, which help reduce the number of burst cold-water pipes. Here’s why.
Water expands when it freezes, increasing in volume about 9% from its liquid state. That’s why ice floats—it’s less dense than liquid water. This increase in volume is the proximal cause of ruptured water pipes when they freeze but probably not for the reason you think. Expanding ice doesn’t push against the pipe walls to cause the rupture; instead, it’s high-pressure liquid water that does the damage.
Read More
