Why Should I Insulate My Pipes?

The main reason to insulate pipes is to limit the transfer of energy (heat) from the contents of the pipe to the air surrounding the pipe. In basic terms, this means not allowing heat from coming into the pipe or letting heat out of the pipe. So if you want to keep a pipe cold, you insulate it to keep hot air from making the pipe warm. And if you want to keep a pipe warm, you insulate it to keep cold air from making the pipe cold.
That is the major reason, but there are many other reasons pipes have to be insulated.

One reason is to prevent the buildup of condensation on the outside of a pipe. When a pipe with cold contents (water or vapors) is surrounded by hot and humid air, condensation will form on the outside of the pipe. On chilled water systems, the condensation may be so great that the pipe may appear to be leaking due to the large amount of condensation runoff! Condensation is not something you do not want, because with those small beads of dew comes the potential for mold growth. Mold inside a basement of a home can lead to health concerns.

Sometimes insulating a pipe may just be for safety concerns. An exposed steam pipe in an apartment or home if left uninsulated can be a potential accident waiting to happen. A child touching a 200 degree steam pipe will be severely burned. By insulating exposed pipes, the surface temperature of the insulation (if insulated with proper thickness) will be the same as the room temperature, eliminating possible burns.

Another important reason to insulate pipes is for frost protection. Pipes that have standing water inside them and are exposed to freezing air temperatures are going to freeze (possibly break). By adding insulation to the pipe, the water inside the pipe will take longer to freeze. By allowing a longer time period until the water freezes, you are more likely to use that pipe and take cold water and bring into the pipe warmer water (starting the freeze cycle again). Another thing people do is add pipe heating cables to exposed pipes to prevent the pipe from freezing.