Q: How can I keep the copper pipes in my house from sweating?
How can I keep the copper pipes in my house from sweating?
—Nicole Sisco, Sault Ste. Marie, Mich.
Richard Trethewey replies: Sweating is a problem only with cold-water supply pipes and only in the summer, when the air is warm and humid; hot-water pipes never sweat. Here's what happens. Water enters your house at 45 to 50 degrees F, or even colder if it comes from a well, and cools the surrounding air. Cool air can't hold as much water vapor as warm air, so moisture condenses on the copper.
The best way to stop pipes from sweating is to insulate them with self-sealing foam or fiberglass sleeves that are split lengthwise. They aren't expensive, they're readily available at home centers, and installation is easy. You just have to butt the straight lengths tightly together and miter the ends where they cover elbows and other angled pipe fittings. You don't want to leave any gaps where moist air can reach the pipes.
These sleeves are made to fit either ½-inch or ¾-inch pipe, so measure yours before you head off shopping. Fiberglass sleeves insulate the best but are harder to miter and fit around angled fittings than foam ones. While you're at it, insulate your hot-water pipes, too. You'll get hotter water out of your faucets.