Q: Why are my copper pipes so noisy?
When I turn on the hot water in the bathroom I hear a sound like dripping water, which stops when I turn the faucet off. In the basement, the horizontal hot-water supply leading to the bathroom is supported by copper wire hangers driven into the joists. Pretty typical, you might say, except that there are a lot of them—six hangers on a length of pipe 14 feet long—and each one is securely soldered to the pipe. Does this seem right to you?
—Frank Pellizzari, Racine, Wis.
Richard Trethewey replies: Maybe your pipe was installed by someone who wanted to get rid of a bunch of hangers and practice his soldering technique at the same time. But what you describe is by no means the correct way to support a pipe.
All copper hot-water supply pipes want to expand and contract as they heat up and cool down, but your pipe is dragging the soldered-on hangers right along with it. I suspect that the sound you hear every time you turn on the hot water is made by those hangers straining against the joists.
The fix is easy: Put in new supports that allow the pipe to move. You need only three of them. According to code, horizontal runs of copper pipe 1¼ inch in diameter or less should be spaced no more than 6 feet apart.
First, install the three new supports. You can use copper-clad pipe hooks, plastic J-hooks, or even perforated copper-clad hanger straps. Just make sure that any metal that touches the pipe is copper or copper-clad to avoid unpleasant corrosion problems down the line.
Once the new supports are on, cut the legs off all the old wire hangers. I bet you won't hear any more noise.
You can leave the old soldered portions on the pipe. They'll make an interesting artifact for future plumbers to wonder at.