Water Heater Rescue: Know-How, Troubleshooting, Anodes graphic

Troubleshooting > Quick> What Causes
Clattering Noises in Water Heaters

If you can hear an annoying rattling sound, especially at night, suspect what are known as heat-trap nipples. These were designed to help water heaters meet federal energy conservation requirements. They consist of a nipple, which is a connector threaded at both ends, the plastic insert you can see at left, and a marble, which is inside.

The heat trap keeps heat from rising when the water heater is not in use. But it also is prone to rattle, especially if the water heater is equipped with a recirculation system that keeps water moving. And the piping will broadcast the noise all over the house. To solve the problem, simply take a pair of needle-nose pliers, firmly grasp the top part of the insert, work it loose, and throw away the marble.

But another cause of noise in the night is sediment rumbling in a water heater, while the noise is broadcast near and far through the piping.