‘Shock Absorbers’ Fix Noisy Pipes

That awful racket your plumbing pipes make usually can be diagnosed by sound and fixed easily, according to the Plumbing-Heating-Cooling Information Bureau.

Banging or hammering results when water moving through a pipe comes to an abrupt stop. This shocks the pipe and causes it to jump.

A capped pipe extension behind faucets and toilets will serve as a shock absorber to prevent this kind of noise. This extension is filled with air.

“The trapped air in each extension, or air chamber, acts like a cushion for the vibrations,” says the bureau’s David L. Weiner. “When the chambers lose air, they fill with water. This causes the banging.”

He suggests draining or refilling the pipes to replace the air, or alternately, injecting air into the chambers mechanically. If your plumbing system doesn’t have these shock absorbers, they can easily be added at the site of the noise, he says.

Some can be threaded onto a fitting or the hose supplying a clothes washer, for example. Others may need to be soldered onto the pipe fitting. Pipes of different materials may need different types of shock absorbers, he adds.

Since pipes expand when hot and contract when cold, they can make creaking sounds. If they are suspended from hangers that fit too tightly, they will bind and release repeatedly with a tapping noise. Loosening the hangers or changing from metal to plastic will let the pipes move freely.

A rushing sound means the pipes are either too small or clogged with corrosion. Plumbing contractors recommend using one-inch pipe for the main water supply and 3/4-inch for main branches and water heater. Half-inch branches can furnish water to dishwashers, sinks, tubs, showers and clothes washers. Toilets and lavatories need 3/8-inch pipe.

Vibrating noises have a number of causes, Weiner says. A loose anchor is the most likely cause if the vibration comes from behind a wall. Loose washers in faucets also can make slamming, hammering or trumpeting sounds. Tightening the screws that hold the washer in place or replacing the washer is the solution.

Baseboard heaters can make gurgling, sloshing sounds when air bubbles get into the hydronic heating system, and thrashing and thumping usually come from a spring coupler in a circulator.

“A plumbing system should be quiet,” Weiner says.