Diagnosing And Repairing A Banging Sprinkler Line

Posted on: 29 December 2016

Sprinklers aren't necessarily silent, but you expect the noises to be those of running water – hisses, gurgling, and spraying noises. Occasionally, though, a sprinkler system may sound like a hammer pounding. The sound can be metallic in nature or just a thump, but it can jar you awake if your sprinklers turn on at night. The following guide can help you diagnose and fix the issue.

Water Hammering – More Than an Annoyance

The name of the noise is water hammering. Not only is the noise annoying, it can also be damaging to the sprinkler system. The hammering noise doesn't come without disturbance to the system. This causes the actual irrigation pipes to shake and vibrate, which can lead to burst pipes or joints shaking loose. Instead of constantly fixing the results of the hammer, it's best to get strait to the source.

Know Your Cause

Water hammering is caused by pressure issues in the pipes. Generally in a sprinkler system, the water leaves the source through a larger pipes. It then divides into each of the lines feeding the different sprinkler heads within a zone. These pipes may be the same size or smaller. This pipe layout is repeated for each zone connected to the system. Between the main supply and the zone lines are valves that help regulate the pressure of the water as it enters the narrower pipes.

There are two main causes for a water hammer:

  1. The supply line is narrower than the zone lines. Water going down a narrow line builds up more pressure, which causes it to hammer when it hits the wider line.

  2. The valve between the main and the zone lines isn't working properly, so water is hitting the smaller lines at too high of pressure.

Repair Options

The options for repair must match the cause, so you will need to unearth at least the main supply line to verify the cause. If the main supply is smaller than the zone lines, then replacing it with a larger line is all that's necessary.

Valves can be trickier since you will need to track down the one that is malfunctioning. Sometimes you can narrow it down by simply tracking the noise of the hammer. At other times it can be difficult to pinpoint the noise. Instead, the pressure will need to be measured at each sprinkler head to determine which one is receiving too much. Once the valve is determined, replacement fixes the issue.

For more help, contact an irrigation systems contractor in your area like Hydrotech Irrigation Co.