Active sprinkler systems make several noises, including fizzing and the sound of flowing water, which are all part of normal operations. Still, these same noises can indicate a problem when they occur during sprinkler inactivity. In fact, different noises indicate different problems with the sprinkler valve and its related components.
A slight whining or high-pitched noise coming from the sprinkler valve is a sign of a small leak or slow leak. While this sound is sometimes accompanied by a telltale trickle of water, the leak may appear not in the exterior of the valve but in the valve shutoff. The sound comes from water channeled through a small hole, the way air is channeled through the stops of a whistle. A leak in the sprinkler valve, whether inside the mechanism or on its exterior, means the valve will require replacement. If a sound is present but no water is streaming out of the valve, try tightening the connectors joining the valve with the pipes before servicing.
A fizzing noise from the sprinkler valve, whether on or off, can indicate a broken valve casing. The sprinkler valve controls the flow of water, directing it up through the spray jet. If part of the casing is crushed, it can cause a gushing leak that fizzes and bubbles water over the immediate area of the lawn. Anything from a careless lawnmower operator to a heavy foot fall can damage the casing of a sprinkler valve. Replacing the valve with a broken valve casing will stop the sound of fizzing as well as any loss of water.
Squeaks During Turn
While some sprinkler valves spray water through perforated pipes, many feature a diffuser which moves back and forth over the jet of water, breaking up the stream and sending water over a greater area. If this diffuser squeaks while turning, try loosening the diffuser screw. This screw holds the diffuser to the rest of the sprinkler valve and, if fastened too tightly, can create squealing noise.
The pipes in an exterior sprinkler system operate on the same principles as an indoor plumbing system. Like indoor plumbing, air trapped in the system can cause a hammering sound along the pipes and especially near the sprinkler valve. This knocking sound is called water hammer and is cured by passing the air through the piping system. Remove the sprinkler heads along the piping that is making the sound and turn on the water, allowing the water unregulated run of the pipes. Once the air is flushed out, reattach the sprinklers and turn on the sprinkler system.