How Do Automated Lawn Sprinklers Work?

Sprinkler Timers

• Sprinkler timers are electronic devices that allow you to set specific times for your sprinklers to turn on and off. These devices send an electronic signal to a sprinkler solenoid, which pushes on a diaphragm within a valve to release water. When the electronic signal stops, the valve shuts off. Timers can control 4, 6, 8 or 12 zones, depending on the model. Some of the most popular models include those manufactured by Rain Bird, Hunter, Toro and Orbit. Timers range from about $30 to more than $100.

Vacuum Breaker Valves

• The pressure vacuum breaker valve is a key safety feature on all sprinkler systems. This device prevents water from flowing from the sprinkler lines back into the main water line. In most municipalities, it's illegal to allow irrigation water to enter the drinking water supply, because once water enters irrigation pipes, it comes into contact with PVC glue and pipes that aren't certified to carry drinking water. Vacuum breakers sit above ground, just above the manifold outside. They're made of brass and shaped like a bell. These devices create a pressure seal that keeps water flowing in only one direction. They're also generally the most expensive piece of a standard sprinkler system, costing about $150 each.

Sprinkler Manifolds

• Sprinkler manifolds are the heart of your sprinkler system. They comprise a single supply tube with multiple valves attached on top. The main line is pressurized with water. When the timer sends a signal to one of the valves, the valve turns on and releases water to a series of smaller supply lines underground. Each valve represents one sprinkler zone. Manifolds can have an unlimited number of zones, but only 1 can operate at a time.

Sprinkler Heads

• Sprinklers come in a wide variety of types and materials. The most common type of sprinkler is the pop-up, which uses water pressure to push the head above the grass and deliver water though a fixed nozzle. Other models include rotating heads; with these, water pressure is used to turn a series of small gears inside the sprinkler body to turn the nozzle. Impact sprinklers are used to water large areas of grass, and use a powerful jet of water to move a paddle back and forth. Most sprinklers are made of plastic, although some models have metal caps or brass nozzles. Metal models are generally more durable.