An automated lawn sprinkler system is a network of underground components designed to deliver water to a landscape efficiently and on a programmed schedule. This technology removes the need for manual watering by using a sophisticated, timed sequence of electrical and hydraulic actions. The system’s primary purpose is to ensure the correct amount of water is distributed to specific areas, promoting plant health while reducing water waste. Understanding the mechanics of these systems involves knowing the function of the main parts, the activation process, and how different devices disperse the water.
Essential Components of an Underground System
At the heart of the system is the controller, which functions as the central scheduling device. It allows users to program specific start times and durations for watering cycles. This unit sends the necessary electrical signals to activate the system’s various sections. Before the water reaches the lawn, it passes through a backflow prevention device, which is a required safety mechanism. This device prevents potentially contaminated irrigation water from flowing backward into the clean, potable household water supply.
The water then enters the main line, a pressurized pipe that carries the supply from the source to the rest of the network. The main line is always under pressure and branches out to several zone valves, which act as gates controlling the flow to different sections of the landscape. Grouping the sprinkler heads into specific zones is necessary because a typical residential water supply cannot provide enough volume and pressure to run all the heads simultaneously. The sprinkler heads are the visible output devices responsible for dispersing the water onto the lawn or garden area.
The Automated Sequence: From Controller to Water Flow
The process of turning on a watering cycle begins when the controller sends a low-voltage electrical current, typically 24 volts AC, to a specific zone. This signal travels through underground wires directly to the corresponding zone valve. Attached to this valve is a component known as a solenoid, which contains a coil of wire wrapped around a metallic plunger.
When the electrical signal reaches the solenoid, it creates a magnetic field that acts as an electromagnet, causing the plunger to lift slightly. This upward movement opens a tiny passage, known as a pilot hole, within the valve body. Water pressure is constantly applied to both the inlet side of the valve and the top side of an internal rubber barrier called the diaphragm.
By opening the pilot hole, the solenoid rapidly releases the water pressure that was trapped above the diaphragm, allowing it to escape into the downstream side of the valve. The high-pressure water pushing up from the inlet side of the valve now encounters significantly less pressure on the top side of the diaphragm. This large pressure differential immediately forces the diaphragm to lift and flex upward, opening the main waterway. Once the diaphragm is lifted, the high-pressure water is permitted to flow freely into the lateral pipes of that zone, traveling toward the sprinkler heads until the controller cuts the electrical signal.
How Different Sprinkler Heads Distribute Water
Once the zone valve is open, water is delivered to the individual sprinkler heads, which distribute water based on the area’s dimensions. One common type is the fixed spray head, which pops up from the ground and distributes water in a static, fan-shaped pattern. These heads are best suited for smaller, irregularly shaped sections of turf or flowerbeds, with a typical throw distance of 5 to 15 feet. They deliver water at a relatively high precipitation rate, meaning they apply water quickly over a short duration.
For larger, open areas, rotor heads are employed, which use the water pressure itself to create a moving stream. Within the rotor head, a small turbine or set of gears is spun by the flowing water, causing the nozzle to slowly rotate and distribute a single stream across a wide arc. Rotor heads can cover distances ranging from about 20 to over 50 feet and apply water at a much lower precipitation rate than spray heads. This slower, more deliberate application minimizes runoff and allows the soil more time to absorb the moisture evenly across the larger coverage area.