A rotary sprinkler head uses a rotating stream of water to cover large areas, making it popular for lawns and expansive garden spaces. Unlike fixed spray heads, rotors deliver water in a sustained stream, which reduces evaporation and wind drift. Correct adjustment is fundamental to maintaining a healthy landscape, preventing dry patches, and minimizing wasteful watering of sidewalks or driveways. The following steps guide you through setting the rotation, distance, and troubleshooting common performance issues.
Required Tools and Initial Preparation
Adjusting a rotary sprinkler head requires only a few specialized items. The most important tool is the specific adjustment key, often a plastic or metal tool with a hex end and a T-shape, usually provided by the manufacturer. A small flathead screwdriver can also serve as a substitute for the manufacturer’s key on many models, particularly for distance control.
Before making any physical adjustments, briefly run the irrigation zone to observe the current spray pattern and determine where the water is landing. This observation helps pinpoint which heads need correction and confirms the existing arc settings. Once the pattern is clear, turn off the water supply. Most adjustments are best performed with the head in the “popped-up” position and the water pressure off to prevent injury and maintain control.
Setting the Fixed Left Stop and Adjustable Arc
The coverage area of a rotary head is defined by the fixed left stop and the adjustable right stop, which create the arc of rotation. The fixed left stop dictates the beginning point of the sprinkler’s rotation and is established by the physical alignment of the entire sprinkler body. To set this stop, grasp the riser—the part of the head that pops up—and rotate it until the nozzle points precisely toward the desired left boundary of the spray.
If the head is threaded tightly into the ground fitting, you may need to dig away soil to grip the entire sprinkler housing and turn it until the fixed left stop is aligned. This initial physical rotation ensures the assembly is oriented correctly before fine-tuning the arc. Once the fixed left stop is set, the adjustable arc mechanism controls the total degrees of rotation. This mechanism is typically a small screw or dial marked with a plus (+) and minus (-) symbol on the top of the head.
To adjust the arc, insert the adjustment key or flathead screwdriver into the corresponding socket on the turret. Turning the key clockwise increases the arc, moving the right stop further away from the fixed left stop. Turning it counter-clockwise decreases the arc. For many models, a full rotation of the adjustment tool changes the arc by about 90 degrees, allowing coverage from a partial spray up to a full 360-degree circle. The mechanism often clicks or ratchets when reaching the maximum or minimum arc limits.
Controlling the Water Throw Distance
Once the rotational arc is defined, the next step is controlling the radius, which is the distance the water travels from the head. This distance is regulated by a radius adjustment screw, sometimes called a stream breaker or diffuser screw. This screw is positioned directly in the path of the water stream, usually near the nozzle on the top of the head, and is identifiable by a small flathead or hex slot.
To decrease the throw distance, turn the radius adjustment screw clockwise, driving the screw further into the water stream. The protruding screw partially obstructs the flow, causing the water to break up into smaller droplets and land closer to the head. This method is effective for reducing the radius, often allowing a reduction of up to 25% of the nozzle’s maximum throw.
To increase the distance, turn the screw counter-clockwise to lift it out of the stream’s path. Avoid turning the screw too far clockwise, as excessive intrusion can cause a distorted spray pattern or lead to the screw falling out of the head. The screw’s secondary purpose is to help secure the nozzle, so careful and incremental adjustments are best for maintaining a consistent spray pattern.
Addressing Pressure and Coverage Problems
Optimal performance of a rotary head depends on consistent water pressure; pressure issues often present as coverage problems. If pressure is too low, the head may fail to rotate completely, or the stream will not reach its intended distance, causing dry spots further from the head. Conversely, excessive water pressure can cause the stream to atomize or mist excessively, resulting in significant water loss due to wind and evaporation.
If misting occurs, install a pressure-regulating mechanism at the zone valve or adjust the flow control stem on the valve to reduce pressure. When a head is not rotating or is spraying erratically, the problem is frequently a blockage rather than a mechanical failure. Debris like dirt, sand, or small stones can accumulate in the filter screen located at the bottom of the riser or directly clog the nozzle orifice.
To resolve this, carefully remove the riser assembly. Extract the filter screen with needle-nose pliers and clean it thoroughly under running water. A small, soft tool like a toothpick can gently clear the nozzle orifice of any lodged particles without causing damage. Re-seating the nozzle correctly after cleaning is important, as an improperly seated nozzle can cause a distorted spray pattern.