The Rain Sensor automatically turns off your irrigation system when it rains.
The rain sensor from Hunter provides the simplest and most effective way to prevent sprinklers from coming on during or after a rain. The rain sensor is easily installed on any controllers that have a sensor connection. The rain sensor will shut off sprinklers or a drip system when there is rain, automatically compensating for the amount of rainfall that occurs. The rain sensor uses disks that absorb water and expand proportionate to the amount of rain that falls; more rain leads to more water absorption and greater expansion of the disc. As the moisture-laden disks expand, they activate a switch that interrupts the circuit from the controller to the solenoid valves, and the system shuts off. Once the discs are dry, they contract and release the switch, allowing irrigation to resume and the irrigation program to automatically reset, without ever affecting your controller. The rain sensor can be set to shut down irrigation with rainfall in increments from 1/8" to 1". Use this accurate adjustable sensor with any of our controllers that offer a sensor connection.
In most installations, the rain sensor acts as a switch to break the circuit to the solenoid valves of the irrigation system when it rains. This allows the irrigation controller to advance as scheduled, but keeps the valves closed. Once the sensor has dried sufficiently, the switch closes again and the controller returns to its normal operation.
The sensor has two blue wires connected to a 25 foot extension.
Using the screws provided, mount the sensor on any surface where it will be exposed to unobstructed rainfall, but not in the path of or close to sprinkler or spray irrigation. The switch-housing portion must be upright (as pictured), but the swivel-bracket can be moved for mounting on any angled surface. Loosen the locknut and screw before swiveling the bracket, and then re-tighten.
Helpful hints for mounting:
1. When looking for a suitable location such as on the side of a building or post, the closer the sensor is to the controller, the shorter the wire run will be. This will also minimize the chance of wire breaks.
2. The ideal location for mounting is not always the most practical location. In the case where a compromise must exist (such as low location on a side wall rather than the preferred high location), note that the sensor will still work as it will always receive some rainfall – it just will not be as accurate in its gauging as it could be.
3. As described in the “Operation” section of the manual, “reset rate” refers to the amount of time it takes the sensor to dry out sufficiently in order for the sprinkler system to be allowed to come back on. The mounting location will affect this rate and should be taken into consideration should extreme conditions exist. For example, mounting the sensor on a very sunny, southern end of a building may cause the sensor to dry out sooner than desired. Similarly, mounting on the northern end of a building with constant shade may keep the sensor from drying soon enough.
Wiring to Your Irrigation System
Important: the sensor is sold and designed for hook up to 24 Volt irrigation controllers only. For wiring to 110V or 220V irrigation controllers, please consult Hunter website for details. All wiring must conform to National Electrical Code or applicable local codes.
The sensor connects directly to the sensor terminal on the AC controller.
1. Route the wires from the sensor up through the same opening used for valve wiring on the controller.
2. Connect one of the sensor lead wires to the C terminal (common)
3. Connect the other lead wire to the valve’s common ground lead wire and connect the valve wires to the correct controller valve number terminals. If the valve common wire is connected to the controller common terminal disconnect it and connect it to the sensor.
Adjustments and Operation
The sensor can keep the irrigation system from starting or continuing after rainfall quantities of 1/8", 1/4", 1/2", 3/4" or 1". To adjust it to the desired shut-off quantity, rotate the cap on the switch housing so that the pins are located in the proper slots (see Figure). Do not forcibly twist the cap as this might break the pins.
The time that it takes the sensor to reset for normal sprinkler operation after the rain has stopped is determined by weather conditions (wind, sunlight, humidity, etc.) These conditions will determine how fast the hygroscopic discs dry out, and since the turf is also experiencing the same conditions, their respective drying rates will roughly parallel each other. So when the turf needs more water, the sensor is already reset to allow the sprinkler system to go at the next scheduled cycle.
There is an adjustment capability on the sensor that will slow down the reset rate. By turning the “vent ring” (see Figure) to completely or partially cover the ventilation holes, the hygroscopic discs will dry more slowly. This adjustment can compensate for an “overly sunny” installation location, or peculiar soil conditions. Experience will best determine the ideal vent setting.
Follow these simple checks first before assuming the unit is bad and replacing it.
1.System will not come on at all: check to see that the sensor discs are dry and the switch “clicks” on and off freely by pressing the top of the spindle. Next, look for breaks in the wire leading to the sensor and check all wire junctions. If the sensor is dry and the wire leading to it is good, check the sensor switch by nicking the insulation of the two “outer” wires near the unit to expose copper. Turn one sprinkler zone on, and apply a “jumper wire” across the two exposed wires. If the sprinkler now comes on, the switch is bad. Wrap all nicked wires with electrical tape.
2.System will not shut off even after heavy rainfall: check wiring for correctness (see “Operation Check to Verify Correct Wiring”). Check sensitivity setting on sensor – move cap to more sensitive setting. The sensor is an accurate rain gauge and can be verified by setting up a “tube” type rain gauge in the same vicinity and making periodic readings. Check if the rainfall is actually hitting the sensor - check for obstructions to rainfall such as overhangs, trees or walls.
All the sensors from Hunter are listed by Underwriters Laboratories, Inc. (UL). Samples of these devices have been evaluated by UL and meet the applicable UL standards for safety.