1. Introduction
The Orbit WM Rain Sensor (Model 57275) is designed to automatically interrupt your irrigation system during rainfall, preventing unnecessary watering and conserving water. This sensor is compatible with all standard 24 VAC irrigation controllers. Please read this manual thoroughly before installation and operation to ensure proper functionality and longevity of your device.
2. Safety Information
Always disconnect power to the irrigation controller before performing any wiring or installation procedures. Ensure all electrical connections are secure and protected from moisture. Do not attempt to modify the sensor or its components, as this may void the warranty and pose a safety risk. Keep the sensor out of reach of children.
3. Product Overview
The Orbit WM Rain Sensor utilizes hydroscopic discs that absorb water and expand, activating a switch that signals your irrigation controller to pause watering. Once the discs dry and contract, the switch resets, allowing the irrigation schedule to resume. The sensor features adjustable rain settings and multiple mounting options for versatile installation.
Key Features:
- Adjustable rain sensitivity: 1/8", 1/4", 1/2", 3/4", 1" (approximately 3.12 mm, 6.25 mm, 12.5 mm, 18.75 mm, 25 mm)
- Hydroscopic discs for reliable rain detection
- Compatible with all 24 VAC irrigation controllers
- Includes 9 meters (approximately 30 feet) of connection wire
- Three mounting options: threaded, slip-on, and gutter mount
Figure 1: Orbit WM Rain Sensor main unit. This image shows the complete rain sensor with its integrated mounting arm and electrical cable.
4. Setup & Installation
4.1 Mounting Location
Select a location that is exposed to unobstructed rainfall, away from eaves, trees, or other structures that might block rain. The sensor should also be accessible for adjustment and maintenance. Avoid locations where water runoff from roofs or other surfaces could falsely activate the sensor.
4.2 Mounting Options
The Orbit WM Rain Sensor offers three primary mounting methods:
- Gutter Mount: Use the included bracket to attach the sensor to the edge of a rain gutter.
- Slip-on Mount: The sensor can be slipped onto a 1/2-inch pipe or conduit using the provided adapter.
- Threaded Mount: Utilize the threaded adapter for secure attachment to a threaded pipe fitting.
Figure 2: Mounting accessories for the Orbit WM Rain Sensor. This image displays the separate mounting bracket and the threaded adapter, illustrating the versatility for different installation needs.
Figure 3: Orbit WM Rain Sensor with the mounting bracket attached. This image demonstrates how the sensor connects to its bracket for installation.
4.3 Wiring to Controller
The sensor comes with a 9-meter (30-foot) two-conductor wire. Connect these two wires to the sensor terminals on your 24 VAC irrigation controller. Refer to your irrigation controller's manual for specific wiring instructions, as terminal labels may vary (e.g., "Sensor," "Rain," "R-SEN," "SEN"). Ensure the power to the controller is off before making any connections.
Figure 4: Orbit WM Rain Sensor with coiled wire. This image provides a visual reference for the length of the included connection cable, shown alongside the sensor unit.
5. Operation
5.1 Adjusting Rain Sensitivity
The Orbit WM Rain Sensor allows you to set the amount of rainfall required to activate the shut-off mechanism. This is typically done via a dial or lever on the sensor unit. The available settings are 1/8", 1/4", 1/2", 3/4", and 1" of rain. Rotate the adjustment mechanism to your desired rainfall threshold. A lower setting (e.g., 1/8") will activate the sensor with less rain, while a higher setting (e.g., 1") requires more rain.
5.2 Drying Time Adjustment
The sensor also features an adjustable vent ring or cap that controls the drying rate of the hydroscopic discs. By opening or closing this vent, you can influence how quickly the discs dry out after rain, thus determining how soon your irrigation system will resume its schedule. A more open vent allows for faster drying, while a more closed vent prolongs the drying time.
6. Maintenance
Regular maintenance ensures optimal performance of your rain sensor.
- Annual Inspection: At the beginning of each irrigation season, inspect the sensor for any debris, leaves, or insect nests that might obstruct the rain collection area or the drying vents.
- Cleaning: Gently clean the sensor housing and the hydroscopic discs with a soft cloth and water if necessary. Do not use harsh chemicals or abrasive materials.
- Wiring Check: Periodically check the wiring connections for any signs of wear, corrosion, or loose connections.
- Functionality Test: To test the sensor, manually pour water over the hydroscopic discs until the sensor activates and stops the irrigation system. After the discs dry, the system should resume normal operation.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Irrigation system runs during rain. | Sensor not wired correctly. Sensor bypass switch on controller is active. Sensor is obstructed. Rain sensitivity set too high. | Verify wiring connections to the controller. Ensure the sensor bypass switch on your controller is in the "ON" or "ACTIVE" position. Clear any debris from the sensor. Adjust rain sensitivity to a lower setting. |
| Irrigation system does not resume after rain. | Hydroscopic discs are still wet. Drying time adjustment is too slow. Sensor malfunction. | Allow more time for discs to dry. Ensure adequate airflow. Adjust the drying time vent to a faster setting. Test the sensor manually. If it fails, consider replacement. |
| Sensor appears to be working but irrigation still runs. | Controller not recognizing sensor signal. | Check controller settings to ensure the sensor input is enabled. Consult your controller's manual. |
8. Specifications
- Model: 57275
- Brand: Orbit
- Compatibility: All 24 VAC irrigation controllers
- Rain Sensitivity Settings: 1/8", 1/4", 1/2", 3/4", 1" (approx. 3.12 mm, 6.25 mm, 12.5 mm, 18.75 mm, 25 mm)
- Cable Length: 9 meters (approx. 30 feet)
- Dimensions (approx.): Width 9 cm (3.5 inches), Height 11 cm (4.3 inches)
- Material: Plastic
- Color: White
- UPC: 046878572751
9. Warranty & Support
9.1 Warranty
The Orbit WM Rain Sensor (Model 57275) comes with an official 1-year warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. Please retain your proof of purchase for warranty claims.
9.2 Technical Support
For technical assistance, troubleshooting beyond this manual, or warranty inquiries, please contact Orbit customer support. Refer to the Orbit website or product packaging for the most current contact information.