RI Lawn Sprinklers Ohio Irrigation Blog


Tuesday, April 14, 2009

Basic Watering 101: Rain Sensors

Having a rain sensor should be mandatory, they pay for themselves the first summer you use them. Each rain sensor will have multiple settings and you will need to find the setting that works for you, typically that would be somewhere in the 1/4 to 1/2 inch range. Meaning that once it rains 1/4 -1/2inch the sensor will interrupt any scheduled run times. There are two types of rain sensors: Wired and Wireless. I actually prefer the wired rain sensors myself unless from a installation standpoint the wireless makes more sense. Remember that wireless rain sensors have a battery inside the unit and it WILL need to be replaced every couple of years. That battery is the main reason why I prefer the wired models. Since I don't think it is fun to climb onto a roof every few years and replace an expensive battery so the sprinkler system can work.

Troubleshooting a RAIN SENSOR:

You don't think the sensor works:

  • Easy enough, take a cup of water and climb up to the sensor and poor the water on the sensor and see if it prevents the system from running. Or take a water hose and soak the sensor if you don't want to climb up to it.
Your Timer won't turn on but the timer LCD display counts down like nothing is wrong:

  • Most wired rain sensors are hard wired into the common wire since they only come with 30' of wire from the manufacturer. When they are hard wired the timer acts normal BUT the valves are not getting the electrical signal since the rain sensor has interrupted the signal. The system will go back to normal once the water in the rain sensor has evaporated. When your rain sensor is hard wired your BYPASS switch WILL NOT WORK.
If you Rain Sensor Wire is Cut:

  • If it is hard wired the system will not work since the common wire to all the valves is cut.
  • If the sensor is wireless the system should work if the timer is turned to BYPASS SENSOR
Any Questions about Rain Sensors, email me (Bob) @




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