How to Install a Rain Sensor for Your Sprinkler System to Curb Your Water Usage

Wireless rain sensors have two parts: a receiver (which connects to your controller) and a transmitter (the part that detects when it’s raining). For your sensor to work correctly, you need to choose the transmitter’s location carefully.

It should have clear access to the sky and not sit underneath trees, roof overhangs, or anything else that might block rain from reaching the sensor.

Depending on the design of your home, you might mount your transmitter to the side of your house, the edge of your gutter, or the top of your fence. Whichever location you pick, make sure your sensor isn’t in the spray path of any sprinklers.

Installing a rain sensor involves working with wires, so taking the proper precautions is important to avoid electrical shock. This means unplugging your irrigation controller from its power source before setting up the sensor.

The rain sensor receiver is an electrical component that connects to your irrigation controller through a set of wires. Using a drill and the screws and brackets that came with your rain sensor, mount the receiver on a flat surface (like a wall) near your controller. It needs to be close enough for the wires to reach inside the controller.

As a heads up, some rain sensor manufacturers refer to the receiver as a “controller interface,” so you might see it called that in your owner’s manual.

Open your irrigation controller to expose the wires inside. Find the two wires on your receiver that provide power to the receiver. You’ll need to check your user manual to identify these wires.

Find the ports labeled “24VAC,” and loosen the screws on top of them using a Phillips head screwdriver. Insert the wires in those ports (alongside any existing ones) and tighten the screws so the wires stay put.

Next, find the sensor ports (they should be labeled “SEN” or “SENS”). If you don’t already have a sensor, there’s probably a jumper wire connecting these ports, which you can remove and put in a safe place inside your home. 

Consult your owner’s manual to figure out which wires are the sensor wires, then insert one sensor wire in each of the sensor ports and tighten the screws. Usually, you can put either sensor wire into either sensor port, but you'll want to confirm this in your manual.

Close the controller and reconnect it to the power source. Insert batteries into the transmitter, which should then pair with the receiver. 

If the pairing was successful, you might see lights or icons on your receiver (depending on your sensor). Otherwise, make sure that the transmitter’s battery is working. If it is, disconnect the power again and check the wiring from the receiver to the controller.

You can customize your rain sensor’s settings to shut off your irrigation system once you’ve received a certain amount of rain. Typically, the minimum threshold is 1/8 inch, but you can increase it to 1/4 inch or more if you’d like.

Read your user guide for detailed instructions on this—you might need to adjust the settings on the transmitter itself or through the receiver.

After pairing the transmitter with the receiver, you can mount the transmitter using a drill and the brackets and screws that came with your sensor.

Depending on where you choose to install the transmitter, you may need to use a ladder to access the area. If so, make sure to follow basic ladder safety tips, like inspecting the ladder for problems and having someone watch you while you’re on it.

Before you wrap up, test your wireless rain sensor to ensure it works properly. You can do this by manually running your irrigation system and then spraying water onto the transmitter until your sprinklers shut off.

If they won’t turn off, check the transmitter’s batteries and the wiring between your receiver and controller. Don’t forget to disconnect the power before adjusting any wires or electrical parts of the sprinkler system.