Common Irrigation Controller Questions

Here at Hillermann Nursery we answer a lot of the same questions year after year.  I thought it would be helpful to answer some of the most common irrigation controller questions and make them available to you all in one place. I will start with the most common problems we see in the spring and move on from there.

Spring is when we come out and start up your sprinkler system and set up your controller. Usually during the spring, it is cool and wet, and the soil has plenty of moisture.  When we finish setting up your controller we turn it back off to make sure you aren’t overwatering your lawn. For the homeowner the best signal it is time to turn your controller to the ON or RUN position is when you start to see the first hint of silvery sheen to your grass. This is a sign that the soil is starting to dry out and the roots are beginning to stress. It is beneficial for the root growth of your lawn to let its roots dry out a bit before irrigating, so let your lawn tell you when it is time to start watering, you will save some money and have healthier grass.


Personally, at spring openings, I like to turn the seasonal adjust down to 50% or so too, so that when you do start watering you are not watering too much.  What is seasonal adjust?  Almost all controllers have a way to adjust how much you water without having to adjust each individual station. Some controllers label it seasonal adjust, water budget, or adjust water. All of them serve the same function, which is to adjust the length of time your sprinklers run by a percentage. For example, if your stations are set to run for 30 minutes each and you turn the seasonal adjust down to 50% they will only run for 15 minutes.  This is a very convenient tool for a homeowner, especially if you have a lot of zones in your system.  Typically, your irrigation tech will set each zone run time to put down about an inch of water a week.  This is fine for moderate temperatures with typical rains, but how often do we have those circumstances?  In the spring its cooler and rains more, in the summer we have the reverse, and all of this affects evaporation.  In the loosest terms I usually would have the seasonal percentages as follows April:50% May:75% June:100% July:125% August:150% September:120% October:100%.      Every year is different, and these numbers are just estimates, so use your best judgement.

Another thing to be aware of, especially in spring, is your rain sensor.   We will check the functionality of your rain sensor when we open your system and repair or replace anything that is necessary, but it is possible for things to fail after we have left. Your rain sensor shuts the irrigation off when it rains by getting soaked enough to send a signal to the controller. In order to work correctly there are a few things that must be working properly, I will go over them in order for you to be able to troubleshoot your own sensor and help diagnose possible simple solutions.  A rain sensor has just a few key components which you will need to understand before you know how to troubleshoot.  A stack of cork disks on a pin is inside the top of the sensor, which expand when they get soaked and depress a button to send a signal to the controller to shut off watering. A wireless rain sensor will have batteries in the base which provide power to send the wireless signal to the relay which is directly connected to the controller.  On most controllers there is a bypass switch which can disengage the rain sensor in case you would want to water even if it rained for some reason.  Now that we know all the parts of a rain sensor and their functions, let’s talk about some simple troubleshooting in the case of your irrigation system running immediately after or during a rain event.  First, most sensors need at least a half inch of rain to shut the system off, so do not expect your system to not run after a light sprinkle.   Next, check your bypass switch and make sure that your rain switch is engaged.  Now, check your relay.  Most have three separate lights, one which indicates that the relay itself has power, one which will indicate the signal from the wireless rain sensor and another that indicates moisture content and will be green if dry and red when wet. Typically, with the signal and power indicator lights, a green light indicates good signal and power, while no light, a red or flashing light indicates signal or power loss.   If all of these are lit up green and your irrigation has still run after a good rain, then most likely your discs have corroded or decomposed and will need to be replaced.  Batteries and the disc assembly are inexpensive, and we keep them in stock for easy replacements.