There are plenty of times when you don’t want your sprinklers to come on like on the wrong watering day, when you’re out mowing the lawn, and especially in the middle of your family BBQ. But if you’re reading this blog, then I’m sure you’re all too familiar with your sprinklers running when they shouldn’t be. This isn’t usually a big problem because you can head to the timer and switch it off. Well, this is your plan anyway. But now you’re standing there scratching your head wondering, why won’t my sprinklers turn off? Let’s take a look at why this is happening.
Why Your Sprinklers Won’t Turn Off (The Short Explanation)
Your sprinkler system won’t turn off because there is a problem with either the irrigation system’s valve manifold or the timer. This can include a timer that will not stop power from going to the solenoids, a valve solenoid not being able to retract and close the valve, or an obstructed/defective valve keeping one of your irrigation zones open and water flowing.
Possible Causes of a Sprinkler System That Won’t Stop Running
So, if your sprinkler system won’t turn off, you’ll need to conduct troubleshooting tests. Don’t worry, if you’re handy with a few basic tools, you should have no trouble figuring out why the irrigation won’t stop running. So, let’s take a look.
A Defective Irrigation System Timer
It’s common for irrigation timers to stick on and not be able to kill the power to the valve solenoids. I’ve also had Rain Bird and Orbit irrigation timers go bad where the rotary switch fails. This meant I couldn’t switch the system on or off, no matter what I did.
So, if you grab a multimeter, you can troubleshoot the timer. To do this, connect the negative side of the multimeter to the common/ground of the zone power and the positive side to the problematic zone number. You shouldn’t have any voltage when the system is off.
The timer is defective if you turn the system on and off, and a voltage is always present. Also, you’ll need to replace the timer if the dials or switches aren’t working and are not turning the power to the solenoid off.
A Defective Irrigation System Solenoid
To check if a solenoid is working or not, you need to give it power and check if it activates. You can do this by wiring the solenoid directly into the timer. So, remove the solenoid from the valve and take it to your irrigation timer and connect the two wires. One wire will need to go to the COM connection and the other to one of the numbered zone connections.
Next, turn on the zone you connected the solenoid to and check what happens. The solenoid center pin should extend from the solenoid with power, then retract when the system is switched off. If this doesn’t happen, then the solenoid is faulty.
Another test you can do with the solenoid is to test how the pin moves by just pulling and pushing it. If it’s jammed or stiff, it may not be retracting when the power is cut.
An Obstructed or Damaged Irrigation System Valve
Inside the irrigation valve, there is a small diaphragm that tells the valve to either open or close. Once the solenoid is activated, it allows water pressure to move the diaphragm and open the valve. However, any trash in the water can become lodged in the diaphragm and prevent it from switching off. So, depending on what type of valve you have, you’ll have to diagnose it.
Valves like Rain Bird have a small thumb screw that you can turn to manually open and close the valve without a solenoid. So, twist this screw and see what the valve does. You could have an obstruction if you can’t start or stop the water flow.
So, turn the main water off and grab a screwdriver. Then, remove the screws on the top of the valve and expose the diaphragm. Once you are in the valve, look for any trash or damage to the diaphragm. This could be why your sprinkler valve won’t shut off.
How to Fix a Sprinkler System that Won’t Shut Off (3 Things to Try)
I hope you were able to use the causes above to find out why your irrigation is not shutting off. If so, here’s how you can fix the problem.
Replacing an Irrigation Timer
If you discover that your irrigation timer won’t turn off, then your sprinkler zone won’t turn off. To fix this, you’re going to need to replace the timer. If you want to keep the work to a minimum, then I recommend you replace your old timer with exactly the same model. This means you’re not going to have to get the drill out. Also, If you have a hard-wired system without a removable plug, I recommend contacting an electrician.
For a plug-in timer, here’s what you need to do. First, remove the plug from the power outlet. Then, open the main timer cover and the control panel. Next, remove the wires from the panel, making a note of which wire goes where. Then, use a screwdriver to loosen the screws holding the panel to the wall. In most cases, the top two screws can stay in place as the timer will lift off with them in place. Once you have the screws loosened, you can lift off the old timer.
Next, grab your new timer and slide it onto the screws you left on the wall. This is where using the exact same timer helps. You’ll have to grab a drill and drill new holes if you have a different timer. So, mount the timer and secure it in place. Next, thread the cables into the side of the timer and connect them into place.
Finally, install a battery so that your timer remembers the program in case of a power outage, and program the timer in accordance with your local irrigation ordinance.
Tools & Parts to Replace an Irrigation System Timer
- New Timer
- Screwdriver
- Drill & Drill Bit
- Battery for the Timer
Replacing an Irrigation Solenoid
If you removed one of your solenoids because you were trying to figure out why your irrigation system is still running and your sprinklers won’t turn off, then you have pretty much done half the work.
To replace a solenoid, you just need to unscrew the old one and screw in the new one. Finally, connect the two wires in the same place as the original wires. It doesn’t matter which way around you connect the cables as long as one is in the COM and one is in the positive.
Parts to Replace an Irrigation Valve Solenoid
- New Solenoid
Replacing an Irrigation Valve
Valve manifolds come in all shapes and sizes. Some are easy to work with, and some are not. Changing an irrigation valve can require a lot of tools, specialist knowledge, and skill. One wrong cut can lead to some very expensive repairs. So, if the system is glued together without any way of removing the valve without cutting the pipes, then I recommend you call a professional.
But if you happen to have an Orbit manifold or similar, you could be in luck. These all-in-one manifold kits use a special union fitting that allows you to remove components without cutting. So, all you need to do is purchase a replacement valve and screw it into place and install the solenoid for the original valve. But again, you might want a professional to take a look first.
Parts to Replace an Irrigation Valve (Union Connection Only)
- Replacement Valve
Tips to Help Prevent This From Happening Again
I’ve used an irrigation system for quite a few years now, and I’ve had my fair share of problems. To help me avoid sprinklers that won’t turn off, I’ve made a few adjustments to my system. So, here are a few tips to help you avoid simpler problems.
Relocate the Timer
Irrigation timers that are mounted outside have to face all types of weather conditions. The heat of summer, the frost of winter, and the wetness of the rainy season. One way to avoid the elements is to relocate the timer inside.
My timer was located on the outside wall of my garage until I moved it to the inside. My new timer looks as good as new, even though it’s a few years old.
Install An Irrigation Filter
You could install a filter to protect your irrigation valves from debris. These are inline filters that catch any junk that comes up the lines.
These are even more important if you have an irrigation water supply from your city. This type of water is less filtered and clean compared to regular, potable drinking water. Some towns even give free inline filters for irrigation systems if you pay for their irrigation water.
Keep the Solenoids Dry
I’ve seen a lot of irrigation systems that have their valves and solenoids underground. This is great for keeping the system out of sight, but they can sometimes become submerged in water. If your solenoid is submerged in water on a weekly basis, you may want to look for a way of keeping them dry. This will stop connections and the solenoid from going rusty and becoming a problem.
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