How to Test Your Sprinkler Solenoid Valve is Not Bad

A sprinkler solenoid valve is a crucial part of a sprinkler system. If it fails, your system won’t work. To test for a bad solenoid, check its voltage, the controller voltage, and the solenoid and valve for mechanical problems.

What is a Sprinkler Solenoid Valve?

A sprinkler valve solenoid controls water flow in the system. Sprinkler controllers send electrical signals to the valve solenoid, allowing water to flow through the valve at the correct pressure. The pressure dictates how much water a head emits and how far it sprays.

So, the sprinkler valve solenoid is a crucial component of the sprinkler system, and it can sometimes fail due to various reasons, including debris or wear and tear. Thankfully, some common signs may indicate you have a bad sprinkler valve solenoid.

Signs Your Sprinkler Valve Solenoid is Bad

There are a few common problems that happen if your sprinkler valve solenoid has broken, including:

  • Constant water flow: The solenoid may stick open, allowing a trickle or full stream of water to move through the sprinkler, even when the system tries to shut it off.
  • Water leaks: High pressure from a broken or faulty solenoid stresses your sprinkler system, causing minor or large cracks and leaks.
  • Low water pressure: With low pressure from a bad valve solenoid, you’ll see dry, brown spots develop on your lawn because of inadequate, uneven watering.
  • A clicking noise from the solenoid when the system is running, may indicate that the solenoid is attempting to open but cannot fully do so.

Testing a Solenoid

Testing a sprinkler solenoid is a relatively straightforward process. Here's a step-by-step guide on how to test a sprinkler solenoid.

Tools and Materials Needed

  • Multimeter
  • Small wire or paperclip
  • Screwdriver (if necessary to access the solenoid)

Check the Solenoid Voltage for Electrical Problems

Always follow manufacturer safety guidelines when working with irrigation systems.

  1. Turn off the sprinkler system to prevent any accidents during the testing process.
  2. Find the solenoid on top of the sprinkler valve. It's a cylindrical device, often with wires coming out of it.
  3. If the solenoid has wires attached, you may need to remove any protective cover or insulation to access them. Note the color of the wires.
  4. Disconnect the wires from the solenoid. You may need a screwdriver or another tool to loosen the terminals.
  5. Set your multimeter tool to the resistance (ohms) setting.
  6. Touch the multimeter probes to the solenoid's terminals (where the wires were connected). A reading of continuity (a low resistance value) should be observed.
  7. Touch one probe to a terminal and the other to the solenoid's body or casing. There should be no continuity (high resistance) to the casing.
  8. Visually inspect the solenoid for any physical damage, such as cracks or burnt areas.
  9. If you have a small wire or paperclip, you can temporarily connect the solenoid to a power source (like a battery) to observe if it clicks, indicating it is functioning.
  10. Once testing is complete and the solenoid is confirmed to work, reconnect the wires to the solenoid.
  11. Turn on the sprinkler system and observe if the zone controlled by the solenoid is functioning correctly.

If the solenoid fails any of the tests, it may need to be replaced, or you could hire someone to replace the circuitry. Truthfully, though, solenoids are relatively inexpensive to purchase and quite easy to install as a DIY project. It may be cheaper to try to replace it yourself instead of replacing the circuitry.

Check the Voltage at the Controller

It’s also important to check the AC voltage at the controller to make sure it is activating the solenoid.

  1. Turn off the sprinkler system.
  2. Set your multimeter to the AC voltage reading.
  3. Touch one probe to the appropriate station terminal.
  4. Touch the other probe to the C (or COM). It usually doesn’t matter which probe touches what terminal, but for consistency, use the red probe for the station terminal and the black probe for the C terminal.
  5. Turn the power on and activate the station you’re testing.
  6. The multimeter should display the voltage across the COM and ST terminals. You should expect around 24 volts AC in a typical residential irrigation system.

Check the Solenoid and Valve for Mechanical Problems

If the electrical is okay, check for mechanical issues with the solenoid and valve. Open up the sprinkler valve, unscrewing it counterclockwise to remove the solenoid from the top of it.

  • The spring-loaded plunger should pop up; if it doesn’t, push on it to try to get it to pop out. Or you may need to push on it to get it to pop up. Either way, if it gets stuck, it needs to be replaced.
  • Inspect the diaphragm inside the valve. It could prevent the solenoid from closing correctly if it’s torn or damaged. Replace the diaphragm if necessary.
  • Ensure there is no debris obstructing the movement of the solenoid. If found, clean the valve thoroughly. Sometimes, just flushing the solenoid and valve with water can solve problems.

How a Sprinkler System Works

Here's a breakdown of how a typical sprinkler system works:

  • Sprinkler Controller: This is the brain of the system. It allows you to set watering schedules, durations, and zones.
  • Valve: The sprinkler valves are responsible for controlling the flow of water to specific zones in your irrigation system. Each valve is typically associated with a particular area or set of sprinklers.
  • Solenoid: The solenoid is an electromechanical device on top of the valve. When an electrical signal is sent from the sprinkler controller, the solenoid opens or closes a diaphragm inside the valve, allowing or blocking the water flow.
  • Pressure Regulator: The pressure regulator is a separate component designed to maintain consistent water pressure within the irrigation system. It ensures that each zone receives the appropriate amount of water with the correct pressure.
  • Sprinkler Heads: These are the actual outlets where water is distributed. The pressure and flow rate determine how far and evenly the sprinkler heads distribute water.
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