How do you tell if a sprinkler valve is open or closed?

Sprinkler valves are a vital part of any irrigation system, translating the instructions from the main control box into changes in water flow. Without these valves, we’d have a much more difficult time telling our sprinkler system what to do, and automated valve control has made backyard irrigation more convenient than ever before. 

When taking a look inside your valve box, it can be confusing to see your solenoids in the ‘off’ position when you want those valves to be open. Does this mean the valves are closed and preventing water flow through to your sprinklers? 

Well, yes and no – it all comes down to the difference between manually opening or closing your sprinkler valves and allowing your control box or timer to do it for you.

Understanding what this means in context of how sprinkler valves operate will help you determine when your sprinkler valves should be open and when they should be closed. 

Like any technical component, sprinkler valves can seem tricky at first, but familiarising yourself with the way an irrigation valve operates will enable you to use it effectively and troubleshoot any issues that may arise in the process. 

• Should My Sprinkler Valves Remain Open Or Closed?
• How Do Sprinkler Valves Operate?
• How To Open And Close Sprinkler Valves 
• Will Closing The Valve Affect The Flow Of Water?
• Related Questions
  • Do I need a professional to open or close the sprinkler valves?

Should My Sprinkler Valves Remain Open Or Closed?

For electronic solenoid valves – the most common type used in sprinkler systems these days – the nature of the valve means they’re ‘normally closed’. This means that when water is flowing through the valve, the water pressure itself keeps the valve closed unless the valve receives a signal (or manual operation) and switches to open. 

When you check your control box and see that the solenoid valves are in the ‘off’ position, that’s not a problem at all. This is exactly where they need to be in order for the control box to then take charge of opening and closing the valves. Switching them to the ‘on’ position is manually adjusting that valve, which isn’t required unless your control box isn’t functioning properly. 

If the valves are manually opened, this prevents the control box from coordinating the open and close of the valve. Leaving the sprinkler valves in the open position means overriding any programming you have set up through your controller. 

You can operate your sprinkler valves manually – while it is very time-consuming compared to the convenience of automation, it can be handy to know what to do in case of a fault or control box failure. 

How Do Sprinkler Valves Operate?

Automatic sprinkler valves use wires running from the control box to the valve itself, connected to a solenoid – the main component which operates the sprinkler valve and allows it to be controlled electronically.

As water flows through the inlet and into the upper chamber of the valve, the larger surface area above the diaphragm is more highly pressurised than the space below it. This downwards force is what keeps the diaphragm in place, preventing water flowing through the valve. This is also why the default or normal position of the valve is ‘off’ or ‘closed’. 

To turn the valve on, a current is sent to the solenoid from the main control box. Using electromagnetic force, the solenoid raises a small plunger or piston when activated, releasing the pressurised water above the diaphragm and allowing the valve to open. When the valve is switched off and the electric signal ceases, the plunger falls again to block the flow. 

How To Open And Close Sprinkler Valves 

If your control box or wiring is faulty, or you simply want to test a valve on the spot, it’s possible – and quite simple – to manually open and close the sprinkler valves yourself.

Depending on the model, you can manually open the valve by flipping a switch under the solenoid or turning the solenoid counter-clockwise, around a quarter turn. Avoid over-turning the solenoid in either direction, as this can cause damage to the components or cause pressurised water to escape the solenoid. When you hear water rush through the device, it’s easy to tell that the valve has opened successfully. 

Another manual method is to open the bleed screw, allowing water to ‘bleed’ from the upper pressurised section and enabling water flow through the valve. Unscrew the bleed screw in a counter-clockwise direction – just as with a solenoid, a little effort goes a long way and a half turn is usually sufficient. You should see some water trickle out as the pressure is released. 

Your sprinkler valve may also have a third ‘flow control’ screw. If you’re having trouble turning off the valve, the flow control may need to be ‘throttled’ or partially closed to adjust the pressure differential until it’s able to hold the diaphragm in place. It’s perfectly fine to leave the flow control screw in this position long-term if required. 

Will Closing The Valve Affect The Flow Of Water?

Leaving your sprinkler valve in the ‘closed’ or ‘off’ position won’t prevent the automatic control box from turning the valve on normally, if everything is functioning correctly.

If something is preventing water from reaching your sprinklers, the control box or wires connecting to the solenoid may be faulty, or the master water valve connecting to the water supply may be closed. 

In case of ‘weeping’ – or failure for the valve to close completely when it’s switched off – the culprit may be a damaged diaphragm, dirt and debris build-up within the valve, or a faulty solenoid. Air trapped in the valve or insufficient water pressure from the mains can also prevent the valve from closing properly. 

Related Questions

Do I need a professional to open or close the sprinkler valves?

Sprinkler valves can be opened and closed without needing professional assistance, even if your control box is malfunctioning and the valves need to be operated manually. A screwdriver is all that’s required to turn a bleed screw or solenoid, and many models can be turned by hand as easily as a tap. 

In case of confusion when it comes to identifying the bleed screw or solenoid, a manual or video specific to your brand and model of sprinkler valve can help make it as straightforward as possible. 

Sam Christie is the owner and operator of Christies landscapes, founded in 2013 Sam and his team of landscapers and designers have many years experience in the landscape construction industry. Over the years they have developed and refined a broad range of skills, qualifications and techniques to deliver outstanding projects throughout the Canberra region.