How to Choose a Solenoid Valve
Use the following guide to learn about the different solenoid valves and how to select the one that suits your system
Options to Consider:
- AC or DC
- Normally Closed or Open
What are Solenoid Valves
Solenoid Valves come in a variety of different designs but function mainly the same.
A solenoid valve aims to hold the water flow and pressure in the line and only let the water through when directed to do so.
This is a standard Normally Closed valve. Normally Open are the opposite and let the water flow through unobstructed until directed to close the flow.
Most solenoid valves come in three main parts, the Body, Diaphragm and Coil.
- The Body of the valve can come in either metal or plastic
- The Diaphragm is the rubber diaphragm dividing the two inside chambers, controlling the water flow
- The Coil is an energized spring that controls access to the top chamber.
Solenoid Valves Components
Most solenoid valves are serviceable, allowing you to access the solenoid valve components to clean and repair etc. Different brands of solenoid valves have parts available for replacement.
AC and DC coils are sometimes interchangeable on the body but depend on the brand.
The coil is usually detachable and wires to the controller. The coils are commonly magnetic charged springs that open and close upon power being delivered. This opens and closes the upper chamber outlet, controlling internal pressure.
The diaphragm is the physical item that opens and closes to allow water to flow. When the upper chamber has filled, the pressure keeps the diaphragm closed. When the pressure equals, the diaphragm lifts to allow the flow.
Why Are They Effective
We go for solenoid valves in the majority of irrigation systems due to the open flow and pressures they can withstand.
Most standard landscape solenoid valves are rated to 12-16 Bar, allowing you to connect directly into the mains water supply or directly after a pump. This is a big advantage over tap timers as they average a pressure rating of 5-8 Bar.
Solenoid valves offer little flow restriction through the valve. Once the diaphragm is fully opened, it's hard to notice the pressure and flow loss. Compared to tap timers where they can restrict down to a 10mm inside diameter size.
The average lifespan of a solenoid valve is 10 - 30 years, with parts easily available for servicing.
AC vs DC - Alternating Current vs Direct Current
Determining whether you need an AC valve or a DC valve is easy and sometimes not in your control. If you don't have a 230-240V power source available, or a 3 pin plug port, your only option is DC.
AC valves are considerably cheaper than DC, but both provide the same function done nearly the same way.
- AC valves need constant power to operate the solenoid coil; once the power cuts off, the coil and the valve close.
- AC Valves are 24 Volt
- DC valves use a pulse of power provided by a battery to open the coil and another pulse to close.
- This is referred to as a DC latching solenoid
- DC Valves are 12 Volt
An indication the valve may be DC is black and red coloured wire.
Pros of AC
Cons of AC
- Requires power supply
Pros of DC
- Perfect for areas where power is not available
Cons of DC
- More Expensive
Normally Closed or Open
9 times out of 10, you are going to want a Normally Closed solenoid valve. Nearly all landscape valves and system require normally closed. Some operations like backwash filtration will need normally open.
Normally Closed valves mean that when the valve is not operating, the valve is shut, and water can not flow through.
On the other hand, Normally Open valves have a resting position of open, so water is free to flow through when power is not provided.
Common Landscape Valves
Below is the landscape valve we use on the majority of our designs and projects. Hunter and Rain Bird are leading brands in the USA and have a good reputation for producing quality made products. Most landscape system can stick with the 25mm size valve.
The Rain Bird DV/DVF valve is the premium valve product chosen by more professionals than any other valve on the market. Its long history of reliable performance makes it the natural choice for your landscape. Its consistent, problem-free performance means you can spend less time thinking about your irrigation system and more time enjoying your landscape.
- Heavy-duty Hunter solenoid Provides dependable operation and long life
- High grade construction, 150 PSI rating Made of durable materials to resist wear.
- Internal and external manual bleed – Two options for manual operation
- Flow control with non-rising handle. Adjust the flow of each zone on a system
The DC latching coil allows the solenoid to connect with battery powered controllers. Hunter 24 VAC Solenoid Valves are also available for connecting to mains powered controllers.
This hard working, heavy-duty performer offers you the best features of Hunter’s top-of-the-line valves…more than enough to handle the rigors of whatever your site has to offer.
If you have power available, go for an AC controller using AC valves, as this is the most economical option compared to the DC.
Most valves will give you better performance and lifespan than tap timers, so the valve brand is not really important.
Hunter and Rain Bird have been around for years, so you can rest assured that their valves will remain with parts available.
Ezy Valve Solenoid Kit
A Good Alternative
The Antelco Ezy Valve 4 is a simple and cost-effective way of upgrading your system to a solenoid valve and controller but without the hassle of assembling the valves and picking the parts.
A compact valve box with 4 internal solenoid valves that connect to a 24VAC or 9VDC irrigation controller. Installation is uncomplicated and provides a trouble-free way to distribute water to an irrigation system suitable to 20 L/min.
The Kit comes with the correct wire connectors and instructions to make the job easy.
If you are unsure about controllers, solenoid valves and all the components that go with them, then maybe this is the perfect step in the right direction for you.
Gem-Sol Valves are another type of solenoid control valves and specifically relate to the coil of the valve. A Gem-Sol Valve is made up of two parts, the Operator and the Coil.
- The Operator is the valve stem that contains the spring and plunger.
- The Coil is still the power source, but fits over the top of the stem and is not pre-wired, like other coils.
For a Gem-Sol valve, we need images of the complete valve and stem as they can change from valve to valve.
The length and diameter are important features as they determine the correct Gem-Sol Coil to suit.
For more information, contact our experts on 0800 130 905.