Water Irrigation Solenoid Valves

Figure 1: Underground automated solenoid valves

Water irrigation solenoid valves are essential components in modern sprinkler systems, providing precise control over water flow to ensure efficient and effective landscape irrigation. These valves, which can be electrically operated from a distance, are versatile tools that cater to a range of pressures and flow rates and are designed with various functionalities to meet the specific needs of different irrigation setups. This article explores the role of solenoid valves in irrigation systems, their selection criteria, common issues, and troubleshooting procedures.

Solenoid valves for sprinkler systems
Installation locations
Selection criteria
Causes of sprinkler solenoid valve failure
Diagnosing a faulty irrigation solenoid valve
FAQs

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Solenoid valves for sprinkler systems

Irrigation solenoid valves are electrically controlled valves that regulate water flow in an irrigation system. When activated by an irrigation controller, the solenoid—a coil of wire that acts as an electromagnet—moves a plunger to open or close the valve, allowing water to flow to the sprinkler heads or stopping it as programmed. Read our solenoid valve overview article for more details on the working and types of solenoid valves.

The main roles of solenoid valves in sprinkler systems are discussed below:

Remote activation: Solenoid valves enable the remote activation of the sprinkler system, allowing it to be controlled from a central panel or smart device when connected to a smart irrigation controller. This feature ensures the garden can be watered regularly and consistently, even when the homeowner is absent.
Zoning: Solenoid valves allow for more efficient watering by controlling water flow to each zone independently. Different zones can be tailored based on plant type, sun exposure, soil conditions, and other factors, leading to healthier plants and a better-maintained garden. Read our zone valve overview article for more information.
Timing: The ability to program solenoid valves for specific times optimizes the watering schedule. This precise control helps conserve water by ensuring the landscape is watered only when necessary and for the appropriate duration. Read our solenoid valve timer article for more details on programming analog and digital times for solenoid valves.
Pressure regulation: Solenoid valves with built-in pressure regulation maintain consistent water pressure, ensuring effective operation of sprinklers and even water distribution.
Integration with sensors: The valves can be integrated with sensors like rain, soil moisture, and flow sensors. These sensors adjust the watering schedule or shut off the system as needed, preventing overwatering and conserving water.
Water conservation: Automated systems can be set to irrigate during cooler times to minimize evaporation. With rain sensors, the system avoids unnecessary irrigation, further conserving water.
Integration with water sources: In remote or water-sensitive areas with a water tank, solenoid valves can work with float switches to monitor water levels, ensuring the system operates within the water supply's capacity.

Installation locations

Water irrigation solenoid valves are typically installed in the following locations within a sprinkler irrigation system:

Valve box: Protective enclosures buried in the ground to protect the valves from the elements and damage.
Main water supply line: Connected to the main line to control water flow to different zones.
Beginning of each zone: Positioned at the start of each irrigation zone to regulate water to that area.
Downstream of backflow preventer: Installed after the backflow prevention device to ensure contaminated water doesn't flow back into the clean water supply.
After the master valve: If a master valve is used, zone valves are installed downstream of it to control individual zones.

The valves are wired to an irrigation controller to manage the watering schedule, usually mounted on an exterior wall or in a garage.

Selection criteria

The main parameters to consider when choosing an irrigation solenoid valve are:

System pressure and temperature
Valve materials
Flow rate

Read our article on water solenoid valve selection criteria for more information on the materials, design, flow rate, and other general parameters to consider when choosing a solenoid valve for an irrigation system.

Additional factors to consider include:

Valve size and type: The size of the solenoid valve should match the size of the irrigation system's pipes. Common sizes range from 1/8 inch to 2 inches (3.2 - 50.8 mm).
Compatibility with controllers: Ensure the solenoid valves are compatible with the irrigation controller. Some smart controllers can provide advanced features like flow monitoring and leak detection, but they must be paired with compatible valves.
Flow control: Some solenoid valves have an adjustable flow control feature, allowing you to fine-tune the amount of water passing through the valve. This can be particularly useful for balancing the water distribution across different zones.
Electrical requirements: Check the electrical specifications of the solenoid valves, including voltage and amperage, to ensure compatibility with your irrigation controller and power supply. Common voltages for irrigation solenoids are 24VAC (volts alternating current), but other voltages may be used in some systems.
Valve configurations:
1. Solenoid valves can be normally closed (NC) or open (NO). Normally closed valves are closed when de-energized and open when energized, the most common type used in irrigation.
2. Water applications use direct, semi-direct, and indirect acting solenoid valves. Choose a direct-acting solenoid valve for applications requiring fast valve response at 0 bar; conversely, for applications with high flow rates and pressure, choose an indirect solenoid valve. Semi-direct valves work well for low to medium pressure applications and moderate flow rates.
3. A 2-way solenoid valve is typically employed to open or close a passage. Three-way solenoid valves can be quite useful in more complex irrigation setups, such as those that require the distribution or mixing of fluids, or where multiple sources or destinations for water are involved.

Manual override: Look for valves with a manual override feature. This allows the valve to open or close manually without electrical power, which is useful for maintenance or in case of an electrical failure.

Causes of sprinkler solenoid valve failure

Solenoid valve failures typically stem from issues with the electromagnetic coil or the valve mechanism. Common reasons for these failures include:

Incorrect voltage: Applying too much voltage to a solenoid valve can burn out the coil, necessitating a replacement. It's crucial to ensure the voltage rating of the valve matches your irrigation system's output. Installing surge protection can safeguard against voltage spikes from events like lightning strikes or static discharge.
Water exposure: The solenoid valve's coil can short-circuit if it comes into contact with water or other liquids. Using a proper DIN connector can protect electrical connections from moisture. While some valves have basic o-rings for water resistance, additional protection may be needed, especially outdoors. A high-quality irrigation control valve box can also help keep solenoid valves dry.
Sediment buildup: Sediment can enter the solenoid valve and cause significant problems, including overheating and damage to internal components. An upstream irrigation filter and vertical valve installation can help prevent sediment from reaching the valves.
Excessive water pressure: Water pressure exceeding the valve's capacity can cause the valve to burst, potentially damaging a larger portion of the irrigation system. Always check the pressure ratings of the system's components before installation.
Temperature fluctuations: Extreme temperatures can damage solenoid valves, rated for specific temperature ranges. Both high and low temperatures can wear out the valves, leading to the need for replacements.

Diagnosing a faulty irrigation solenoid valve

Look for these signs to diagnose a faulty irrigation solenoid valve:

Low water pressure: Brown spots on the lawn may indicate low water pressure, suggesting that water isn't reaching far enough from the sprinklers.
Water leaks: Leaks can result from excessive water pressure, which puts too much stress on the system.
Continuous water flow: A valve that won't stop releasing water could be stuck open due to mechanical issues or debris.

Diagnosing solenoid valve problems typically starts with checking the electrical signal. If the signal is incorrect, the circuitry may need replacement. If the electrical check is clear, the next step is to look for mechanical issues with the valve or solenoid. Finally, if no issues are found externally, the valve should be opened, cleaned, and inspected for internal damage. Read our solenoid valve maintenance article for more details on maintaining and troubleshooting solenoid valves.