Solenoid Controller Watering Systems

Solenoid Irrigation Overview

• A solenoid irrigation system's timer box, also called a controller, is a small computer programmed with the watering schedule needed in each area of the landscape. The controller opens and closes the irrigation valves, each of which is responsible for watering an area of the yard. When the valves open, water rushes through a system of underground pipes and is delivered to plants via sprinkler heads or other types of water-emitting devices. Solenoids are the key components of the system, transforming the electrical signal from the controller to open the valves.

System Design

• The controller typically is located in a garage while the valves often are installed next to the water main where it enters the house. A low-voltage wire runs between them, tying the solenoids on each valve to terminals in the controller. The valves need to be tied into the water supply with a device called a back-flow valve, which prevents irrigation water from entering the household water supply. A branched network of supply pipes must be carefully laid out from each valve to take water to each part of the yard.

Controller Program

• Plants with different water needs should be grouped into separate zones, each with its own valve assigned to it. For example, lawns need frequent, shallow watering and should not be in the same zone as an area of trees and shrubs, which require deep, infrequent watering. The duration and frequency of watering for each zone is set in the controller, as well as the time of day that the valve opens. Most controllers also include a feature to increase or reduce the watering duration of all zones simultaneously as the weather warms in spring and cools in fall.

Irrigation Options

• Particular kinds of irrigation devices are better suited than other kinds to watering certain areas of a landscape, and all of those devices are compatible with a solenoid system. Pop-up sprinklers are effective for watering lawns and other ground-cover plants while taller plants need a sprinkler mounted on an above-ground riser so their vegetation doesn't interrupt the sprinkler's spray of water. Drip irrigation, a system of flexible tubing and tiny emitters that drip water right onto the soil next to each plant, is a better method for vegetable gardens and planters.