Because closing the valve relies on internal pressure build-up, it usually takes a few seconds to completely stop the water flow. This allows the water pressure to build up internally hence stopping the flow. Removing the voltage causes the rod to revert back to its original position. This releases the internal water pressure thus opening the valve, allowing water to flow through the valve. Applying 24VAC on the two wires energizes the coil, and causes the rod to contract into the solenoid. The solenoid has two wires connected to its internal coil. At the center of the solenoid is a rod supported by a spring. The electric part of a sprinkler valve is the solenoid - it’s a cylindrical-shaped thing screwed into the valve. That’s why if you look at a standard sprinkler transformer, the output is usually AC. While most valves indeed CAN be powered by DC voltage (see below), they are designed to work with AC voltage in the range of 22VAC to 28VAC. It’s a common mistake to assume sprinkler valves work with DC voltage. If you are designing a sprinkler controller circuit, understanding these properties can be helpful. I often get questions about sprinkler valves, so in this post I will explain the basic electric properties of sprinkler valves. Note: check out our OpenSprinkler DC-powered version, which uses an innovative circuit design that drives sprinkler solenoids using DC-only voltage.

Farymann electric solenoid valve 24v