The Brain of the Outfit
This unit, called an irrigation controller, sends signals through wires that turn the system’s valves on or off.
The sensor switch is set to “bypass” because the sensor is optional, so it wasn’t installed with this controller.
The industry is currently in a transition period from this type of system, where each valve has its own control wire to a new technology where only two wires (common and hot) will run from the controller to all valves. The valves in this two-wire system are controlled by digital decoders that communicate with the controller.
There are several advantages to a two wire system. One is that troubleshooting is much easier, as there is only a single circuit to check. Another is that it’s easy to add valves to the system. Instead of having to run a new control wire all the way from the controller (also called a “clock”) to each new valve, wires can simply be spliced from an existing valve and new decoders added to run the added valves.
Currently, the disadvantage of two wire systems is their cost. As the technology evolves, valve solenoids (the gizmo that turns them on or off) will probably be integrated with the decoders. Controllers can shrink, too – since only two wires need to be hooked up to run even large numbers of valves .
Hopefully in the future, controllers will use Wi-Fi or some other technology that will allow them to be programmed from any web browser, even remotely with a user name and password. This would also let the system’s designer or maintenance personnel re-program the clock as needed.
The switch is set to “bypass” because no weather sensor is installed.