Controlling Irrigation Systems
To operate the system a controller sends a low voltage current (normally 24 volts on the small controllers and 32 volts on the larger controller) to the solenoid valve which in turn allows water to the sprinklers.
Small systems can have a tap mounted controller but they are normally limited to one to four stations. Larger systems have wall mounted controllers with separate valve assemblies. These controllers can be either multi wire which normally go up to about 48 zones / stations or a two wire system which give a greater flexibility and can have in excess of four hundred zones / stations