How a lawn sprinkler system works.
During the watering season the system has pressurized water that is held back by the valves. When the timer sends an electrical current to the valve it opens and allows water to flow to the sprinkler heads. Timers need a common and a hot to each valve. Most wires used in the last few years are color coded.
Some irrigation systems have “dirty water” also referred to as non-potable, or pressurized irrigation. These systems should be protected with a filter to prevent foreign materials from clogging nozzles and valves. The filter should be cleaned as necessary.
Pumps can be installed on sprinkler systems to supply or boost the pressure to the system. If a pump is used the timer can turn the pump on and off using the master valve feature.
Manual valves are not common but still exist, these need to be turned on and off using a short tool.
Most timers use low voltage twenty four volts.
Remote timers are battery operated timers in close proximity to the valves; the valves require a special latching lower voltage solenoid. The batteries, usually AA, last a full season and should be replaced annually.