Timer or Clock Controller

• The timer, or clock controller, activates and controls the sprinkler system according to preset conditions. These units are either electromechanical clocks or clocks with a digital readout. The latter is the more popular type of timer and is known to be more accurate than the electromagnetic clock controllers. Both types of controllers work in the same way. Each lets you program a watering cycle according to certain days, times, length of watering and area to be watered.
  
  

Pipes

• The connecting of the pipes and installation, is best done by a professional, although it is possible to do it yourself. A pipe is connected to the water service line. This pipe is called the central water supply line and is almost always a PVC, or polyvinyl chloride, pipe. This pipe carries water to your sprinkler system's zone valves. These zone valves allow water to flow from the larger PVC line to smaller, branching lines and finally out the sprinkler heads. Each zone valve is in effect, the "door" to a zone, or area, of your yard. These valves can be closed or opened by the clock controller, depending on which area of the yard is scheduled to be watered. With the exception of very small yards, all sprinkler systems have several zones that are controlled by this valve. The smallest pipes run from the zone valves to the sprinklers themselves. These pipes are made of something called polyethylene and are often called poly pipes. The sprinkler heads are attached to the poly pipes by simply sliding them onto protrusions that project upwards from the poly pipes. Sprinkler heads come in various sizes and spraying power, but they are all made to "pop up" and open up with the application of water pressure, which again, is controlled by the clock timer.