Open Lawn Sprinkler Valve

Rich has a sprinkler valve question:
hello craig, how do you turn on a zone manually from the valve. in a automatic system i had in san diego, on the top of the valve there was a + screw that you could turn and that zone the sprinklers would turn on until you turned the + screw off. when you did this you weren't closing the valve itself. i have an automatic system but dont know where i can't manually turn it on. any thoughts. rich

All of the automatic sprinkler valves that I am familiar with can be manually opened by turning the solenoid counter clock wise. This releases water off the top of the diaphragm, which is exactly what a solenoid does when activated by the sprinkler timer. The area on the top of the valve diaphragm is slightly larger than the area below it, which means that the pounds per square inch (psi) is greater. Any release of this upper chamber pressure will open the valve.

When you open a valve manually in this fashion, do it very slowly and stop as soon as you hear the water rushing through. If you turn the solenoid too far, it will pop off!