I have a Nelson valve that will not shut off. At the beginning of the season it started. I have replaced the solenoid, taken the valve apart (no cracks or dirt) and checked the voltage (fine-24v). Still have the problem....HELP!!, I can not run my system, becuase if I turn it that zone continually runs. The rest will barly run with the timer on.
Besides replacing the entire valve, which might have some debris clogging something, you could also get a Nelson valve with a flow-control top, use the top to replace the existing one, and throttle it down if it sticks open.