Question
I have a 5-zone residential sprinkler system.

All the valves are Orbit Water Master, model # 57020 1?in-line 24 volt solenoid valves.

All the valves are identical.

The system is controlled by an automatic timer controller.

The water pressure is 60-80 lbs.

All five zones are sequenced (1-2-3-4-5) in succession and are programmed for the same amount of time.

Zone 1,2, 4 & 5 all work fine and have adequate water flow to all heads and good coverage. All these zones come on with the timer controller as programmed.

Zone 3 has a problem. The valve is energized when the timer controller calls for it in the given sequence.

However the zone 3 valve will not open up unless the bleeder valve is adjusted (opened until water is leaking from the area around the bleeder screw & then closed) each time the zone 3 valve is energized. Once adjusted the zone works fine with adequate water flow and coverage.

This problem is persistent. Each time the timer controller is cycled the bleeder must be adjusted (opened until water is leaking from the area around the bleeder screw & then closed).



We have changed the solenoid, the diaphragm, plunger and in short all the internal components. In fact we have changed everything except the bottom half valve body. There is more than adequate water flow to the valve and out of the valve.



The valve will work under the following condition only.



(Automatically) If the bleeder is left partially unscrewed to bleed all the time(wasting water).  

Answer
Hi Jay

There are a couple of options to consider for a valve that will not open from the controller.   

Is the valve installed correctly?  Make sure that the arrows point in the direction of water flow through the valve.  

Check to ensure there is no debris in the plunger port-hole or anything that would prevent the plunger from opening completely.  There may be debris in the port hole.  Try this:  Turn off the water to the system. Remove the solenoid. Push a wire or large paper clip down through the round port hole working it up and down to free any debris. Be sure the plunger and O-ring are in place when reassembling.

Or you could test the existing wiring and voltage.  Valves typically require voltage minimums to operate.  The 57020 requires a minimum of 18 VAC to charge the coil (in the solenoid casing) and pull the plunger away from the port hole.  There is usually an audible "click" when the plunger has been successfully pulled up.  The first thing to troubleshoot in this case is the controller.  Ensure that there is a minimum of 18VAC being supplied by the controller to the valve in question.  Where the valve wires connect to the terminal strip on the controller, use a multimeter to monitor the line voltage when the zone is supposed to be on.  Put the black probe on the Common terminal and the red one on a zone terminal after you manually turn on the zone from the controller.  It should read between 24VAC and 27VAC consistently without too much variation..

If the voltage does not vary beyond the range noted above, you may want to ring out the wires and check the continuity from the controller to the valve(s).  Set the multimeter to the ohm setting. The symbol for ohm is the Greek letter omega. If there is more than one ohm setting, choose X1.  A digital meter performs the test providing a numeric reading.  

Note that while the probes are not touching anything, the multimeter will indicate a reading of infinity. A reading of infinity means that the circuit is open. When you touch the two probes together, the reading changes to zero. A reading of zero indicates that the circuit is closed or complete. A complete circuit is one that can conduct electricity; an open circuit cannot.  Place the black probe on the common wire and the red one on the suspect valve wire.  Check the resistance of the problem circuit. If the system has operational valves that typically measure about 30 ohms of resistance (for example), and the one in question measures 6 to 8 ohms, suspect a short circuit. To verify this, go to the valve box and disconnect the field wires from the valve. Check the resistance directly at the valve on the solenoid wires. Confirm whether the short is in the solenoid. If so, replace the solenoid. If not, it's time to look closer at the field wiring.  

Return to the controller and check the resistance through the circuit. With the solenoid removed from the loop and the wires removed from the controller terminal strip, the resistance reading through only the field wiring is probably just a couple of ohms. If the resistance measures more than this, the issue lies in the wiring, not the solenoid.

Hope this helps

Tony