Sprinkler Zones Won’t Respond

Hello all, I’m reaching out for guidance as I’ve met the limitations of my own experience and troubleshooting abilities.
I’m helping a friend fix her sprinkler system and have run into a serious problem. When main water supply is turned on to the sprinklers zones 1 and 2 flow freely. I’ve checked the solenoids which are operational and get voltage when the control panel sends it. I’ve checked the diaphragms which were old, and I replaced. We’ve replaced several bad heads located throughout her system.
If I turn zone 3 or 4 on, which are located further down the system, zones 1 and 2 will start behaving more like expected.
Is this a pressure problem? My mind leads me to believe that the pressure through the system is too high, which allows it to bypass the valves for Z1 and Z2 but once Z3 or Z4 are turned on pressure drops and valves at Z1 and Z2 operate properly.
She obviously wants to control her sprinklers from the control panel instead of having to go down to the water main and turn on the valve to the sprinklers. Can anyone offer some insight to this
Cheers
Benjamin

 

This doesn't make a great deal of sense. The zones should be isolated and come on independently. Are you saying when you turn on zone 3 or 4 that zone 1 or 2 comes on? If you're trying to run all the zones at once, yes you will have a pressure problem. That's the point of having zones.

 

apologies for the confusion.
Zones 1 and 2 turn on as soon as main water supply is turned on to the sprinklers. Regardless of the control box.
If I turn on either zone 3 or zone 4 from the control box things begin to behave as normal with zones 1 and 2 turning off and zone 3 or 4 working as should be.

 

None of the valves should be normally open. Irrigations system circuits should always be normally closed. Zones 1 and 2 coming on when the main is open is not the proper operation. I suspect the valves may have been manually set to open. There is a knob on top of the valves which can be used to manually open the valves. Twist the knob clockwise to close the valve. What is likely happening is when you turn on either zone 3 or 4 the pressure drops so much there isn't enough to supply water to zone 1 and 2 and they appear to be off. You shouldn't be running more than one zone at a time.

 

Thank you Hudson. I concur about the pressure drop when zones 3 or 4 are turned on. But have been having difficulties even ensuring that the valves at zones 1 and 2 are working. I’m certain I’ve opened them and closed them several times at this point, but I will definitely check again. I hope it’s the fix!

 

What did she fix? First, disconnect all the zone wires from the controller. With just one zone connected (wired) turn on that zone. If none of the other zones operate (as they should not), you do not have a valve problem. Do this for all zones with one zone at a time. If nothing happens but the one zone, then it could be the controller or wiring.

At the controller with all wires disconnected except the common, operate each zone and only that zone terminal will have ~24v AC. If you read 24 v on more than two terminals with one zone active, then it is a controller problem or depending on the controller, a bad module. A very common type of failure for modules. You need to check that the common wire is not crossed up and connected to a zone wire. The common wire is connected to all valves. If this is on city water and no master valve, be sure nothing is connected to the MV terminal. If you are using a pump, then the MV would be for the motor start relay.