# Valve not turning off



## zuburg (Aug 10, 2020)

New to irrigation but learning a lot. When I had my system installed 7+ years ago, I had them stub two extra zones complete with valves, etc. One for the front landscape bed and one for the back landscape bed. I am now trying to hook into one of these zones.

I laid the PVC pipe and attached one sprinkler head. I went to the valve and turned the solenoid to turn on the new zone. That worked as expected but when I turned the solenoid back to turn it off, it would not turn off. I had to turn off the manual water valve that feeds the whole system to get it to turn off and drop the pop-up head.

I also noticed the valve was leaking (it appeared it was leaking around the flow control as well as between the valve body and the bonnet. I disassembled the top of the valve and saw several small black pieces of plastic in the screen at the top of the body. I bought a new valve and replaced the diaphragm, spring and seat. I no longer see any leaks but the valve still will not turn off.

Now questions. I think I basically understand how the valve works (Pretty ingenious design). I understand that you normally have the solenoid in the off position and when the controller sends the electrical current, a magnet pulls the plunger up allowing water in the top of the valve to flow out until the pressure changes and opens the valve. And when the current is turned off, the plunger drops back down causing the water pressure to change until the diaphragm closes the valve again. What I don't understand is what happens when manually turning the valve in and off by turning the solenoid. When manually turning the solenoid, does it physically move the plunger off the dump port?

I did not replace the solenoid Since it opened both manually and by the controller, but plan to try that next. Is it possible for the solenoid to work to open the valve but not close it? If you can turn the solenoid to manually open the valve, why won't it close the valve when you turn it back off?

Unrelated question: I have 9 zones counting the two unused zones for expansion. Only one zone (the one I just added a sprinkler to) had a valve with flow control. Is there any reason for this or did the installer more likely run out of the cheaper non-flow control valves?

Thanks all


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## RVAGuy (Jul 27, 2020)

The valves function by removing pressure on the top of the valve when you want water to flow. This either happens when a solenoid opens or the manual part is turned. Check out this small powerpoint from Hunter. https://www.hunterindustries.com/sites/default/files/null/basic-valve-hydraulics-illustration.ppt. It uses the higher surface area on the top of the valve to hold the diaphragm down and shut off flow.

When you manually turn the solenoid, you pick it up off it's seat and allows flow through both ports and opens the valve. It's entirely possible the solenoid isn't returning to it's seat and should be replaced. It may have gotten crap in it like the rest of the valve. At least check it for crap on the seat.

On you other question, your sprinkler bodies may regulate pressure at the body. Hunter PRS-40's do that as with the PRS-30's. It's possible they ran out or wanted a lower pressure at that section for whatever reason. It's easier to drop the flow there than at each individual body. It's also possible they wanted lower pressure for micro irrigation (drip lines) or something.


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