Question
My question is that we are have a problem with a control valve for our sprinkler system. the sprinklers are on a clock and the clock was not on but the sprinklers were on and when i checked the control valve it was in the off position. the only way i could shut it down was by the pressure valve on the control valve. i replaced the diaphragm but it is still doing the same problem. So my question is what else could the problem be or what else could i do to fix it. thank you for your time.

Answer
there are really only 2 main reasons the valve would be on in this case: being powered from the controller or being stuck open from debris or a worn/torn diaphragm or solenoid. If you are sure the valve is not getting power (double check by disconnecting the wire at the controller/clock) and you have changed the diaphragm then at this point the easiest fix may be to replace it. Its not too difficult. purchase the same model and brand if available and remove the bonnet/top as you did when replacing the diaphragm and place the bonnet/top of the new valve in its place.

There are so many minor things that can happen when working on a valve that giving you all the options may be too long for an e-mail message. For example when you replaced internal parts it is important to make sure they fit into the body properly, were not pinched, that the spring and solenoid were lined-up correctly etc... If it is a small plastic valve too much fiddling with it can also give you grief in that it wont quite do its thing again.

So, replacement is probably the easiest and most effective use of your time. mainly because it is glued or clamped in the ground and can be a challenge to remove completely and repair.

Let me know how this grabs you and I would be happy to discuss it further. Good luck!!!