Question
I have 3/4 inch richdell valves on my sprinkler system. how do I tell if they are the reason there is not enough pressure to my sprinkler heads. They worked fine two days ago, water is coming out of the heads but not enough to rotate, if the valves are not the problem what else should I check. I have had the system for approx 20 years     thank you

Answer
David,
It is possible that the valve is the problem. On the valvwe there should be a little thumbscrew on the top. Manually bleed the valve by slowly turning the thumb screw until water starts to run out of it. The valve should open up like that. If you do that and it seems to make a difference then the plunger in the solenoid part of the valve has swollen and replace the solenoid or plunger. If that is not helpful, then look for leak(s), tree root restriction, and check the shut off valves to make sure they are fully open. Jim