Question
My gardener recently replaced the valve for zone 1 of my yard sprinkler system.  Now, when it comes on, the valve shakes and one of the water pipes with a spout shakes also.  None of the other 3 zones shakes or makes pipes shake when they come on.  He cannot figure it out.  We tried opening the flow control all the way, closing while counting the number of turns and reopening halfway.  It still shakes.  What do you suggest?

Answer
Usually when that kind of shaking occurs, it is because there is a considerable pressure differential between the upstream and downstream side of the valve.  If your other valves are the same size, and are connected to the same size supply line, then I would guess that the new valve is not opening all the way, or is malfunctioning in some way that makes it open very slowly.  If it is a different type or brand from the other valves, it may have a different flow rate, and may need to be open more than halfway.