One site guy is a real lazy astard-bay. He turns on the manual zone valves, leaves them on and then just uses the shut-off valves on the PVBs to activate multiple zones at once. But what happens when you don't get the PVB shut down all the way? We ended up removing the handles from four PVBs so hopefully it will stop this practice. If he spalls the valve stems by using pliers then he'll have to answer to the plumbers.