Whatever the technical term for it, those are the two I have learned for the vertical pipe that comes off a water line at an elbow to stop the water from "hammering" into the pipe when the flow is stopped. Anyhow, right now they come up behind the knee wall in my second floor, about 18" high. Of course, the only place I can put a door to access that area behind the wall is right where they are. Can I cut the vertical pipe off, run the main line over another 16", and then go vertical with it? Or will this lose effectiveness?