The problem occurs when turning the bathroom faucet (Moen single lever) on for water. When first turned on and the water flow is low there is no sound but as the lever is moved higher to call for more water pressure, either cold or hot, there is a noise similar to water hammer in the piping and the water flow slows down, and if the lever is moved still higher for more water then the water flow suddenly slows to just a slow trickle with the hammering noise stopping. To get the water flow to resume the lever handle must be closed to off and again opened to get water flow going again. I have replaced the faucet cartridge without luck, problem still occurs, no change. The Moen faucet is a fairly new one that is flow restricted at 2.2 gpm I believe.