We apologize for the issue you are experiencing with your SharkBite Pressure Regulator. The Chatter or Hammering is generally caused by low-flow high inlet pressure, where you have a high incoming pressure and are drawing a very low flow, IE Flushing a toilet. Or it can be caused by High-flow low pressure where your inlet water pressure is close to the pressure setting of the valve and in high demand scenarios, IE Taking 2 showers running the dishwasher and washing machine together. We recommend that you adjust the pressure set net up or down 1 full turn from the factory setting of 45 PSI, this usually fixes the issue, if you are still having trouble or need a refund please call our customer service line at 1-877-700-4242 and we will be happy to help you with this issue and resolve it for you,if possible we would like to get your regulator back for testing in our Lab, we'd be happy to send a paid postage envelope for you to return to us.