I am in a townhouse and since my new neighbors have moved in I've been having trouble with my pipes making banging noises at random times during the day. When I say banging, I mean it sounds like someone is hammering against the wall very loud and very fast and I can hear it anywhere in my house. This does not happen when I am running water, it will happen when I'm sitting on the couch doing absolutely nothing. It normally starts at about 6 pm and can go on and off throughout the night. I've spoken with a couple of different plumbers and they have said the noise has nothing to do with my neighbors, and that it is the pressure reducing valve which they can fix for $400, but my neighbors were gone on vacation last week & the noise didn't happen once. They got back today & within an hour, the pipes were banging. Anyone have any ideas on how I can fix this? If it is the pressure valve, I'm happy to pay, I just want to know if other people have experienced this too.