I’ve had a 4-8 knock banging (repeating 3-7 times with 2-5 minute intervals) at odd times during night and/or day. I can’t create the noise through any use of water in my single story apartment. It started 5 months ago.
I have a hole in the wall at main shut off and can put my hand on the main water pipe to feel this banging. Pipe isn’t loose. I have a pressure reducing valve on which is 1 year old.
What is going on? My regular plumbers are stumped.