Knocking sounds in hot water pipes
Hi. I have annoying loud knocking sounds coming from a 3 inch diameter hot water pipe that feeds part of the 23 story apartment building that I live in. It feeds each apartment's heat register ( a 1 inch pipe coming off the 3 incher)Management can't figure out the problem. Only a few apartments experience this sound. I opened up the wall in my apartment out of desperation to see what I could see. (I thought maybe a small leak but no, no leak). This pipe is surrounded by concrete and there is no gap (to allow for expansion) between the pipe and concrete. My question is: Would drilling some 1/4 inch "relief holes" in the concrete surrounding the pipe relieve the pressure and allow for better contracting/expanding and hopefully end the knocking? Thanks for a reply.
Sincerely,
John