Hi,I've read a lot about water hammer and it sounds like that is what is going on in our two family house but the only thing is our pipes bang quite frequently and very loud, it happens even when no one is using water. I have been home by myself when even our downstairs neighbor was gone and the pipes continue to shake pretty violently it is also extremely annoying especially when trying to sleep. Please help! Thanks!

Do you have a pressure reducing valve (PRV)?