That’s not water hammer. It’s probably the pressure reducing valve, it doesn’t matter if it’s new.
What’s your starting pressure before you reduce it with the PRV ?
Doesn't sound like water hammer. Something is clicking or vibrating. Place your hand on the pipe especially near the PRV. You should feel the vibration and the more vibration you feel, closer you are getting to the source. Do you have a hot water heating (hydronic) system? Do you know if you have an anti backflow device at or near the water meter?
Shut off stop valves around the home to isolate the noise at sinks, washing machine, ice water line to the refig, etc?
You know what, you are right , this has been something to do with PRV. and water pressure.
Yesterday I accidently solved this problem that has been there for years!
And the solution has been simple and I think one of the plumbing companies kind of cheated on us now that i know what the problem was.
So just a few months ago after checking high water pressure of 100 psi, we called a plumbing company to check if our old water pressure regulator is working or not and adjust it so the water pressure is less and this sound goes away.
They came and looked at the old regulator, not sure if they checked it to test if it's working or not, and told us to install a new one.
They did not replace the old one , but installed a new one above the main supply faucet. This old regulator was left as it is below the supply faucet.
So we paid 667$ and after the new regulator and reduced water pressure to 55 psi, still this sound persisted.
Just now, i was planning to get a hammer arrestor but then i thought may be i will try to turn the pressure regulator screw on the old regulator and see if it works, if nothing it wont do any harm.
So i did.
And guess what, that did it! All i did was turn it a bit loose, and there is no more sound. No clicking, hammering sound, water flows smooth and shuts off without any sound.
Solved!
So it seems now we have two working regulators.
If only that plumbing company had done their job thoroughly and checked the old regulator to test if its working, instead of just looking at it and installing a new one above the faucet,
We didn't have to spend 667$.
Also we could have tried to adjust pressure ourselves before calling them, but since we didnt know how old the regulator was, didnt want to mess with it, so we called this company. But they didnt test it and installed a new one without replacing it.
So apparently the water pressure from old to the new regulator was a lot, and that was causing the sound. After adjusting the screw on old regulator, the sound is gone!
