Copper Pipes "Ticking" Mystery

[jjtrindc]

Have a bit of a mystery on my hands that I'm hoping this group can help me with some ideas. A few weeks ago, we started getting a "ticking" noise coming from our copper water pipes. I'm pretty sure it's not water hammer as there is no banging. And this is also different than the PVC pipes expanding as hot water discharges (we have that too, so I know the difference).

As best as I can tell it is coming from the area right where the water enters the house on the main line in our basement, in the pipe above the whole house water filter (GE GXWH30C), but before the PRV (seen upper right). If I put my hand on that pipe when I hear the noise, I can also feel a slight vibration. I've tried checking the pipe below the water meter and I usually can't feel anything or very very slight. It could be possible that it's traveling down the pipe from the PRV.



It seems to usually happen a few minutes after water has been running in another part of house, though while the water is running or immediately after. But it doesn't happen every time either. Sometimes the noise is loud, sometimes soft. Sometimes it lasts for only 10 seconds, sometimes upwards of a minute off and on for a bit. Sometimes the ticking is slow, sometimes it's faster. Time of day doesn't seem to be a big factor though it does seem to happen more in the evening than the morning (though that could be because more water activity). Really there doesn't seem to be any consistency to it. Case in point, sometimes it will happen in the middle of the night when no water is running. We can expect it to happen every day.

Here are some things we've tried:

The one thing that seemed to stop if for a while is when I changed the filter on the whole house water filter (it was well past due). That stopped the noise for about 24 hours but then it came back.

I had the water company come out and put in a new water meter, but that didn't solve the problem.

A plumber did come out and of course the noise didn't happen. He tested the water pressure and played with the PRV to get a couple of readings but felt it was all in spec. He suggested changing the water meter before changing out the PRV. The PRV was replaced about 9 years ago after it had been found leaking.

If I turn off the water above the PRV the noise stops immediately.

I put rubber strips between the copper pipe and the stud in case there was expansion.

Tried to empty all of the air out of the system (though in retrospect, I realized that I didn't run the washing machine or dishwasher in the process so not sure if that would have made a difference).

Lastly, I'll just note again that this is a new noise in the past few weeks. No modifications have been done to the plumbing system. Basement temps are relatively constant. So that is why it's a mystery. About to start replacing the PRV and perhaps the whole house water filter mechanism (about 5 years old or so), but thought I'd check this forum first for any ideas to try! Thanks in advance.

[jadnashua]

Do you have an expansion tank? With a PRV, you need one. The PRV could be getting old, but when you have one, you must have a working expansion tank. When you heat water, it expands. The PRV won't let water push back into the main (normally). The ticking could be from expansion from the WH, but regardless, if you have an expansion tank, it could be bad and need replacement, or if you don't, you need to install one.

[Terry]

I often find that it's the old PRV causing the problem. Replacing it seems to solve the issue.

[hj]

It is probably the sound of the water meter as water is flowing through it. If the PRV is getting "slow" it will continue to feed water after the faucet is turned off as it starts to stablize at its setting. Turning off the valve does not isolate it because it stops water from flowing through the meter, but also stops water flow in the house. Either one would make the noise cease.