could be either the PRV or the meter.Ever since I replumbed my house from rusty galv. to PEX my pipes are generally much quieter. However there is a mysterious, very faint, tapping noise.
Sounds like a faint rhythmic tapping.The cadence of the tapping changes with water flow, from, say, a couple of taps per second to 5 taps per second. Seems like, the higher the water flow the higher the cadence. The cadence is constant over time for a particular flow rate (does not sound like thermal expansion).
Happens only when water is running. The noise is present regardless of which faucet throughout the house is on (although the cadence changes with the flow rate). Does not matter whether hot or cold water is on.
When the flow is low it often sounds like a two pitched tapping, a bit like the tik-tak of an old mechanical grandfather clock.
The noise is faint and is really audible only under my main bath. This is also where my 1" copper service line enters the house and connects to the 1" PEX line which then goes to the main PEX manifold in the garage. All pipes are in crawlspace.
The noise is faint so it does not really bother me. Iím just wondering if it may be a sign of a problem.
P.S. Water Pressure 63 PSI. My water heater is set low (probably 110-120F water temp)