Mysterious Water/Pipe noise at midnights

[Jessicayiyi]

Dear Jadnashua,

Here are some updates:

We did not hear anything last night (fortunately).

We installed the gauge right above the main valve in the garage around 12pm on 10/31, (the reading was around 60psi). This morning (11/1) around 10am, we took the first reading. The peak is 70psi (please see attached picture). We wound the red hand back and will read again tomorrow morning.

 

[Jadnashua]

Well, the good news is your pressure seems to be reasonably well controlled. That appears to be a PRV there. Do you have an expansion tank in the system? If not, that could account for the 20psi difference. A PRV and an expansion tank go hand in hand... Any residential valve is designed to work up to 80psi, and is tested for more (your WH is tested to 300psi and has a safety valve set at 150psi). Often, the weakest link is a toilet fill valve, and with high pressure, those can make some weird sounds.