Decreasing Water Pressure

[Wpollock]

Facts:
1. Single story home built in 2019 with city water supply.
2. 60 psi pressure at nearest and farthest hose bibs from pressure regulator at move in.
3.Hot water tank has expansion tank.
4. Current pressure at same two bibs is 51 psi.
5. No leaks in any visible locations( city main meter box, owner's main shutoff valve box, pressure regulator box, all lawn irrigation valve control boxes, no running toilets, faucet leaks or pressure release valve, main water meter doesn't show any flow when all water outlets are in closed positions, no signs of any leak on sheetrock or floors.
No notification from city that there has been a pressure drop on main supply line for my area.
Is it possible that I simply need to adjust the incoming pressure back to the original 60 psi supply at the pressure regulator?
If so, how do I adjust the pressure on the hot water tank expansion tank to have the same pressure if needed?
Thanks for any thoughts.

 

[Reach4]

I applaud your rigor.

Do you have a way to read the pressure before the PRV? If not, I would consider asking the water department what to expect as the lowest incoming pressure, and if there have been changes.

To adjust the air precharge pressure of the thermal expansion tank, the water pressure should be near zero.

 

[Sponsor]

 

[WorthFlorida]

If so, how do I adjust the pressure on the hot water tank expansion tank to have the same pressure if needed?
Thanks for any thoughts.

With the water off to the expansion tank or WH, and if possible disconnect the tank to allow it to drain. Then pressurize it to 60 psi. Expansion tank should equal the average pressure, usually during the daytime.
The PRV only reduces pressure, not maintain 50 psi if the supply side pressure drops below 50 psi.

My home it's 70 psi. Over night it would go to 125 psi. Now it's about 90 psi with the expansion tank.