Watts Pressure regulator does not hold water pressure

[GoshenPlumber]

I have a Watts 1 inch pressure regulator (series 25AUB) in an outdoor underground pit (about 3.5 feet below the surface) that was installed in 2005. The regulator is used to drop the city supply pressure which ranges from 100 to 130 PSI (as measured at the water meter) to a pressure of about 40 PSI (as measured in my basement). About a week ago the water utility repaired a main line leak about 1/2 mile from my house and had the water shut for about 4 hours. Ever since this repair, the regulator no longer holds the pressure to 40 PSI. When I go to sleep the pressure is at 40 PSI but overnight the pressure creeps up to about 60 PSI. I did an experiment last night where I isolated the hot water tank (by closing the inlet valve) from the cold water supply. The pressure this morning still had increased to about 60 PSI which means the pressure increase is not due to thermal expansion from the hot water tank.

Why can't the regulator hold the pressure? Could this be due to dirt on the seat where the dirt was introduced into the system by the utility's repair? If so, is there a way to flush the dirt without taking apart the regulator? Is there another possible cause? Do I need to replace the regulator?

Should I ignore the problem or is the regulator about to fail and should be replaced?

Thank you.

 

[johnjh2o]

I would replace the regulator. If possible I would install the new one in your home to make it more accessible. It's not uncommon for them to need repairs.

 

[GoshenPlumber]

I solved my problem! Now I would like your opinions as to why my solution worked.

Here is what I did. First I turned on an outside faucet so that there was constant water running through the house piping. Then in the water meter pit upstream of the PRV, I turned the shutoff valve off and on several times. Each time when I turned the valve on, I did so quickly in order to force a gush a water through the PRV. Two tests where we did not turn on any water for at least 8 hours have showed no pressure increase overnight as measured at the pressure gauge in the basement.

My weak opinion is that there was dirt on the PRV seat and my turning the shutoff valve on quickly cleaned the seat.

Comments anyone?