What's wrong with my water pressure?? (trying to lower water pressure)

[CTHaze]

My house has a pressure regulating valve and a expansion tank above the water heater. House was built in 2000.

I'm trying to lower my water pressure which currently reads 82 psi when idle.

When I run the kitchen faucet it falls to 50 psi and when I shut it off it then slowly climbs (I hear a faint water flowing sound even though nothing is turned on), takes about 3 min to get to 60 psi, 6 min to get to 70 psi, and 9 min to get to 80 psi again and the water flow sound stops.

If I do the same thing with the kitchen faucet to get fall to 50 psi, and go shut off the cold water intake right before the expansion tank at the water heater, the pressure would immediately jump to 80 psi.

Is this normal?? Any idea what has failed???

 

[Breplum]

The PRV (pressure reducing valve) has failed. This is VERY common.
Many mfrs make rebuild kits but from my personal experience over 40 years, they are not that easy to rebuild and at least twice, the rebuild didn't end up with a fixed PRV.
Better to replace with a model that has double unions, like Wilkins NR3XLDU or if on a budget the 70XLDU.
With double union model in place, swap outs are so easy.

 

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[Jeff H Young]

I've rebuilt but not really worth it. last time the reg was an 1 1/4 and only around 3 years old. I'm not considering rebuilding 20 year old ones.
CThaze yes common problem just one of those things don't know how to avoid perhaps if pressure is real high consult manufacture they might suggest 2 regulators but I've never done that

 

[Jadnashua]

Some of the regulators have a maximum differential, and while rare, you might have to step it down in steps with more than one in series. If it was working since 2000 and now has stopped, as others have said, it's likely shot...on a 20-year old one, rebuild is not all that useful, if you can find the kit at all.