I asked r/homeimprovement for help about a week and a half ago about a sudden increase in water pressure when i turned on my faucets. Several people suggested it was the PRV.

I thought I would DIY it and ran into some difficulties so I cried uncle and called in a plumber. He said its likely not my PRV since when he gauged the pressure at an outside hose connection it read 80PSI. Despite my insistance that everything I had read said 80 was relatively high, he said its at the highest acceptable pressure by code and that the expansion tank should be replaced, not the PRV.

During the expansion tank replacement, he manually released the t&p valve on the water heater for a split second. Ever since it has dripped.

Even after replacing the expansion tank, I still experienced higher water pressure when turning on faucets. My toilets also flushed as if they were under higher pressure and after a while i would hear water trickling down the overflow. I bought a gauge and confirmed 80PSI outside and 90 PSI at the water heater drain. I adjusted my PRV to what seemed to be 55PSI via the gauge, but my T&P valve still seems to be dripping.

I just measured the pressure at my cold water connection for my washer and it was 105PSI. At this point am I correct in assuming it IS the PRV???

This would explain the t&p valve dripping, the continued high pressure, etc right???

Any advice is welcome!!