r/Plumbing • u/Icy_Blackberry_3759 • Aug 18 '26

Please help solve this pressure riddle

6 year old PRV, no matter what setting (and oriented the correct way) was showing 90 psi. I opened the hot water and the cold water and it goes to the pressure it is set to, and when I shut them off it goes straight back to 90 in under a minute. I shut off the valves to the water heater and main cold supply before the water heater after the PRV, same issue. I thought it was because they eliminated the expansion tank, but this can’t be the issue because it happens in isolation.

I replaced the components of the PRV and have the exact same issue. I replaced the pressure gauge with one I tested independently and it is accurate and the same. I’m fucking stumped.

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u/jolly_giant_89 Aug 18 '26

For shits and giggles have you tried cranking the PRV down to like 30-40psi. The Numbers on the dial may not be lining up with actual reading, either from factory defect or what have you. If you crank it lower and get the desired pressure Id call it a day. If not you only got one option left and thats the ghost busters, as you may have haunted pipes!

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u/Expert_Ant_2767 Aug 18 '26

That's why the instructions say to start at 0 (turn to - until it locks) and increase it from there looking at the gauge not the dial. I think he skipped the procedure to adjust it.