Plumbing – How to determine if a Water Pressure Reducing Valve (PRV) is working properly

plumbingrepairwater-pressure

I've been trying to track down water pressure/flow issues throughout the plumbing in my entire house, but haven't found anything which made any significant difference. For example, I discovered that the main valve and a few others were not fully open. I am able to access all other valves and they are fully open. All lines are copper. My house is a single level with a basement (where the main is located). My neighbors do not have any problems.

Here's my configuration:

City Water -> 3/4" lines -> main -> gauge (reading is maxed out over 100 psi) -> PRV -> gauge reading static 60 psi -> valve -> continue 3/4" lines feeding 1/2" lines for all fixtures.

I have a thermal expansion tank with the hot water heater which is also set to 60 psi.

As soon as any water fixture is turned on (sink, shower, toilet flush, washing machine, etc.), the pressure on gauge immediately following my PRV drops significantly (falls to 20psi or less). As a result, trying to use a second fixture is difficult and a third is near impossible. Additionally, I attempted to turn all water fixtures through the house on. During this test, the water fixtures on the main level did not put out any water.

I'm inclined to believe there is an issue with the PRV. Is that the right place to be looking? Should a PRV have such a large drop in pressure when one fixture is open?

Best Answer

I replaced the PRV with an exact match and it fixed the issue. It was a fairly straight forward replacement since the PRV had one union and my backflow preventer (about 10" down the line) had another.