Quick Answer:
If the adjustment screw turns but measured outlet pressure does not change, first confirm your gauge is accurate and that you are testing under steady flow. Use a known-good gauge and make the adjustment while a tap or hose is running. If the adjuster moves but the pressure still does not budge, the PRV’s internal spring or seat is likely jammed and the valve should be replaced. For troubleshooting help with unstable readings, see Pressure gauge readings unstable at PRV.
Why This Happens
- The adjuster can rotate without pushing the spring if its linkage is stripped or disconnected inside the bonnet.
- A faulty gauge or testing without flow can hide pressure changes.
<liMineral scale, debris, or corrosion can lock the spring or seat so the valve no longer responds.
Step-by-Step What to Do
1. Gather the right tools
- Known-good pressure gauge (calibrated or recently verified).
- Wrench to open the gauge port if needed, and tools to remove the bonnet if you can safely do that.
- A nearby fixture (hose, tub, or sink) to produce steady flow.
2. Verify the gauge
- Check the gauge on a known pressure source or swap with a second gauge you know works.
- Do not trust a single unverified reading.
3. Create steady flow at the outlet
- Open a fixture downstream of the PRV so water flows steadily while you adjust.
- This prevents the valve’s pilot action or momentary surges from masking the change.
4. Adjust the screw while the fixture is flowing
- Turn the adjuster slowly and watch the gauge for steady movement.
- If the needle moves, let the system settle and re-check at the fixture to confirm the change.
5. Check the adjuster’s mechanical action
- With the bonnet off (only if you are comfortable and have shut off supply and relieved pressure), verify the adjuster actually compresses the spring as you turn it.
- If you can’t access the internal parts, look for obvious play or looseness at the adjuster that indicates stripped threads or a broken linkage.
6. If there is no response
- When the adjuster turns but the spring and seat don’t move or the pressure stays the same under steady flow, the internal spring or seat is likely jammed.
- Replace the PRV if internal parts are stuck or damaged. For detailed failure checks, consult How to test PRV failure.
What Not to Do
- Don’t replace the PRV based on one gauge reading—verify with steady-flow testing.
- Don’t force internal parts if you are unsure; you can cause more damage or create a leak.
- Don’t ignore a recurring problem; a stuck PRV can allow unsafe pressures or continuous leaks downstream.
When to Call a Professional
- If you can’t safely depressurize and remove the bonnet to inspect the spring and seat.
- If replacement requires re-piping, soldering, or compliance with local codes (many areas require a licensed plumber for pressure-regulating device work).
- If the problem recurs after replacement or if you suspect other system issues like a failing service line regulator or city-side problem.
Safety Notes
- Always shut off the main supply and relieve pressure before disassembling a PRV.
- Wear eye protection and follow basic plumbing safety when working on pressurized systems.
- Replacing a faulty PRV may require a permit or inspection in your area—check local rules if you are unsure.
Common Homeowner Questions
- Why must I test while a fixture is flowing? Pressure regulators respond under load; testing without flow can give false or unchanged readings.
- Can I repair the spring or seat instead of replacing the whole PRV? Sometimes internal rebuild kits exist, but often it’s safer and more reliable to replace the valve assembly.
- How do I know the PRV is the only problem? Verify stable gauge readings during steady flow and rule out supply-side pressure spikes before replacing the PRV.