Pressure Relief & Pressure Sustaining Valve Troubleshooting
| Symptom | Probable Cause | Remedy |
| Main valve won't open | Inlet pressure below setting of pilot valve | Reset pilot valve. If change in setting is from tampering, seal cap with wire and lead seal |
| Pilot valve stuck closed mineral deposit or foreign material between disc retainer and power unit body | Disassemble control and clean | |
| Pilot valve diaphragm ruptured or diaphragm nut loose. Water coming out of the vent hole in cover | Disassemble and replace diaphragm. Tighten nut. | |
| Main valve stuck closed. Mineral buildup on stem. Stem damaged. | Disassemble main valve, clean parts and/or replace damaged part. Check downstream and cover isolation valves are open. | |
| Main valve won't close | Inlet pressure above setting of pilot valve | Reset pilot valve. |
| Clogged needle valve or strainer | Disassemble and clean. | |
| Pilot valve stuck open. Mineral deposit or foreign material under disc retainer or under diaphragm assembly. | Disassemble and clean. | |
| Main valve stuck open. Mineral buildup on stem. Foreign material between seat and disc assembly. | Disassemble and clean. | |
| Main valve diaphragm worn | Disassemble and replace. | |
| Valve leaks continuously | Pilot valve disc worn out. | Disassemble and replace. |
| Main valve disc worn or small pin hole in main valve diaphragm | Disassemble and replace. | |
| Set point too close to inlet pressure | Reset CRL pilot |
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