Lochinvar
Overpressure / Expansion Control Problem
Boiler pressure relief valve drips or discharges water periodically
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed expansion tank, overfilled system, faulty pressure reducing valve, debris under relief valve seat
How to Fix / Troubleshooting
Safety first: Water from the relief valve can be very hot. Use caution.
- Check system pressure: Read the pressure gauge when the system is cold and when hot. If pressure rises close to or above the relief valve rating (typically 30 psi), the expansion tank may be waterlogged.
- Inspect expansion tank: For diaphragm tanks, tap the tank; a fully waterlogged tank sounds solid. A professional can check and recharge or replace it.
- Verify fill pressure: Ensure the automatic fill valve is not over-pressurizing the system. Adjust or replace as needed.
- Relief valve seat: Sometimes debris prevents full closure. After correcting pressure issues, a technician may need to replace the relief valve if it continues to drip.
Professional help: Overpressure issues should be evaluated by a heating technician to prevent damage to the boiler and piping.
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Repair Difficulty
Medium
3/5
Required Part
Expansion Tank
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