Protherm
Overpressure / Expansion Relief Discharge
Water heater's safety valve or relief valve is dripping water regularly
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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
Thermostat set too high, Expansion vessel (if fitted) lost charge, Faulty pressure relief valve, Non-return valve on cold inlet without expansion control
How to Fix / Troubleshooting
Safety first: Hot water from the relief valve can cause burns. Do not cap or block the discharge pipe.
- Check pressure: Measure system pressure when cold and when hot. Excessive rise indicates lack of expansion capacity.
- Test expansion vessel: On models with an internal vessel, check pre-charge pressure and recharge or replace if the diaphragm has failed.
- Verify thermostat setting: Ensure water temperature is not set unnecessarily high.
- Replace relief valve: If the valve drips even at normal pressure, replace it with the correct Protherm-rated valve.
Warning: Never plug or seal the relief valve outlet; it is a critical safety device.
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Repair Difficulty
Medium
3/5
Required Part
Pressure Relief Valve / Expansion Vessel
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