Elnur
Intermittent Overheat
Boiler trips its internal manual reset thermostat occasionally but then works again after reset.
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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
Partially blocked heat exchanger, Pump intermittently failing, Air pockets in boiler, Incorrect flow rate through boiler
How to Fix / Troubleshooting
Safety first: Allow the boiler to cool fully before resetting any manual thermostats. Do not repeatedly reset without finding the cause.
- Check pump reliability: Observe the pump during operation. If it stops intermittently or is very hot to touch, it may be failing.
- Flush boiler: Consider flushing the boiler and nearby pipework to remove sludge that can cause localised overheating.
- Verify flow rate: Ensure all isolation valves are fully open and that the system is not over-zoned with closed valves restricting flow.
- Bleed air: Remove air from the boiler and system to prevent hot spots.
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Repair Difficulty
Hard
4/5
Required Part
High Limit Safety Thermostat
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