A02
Ferroli
Boiler Overheat / Safety Lockout Feedback
Thermostat indicates A02 and heating stops; boiler status shows overheat or safety shutdown.
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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
Blocked or closed radiator valves causing poor circulation, Faulty boiler pump not circulating water, Air trapped in system causing local overheating, Boiler NTC sensor fault reported back to thermostat
How to Fix / Troubleshooting
Safety first: Overheat conditions relate to the boiler and water circuit. Do not remove boiler covers. Work only on radiators and the thermostat.
- Check system circulation:
- Ensure most radiators are open (thermostatic radiator valves not all turned to minimum).
- Feel the flow and return pipes near the boiler (carefully). If one is extremely hot and the other is cold, circulation may be poor.
- Bleed radiators:
- Turn off heating and allow system to cool.
- Use a radiator key to bleed air from the top of each radiator until water flows steadily.
- Top up system pressure at the boiler (if sealed system) to the recommended level.
- Thermostat reset:
- Power cycle the Ferroli smart thermostat and clear any lockout message.
- Request heat again and monitor if A02 reappears.
- If A02 recurs frequently:
- The boiler may have a faulty pump or NTC sensor, or severe sludge/scale.
- Contact a qualified Ferroli engineer; mention that the thermostat is receiving an A02 overheat/lockout signal from the boiler.
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Repair Difficulty
Hard
4/5
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