FC
Protherm
Real-Time Clock (RTC) or Backup Power Failure
FC error and thermostat time/date frequently resets or drifts significantly.
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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
Depleted backup battery or supercapacitor on PCB, RTC crystal fault, Firmware bug affecting time sync, No internet time synchronization
How to Fix / Troubleshooting
Safety: Disconnect power before opening the thermostat housing.
- Step 1 – Enable network time sync:
- If the thermostat is online, enable automatic time synchronization in settings.
- Ensure internet access is available.
- Step 2 – Check backup power component:
- Some Protherm models use an internal coin cell or supercapacitor to maintain time.
- If accessible and user-replaceable, replace with the exact specified component.
- Step 3 – Firmware update:
- Update thermostat firmware via app if an update is available.
- Step 4 – Manual time setting:
- Set the correct time and date manually.
- Monitor for drift over several days.
- Step 5 – Replace thermostat if RTC is defective:
- Persistent FC with rapid time loss indicates RTC hardware failure.
- Replace the Protherm smart thermostat main unit.
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Repair Difficulty
Medium
3/5
Required Part
Protherm Thermostat RTC / Backup Battery
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