E20
Heatmiser
Firmware Update Error
Thermostat shows E20 and fails to update firmware via app or NeoHub
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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
Interrupted power during update, Weak Wi‑Fi or RF signal, Incompatible firmware file, Insufficient internal memory
How to Fix / Troubleshooting
Safety first: Do not remove power during any firmware update attempt.
Steps:
- Ensure the thermostat has a strong and stable connection to the NeoHub or Wi‑Fi network.
- Retry the firmware update from the Heatmiser app, ensuring your phone remains connected and close to the router.
- If the thermostat is stuck in a bootloader or error state, follow Heatmiser's recovery procedure (often a long-press reset or special power-on sequence).
- If multiple attempts fail, contact Heatmiser support; a replacement thermostat may be required if the firmware is corrupted beyond recovery.
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Repair Difficulty
Medium
3/5
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