Thermostat shows E12 and cannot control a specific heating zone or room

Safety first: This is a configuration issue; no mains work is required.

• Review room setup: In the Wiser app, open the affected room and verify which devices (room thermostat, TRVs) are assigned. Remove any devices that are no longer installed.
• Rename and reassign: Temporarily rename the room and reassign the thermostat and actuators to ensure a clean mapping.
• Delete and recreate room: If the error persists, delete the room entirely and create it again, then add devices fresh.
• Sync schedules: Reapply schedules to the new room and test manual temperature changes to confirm control.
• If E12 continues: Perform a soft reset of the Heat Hub via the app or its reset button. As a last resort, factory reset the system and reconfigure all rooms.