F12 error, appliance does not respond correctly to temperature settings

Safety first: Disconnect power before removing the front control panel.

• Visual inspection: Check the front panel for signs of water damage, cracks, or stuck keys.
• Dry moisture: If condensation or water has entered, carefully dry the area and identify the source of ingress (e.g., leaking flue, poor casing seal).
• Reseat connectors: Disconnect and reconnect the keypad/display cable at both ends.
• Replace UI board: If keys do not respond or F12 persists, replace the user interface board with the correct Protherm spare.

Warning: Do not spray cleaning liquids directly onto the control panel; apply to a cloth first.