F11 displayed; thermostat time and schedules keep resetting.

Safety first: If the thermostat is mains-powered, isolate power before removing it from the wall.

Steps:

• 1. Check main power stability: Ensure the fused spur is not loose and that there are no frequent trips or outages on the circuit feeding the thermostat.
• 2. Replace user-replaceable batteries: If your Ideal smart thermostat uses AA/AAA batteries for backup, replace them with high-quality alkaline cells, observing polarity.
• 3. Firmware update: Connect the thermostat to Wi-Fi and check via the Ideal app for firmware updates that address clock or schedule issues.
• 4. Factory reset: Back up your schedules (note them down or via app), then perform a factory reset from the settings menu. Reconfigure time and schedules.
• 5. Replace thermostat if RTC hardware failed: If F11 persists and time resets after short power cuts, the internal RTC or backup capacitor is likely faulty and the thermostat should be replaced.