Vaillant smart thermostat schedules do not follow the programmed times; heating turns on or off at unexpected times.

Safety: No electrical work required.

• 1. Verify time and date: Check that the thermostat shows the correct time, date, and day of week. Enable automatic time sync if available.
• 2. Review schedules: In both the thermostat and app, review all schedules for each zone. Remove overlapping or conflicting entries.
• 3. Check special modes: Ensure holiday, frost protection, or party modes are not overriding normal schedules.
• 4. Sync app and device: Log out and back into the Vaillant app, then force a sync. Avoid programming from two devices simultaneously.
• 5. Reset schedules: If issues persist, clear all schedules and re‑enter them from scratch.