Thermostat frequently loses time schedules or reverts to default settings after power interruptions.

Safety: For mains models, isolate power before opening the unit.

• Replace main batteries: For battery-powered Eurotronic thermostats, install fresh batteries to ensure stable voltage during writes.
• Follow battery change procedure: Use the manufacturer’s recommended method for battery replacement to avoid memory corruption.
• Minimize power cuts: If possible, keep the thermostat circuit on a stable supply that is not frequently switched off.
• Factory reset and reprogram: Perform a full reset, then re-enter schedules. Monitor if they are retained.
• Replace thermostat: Persistent loss of settings indicates a memory or backup circuit fault; replace the thermostat.