@Alvin I dont think think that the away mode will permit less than 5 degrees C. This, however, could be nullified by the settings of your boiler. Looking across Google shows significant differences between manufacturers,
with Vaillant, for example:
Typically, across our boiler ranges the frost protection system operates the boiler pump as soon as the heating circuit water temperature falls below 12 degrees centigrade. The pump stops as soon as the temperature of this water reaches 15 degrees centigrade. If the heating system falls below 3 degrees centigrade, the burner ignites.
If the temperature within the boiler falls below 8°C the pump will run to circulate water and prevent the system freezing. If the temperature within the boiler falls below 5°C the boiler will fire periodically, bringing the boiler temperature up to 12°C to avoid the possibility of the system freezing. This process will be repeated until such time that the boiler temperature does not drop below 5°C.
So in AWAY mode Tado turns down radiators to the minimum level permitted by the boiler manufacturers? In Denmark we have Danfoss. I share a boiler as I live in an apartment building. It seems Tado aims to keep a temperature in AWAY mode in the rooms that is just a few degrees below the scheduled set temperature. Maybe this is in order to be able to warm up faster in case I come within 500m and the system has to reheat the apartment? While I'm at work it seems the best temperature allowed should be just above the minimum ? Apartments are insulated so it would have to be super cold for it to go below 15 degrees.
@Alvin the App setting “Preheat before arrival” will affect the away temperature. If this setting is off then once you leave your home area the radiators are OFF until the room temperature drops to the preset minimum temperature.
Eco, Balance and Comfort options may continue to heat your home while you are away. The minimum temperature when using these options depends on your distance from home. If you work within a few kilometres of home then the minimum temperature will be relatively high. Go on holiday and the minimum temperature will be quite low.