During normal running mode (not Away mode and not Summer Mode) the heating is generally controlled by the settings of time and temperature in your time clock
If you find that the heating is coming on outside of the pre set times this is usually due to one of two valid scenarios.
1) The Heating will come on generally up to 1 hour prior to a time clock setting and this is known s the "Warm up" time, this is designed to warm the house up to reach your desired temperature by the set time in your time clock
2) The standby temperature is designed to set a minimum temperature at which the house will maintain when the time clock is active but is between heating periods. Quite often though the night your house temperature may decrease and the ambient temperature may fall below the set standby temperature.
It is not advisable to set the standby temperature too high this will result in the boiler coming on regularly 24 hours a day to maintain a constant high temperature and this will be more prominent at night when the genera ambient temperature falls.
The standby temperature is a personal choice, however most households generally set this to around 15c
If you see find your heating is coming on when not required please review the heating graphs on your dashboard view - these will show the required temperature and the times that the boiler is on. From the graphs you can determine if your settings are incorrect , set too high or there is a genuine fault.