What is the Absence function and when should I use it?

The Absence function is designed for winter use to keep the indoor ambient temperature above 0°C to prevent freezing when the space is unoccupied. It is only available in heating mode and can be activated by pressing the CLOCK and TEMP buttons simultaneously; the temperature display will show '8' when active. The function will automatically exit if you switch modes or activate the sleep function. (Page 7)