Running Mode; Frost Mode - LightwaveRF JSJSLW921 Instruction Manual

Device Setup
Modes
Pressing the Mode button toggles between the four Thermostat modes. Each
mode contains pre-set programmable target temperatures. When a mode is
selected, the Thermostat will be set to these target temperatures until the
mode is changed.

Running mode

The main Thermostat mode is 'Running'. Unlike the other modes which can
only store temperatures, Running mode also allows you to create a weekly
heating schedule which can change the target temperature up to 8 times per
day. When the home is occupied, this mode should be constantly running.
Away & Holiday modes
Away and Holiday modes allow you to specify a temperature that you want
to set the heating to whilst you are away. Holiday mode also allows you to
specify the number of days that you want this to be active for.

Frost mode

This mode should be activated when the home is unoccupied for long
periods. It prevents pipes from freezing by setting a minimum temperature.