You can set the Boost Time and Temperature on the Settings page in the App or Web Interface.
Boost can be activated from the Home page in the App or Web Interface, or directly on the thermostat by pressing the Radiator Icon until Boost is highlighted.
If the Boost Only option is enabled (found on the Locks page), tapping the left-hand side of the thermostat screen will activate heating boost. If hot water is disabled by setting the boiler type is set to Combi, tapping anywhere on the screen will activate boost.