In the Link Plus app, you add the heating devices first , Go to Automation, You can either create a Timer or add heating to Schedules. Please note that your Boiler Switch must be added to the LW922 Thermostat and then you add the Thermostat to the app. Please do not add the boiler Switch LW920 to the app direct.
LightwaveRF strongly recommends using Energizer Ultimate Lithium batteries for maximum battery life and device performance.
To ensure the heating will remain operable without an internet connection the schedule is necessary for operation. If, as I believe you would like to operate the system, you would like it to be off/setback all day and only turn on 'on demand' then this may be possible by setting a simple schedule to have a setback temperature at a lower temperature and a single on temperature with 1C difference.
An example of this could be to have the heating at 10C setback, with a 12AM-1AM target of 11C.
When not in operation, the heating would only come on if the temperature dropped below 11C. If you were to set a higher temperature on demand throughout your day, then this would stay on until midnight when the 11C schedule change would occur.
The system has a non-changeable 0.5C threshold in place to avoid the heating constantly switching on and off. The system will switch the heating on when the temperature drops below 0.5C, and then switch it on when the temperature rises above 0.5C. So in your instance your thermostat will switch off when the temperature rises above 16.5C.
The schedules for heating products are stored in the peripheral products themselves, so are not reliant on the Link being powered or an app being open. A record of the schedules are stored on the server and the apps. If you make any changes on one app, they will be stored immediately to the server, then you can obtain these changes by doing a "Pull to Refresh" on the second device, where the settings will sync.