The thermostat controller is located in a central location of the building (not too close to windows or radiator panels) so it reads the overall temperature of the house. Thermostats can be programmed to activate the heating at set times of the day. This can be multiple times of the day at different temperatures. Different for weekdays and weekends, individual days or if the house temperature drops to below a set point. You can also override the programmed times and turn the system on and off manually.