The Mysa app allows you to easily group your thermostats into zones, which is a necessity for line voltage thermostats. All thermostats in a zone can then be controlled as if they were an individual thermostat. A line volt thermostat is installed in series with the heating system at line voltage. They operate by switching the mains power to the heating system ON/OFF intermittently, according to the temperature settings. When a room/space attains the desired temperature, the heating system is turned OFF. WiFi line voltage thermostat for baseboard heaters - Caleo by CaSA; ›; Customer .... Once configured, you do NOT use the app to control the thermostat remotely.