Important comment: Wired Series thermostats WFHT and BT Series are connected to the actuators through the connection boxes WFHC. Thermostats Series WFHT are connected by 3 core wire and the thermostat BT Series and BELUX DIGITAL with 2 wire as they  work on 2 AAA batteries. When selecting thermostats, connection boxes and actuators make sure that  parameters such as device type NO or NC, 230V or 24V match.