In the 4-pipe system mode, the switch number 1 has to be set to the OFF position as shown in figure below. By default, this mode is ON.
In this configuration, the fan coil unit is equipped with two separate heating and cooling devices. The electric connection for the actuators of 24 V AC heating and cooling valves controlled by analog signal (0-10 V DC) is presented in the figure below.
The FCU controller can work with thermal valves actuators. For this option, the FCU controller is equipped with 2 built-in triac outputs. The triac outputs can work in digital (open/close) or PWM mode, selected by the CFG DIP switch number 4. Depending on the hardware version, the FCU controller can work with 230 V AC thermal valve actuators (iSMA-B-FCU-HH) or with 24 V AC thermal valve actuators (iSMA-B-FCU-HL and iSMA-B-FCU-LL). In both cases, thermal valve actuators are supplied with power from the FCU controller.
In the 2-pipe system mode, the switch number 1 has to be set to the ON position as presented in the figure below. By default, this mode is OFF.