FCU - Default Application - Piping modes supported/piping mode selection

This document shows how to set up the default fan coil control application depending on its type of piping. The default application allows for controlling two types of piping.

1. Two-pipe fan coil units have two water connections, supply/return, and can operate in heating or cooling mode. By default, the two-pipe system is off, please turn number 1 'DIP switch' to the 'ON' position to enable this mode. Two outputs can be used to control the valves, analog output A1 or Triac output TO1.

Picture 1. Exemplary connection of heating/cooling devices in a two-pipe system.

2. The four-pipe fan coil units have four water connections, two pairs of supply/return, one pair is used for heating with heating water, and the other for cooling with chilled water. The fan coil unit works in heating or cooling mode, depending on the needs. By default, the 4-pipe system is on. 'DIP switch' number 1 is in the 'OFF' position. Four outputs can be used to control the valves, analog output A1, A2 or Triac output TO1, TO2.

Picture 2. Example of connection of heating/cooling devices in a four-pipe system in analog mode.

The image above shows valve control using analog outputs, iSMA-B-FCU also allows for controlling PWM type valves using TO1, TO2 outputs. Depending on iSMA-B-FCU version, it is possible to use a 24V or 230V valve.

Picture 3. Example connection of heating/cooling devices in a four-pipe installation in digital mode.