Controlling fan-coil units with electronically commutated motors

Designed to maximise the capabilities of fan-coil units with DC electronically commutated motors is the Desigo RXC31 controller from Siemens Building Technologies. It enables fan speed to be matched to demand, compared with traditional controllers that run the fans at fixed speeds. These controllers monitor the position of the modulating water-control valves in the fan-coil unit and set the fan speed to ensure that the setpoint temperature is achieved. If the fan coil reaches 100%, the modulating fans speed up to increase heating or cooling output. As the setpoint is approached, the fans slow down. Maximum and minimum speeds can be programmed independently for heating and cooling sequences. These controllers can be supplied for 2-pipe, 4-pipe and airside applications. The I/O mix of the units allows the use of 3-point modulating valve actuators, as well as on/off or modulating electric heating. Siemens also provides room units for commercial buildings or high-end residential apartments. Options include flush-mounted variants for standard MK wall boxes. These controllers support the LonMark protocol.

Related links:

• www.sbt.siemens.com