Siemens RDF300 Operations Instructions download pdf (Page 16)

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Siemens RDF300… / RDF340... / RDF400… / RDF600… Basic Documentation CE1P3076.en

Building Technologies Functions 2012-10-02

4.6.1 2-pipe fan coil unit

In 2-pipe applications, the controller controls a valve in heating/cooling mode with

changeover (automatic or manual), heating only mode, or cooling only mode.

Cooling only is factory set (P01=1).

The diagram below shows the control sequence for on/off (2-position) control.

Heating mode Cooling mode

½ SDH

3076D01

T[°C]

½ SDC

3076D02

T[°C]

T[°C] Room temperature SDH Switching differential “Heating”

w Room temperature setpoint SDC Switching differential “Cooling”

Y1 Control command “Valve” or “Compressor”

The diagram below shows the control sequence for continuous PI control.

Heating mode Cooling mode

XpH

100

Y [%]

3076D03

T[°C]

XpC

Y [%]

100

3076D04

T[°C]

T[°C] Room temperature XpH Proportional band “Heating”

w Room temperature setpoint XpC Proportional band “Cooling”

Y1 Control command “Valve”

 The diagrams only show the PI thermostat’s proportional part.

 For the fan sequence see section 4.8.

On/off o

utput

Heating or cooling

Control sequence

on/off output

Control sequence

modulating output

Notes:

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