Control Sequences; 2-Pipe Fan Coil Unit - Siemens RDF300 Documentation

Sequence
Parameter
Mode Heating mode
Available for:
2-pipe,
2-pipe & el. heater
4-pipe
On/off output
Heating or cooling
Control sequence
on/off output
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Siemens
Building Technologies
4.6

Control sequences

The controller can be used in systems featuring:
• Heating or cooling mode (P01=0 or P01=1)
• Manual heating/cooling changeover (P01=2)
• Automatic heating/cooling changeover (P01=3)
• Heating and cooling mode (e.g. 4-pipe system) (P01=4)
The relevant modes are available and can be adjusted via commissioning
parameter "Control sequence" P01, depending on the selected application.
T °C
P01 = 0 P01 = 1
Cooling mode
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
Y
Y1
1
w
0
½ SDH ½ SDH
T[°C] Room temperature
w Room temperature setpoint
Y1 Control command "Valve" or "Compressor"
RDF300.../RDF340.../RDF400... Basic Documentation
4BFunctions
T °C
T °C
P01 = 2
Manually select
heating or
cooling mode
Cooling mode
Y
1
T[°C]
0
SDH
SDC
T
T °C
P01 = 3
Automatic Heating and
heating/cooling cooling mode,
changeover via i.e. 4-pipe
external water
temperature
sensor or
remote switch
Y1
w
½ SDC ½ SDC
Switching differential "Heating"
Switching differential "Cooling"
T °C
P01 = 4
T[°C]
CE1P3076en
28 Aug 2008