Fan Control - Siemens RDG100 Documentation

Overview of fan
outputs
3-speed fan control
with modulating
heating / cooling
control
Note:
3-speed fan control
with on/off heating /
cooling control
Look-up table with
on/off control
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Building Technologies
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4.9

Fan control

Different fan output signals are available depending on the thermostat type:
Control output
Product no.
RDG100, RDG100T
RDG110
RDG140
RDG160
( ) Number of outputs
The fan operates in automatic mode or at the selected speed with manual mode.
In automatic mode, the fan speed depends on the setpoint and the current room
temperature. When the room temperature reaches the setpoint, the control valve
closes and the fan switches off or stays at fan speed 1 (parameter P60; factory
setting: fan speed 1 in dead zone).
The individual switching points for ON of each fan stage can be adjusted via control
parameters P55...P57. The fan speed switch off point is 20% below the switch on
point. The diagram below shows fan speed control for modulating PI control.
Q
Q3
Q2
Q1
100 0
w
x
Y [%] XpH
dz
H
The diagram only shows the PI controller's proportional part.
On applications with 2-position control:
1) The switching point for low fan speed (Q1) is synchronized to the heating /
cooling output. Parameter "Switching point fan speed low" P57 is not relevant.
2) The maximum switching range of the fan (XpH
switching differential (SDH/SDC) via a look-up table.
Y
x
dz
1
0
w
SDH
Q
Q3
Q2
Q1
w
XpH
Fan
SDH/SDC [K] 0.5
XpH /XpC [K] 2
Fan Fan
RDG100, RDG100T, RDG110, RDG140, RDG160 Basic Documentation
Functions
www.heronhill.co.uk
On/off
1- / 3-speed fan
Q1,Q2,Q3 (3)
Q1,Q2,Q3 (3)
Q1,Q2,Q3 (3)
w
Q
Y
Y
XpH
XpC
X
0 100
Y [%]
XpC
C
Fan
T[°C]
w
Q
Y
T[°C]
SDH
SDC
SDC
X
Cool
XpH
XpC
T[°C]
XpC
Fan
1.0 1.5 2.0 2.5
3 4 5 6
Modulating fan
DC 0...10 V
Y50 (1)
Room temperature setpoint
Fan speed
Control demand "Heating"
H
Control demand "Cooling"
C
Proportional band "Heating"
Proportional band "Cooling"
Dead zone
dz
/ XpC ) is defined by the
Fan
Room temperature
Room temperature setpoint
Fan speed
Control command "Valve"
Switching differential "Heating"
Switching differential "Cooling"
Dead zone
dz
Switching range for fan "Heating"
Fan
Switching range for fan "Cooling"
Fan
3.0 3.5 4.0 >4.5
7 8 9 10
CE1P3181en
28 May 2009
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