Technical data

3.8 Fan control
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 according to the setting of
parameters P15 (fan stage in dead zone Comfort on RDF600KN) and P60 (fan
kick).
Factory setting for "Fan in the dead zone":
• RDF600KN: Fan speed OFF: (P15 = 0, P60 = OFF)
• RDF301…: Fan speed 1 (P60 = 0)
P15 is not implemented into RDF600KN SW version < V1.8.
The fan speed and mode can be changed via bus.
For this purpose, the fan command value needs to be enabled.
The fan speed and mode can be monitored via bus.
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 diagrams below show fan speed control for modulating PI
control.
w
XpH
Y
C
[%]
Q
Q3
Q2
Q1
Y
H
[%]
0
0
XpC
100
100
x
dz
w Room temperature setpoint
Q Fan speed
Y
H
Control demand "Heating"
Y
C
Control demand "Cooling"
XpH Proportional band "Heating"
XpC Proportional band "Cooling"
X
dz
Dead zone
The diagram only shows the PI thermostat’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
Fan
/ XpC
Fan
) is defined by the
switching differential (SDH/SDC) via a look-up table.
Note:
KNX
R
Fan command value
Enable fan command
value
KNX
R
Fan operation
Fan
stage 1-2-3
Fan output
3-speed fan control
with modulating
heating
/ cooling
control
Note:
3
-speed fan control
with
ON/OFF heating /
cooling control
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Siemens RDF301, RDF301.50..., RDF600KN Basic documentation CE1P3171en
Building Technologies Functions 2014-05-23