Basic Documentation

Functions
Fan control
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4.8 Fan control
The fan is in automatic mode or runs at the selected speed in manual mode.
In automatic mode, the fan speed is based 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 remains at fan speed 1 (parameter P15, factory
setting: 0 = disabled).
In applications with On/Off (2-position) control:
1. The switching point for low fan speed is synchronized to the heating / cooling
output.
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.
Heating/cooling
DC 0...10 V fan
T [°C] Room temperature
w Room temperature setpoint
Q Fan speed
Y Control command "Valve"
SDH Switching differential
"Heating" (P30)
SDC Switching differential
"Cooling" (P31)
X
dz
Dead zone (P33)
XpH
Fan
Switching range
for fan
"Heating" (Table)
XpC
Fan
Switching range
for fan
"Cooling" (Table)
Fan_max Max.
DC 0...10 V fan speed (P55 )
Fan_min Min. DC 0...10 V
fan speed (P56)
SDH/SDC [K]
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
>4.5
XpH
Fan
/XpC
Fan
[K]
2
3
4
5
6
7
8
9
10
Fan speed I = min. fan speed selectable via P56
Fan speed II = half-way between min. fan speed and max. fan speed
Fan speed III = max. fan speed selectable via P55
Note: Manual fan settings
do not influence the
control signals for
"Heating" and "Cooling".
Fan control with On/Off
heating/cooling control
Look-up table with
On/Off (2-position)
control
Manual operation
DC 0...10 V fan