Basic Documentation

Functions
Fan control
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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".
When heating with the electric heater only (RDF660MB only), manual fan speed I
is unavailable to ensure the required minimum air flow for the electric heater and to
avoid overheating of the system.
Fan operation can be limited to be active with cooling only or heating only, or even
be totally disabled via control parameter “Fan control” P52.
When fan operation is disabled, the fan symbol on the display disappears and
pressing the fan button has no impact.
Note
Fan control with On/Off
heating/cooling control
Look-up table with
On/Off (2-position)
control
Manual operation
DC 0...10 V fan
Fan operation as per
heating/cooling mode, or
disabled