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 low speed (parameter P30, factory setting: 1= disable).

Fan is disabled when operating mode switches to Protection.


Fan speed command

Both fan speed and mode can be changed via BACnet/Modbus.


Fan operating state
Three-speed fan, variable speed fan

Fan speed and mode can be monitored via BACnet/Modbus.

Fan control with On/Off heating/cooling control

In applications with On/Off control:

  1. The switching point for low fan speed is synchronized to the heating / cooling output.
  2. The maximum switching range of the fan (XpHFan /XpCFan) is defined by the hysteresis (SDH/SDC) via a look-up table.

 

Heating/cooling

 

 

 

 

 

 

DC 0...10 V fan

T [°C]

Room temperature

Xdz

Zero energy zone (P30)

w

Room temperature setpoint

XpHFan

Switching range for fan "Heating" (Table)

Q

Fan speed

XpCFan

Switching range for fan "Cooling" (Table)

Y

Control command "Valve"

Fan_max

Max. DC 0...10 V fan speed (P72)

SDH

Hysteresis "Heating" (P43)

Fan_min

Min. DC 0...10 V fan speed (P74)

SDC

Hysteresis "Cooling" (P44)

Look-up table with On/Off control

SDH/SDC          [K]

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

>4.5

XpHFan/XpCFan   [K]

2

3

4

5

6

7

8

9

10

Manual operation DC 0...10 V fan

Fan speed I = min. fan speed selectable via P74

Fan speed II = medium (selectable via P73) between min. fan speed and max. fan speed

Fan speed III = max. fan speed selectable via P72

Note: Manual fan settings do not influence the control signals for "Heating" and "Cooling".

Fan operation in zero energy zone (fan kick)

In automatic fan mode and with the room temperature in the zero energy zone, the control valve is normally closed and the fan is disabled. With the fan kick function, the fan can be released periodically at low speed for a minimum on-time (2 minutes) even if the valve is closed.

This function is used to avoid damage from moisture due to a lack of air circulation, or to allow the return air temperature sensor to acquire the correct room temperature.

Periodic fan kick

Minimum on-time

 

The periodic fan kick time can be selected for Economy via parameter P70.

Notes

  • Fan kick value 0 (OFF) means the fan does not run in the zero energy zone.
  • Economy:
    • Fan kick value 1...359 means the fan turns on at low speed every "x = 1...359" minutes and the duration is equal to the fan minimum on-time.
    • Fan kick value 360 means the fan runs continuously in the zero energy zone.

Fan start kick

When the fan starts from a standstill, it starts at high speed for 1 second to ensure safe fan motor startup by overcoming inertia and friction (selected via parameter P71).

Fan operating hours

When P75 = 1, device starts counting fan operating hours. The hour counting stops if operating hours reach 1999 and recounts after operating hours is reset via P75 (3: automatically changes to 1).