NRT405F902
2
Occupancy detection
Parameter 3 determines if the DI is window contact input or
occupancy detection input. An occupancy detector can be connected
to the DI in order to switch between Comfort and Economy mode.
Setpoint
The setpoint is set using the INCREASE and DECREASE buttons.
Parameter 24 determines what is shown in the display. Refer to the
parameter list for details.
Setpoint limitation
In parameters 34 and 35, it is possible to set the maximum allowed
setpoint increase and decrease respectively.
Example: If P35=5 and P34=3, the setpoint can be changed between
17°C and 25°C (see the picture below).
The basic setpoint can be changed in parameter 64 (factory
setting=22°C).
Figure 3: Example of setpoint limitation
Fan control
The fan can be controlled via NRT405F902 with the following modes:
Low speed, Medium speed, High speed, Auto. The current fan speed
in the Auto mode depends on the heating or cooling demand and the
settings for each speed.
When using automatic control, ”AUTO” is shown in the display.
The number of fan speed steps can be selected via parameter 30. If
the parameter is set to 1, the first fan speed step will be used for fan
control.
Via parameter 31, it is possible to set the fan to the lowest speed
level when Auto mode is selected. If this parameter is set to 1, the fan
will run in all operating modes except Off and Window (unless mould
protection is active, in which case the fan will run in these modes as
well).
Manual control of the fan speed
By pressing the fan button, you change the fan speed according to
the sequence I
à
II
à
III
à
AUTO. When using manual control, ”MAN” is
shown in the display.
If the fan has been configured not to be affected by the heating or
cooling demand, ”AUTO” will not be shown when pressing the fan button.
Indications
The display has the following indications:
HEAT Heating control
COOL Cooling control
The open window symbol is shown if this function has
been configured and a window is open.
OFF The controller does not heat or cool
On/Off button
By pressing the On/Off button, NRT405F902 will switch between Off
mode and Comfort/Economy mode.
Parameter list
When the controller is in Comfort mode or Window mode, different param-
eter values can be set in a parameter list.
Hold the INCREASE and DECREASE buttons depressed simultaneously
for about 5 seconds until the Service symbol is displayed and then press
the INCREASE button twice.
First the display will show parameter 1. Use the INCREASE and DE-
CREASE buttons to scroll between the parameters and press the On/Off
button to select the desired parameter. The parameter number will then
be replaced by the parameter value. The value can be changed using the
INCREASE and DECREASE buttons. If a button is held depressed the
value will start scrolling, first slowly and then with increasing speed.
To exit the parameter list and go back to the basic display, press the IN-
CREASE button until “EXIT” is shown (one step before parameter 1) and
press the On/Off button. You can also exit the parameter list by pressing
down the INCREASE and DECREASE buttons simultaneously.
Parameters
The following parameters can be changed in the parameter list.
Nº = parameter number
FS = factory setting
NO = normally open
NC = normally closed
Nº
Description
FS
1
Control mode:
2=2-pipe system
3=4-pipe system
4=Electric heater
(not used for this model)
3
2
Change-over mode:
0=Heating control, 1=Cooling control, 2=Automatic
change-over depending on analogue temperature
sensor or digital input
2
Nº
Description
FS
3
Operating mode when activating digital input 1:
0=Economy mode (occupancy detector)
1=Off mode (window contact)
0
4
Mould protection:
0=Not active
1=Active (fan never stops)
0
5
Neutral zone at Comfort mode (NZC). If the neu-
tral zone is 2 K, the heating setpoint equals the
setpoint minus 1 and the cooling setpoint equals
the setpoint plus 1.
2 K
6
Heating setpoint when unoccupied.
15°C
7
Cooling setpoint when unoccupied.
30°C
8
P-band for the room controller.
10 K
9
I-time for the room controller.
300 s
10
Not used for this model
11
Switch off timer for Comfort mode.
0 min
12
Switch on delay for Comfort mode.
0 min
13
Sensor connected to AI1:
0=Internal sensor, 1=External room sensor
0
14
Sensor connected to UI1:
0=None, 1=Change-over digital, 2=Change-over
analogue
0
15
Not used for this model
16
Output signal for actuator connected to AO1:
0=0...10V, 1=2...10V, 2=10...2V, 3=10...0V
0
17
Output signal for actuator connected to AO2:
0=0...10V, 1=2...10V, 2=10...2V, 3=10...0V
0
18-
21
Not used for this model
22
Time in hours between exercise of heating actua-
tor.
23
23
Time in hours between exercise of cooling actua-
tor.
23
24
Setpoint or actual value shown in the display:
0=Actual, setpoint when changing the setpoint,
1=Actual, setpoint adjustment when changing the
setpoint, 2=Setpoint, 3=Only the setpoint adjust-
ment
2
