TIP
Some of the following functions can also be activ-
ated and scheduled via menu settings.
Selectable inputs
Selectable inputs on the base board (AA2) for these func-
tions are AA2-X28:3-11. Each function connects to any input
and GND (AA2-X29).
6 7
8
54
3
AUX4
AUX5
AUX6
AUX3
AUX2
AUX1
AA2-X28
AA2-X29
GND
The example above uses the inputs AUX1 (AA2-X28:3) and AUX2 (AA2-X28:4).
Selectable outputs
A selectable output is AA2-X27.
The output is a potential-free switching relay.
If S1256 is switched off or in emergency mode, the relay is
in C-NC position.
Caution
The relay output may be subjected to a max load
of 2 A at resistive load (230 V~).
TIP
The AXC accessory is required if more than one
function is to be connected to the AUX output.
Possible selection for AUX inputs
Temperature sensor
Available options are:
• six dedicated sensors (BT37.1 – BT37.6) for placing
wherever you want.
• cooling/heating (BT74), determines when it is time to
switch between cooling and heating mode (selectable
when the cooling function is activated in menu 7.2.1 -
"Add/remove accessories").
• external return line sensor (BT71)
• displayed hot water sensor for HWC (BT70). Placed on the
supply line.
• displayed hot water sensor for HWC (BT82). Placed on the
return line.
Monitor
Available options are:
• alarm from external units.
The alarm is connected to the control, which means that
the malfunction is shown as an information message in
the display. Potential free signal of type NO or NC.
• pressure switch for climate system (NC).
• level monitor
1
/ pressure switch / flow monitor for brine
(NC).
External activation of functions
An external switch function can be connected to S1256 to
activate various functions. The function is activated during
the time the switch is closed.
Possible functions that can be activated:
• forced control of brine pump
• hot water demand mode "More hot water"
• hot water demand mode "Small"
• “External adjustment”
When the switch is closed, the temperature is changed in
°C (if a room sensor is connected and activated). If a room
sensor is not connected or not activated, the desired
change of "Temperature" ("Offset") is set with the number
of steps selected. The value is adjustable between -10
and +10. Setting the value for the change is performed in
menu 1.30.3 - "External adjustment".
• activation of one of four fan speeds.
(Can be selected if ventilation accessory is activated.)
The following options are available:
– "Activate fan speed 1 (NO)" - "Activate fan speed 4 (NO)"
– “Activate fan speed 1 (NC)”
The fan speed is activated during the time the switch is
closed. Normal speed is resumed when the switch is
opened again.
1
(Accessory NV10)
NIBE S1256Chapter 5 | Electrical connections26
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