Nibe S1255 User guide

Installer manual
Ground source heat pump
NIBE S1255
IHB EN 2150-1
631729

Quick guide
NAVIGATION
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edge show that there
are more pages.
If the menu has several
sub-menus, you can
see more information
by dragging up or
down with your finger.
Most options and func-
tions are activated by
lightly pressing on the
display with your finger.
Drag to the right or left
with your finger to
browse between the
pages.
Setting the indoor temperature.
13.45 3 October
Climate system 1
Offset
Heating
Smartguide
Hi!
Your system is working properly. Do you want help making
changes?
Yes please, take me to Smartguide.
October13.45 3
Here, you can set the temperature in the installation's zones.Smartguide helps you both to view information about the current
status and to make the most common settings easily. The inform-
ation that you see depends on the product you have and the ac-
cessories that are connected to the product.
Product overview
Company AB
Phone number
S1255
01234567890123
1.0.0
Product
overview
Product name
Serial number
Software
Service
October13.45 3
Update
Increasing hot water temperature
13.45 3 October
More hot water
Hot water
Here, you can find information about product name, the product's
serial number, the version of the software and service. When
there is new software to download, you can do it here (provided
that S1255 is connected to myUplink).
Here, you can start or stop a temporary increase in the hot water
temperature.

41 Important information
4Safety information
4Symbols
4Marking
4Serial number
5Inspection of the installation
62 Delivery and handling
6Transport
6Assembly
7Supplied components
7Handling panels
9Removing insulation
103 The heat pump design
10General
11Distribution boxes
11Cooling sections
134 Pipe connections
13General
14Dimensions and pipe connections
15Brine side
16Climate system
16Cold and hot water
16Installation alternative
185 Electrical connections
18General
20Connections
25Settings
286 Commissioning and adjusting
28Preparations
28Filling and venting
29Start-up and inspection
31
Setting the cooling/heating curveSetting the
heating curve
337 myUplink
33Specification
33Connection
33Range of services
348 Control - Introduction
34Display unit
35Navigation
35Menu types
37Climate systems and zones
389 Control - Menus
38Menu 1 - Indoor climate
41Menu 2 - Hot water
43Menu 3 - Info
44Menu 4 - My system
47Menu 5 - Connection
48Menu 6 - Scheduling
49Menu 7 - Installer settings
5710 Service
57Service actions
6211 Disturbances in comfort
62Info-menu
62Manage alarm
62Troubleshooting
6412 Accessories
6613 Technical data
66Dimensions and setting-out coordinates
67Electrical data
68Technical specifications
73Energy labelling
84Item register
87Contact information
3Table of ContentsNIBE S1255
Table of Contents

Safety information
This manual describes installation and service procedures
for implementation by specialists.
The manual must be left with the customer.
Symbols
Explanation of symbols that may be present in this manual.
NOTE
This symbol indicates danger to person or machine.
Caution
This symbol indicates important information about
what you should consider when installing or servi-
cing the installation.
TIP
This symbol indicates tips on how to facilitate us-
ing the product.
Marking
Explanation of symbols that may be present on the product’s
label(s).
Read the User Manual.
Read the Installer Manual.
Serial number
The serial number can be found at the bottom right on S1255,
in the display on the home screen "Product overview" and
on the type plate(PZ1).
Caution
You need the product's (14 digit) serial number for
servicing and support.
NIBE S1255Chapter 1 | Important information4
Important information

Inspection of the installation
Current regulations require the heating installation to be inspected before it is commissioned. The inspection must be
carried out by a suitably qualified person. In addition, fill in the page for the installation data in the User Manual.
DateSignatureNotesDescription
✔
Brine side
System flushed
System vented
Antifreeze
Level/Expansion vessel
Filterball (particle filter)
Safety valve
Shut off valves
Circulation pump setting
Climate system
System flushed
System vented
Expansion vessel
Filterball (particle filter)
Safety valve
Shut off valves
Circulation pump setting
Electricity
Connections
Main voltage
Phase voltage
Fuses heat pump
Fuses property
Outside sensor
Room sensor
Current sensor
Safety breaker
Earth circuit-breaker
Set emergency mode in menu 7.1.8.2
5Chapter 1 | Important informationNIBE S1255

Transport
S1255 should be transported and stored vertically in a dry
place. When being moved into a building, S1255 may be leant
back 45 °.
Ensure that S1255 has not been damaged during transport.
Caution
The product can be tail heavy.
Remove the outer panels in order to protect them when
moving in confined spaces inside buildings.
R
0
R
0
EXTRACTING THE COOLING MODULE
To simplify transport and service, the heat pump can be
separated by pulling the cooling module out from the cabin-
et.
See page 59 for instructions about the separation.
Assembly
•Place S1255 on a solid foundation indoors that can take
the heat pump’s weight.
Use the product’s adjustable feet to attain a horizontal
and stable set-up.
30 - 50 mm
30 - 50 mm
15 - 40 mm
20-55 mm
•Because water comes from S1255, the area where the
heating pump is located must be equipped with floor
drainage.
•Install with its back to an outside wall, ideally in a room
where noise does not matter, in order to eliminate noise
problems. If this is not possible, avoid placing it against a
wall behind a bedroom or other room where noise may be
a problem.
•Wherever the unit is located, walls to sound sensitive
rooms should be fitted with sound insulation.
•Route pipes so they are not fixed to an internal wall that
backs on to a bedroom or living room.
INSTALLATION AREA
Leave a free space of 800 mm in front of the product. Ap-
prox. 50 mm free space is required on each side, to allow
the side panels to be removed (see image). All service on
S1255 can be carried out from the front, however the right-
hand panel may need to be removed. Leave free space
between the heat pump and the wall behind (and any routing
of supply cables and pipes), to reduce the risk of any vibra-
tions being propagated.
(50) (50)
800
*
*
* A normal installation needs 300 – 400 mm (any side) for
connection equipment, e.g. level vessel, valves and electrical
equipment.
NIBE S1255Chapter 2 | Delivery and handling6
Delivery and handling

Supplied components
LEK
Current sensor1
3 x
Room
sensor(BT50)
1 x
Outdoor temperat-
ure sensor (BT1)
1 x
LEK
Safety valve (FL3)
0.3 MPa (3 bar)1
1 x
LEK
Level vessel (CM2)1
1 x
O-rings
8 x
Compression ring
couplings
6 KW
2 x (ø28 x G25)
2 x (ø22 x G20)
12/16 KW
4 x (ø28 x G25)
Filterball (QZ2)
6 KW
1 x G1
1 x G3/4
12/16 KW
1 x G1
1 x G1 1/4
1Not Italy and the DACH countries.
LOCATION
The kit of supplied items is placed in packaging on top of
the heat pump.
Handling panels
OPEN FRONT HATCH
Press the hatch's top left corner to open it.
REMOVE THE FRONT
1. Remove the screw in the hole next to the on/off button
(SF1).
2. Pull the panel's top edge towards you and lift diagonally
upwards to remove it from the frame.
UN
ASSEMBLE THE FRONT
1. Hook one bottom corner of the front onto the frame.
7Chapter 2 | Delivery and handlingNIBE S1255

2. Hook the other corner in place.
3. Check the display is straight. Adjust if necessary.
4. Press the top of the front section against the frame and
screw it into place.
REMOVE SIDE PANEL
The side panels can be removed to facilitate the installation.
1. Remove the screws from the upper and lower edges.
UN
2. Twist the panel slightly outwards.
UN
3. Move the panel outwards and backwards.
UN
4. Assembly takes place in the reverse order.
NIBE S1255Chapter 2 | Delivery and handling8

Removing insulation
The insulation can be removed to make installation easier.
UN
9Chapter 2 | Delivery and handlingNIBE S1255

General
UN
BT7
QN10
BT2
EB1
PZ1
EP14-QM34
EP14-QM31
BT6
EP14-QM32
EP14-QM33
PZ2
QM22
UB1
AA4
SF1
XL1
XL6
XL4 XL3
XL7
XL2
BF1
UB2
FC1
XL5
XF8
FR1
XF3
EP14
PIPE CONNECTIONS
Connection, heating medium flowXL1
Connection, heating medium returnXL2
Connection, cold waterXL3
Connection, hot waterXL4
Connection, HWC1 XL5
Connection, brine inXL6
Connection, brine outXL7
1Only heat pumps with enamelled or stainless steel vessel.
HVAC COMPONENTS
Cooling sectionEP14
EP14-QM31 Shut-off valve, heating medium supply
EP14-QM32 Shut off valve, heating medium return
EP14-QM33 Shut off valve, brine out
EP14-QM34 Shut-off valve, brine in
Venting, coilQM22
Shuttle valve, climate system/water heaterQN10
SENSORS ETC.
Flow meterBF1
Temperature sensors, heating medium flowBT2
Temperature sensor, hot water chargingBT6
Temperature sensor, hot water topBT7
ELECTRICAL COMPONENTS
Display unitAA4
Immersion heaterEB1
Miniature circuit breaker1 FC1
Electrical anode2 FR1
Choke3 RA3
On/off buttonSF1
USB socketXF3
Network connection for myUplinkXF8
1S1255-6 3x400 V is not equipped with miniature circuit breakers (FC1).
2Only heat pump with enamelled vessel.
3Only for S1255-12 3x400 V.
MISCELLANEOUS
Rating platePZ1
Identification plate, cooling modulePZ2
Cable glandUB1
Cable glandUB2
Designations according to standard EN 81346-2.
NIBE S1255Chapter 3 | The heat pump design10
The heat pump design

Distribution boxes
UN
-X29
-X28
1 0-5V 2 +5V
3 AUX1 4 AUX2 5 AUX3 6 AUX4 7 AUX5 8 AUX6 9 AUX7
10 AUX8 11AUX9 12 BT25
1
1
2
3
2 3 4 5 6 7 8 9
10
11
12
GND
+12V
B
A
OT+ OT−
0-5V
PWM0 PWM1
CPU
EXT COM
INT COM
ERROR
POWER
+5V
GND
BE1 BE2 BE3
K10
-X27
NO
O
NC
AUX-RELAY
13 BT50 14 BT1
-X30
FQ10-S2
FQ10
AA2
RA3
AA8
ELECTRICAL COMPONENTS
Base cardAA2
Electrical anode board1 AA8
Temperature limiterFQ10
FQ10-S2 Reset button for temperature limiter
Choke2 RA1
Choke2 RA3
1Only heat pump with enamelled vessel.
2Only for 12 kW 3x400 V
Cooling sections
6 kW
UN
BT11
BT12
BT10
BT3
GP2
QM2 QM1
GP1
AA3
RF2
1x230V 12 kW
3x230V 12 kW
UN
BT11
BT12
AA3 BT10
BT3
GP2
QM2 QM1
GP1
RF2
3x400V 12 kW
UN
BT11
BT12
BT10
BT3
GP2
QM2 QM1
GP1
AA3
RF2
16 kW
UN
BT11
BT12 RF2
BT10AA3
BT3
GP2
QM2 QM1
GP1
11Chapter 3 | The heat pump designNIBE S1255

6 kW
EP2
CA1
RA1
BP1
BT14
QA40
BT15
GQ10
BP2
QN1
EB10
EP1
HS1
XL21
XL20
BT17
1x230V 12 kW
3x230V 12 kW
UN
EP2
CA1
RA1
XL21
BP1
QA40
BT17
BT15
EP1
HS1
XL20
EB10
BT14
GQ10
QN1
BP2
3x400V 12 kW
UN
EP2
XL21
BP1
QA40
BT17
BT15
EP1
HS1
XL20
EB10
BT14 GQ10
QN1
BP2
16 kW
UN
BP2
EP2
GQ10
EP1
BT17
BP1
BT15
EB10 XL21
HS1
BT14
QA40
XL20
QN1
PIPE CONNECTIONS
Service connection, high pressureXL20
Service connection, low pressureXL21
HVAC COMPONENTS
Circulation pumpGP1
Brine pumpGP2
Drainage, climate systemQM1
Draining, brine sideQM2
SENSORS ETC.
High pressure pressostatBP1
Low pressure pressostatBP2
Temperature sensors, heating medium returnBT3
Temperature sensor, brine inBT10
Temperature sensor, brine outBT11
Temperature sensor, condenser supply lineBT12
Temperature sensor, hot gasBT14
Temperature sensor, fluid pipeBT15
Temperature sensor, suction gasBT17
ELECTRICAL COMPONENTS
Input circuit boardAA3
CapacitorCA1
Compressor heaterEB10
InverterQA40
ChokeRA1
EMC-filterRF2
COOLING COMPONENTS
EvaporatorEP1
CondenserEP2
CompressorGQ10
Drying filterHS1
Expansion valveQN1
NIBE S1255Chapter 3 | The heat pump design12

General
Pipe installation must be carried out in accordance with
current norms and directives. S1255 can operate with a re-
turn temperature of up to 58 °C and an outgoing temperat-
ure from the heat pump of 70 (65 °C with only the com-
pressor).
S1255 is not equipped with external shut off valves; these
must be installed to facilitate any future servicing.
Caution
Ensure that incoming water is clean. When using
a private well, it may be necessary to supplement
with an extra water filter.
Caution
Any high points in the climate system, must be
equipped with air vents.
NOTE
The pipe systems need to be flushed out before
the heat pump is connected so debris cannot
damage component parts.
NOTE
Water may drip from the safety valve’s overflow
pipe. The overflow pipe must be routed to a suit-
able drain, so hot water splashes cannot cause
harm. The entire length of the overflow pipe must
be inclined to prevent water pockets, and must
also be frost-proof. The overflow pipe must be at
least the same size as the safety valve. The over-
flow pipe must be visible and its mouth must be
open and not placed close to electrical compon-
ents.
SYMBOL KEY
MeaningSymbol
Unit box
Shut-off valve
Non-return valve
Mixing valve
Circulation pump
Expansion vessel
Filterball
Fan
Pressure gauge
Level vessel
Control valve
Particle filter
Safety valve
Temperature sensor
Trim valve
Reversing valve/shunt
Manual reversing valve/shunt
Heat exchanger
Overflow valve
Bore hole
Ground collector
Under floor heating systems
Ground source heat pump
Cooling system
Pool
Radiator system
Domestic hot water
Hot water circulation
13Chapter 4 | Pipe connectionsNIBE S1255
Pipe connections

SYSTEM DIAGRAM
S1255 consists of heat pump, water heater, immersion
heater, circulation pumps and control system. S1255 is
connected to the brine and heating medium circuits.
In the heat pump evaporator, the brine (water mixed with
anti-freeze, glycol or ethanol) releases its energy to the re-
frigerant, which is vaporised in order to be compressed in
the compressor. The refrigerant, of which the temperature
has now been raised, is passed to the condenser where it
gives off its energy to the heating medium circuit and, if
necessary, to the water heater. If there is a greater need for
heating/hot water than the compressor can provide there
is an integrated immersion heater.
XL 1 6 3 7 2
4
Connection, heating medium flowXL1
Connection, heating medium returnXL2
Connection, cold waterXL3
Connection, hot waterXL4
Connection, brine inXL6
Connection, brine outXL7
Dimensions and pipe
connections
560 440
70
1800
650*
20-50
650*
600
60
135
210
390
465
540
25
622
622
600
560 440
70
1800
650*
20-50
25
60
135
210
390
465
540
650*
XL1 XL6 XL7XL4 XL3 XL2
PIPE DIMENSIONS
16
kW
12
kW
6
kW
Connection
2822(mm)(XL1)/(XL2) Heating medium supply/re-
turn ext. Ø
22(mm)(XL3)/(XL4) Cold/hot water Ø
28(mm)(XL6)/(XL7) Brine in/out ext. Ø
* Can be angled for side connection.
NIBE S1255Chapter 4 | Pipe connections14

Brine side
COLLECTOR
Caution
The length of the collector hose varies depending
on the rock/soil conditions, climate zone and on
the climate system (radiators or underfloor heat-
ing) and the heating requirement of the building
Each installation must be sized individually.
Max. length per coil for the collector should not exceed
400 m.
In those cases where it is necessary to have several collect-
ors, these should be connected in parallel with the possibility
for adjusting the flow of the relevant coil.
For surface soil heat, the hose should be buried at a depth
determined by local conditions and the distance between
the hoses should be at least 1 metre.
For several bore holes, the distance between the holes must
be determined according to local conditions.
Ensure the collector hose rises constantly towards the heat
pump to avoid air pockets. If this is not possible, airvents
should be used.
Because the temperature of the brine system can fall below
0 °C, it must be protected against freezing down to -15 °C.
When making the volume calculation, use 1 litres of ready
mixed brine per metre of collector hose (applies when using
PEM-hose 40x2.4 PN 6.3) as a guide value.
SIDE CONNECTION
It is possible to angle the brine connections, for connection
to the side instead of top connection.
To angle out a connection:
1. Disconnect the pipe at the top connection.
2. Angle the pipe in the desired direction.
3. If necessary, cut the pipe to the desired length.
CONNECTING THE BRINE SIDE
Insulate all indoor brine pipes against condensation.
Mark the brine system with the antifreeze that is used.
Install as follows:
•enclosed level vessel (CM2)/expansion vessel
The level vessel must be installed as the highest point in
the brine system on the incoming pipe before the brine
pump (Alternative 1). If the level vessel cannot be placed
at the highest point, an expansion vessel must be used
(Alternative 2).
NOTE
Note that condensation may drip from the level
vessel. Position the vessel so that this does not
harm other equipment.
•enclosed safety valve (FL3)
Install the safety valve under the level vessel as illustrated.
•pressure gauge
The pressure gauge is only required if an expansion vessel
is used.
•shut-off valve
Install the shut-off valve as close to S1255 as possible.
•enclosed filterball (QZ2)
Install the filterball as close to S1255 as possible.
TIP
If filling connection KB25/KB32 is used, the en-
closed filterball does not need to be fitted.
•vent valve
When necessary you should install venting valves in the
brine system.
In the case of connection to an open groundwater system,
an intermediate frost-protected circuit must be provided,
because of the risk of dirt and freezing in the evaporator.
This requires an extra heat exchanger.
P
-QZ20
Alt. 1 Alt. 2
XL6
XL7
15Chapter 4 | Pipe connectionsNIBE S1255

Climate system
A climate system is a system that regulates the indoor
temperature with the help of the control system in S1255
and, for example, radiators, underfloor heating, underfloor
cooling, fan coils, etc.
CONNECTING THE CLIMATE SYSTEM
Install as follows:
•expansion vessel
•pressure gauge
•pressure relief valve
Recommended opening pressure is 0.25 MPa (2.5 bar).
For information about max opening pressure, see technical
data. Install the safety valve as illustrated.
•enclosed filterball (QZ2)
Install the filterball as close to S1255 as possible.
•shut-off valve
Install the shut-off valve as close to S1255 as possible.
•When connecting to a system with thermostats on all ra-
diators/underfloor heating coils, either a bypass valve
must be fitted or some of the thermostats must be re-
moved to ensure there is sufficient flow and heat emission.
P
XL1
XL2
Cold and hot water
The settings for hot water are made in menu 7.1.1 - "Hot
water".
CONNECTING COLD AND HOT WATER
Install as follows:
•shut-off valve
•non-return valve
•pressure relief valve
The safety valve must have a maximum 1.0 MPa (10.0 bar)
opening pressure and be installed on the incoming domest-
ic water line as shown.
•mixing valve
A mixer valve must also be installed, if the factory setting
for hot water is changed. National regulations must be
observed.
XL3
XL4
Installation alternative
S1255 can be installed in several different ways, some of
which are shown here.
Further option information is available at nibe.eu and in the
respective assembly instructions for the accessories used.
See page 64 for a list of the accessories that can be used
with S1255.
EXTRA HOT WATER HEATERS
The system should be supplemented with an extra water
heater, if a large bath tub or other significant consumer of
hot water is installed.
Water heater with immersion heater
In a water heater with an immersion heater, the water is
initially heated by the heat pump. The immersion heater in
the water heater is used for keeping warm and when the
heat pump does not have sufficient power.
The water heater’s flow is connected after S1255.
GROUND WATER SYSTEM
An intermediate heat exchanger is used to protect the heat
pump’s exchanger from dirt. The water is released into a
buried infiltration unit or a drilled well. See page Possible
selections for AUX output for more information about con-
necting a groundwater pump.
If this docking alternative is used, "min. brine out" in menu
7.1.2.8 "br pmp al set." must be changed to a suitable value
to prevent freezing of the heat exchanger.
-EP12-GP3
-EP12-HQ40
-EP12-EP4
-EP12-AA25
-EP12
NIBE S1255Chapter 4 | Pipe connections16

VENTILATION RECOVERY
The installation can be supplemented with the exhaust air
module NIBE FLM S45 to provide ventilation recovery.
•Pipes and other cold surfaces must be insulated with dif-
fusion-proof material to prevent condensation.
•The brine system must be supplied with a pressure expan-
sion vessel. If there is a level vessel this should be re-
placed.
P
COOLING
The accessory PCS 44 allows the connection of passive
cooling, for example with fan coils. The cooling system is
connected to the heat pump brine circuit, whereby cooling
is supplied from the collector via a circulation pump and
shunt valve.
•Pipes and other cold surfaces must be insulated with dif-
fusion-proof material to prevent condensation.
•Where the cooling demand is high, fan convectors with
drip trays and drain connection are needed.
•The brine system must be supplied with a pressure expan-
sion vessel. If there is a level vessel this should be re-
placed.
-EP25-AA25
-EP25-QN18-EP25-BT64
-EP25-GP13
-EP25-BT65 -EP25-RM1
-EP25
EXTRA CLIMATE SYSTEM
In buildings with several climate systems that require differ-
ent supply temperatures, the accessory ECS 40/ECS 41 can
be connected.
A shunt valve then lowers the temperature to the underfloor
heating system, for example.
-EP21-GP10-EP21-BT2
-EP21-AA25
-EP21-BT3
-EP21-QN25
-EP21
POOL
With the POOL 40 accessory, you can heat the pool with
your system.
During pool heating, the heating medium circulates between
the S1255 and the pool exchanger using the heat pump’s
internal circulation pump.
-CL11-HQ4-CL11-BT51-CL11-GP9
-CL11-EP5
-CL11-AA25
-CL11
HOT WATER CIRCULATION
A circulation pump can be controlled by S1255 to circulate
the hot water. The circulating water must have a temperat-
ure that prevents bacterial growth and scalding, and national
standards must be satisfied.
The HWC return can be connected to XL5 or a freestanding
water heater. If an electric water heater is connected after
the heat pump, the HWC return must be connected to the
water heater.
The circulation pump is activated via the AUX output in menu
7.4 -"Selectable in/outputs".
-QZ1-FQ3
-QZ1-GP11
-QZ1-RM1
-QZ1-RN1
-QZ1
17Chapter 4 | Pipe connectionsNIBE S1255

General
All electrical equipment, except the outdoor sensors, room
sensors and the current sensors are ready connected at the
factory.
•Electrical installation and wiring must be carried out in
accordance with national provisions.
•Disconnect S1255 before insulation testing the house
wiring.
•If the building is equipped with an earth-fault breaker,
S1255 should be equipped with a separate one.
•S1255 must be installed via an isolator switch. The cable
area has to be dimensioned based on the fuse rating used.
•If a miniature circuit breaker is used, this must have at
least triggering characteristic "C". See section "Technical
specifications" for fuse size.
•To prevent interference, sensor cables to external connec-
tions must not be laid close to high voltage cables.
•The minimum area of communication and sensor cables
to external connections must be 0.5 mm² up to 50 m, for
example EKKX, LiYY or equivalent.
•Electrical wiring diagram for S1255, see separate handbook
(WHB).
•When cable routing in S1255, the cable grommets (UB1
and UB2) must be used.
UB1
UB2
FC1
NOTE
Electrical installation and any servicing must be
carried out under the supervision of a qualified
electrician. Disconnect the current using the cir-
cuit breaker before carrying out any servicing.
NOTE
If the supply cable is damaged, only NIBE, its ser-
vice representative or similar authorised person
may replace it to prevent any danger and damage.
NOTE
Check the connections, main voltage and phase
voltage before the product is started, to prevent
damage to the heat pump electronics.
NOTE
Do not start the system before filling up with wa-
ter. Components in the system could be damaged.
MINIATURE CIRCUIT-BREAKER
The operating circuit in S1255 and some of its internal
components are fused internally by a miniature circuit
breaker (FC1).
S1255-6 3x400 V is not equipped with miniature circuit
breakers (FC1).
NIBE S1255Chapter 5 | Electrical connections18
Electrical connections

ACCESSIBILITY, ELECTRICAL CONNECTION
Removing the cover
The cover is opened using a screwdriver.
Removing the covers
The cover is opened using a screwdriver.
CABLE LOCK
Use a suitable tool to release/lock cables in the heat pump
terminal blocks.
Terminal block
1.
2.
TEMPERATURE LIMITER
-X29
-X28
1 0-5V 2 +5V
3 AUX1 4 AUX2 5 AUX3 6 AUX4 7 AUX5 8 AUX6 9 AUX7
10AUX8 11AUX9 12 BT25
1
1
2
3
2 3 4 5 6 7 8 9
10
11
12
GND
+12V
B
A
OT+ OT−
0-5V
PWM0 PWM1
CPU
EXT COM
INT COM
ERROR
POWER
+5V
GND
BE1 BE2 BE3
K10
-X27
NO
O
NC
AUX-RELAY
13 BT50 14 BT1
-X30
FQ10-S2
The temperature limiter (FQ10) cuts the power supply to the
electric additional heat if the temperature rises above 89 °C
and it is reset manually.
Resetting
The temperature limiter (FQ10) is accessed behind the front
cover. Reset the temperature limiter by pressing its button
(FQ10-S2).
19Chapter 5 | Electrical connectionsNIBE S1255

Connections
TERMINAL BLOCKS
The following terminal blocks are used on the base board
(AA2).
-X29
-X28
1 0-5V 2 +5V
3 AUX1 4 AUX2 5 AUX3 6 AUX4 7 AUX5 8 AUX6 9 AUX7
10 AUX8 11AUX9 12 BT25
1
1
2
3
2 3 4 5 6 7 8 9
10
11
12
GND
+12V
B
A
OT+ OT−
0-5V
PWM0 PWM1
CPU
EXT COM
INT COM
ERROR
POWER
+5V
GND
BE1 BE2 BE3
K10
-X27
NO
O
NC
AUX-RELAY
13 BT50 14 BT1
-X30
AA2
X1
X5X6-2X6-1
X7-2
X9
POWER CONNECTION
Supply voltage
Enclosed cable for incoming supply electricity is connected
to terminal block X1 and X6-1 on the PCB (AA2).
Connection 3x230V
AA2-X1
PE (L2) L1 L2 L3
1234
AA2-X6-1
Connection 1x230V
AA2-X1
PE N L (L) (L)
1234
AA2-X6-1
Connection 3x400V
AA2-X1
AA2-X6-1
PE N L1 L2 L3
1234
If separate supply to the compressor and immersion heater
is required, see section "External blocking of functions" ".
Tariff control
If the voltage to the immersion heater and/or compressor
is lost for a period, this must be blocked at the same time
via the selectable inputs, see section "Selectable inputs/out-
puts – Possible selections for AUX inputs".
External control voltage for the control
system
NOTE
Mark up any junction boxes with warnings for ex-
ternal voltage.
Control voltage (230 V ~ 50Hz) connects to AA2:X5:N, X5:L
and X6-2 (PE).
When connecting external control voltage, remove the
bridges from terminal block X5.
L
N
1. 2.
3. 4.
X5
NIBE S1255Chapter 5 | Electrical connections20