Viessmann Vitotronic 300, GW2 Installation And Service Instructions Manual

Installation and
Service Instructions

for use by heating contractor

Vitotronic 300, Model GW2

Outdoor-reset logic digital boiler and
heating circuit control unit

Please file in Service Binder

VITOTRONIC 300

Certified as a component part
of Viessmann boilers only

5285 941 v1.6 12/2012

IMPORTANT

Read and save these instructions
for future reference.

1

General information

Safety, Installation and Warranty Requirements

Please ensure that this manual is read and understood before commencing installation. Failure to comply with the issues

listed below and details printed in this manual can cause product/property damage, and/or severe personal injury. Ensure all
requirements below are understood and fulfilled (including detailed information found in manual subsections).

Licensed professional heating
contractor

The installation, adjustment, service,
and maintenance of this equipment
must be performed by a licensed
professional heating contractor.

Please see section
entitled “Important
Regulatory and
Installation
Requirements.”

Product documentation

Read all applicable documentation

before commencing installation. Store
documentation near boiler in a readily
accessible location for reference in the
future by service personnel.

For a listing of
applicable literature,
please see section
entitled “Important
Regulatory and
Installation Requirements.”

Advice to owner

Once the installation work is complete,
the heating contractor must familiarize
the system operator/ultimate owner
with all equipment, as well as safety
precautions/requirements, shut-down
procedure, and the need for
professional service annually before
the heating season begins.

Warranty

Information contained in
this and related product
documentation must be
read and followed. Failure

to do so renders warranty
null and void.

Safety Terminology

The following terms are used throughout this manual to bring attention to the presence of potential hazards or important
product information. Please heed the advice given!

DANGER

Indicates an imminently hazardous
situation which, if not avoided, will
result in death, serious injury or
substantial product / property damage.

2

WARNING

Indicates an imminently hazardous
situation which, if not avoided, could
result in substantial product/property
damage, serious injury or loss of life.

WARNING

Indicates an imminently hazardous
situation which, if not avoided, may
result in minor injury or product /
property damage.

IMPORTANT

Helpful hints for installation,
operation or maintenance which
pertain to the product.

5285 941 v.1.6

Product Information

Vitotronic 300, Model GW2

For installation in or mounting on
Viessmann boilers only.

Applicable to the following control
units

Order No. 7134 555, 7143 156, 7511 362 from
Serial No. 7143 000

Order No. 7134 555, 7143 156, 7511 362 from
Serial No. 7187 101

Order No. 7134 555, 7143 156, 7511 362 from
Serial No. 7248 248







General information

5285 941 v.1.6

3

Index

General information

Page

Safety Requirements 2

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Heating system types

Installation

Product information 3

System types for modulating boilers 6

System types for condensing boilers 12

Overview of electrical connections 18

Routing and strain relief of cables 21

Inserting the boiler coding card 22

Adjustment of the fixed high limit 23

Adjustment of the adjustable high limit 24

Connection of the outdoor temperature sensor 25

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Connection of the boiler temperature sensor
and other sensors 26

Connection of the pumps 30

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Connection of boiler return mixing-valve or
modulating valve actuator 32

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Making space for accessory adaptors on the DIN rail
(CM2 only) 34

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Start-up

Connections to plug aBÖ 35

Compiled failure alarm indicator 36

Connection of external equipment to plug aVD 38

Connection of external equipment to plug aVH 39

Connection of external controls 40

Connection of combustion air device 45

Connection of low water cut-off device 49

Burner connection, burner control wiring 51

Power supply connection, boiler control 55

Mounting the front part of the control unit 57

Opening the control unit 59

Procedure (overview) 63

Steps 64

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4

5285 941 v.1.6

Index

Page

Scanning service information

Troubleshooting

Functional description

Additional information

Overview of service levels 72

Temperatures, boiler coding cards and scanning 73

Scanning operating status information 77

Scanning and resetting the ”Service” display 78

Troubleshooting steps 79

Diagnosis 80

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Boiler temperature control 86

Heating circuit control 87

DHW tank temperature control 90

Overview 92

Technical data 93

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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System components 94

Coding 1 114

Coding 2 116

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Wiring diagram 135

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5285 941 v.1.6

5

Heating system types

Heating system types for modulating boilers

System type 1 – Single-boiler system with shunt pump for raising the return temperature

in conjunction with
Vitorond 200, VD2

C C

A1 M2 M3

202205222052

1

28
21

5

40

M2

2

20

52

29

17B
17A

3

90

41

146

143

T2

T1

M3

2

20

52

B

A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve

*1

On the Vitorond the boiler supply and return are at the rear of the boiler.

6

*1

A

plugs

! Outdoor temperature sensor
? M2 Supply temperature sensor,

mixing valve circuit 2

? M3 Supply temperature sensor,

mixing valve circuit 3

§ Boiler temperature sensor
% DHW tank temperature sensor
aJA Temperature sensor T1
aJB Temperature sensor T2
sÖ A1 Close mixing valves with

external heating circuit controls

sÖ M2 Heating circuit pump, mixing

valve circuit 2

sÖ M3 Heating circuit pump, mixing

valve circuit 3

sA DHW pump
sK DHW re-circulation pump
sL Shunt pump
fÖ Power supply connection,

120 VAC

fA Burner (1st stage)
gS M2 Mixing valve motor, mixing

valve circuit 2

gS M3 Mixing valve motor, mixing

valve circuit 3

lÖ Burner (2nd stage/modulating)
aVD Connection of external

equipment (see page 38)

aVH Connection of external

equipment (see page 39)

5285 941 v.1.6

Heating system types

Heating system types for modulating boilers

Possible applications

Heating systems with manifold
arranged close to the boiler. The boiler
water flow is required to be reduced.

Please note:

This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the heating contractor to check that
this recommendation is complete and
fully functional. Three-phase equipment
must be connected via additional
power contactors.

When the return temperature falls
below the required minimum value,
the temperature sensor T2 switches
on the shunt pump. If the minimum
return temperature is not reached
despite raising the return temperature,
the flow must be reduced by at least
50% via the temperature sensor T1.

The shunt pump must be sized so that
bypassed water accounts for approx.
30% of the total flow rate of the
boiler.

(continued)

Temperature sensor T1

Wiring of the temperature sensor
T1 in heating systems with heating
circuit control units which are not
connected via the LON BUS to the
boiler control unit.
Coding required: ”4C : 2” – use
plug sÖ for closing the mixing
valves of the heating circuits
connected downstream.

sÖ A1 Close mixing valves

A Contactor relay, field supplied
B Heating circuit controls

connected downstream
Switch contact closed: signal
for ”close mixing valve”.

Available system accessories

Vitotrol remote control
Flue gas temperature sensor

Coding of
system type

00: 1 If no system circuit A1 is connected, set

02: 1 Set coding ”02: 2” for operation with

03: 0 Set coding ”03: 1” for oil-fired operation

4A: 0 –– Connection of the temperature sensor T1 at

4b: 0 –– Connection of the temperature sensor T2 at

Change required Automatic change

The system type is recognized automatically
coding ”00: 3”, ”00: 4”, ”00: 7” or ”00: 8”
(see page 101)

modulating burner

(re-setting is not possible)

when the sensors are connected

plug aJA;

Coding ”4A: 1” is set automatically

plug aJB;

Coding ”4b: 1” is set automatically

––

––

5285 941 v.1.6

7

Heating system types

Circuit Diagram 1

Single-boiler system with Therm-Control and three-way mixing valve

in conjunction with Vitorond 200, VD2A

A Heating circuit with mixing valves
B DHW tank

Plug

! Outdoor temperature sensor
?M2 Flow temperature sensor,

mixing valve

?M3 Flow temperature sensor,

mixing valve

§ Boiler water temperature

sensor

% DHW tank temperature sensor
aJA Therm-Control temperature

sensor

8

sÖM2 Heating circuit pump, mixing

valve

sÖM3 Heating circuit pump, mixing

valve

sÖA1 Closing the mixing valves with

external heating circuit control
units

sA DHW primary pump
sK DHW circulation pump

fÖ Power supply, 120 VAC

60 Hz
Install the main isolator in
accordance with regulations

fA Burner (stage 1)
gSM2 Mixing valve motor
gSM3 Mixing valve motor
lÖ Burner

(burner stage 2 / mod.)

aVD/aVH External connections

Please refer to the control
manual Vitocontrol-S,
VD2/CT3.

5285 941 v1.6

Heating system types

Circuit Diagram 1

(continued)

sÖ A1 Close mixing valves

A Contactor relay, field supplied
B Heating circuit controls

connected downstream
Switch contact closed: signal
for ”close mixing valve”.

Wiring diagram

Wiring of the Therm-Control in heating
systems with heating circuit control units
are not connected to the boiler control
unit via the LON.
Required coding:
Change “4C” to “2” - use the plug-in
connector 20 A1 to close the
downstream mixing valve. Change “0D”
to “1” - the Therm-Control acts on the
mixing valve of the downstream heating
circuits (for Vitotronic 200 and 300,
delivered condition).

5285 941 v1.6

9

Heating system types

Heating system types for modulating boilers

(continued)

System type 2 – Single-boiler system with shunt pump and return valve for raising the return temperature

in conjunction with
Vitorond 200, VD2

C C

M3

2

20

52

1

28
21

5

M2 M3

22052220

41

40

M2

2

20

52

A1

29

52

52

17B
17A

3

90

146

143

T2

T1

B

A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve

*1

On the Vitorond the boiler supply and return are at the rear of the boiler.

10

*1

A

plugs

! Outdoor temperature sensor
? M2 Supply temperature sensor,

mixing valve circuit 2

? M3 Supply temperature sensor,

mixing valve circuit 3

§ Boiler temperature sensor
% DHW tank temperature sensor
aJA Temperature sensor T1
aJB Temperature sensor T2
sÖ M2 Heating circuit pump, mixing

valve circuit 2

sÖ M3 Heating circuit pump, mixing

valve circuit 3

sA Circulation pump for heating

the DHW tank

sK DHW re-circulation pump
sL Shunt pump
fÖ Power supply connection,

120 VAC

fA Burner (1st stage)
gS A1 Mixing valve motor for raising

the return temperature

gS M2 Mixing valve motor, mixing

valve circuit 2

gS M3 Mixing valve motor, mixing

valve circuit 3

lÖ Burner (2nd stage/modulating)
aVD Connection of external

equipment (see page 38)

aVH Connection of external

equipment (see page 39)

5285 941 v.1.6

Heating system types

Heating system types for modulating boilers

Possible applications

Heating systems with distributor
arranged close to the boiler. The boiler
water flow is required to be reduced.

Please note:

This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the heating contractor to check that
this recommendation is complete and
fully functional. Three-phase equipment
must be connected via additional
power contactors.

Available system accessories

Vitotrol remote control
Flue gas temperature sensor

Coding
system type

00: 1 If no system circuit A1 is connected, set

02: 1 Set coding ”02: 2” for operation with

03: 0 Set coding ”03: 1” for oil-fired operation

0C: 0 Set coding ”0C: 1” for continuous return

4A: 0 –– Connection of the temperature sensor T1 at

4b: 0 –– Connection of the temperature sensor T2 at

Change required Automatic change

coding ”00: 3”, ”00: 4”, ”00: 7” or ”00: 8”
(see page 114)

modulating burner

(re-setting is not possible)

temperature control

When the return temperature falls
below the required minimum value,
the temperature sensor T2 switches
on the shunt pump. If, as a result,
the required minimum return
temperature is not reached, the
return valve is proportionally closed
via the temperature sensor T1 and
the minimum return temperature is
assured.

The shunt pump must be sized so that
bypassed water accounts for approx.
30% of the total flow rate of the
boiler.

(continued)

The system type is recognized automatically

when the sensors are connected

––

––

––

plug aJA;

Coding ”4A: 1” is set automatically

plug aJB;

Coding ”4b: 1” is set automatically

5285 941 v.1.6

11

Heating system types

Heating system types for condensing boilers

System type 3 – Single-boiler system with Vitocrossal 300

C C

A1 M2 M3

20220

1

28
21

5

41

40

52220

90

143

M2

2

20

52

52

3

146

M3

2

20

52

B

A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve
D Neutralizing unit

D

A

plugs

! Outdoor temperature sensor
? M2 Supply temperature sensor,

mixing valve circuit 2

? M3 Supply temperature sensor,

mixing valve circuit 3

§ Boiler temperature sensor
% DHW tank temperature sensor
sÖ A1 Heating circuit without mixing

valve (if installed)

sÖ M2 Heating circuit pump, mixing

valve circuit 2

sÖ M3 Heating circuit pump, mixing

valve circuit 3

sA Circulation pump for heating

the DHW tank

sK DHW re-circulation pump
fÖ Power supply connection,

120 VAC

fA Burner (1st stage)
gS M2 Mixing valve motor, mixing

valve circuit 2

gS M3 Mixing valve motor, mixing

valve circuit 3

lÖ Burner (2nd stage/modulating)
aVD Connection of external

equipment (see page 38)

aVH Connection of external

equipment (see page 39)

5285 941 v.1.6

12

Heating system types

Heating system types for condensing boilers

Please note:

This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the heating contractor to check that
this recommendation is complete and
fully functional. Three-phase equipment
must be connected via additional
power contactors.

Available system accessories

Vitotrol remote control
Flue gas temperature sensor

Coding
system type

00: 1 If no system circuit A1 is connected, set

02: 1 Set coding ”02: 2” for operation with

0d: 1 Set coding ”0d: 0” ––

Change required Automatic change

coding ”00: 3”, ”00: 4”, ”00: 7” or ”00: 8”
(see page 114)

modulating burner

The Vitocrossal 300 is operated with
modulating boiler water temperature
by means of the outdoor re-set boiler
control unit. Viessmann modulating
burner is operated through Vitotronic
control.

The boiler water temperature which
is established in the heating mode is
higher than the maximum heating
circuit supply temperature by an
adjustable difference.

(continued)

The system type is recognized automatically

when the sensors are connected

––

5285 941 v.1.6

13

Heating system types

Heating system types for condensing boilers

(continued)

System type 4 - Single-boiler system with Vitocrossal 300 with several heating circuits and one modulating supply
temperature heating circuit

M3

2

F

20

52

or

A1 M2 M3

20220

1

28
21

5

41

40

52220

90

143

C D

M2

2

20

52

52

3

146

M3

2

20

52

E

B

G

A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve
D Modulating supply temperature

heating circuit
or

E Underfloor heating circuit
F High limit thermostat (max. limit)
G Neutralizing unit

14

A

plugs

! Outdoor temperature sensor
? M2 Supply temperature sensor,

mixing valve circuit 2

? M3 Supply temperature sensor,

mixing valve circuit 3

§ Boiler temperature sensor
% DHW tank temperature sensor
sÖ A1 Heating circuit without mixing

valve (if installed)

sÖ M2 Heating circuit pump, mixing

valve circuit 2

sÖ M3 Heating circuit pump, mixing

valve circuit 3

sA Circulation pump for heating

the DHW tank

sK DHW re-circulation pump
fÖ Power supply connection

120 VAC

fA Burner (1st stage)
gS M2 Mixing valve motor, mixing

valve circuit 2

gS M3 Mixing valve motor, mixing

valve circuit 3

lÖ Burner (2nd stage/modulating)
aVD Connection of external

equipment (see page 38)

aVH Connection of external

equipment (see page 39)

5285 941 v.1.6

Heating system types

Heating system types for condensing boilers

Possible applications

For heating circuits with different
temperatures.

Please note:

This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the heating contractor to check that
this recommendation is complete and
fully functional. Three-phase equipment
must be connected via additional
power contactors.

The Vitocrossal 300 is operated with
modulating boiler water temperature
by means of the outdoor re-set boiler
control unit. Two-stage or modulating
burners can be controlled.

The Vitocrossal 300 has two return
connections. The heating circuits with
the higher return temperature are
connected to the return connection
at the top, those with the lower
temperatures to the return connection
at the bottom. Please note: At least
15% of the take-off from the rated
output must be connected to the
return connection at the bottom.

The boiler water temperature which
is established in the heating mode is
higher than the maximum heating
circuit supply temperature by an
adjustable difference.

(continued)

Pumps in the underfloor heating
circuit

20

20

LN

A B C

sÖ Heating circuit control unit

A Primary pump of underfloor

heating circuit

B High limit thermostat (max. limit)
C Secondary pump of underfloor

heating circuit (after system
separation)

Coding
system type

00: 1 If no system circuit A1 is connected, set

02: 1 Set coding ”02: 2” for operation with

0d: 1 Set coding ”0d: 0” ––

5285 941 v.1.6

Change required Automatic change

The system type is recognized automatically
coding ”00: 3”, ”00: 4”, ”00: 7” or ”00: 8”
(see page 114)

modulating burner

when the sensors are connected

––

15

Heating system types

Heating system types for condensing boilers

System type 5 – Single-boiler system with Vitocrossal 200

A Boiler with Vitotronic 300
B Domestic hot water tank
C Heating circuit with mixing valve
D Neutralizing unit

16

plugs

! Outdoor temperature sensor
? M2 Supply temperature sensor,

mixing valve circuit 2

? M3 Supply temperature sensor,

mixing valve circuit 3

§ Boiler temperature sensor
% DHW tank temperature sensor
sÖ A1 Heating circuit without mixing

valve (if installed)

sÖ M2 Heating circuit pump, mixing

valve circuit 2

sÖ M3 Heating circuit pump, mixing

valve circuit 3

sA Circulation pump for heating

the DHW tank

sK DHW re-circulation pump
fÖ Power supply connection,

120 VAC

fA Burner (1st stage)
gS M2 Mixing valve motor, mixing

valve circuit 2

gS M3 Mixing valve motor, mixing

valve circuit 3

lÖ Burner (2nd stage/modulating)
aVD Connection of external

equipment (see page 38)

aVH Connection of external

equipment (see page 39)

5285 941 v.1.6

Heating system types

Heating system types for condensing boilers

Please note:

This circuit diagram represents a
recommendation only. It is the
responsibility of the customer and/or
the heating contractor to check that
this recommendation is complete and
fully functional. Three-phase equipment
must be connected via additional
power contactors.

Available system accessories

Vitotrol remote control

Coding
system type

00: 1 If no system circuit A1 is connected, set

02: 1 Set coding ”02: 2” for operation with

0d: 1 Set coding ”0d: 0” ––

Change required Automatic change

coding ”00: 3”, ”00: 4”, ”00: 7” or ”00: 8”
(see page 114)

modulating burner

The Vitocrossal 200 is operated with
modulating boiler water temperature
by means of the outdoor re-set boiler
control unit. Viessmann modulating
burner is operated through Vitotronic
control.

The boiler water temperature which
is established in the heating mode is
higher than the maximum heating
circuit supply temperature by an
adjustable difference.

(continued)

The system type is recognized automatically
when the sensors are connected

––

5285 941 v.1.6

17

Installation

Overview of electrical connections

52

M3

52

M2

20

M3

20

M2

2

M3

2

M2

145
145

1

17

B

17

A

5

3/2

15

143

146

28
21
52
20
29
50

40
156
156

A1
A1

151

90

41

150

Mixing valve extension circuit board

? M2/M3 Supply temperature sensor
sÖ M2/M3 Heating circuit pump
gS M2/M3 Mixing valve motor

18

Low-voltage motherboard

! Outdoor temperature sensor

(ATS)

§ Boiler temperature sensor (BTS)
% DHW tank temperature sensor

(STS)

aG Flue gas temperature sensor

(AGS) (accessory)

aJA Therm-Control temperature

sensor
or
return temperature sensor T1
(RLS) (accessory)

aJB Return temperature sensor T2

(RLS) (accessory)

aVD Connection of external

equipment

aVG KM BUS participant, e.g.

Vitotrol remote control
(accessory)

aVH Connection of external

equipment

Line voltage motherboard

sÖ A1 Heating circuit pump or

control output

sA Circulation pump for heating

the DHW tank (accessory)

sK DHW re-circulation pump

(provided by customer)

sL Shunt pump
fÖ Power supply connection
fA Burner (1st stage)
gÖ Central fault indicator
gSA1 Continuous return

temperature control
or
3-way mixing valve for DHW
tank loading system

lÖ Burner (2nd stage/modulating)
aBÖ Connection of external

equipment, e.g. additional
safety equipment

aBA Safety circuit, potential free
aBH Power supply connection for

accessories

5285 941 v.1.6

Overview of electrical connections(for VD2/VD2A/CT3 only)

Installation

5285 941 v.1.6

19

Installation

Overview of electrical connections (for CM2 only)

20

5285 941 v.1.6

Routing and strain relief of cables

1. Run the cables from the connection enclosure into the control unit.

2. Apply strain relief to cables (see below).

Installation

Cables with moulded strain relief
clamp

Connect cable and strain relief
clamp.

OR

Fasten cable to the cable lead with
cable tie.

5285 941 v.1.6

21

Installation

Inserting the boiler coding card

CAUTION

For matching the operation of the
control unit to the boiler, only the
boiler coding card which is supplied
as part of the standard delivery of
the boiler may be used.

Only use the boiler coding card included with the boiler.

Boiler Coding card Part No.

Vitocrossal 300, type CT3 1040 7820 144

Vitorond 200, VD2 / VD2A 1020 7820 142

Vitocrossal 200 CM2 1041 7820 145

1. Push the boiler coding card
through the recess in the cover
and insert it in plug-in location
”X7”.

22

5285 941 v.1.6

Installation

Adjustment of the fixed high limit

The fixed high limit is supplied with a factory setting of 110°C / 230°F.

3.

(if required)

A

Adjustment to 99°C / 210°F

¨ Disconnect power to control

and burner!

1. Unclip the fuse box and swing

upwards.

2. Turn the slotted screw on the
rear of the fixed high limit until
the slot points to 99°C / 210°F
(once adjusted, the fixed high limit

cannot be reset to 110°C/ 230°F).

3. Re-fit the fuse box.

WARNING

If adjusted to 99°C / 210°F, do
not set the adjustable high limit
above 75°C / 167°F.

Please note:

Adjustment is required for the

1.

Vitocrossal 300.

See Service Instructions
for Vitocrossal 300.

2.

Non-condensing boiler
(VD2/VD2A) °C / °F

Fixed high limit 110 / 230 99 / 210 99 / 210 99 / 210

Adjustable high limit 100 / 212 95 / 203 95 / 203 95 / 203

Coding for the electronic maximum
temperature limiter of Vitotronic 100;
set code 06 to the temperature as
shown or less

93 / 200 87 / 188 87 / 188 88 / 190

Condensing boiler
(CT3) °C / °F

Condensing boiler
(CM2) °C / °F

5285 941 v.1.6

23

Installation

Adjustment of the adjustable high limit

The adjustable high limit is supplied with a factory setting of 95°C.

A

3.

2.

(if required)

Adjustment to 100°C / 212°F

1. Using a suitable screwdriver,

lever out and remove the
selector knob ”R” behind the
hinged cover.

2. Using a pair of pointed pliers,
break off the cams identified by
the shaded areas in the Fig.
from the stop dial.

A 75 to 100°C

167 to 212°F

3. Fit the selector knob ”R” so
that the marking is in the centre
of the selected range.

Please note:

Note the setting of coding address
”06”!

1.

WARNING

If the system is operated in
conjunction with a domestic hot
water tank, ensure that the
maximum permissible domestic
hot water temperature is not
exceeded. If necessary, install a
suitable safety device for this
purpose.

24

5285 941 v.1.6

Connection of the outdoor temperature sensor

The outdoor temperature sensor should be mounted 2 to 2.5 metres / 6.5 to
8 ft above ground level on the north or north-west facing wall of the building.
In the case of multi-storey buildings, it should be mounted in the upper half of
the second storey.
Make sure that the sensor is not located over windows, doors and air vents,
nor immediately beneath a balcony or guttering.
Do not paint over the outdoor temperature sensor housing.

1.

5.

3.

Installation

1. Remove the cap.

2. Mount the bottom part of the

sensor housing.

3. Pull the sensor wire through the
opening in the terminal
compartment and through the
strain relief provided.

4. Connect the wires to the
terminals.

600

580

560

540

520

500

480

460

4.

2.

5. Place the cap over the outdoor
temperature sensor.

WARNING

When extending wire, there is the
possibility of exposure to
electromagnetic interference. Avoid
running wires beside or near high
voltage 120/240 VAC conductors.
If proximity to high voltage
conductors cannot be avoided, use
stranded, twisted pair or shield design
wire. Ensure that only one end of the
shielding is grounded.

440

420

Resistance in

400

-40 -30 -20 -10 0 10 20 30

-40 -22

Outdoor temperature sensor °C / °F

5285 941 v.1.6

-4

14 32 50 68 86

25

Installation

Connection of the boiler temperature sensor

The sensor measures the boiler
water temperature.

3

760

740

The boiler temperature sensor is
installed at the same time as the
boiler insulation.

Check the sensor

1. Disconnect plug § in the

terminal compartment of the
boiler control.

2. Measure resistance of sensor
at terminals ”1” and ”2” of the
plug.

Boiler water
temperature
in °C / °F

40 / 104
50 / 122
60 / 140

3. Compare the value measured
with the current temperature.
If the value differs significantly,
check installation and, if
necessary, replace sensor.

Resistance
in ΩΩΩΩ

578
597
616

720

700

680

660

640

620

Resistance in

600

580

560

4000540

32 68 141 176 212 248 284104

Boiler temperature in

Technical data

Degree of protection: IP 32
Ambient temperature
During operation:

0 to + 130°C

32 to + 266°F

During storage and transport:

-20 to + 70°C

-4 to + 158°F

Electrical connection

The sensors are ready to plug in.
Insert the boiler temperature
sensor in socket ”3” of the boiler
control.

20 40 60 80 100 120 140

°C / °F

26

5285 941 v.1.6

Connection of the DHW tank temperature sensor

Installation

The sensor measures the domestic hot
water tank temperature.

5

sensor and tank
temperature sensor

720

Heating systems with domestic hot
water heating (single-boiler systems
only)

1. Install the DHW tank temperature

sensor.

See Installation
Instructions for domestic
hot water tank.

Please note:

When installing the sensor in DHW
tanks of other makes, make sure
that the sensor is pressed against
the sensor well of the DHW tank
by means of a suitable device.

2. Ensure that the maximum
permissible domestic hot water
temperature is not exceeded. If
necessary, install a suitable safety
device for this purpose.

Heating systems without domestic
hot water heating

Do not connect the DHW tank
temperature sensor.

Check the sensor

1. Disconnect plug % in the

terminal compartment of the
boiler control.

2. Measure resistance of sensor
at terminals ”1” and ”2” of the
plug.

DHW tank
temperature
in °C / °F

40 / 104
50 / 122
60 / 140

3. Compare the value measured
with the current temperature.
If the value differs significantly,
check installation and, if
necessary, replace sensor.

Technical data

Degree of protection: IP 32
Ambient temperature
During operation:

0 to + 90 °C

32 to + 194 °F

During storage and transport:

-20 to + 70 °C

-4 to + 158 °F

Resistance
in ΩΩΩΩ

578
597
616

700

Electrical connection

680

660

640

620

The sensors are ready to plug in.
Insert the DHW temperature
sensor in socket ”5” of the boiler
control.

Resistance in

600

580

560

540

0 20 40 60 80 100
32 68 104 140 176 212

DHW tank temperature in ºC / ºF

5285 941 v.1.6

27

Installation

740

R

e

s

i

s

t

a

n

c

e

i

n

Connection of the return temperature sensor

Strap-on temperature sensor and immersion temperature sensor

17A or 17B

17A or 17B

For measuring the boiler return
temperature.

Electrical connection

The sensor is inserted in socket
”17A” or ”17B” on the boiler
control.

Check the sensor

1. Disconnect plug aJA or aJB

in the terminal compartment of
the boiler control.

2. Measure resistance of sensor
at terminals ”1” and ”2” of the
plug.

720

700

680

660

640

620

Return
temperature
in °C / °F

30 / 86
40 / 104
60 / 140

3. Compare the value measured
with the current temperature. If
the value differs significantly,
check installation and, if
necessary, replace sensor.

Technical data

Degree of protection: IP 32
Ambient temperature
During operation:

0 to + 100°C

32 to + 212°F

During storage and transport:

-20 to + 70°C

-4 to + 158°F

Resistance
in ΩΩΩΩ

569
592
643

600

580

560

540

28

30 40 50 60 7070 80 90

20 100
68 86 104 122 140 158 176 194 212

Return temperature in

°C / °F

5285 941 v.1.6

Connection of the flue gas temperature sensor (VD2/VD2A/CT3 only)

The sensor measures the flue gas
temperature and monitors the
selected limit value.

Electrical connection

The sensor is inserted in socket
”15” on the boiler control.

Check flue gas temperature sensor

1. Disconnect plug aG in the

terminal compartment .

2. Measure resistance of sensor
at terminals ”1” and ”2” of the
plug.

Installation

1020

980

940

900

860

820

Ω

Ω

Ω

Ω

780

740

700

Resistance in

660

Flue gas
temperature
in °C / °F

180 / 176

160 / 320
200 / 392

3. Compare the value measured
with the actual temperature If
the value differs significantly,
check installation and, if
necessary, replace sensor.

Technical data

Degree of
protection: IP 60
Ambient temperature
During operation:

0 to + 600°C

32 to + 1112°F

During storage and transport:

-20 to + 70°C

-4 to + 158°F

Resistance
in ΩΩΩΩ

650
800
880

620

580

540

500

0

40 80

32 104 176

Flue gas temperature in °C / °F

5285 941 v.1.6

120 160 200 240 280
248 360 392 464 536

29

Installation

Connection of the Pumps (VD2/VD2A/CT3 only)

Available pump connections

sÖ A1/M1Heating circuit high

temperature (without mixing valve)

Terminals 5 - L, - G , - N

sA Circulation pump for heating

up the domestic hot water tank ­Terminals 4 - L, - G , - N

sL Shunt pump, boiler circuit pump

Terminals 6 - L, - G, - N.

sK

DHW recirculattion pump

terminals 3 - L, - G, - N

sÖM2

M2 Heating circuit high
temperature (with mixing valve)
Terminals 2 - L, - G , - N

sÖM3

M3 Heating circuit high
temperature (with mixing valve)
Terminals 1 - L, - G , - N

Install pumps: see
manufacturer’s
instructions.

120 VAC pumps

Note:

The maximum power consumption of
all pumps is 4A .
Rated current: max. 2 FLA
Recommended connection
cable: AWG 14

Use contactor for pumps with higher
current rating

Connect the 3-wire cable from the
pump to the corresponding terminals.

240 VAC or 3 PH pumps

Please note:

Use contactor and/or motor starter to
power pump.
For activating the contactor:
Rated current: max. 2 FLA
Recommended connection
wire size: AWG 14

Please ensure that all connections and
wire sizes comply with local and
national codes.

1.Select the contactor and the
connecting wire in accordance with
the rating of the pump that is to be
connected.

2.Connect pump and power supply to
the contactor.

3.Connect contactor coil to the
corresponding terminals.

30

5285 941 v1.6