Strebel SC-B Assembly instructions

Strebel SC-B Wall-Hung
Condensing Boiler
INSTALLATION OPERATING & MAINTENANCE INSTRUCTIONS
Version 3.1-Jul/06
Strebel is not liable for any damage caused by incorrectly following these instructions.

Page 2 of 51
1. SAFETY GUIDELINES 4
2. TYPICAL SYSTEM LAYOUT 5
2.1. Single Boiler layout & quick Reference 5
2.2. Cascade Boiler layout & quick reference 6
3. TECHNICAL DATA S-CB BOILERS 7
4. INTRODUCTION 8
4.1. Operation of the S-CB Boiler 8
4.2. Controls 8
4.3. Frost Protection 8
4.4. Cascade Control 8
5. ACCESSORIES 9
6. INSTALLATION OF THE S-CB 9
6.1. Unpacking 9
6.2. Select the position of the boiler 10
6.2.1 Important provisions 11
6.3. Mounting the boiler 12
6.4. Air Supply & flue gas discharge types 12
6.5. The air inlet and gas outlet system 12
6.5.1 SC-B Flue resistance table and example calculation 1 13
6.5.2 Single & cascade table air inlet resistance 14
6.5.3 Single & cascade table flue resistance 15
6.6. Example flue resistance calculation 2 16
6.7. Example flue resistance calculation 3 16
6.8. Condense water drain 17
6.9. Central heating material 17
6.9.1 Central Heating circuit 17
6.9.2 The expansion vessel 17
6.9.3 S-CB Internal Pump 18
6.10. Low loss header & cascade layout 18
7. INSTALLATION INSTRUCTION FOR THE ELECTRICIAN 19
7.1. Connecting to the mains power supply 19
7.2. Connector strip 19
7.3. Polarity sensitivity 23
7.4. Fuses – Main & boiler internal 23
7.5. Sample Cascade Electrical Layout 23
7.6. Electrical Circuit Diagram 24

Page 3 of 51
Page No
8. PUTTING INTO OPERATION 25
8.1. Control panel, control knobs & L.E.D. 25
8.2. Sensors 26
8.3. Run and Fault Codes and Display meanings 27
8.4. Display buttons 28
8.4.1 Service Button 28
8.5. Filling and venting the boiler and system for light up 28
8.6. Starting the boiler and Commissioning 29
8.6.1 General 29
8.6.2 Commissioning 29
8.7. Adjusting and setting the output 29
8.7.1 Setting the maximum output 29
8.7.2 Setting the minimum output 31
8.8. Gas conversion 31
9. LONG TERM SHUTDOWN 32
10. LOCK OUT / USER COMPLAINT 33
11. TROUBLESHOOTING 34
11.1. Cause of the fault 34
11.2. Troubleshooting table 36
12. INSPECTION AND MAINTENANCE 38
12.1. General 38
12.2. Inspection 38
12.3. Maintenance 39
13 LPG Settings
SCB 60 to 120 40
SCB 150 to 180 41
14 EXPLODED VIEWS AND SPARES 42
14.1Burner, fan, gas pipe, heat exchanger, casing S-CB60 – S-CB120 43
14.1.1Spare Parts S-CB60 – S-CB120 44
14.2.Burner fan, gas pipe, heat exchanger, casing S-CB150 – S-CB180 45
14.2.1 Spares Parts S-CB150 – S-CB180 46
14.3 Pipelines & pumps S-CB60 – S-CB120 47
14.3.1 Spare Parts S-CB60 – S-CB120 48
14.4 Pipelines & pumps S-CB150 – S-CB180 49
14.4.1Spare Parts S-CB150 – S-CB180 50

Page 4 of 51
1. SAFETY GUIDELINES
Read all these instructions before commencing installation.
This appliance is free from any asbestos material.
It is the law that all gas appliances and fittings are installed by a competent person (such as a CORGI
registered installer) and in accordance with the Gas Safety (installation and Use Regulations), the relevant
British standards for installation, codes of practice or rules in force and in accordance with the Manufactures’
instructions.
The installation shall also be carried out in accordance with the following regulations, codes and standards:
The Building Regulations issued by the Department of the Environment.
The Building Standards (Scotland) (Consolidation) Regulations issued by the Scottish Development
Department.
The Local Building Regulations and Local water by-laws, the gas services area and the Local Authority
recommendations.
Wiring to the appliance must be in accordance with the IEE (BS 7671) Wiring Regulations the Health
and Safety Document No 635 “The Electricity at Work Regulations 1989” and any local regulations that
apply.
Relevant British standards insofar as the relevant areas that are not covered by these instructions.
BS 5440: Parts 1 and 2 (Flues and Ventilation).
CP 342: Part 2, 1994. Code of practice for centralised hot water supply – buildings other than individual
dwellings.
British Gas Publications: IM/2 purging procedures, IM/5 soundness testing, IM/11, IM/16 Installation of
gas pipe work and boosters.
HSE guidance note PM 5, automatically controlled steam and hot water boilers.
CIBSE, IHVE, Guide ports A, B and C.
IGE/UP/1, IGE/UP/2 and IGE/UP/7.
Failure to comply with these regulations could lead to prosecution and deem the warranty invalid. This
appliance must be installed in accordance with the rules in force and used only in a sufficiently ventilated
space when not in a room sealed application or compartment ventilation as current regulations.

Page 5 of 51
2. TYPICAL SYSTEM LAYOUTS
2.1 Single Boiler Layout

Page 6 of 51
2.2 Typical Cascade Layout
Equipment shown may
not be supplied. Please
see tender for the actual
equipment supplied

Page 7 of 51
3. TECNICAL DETAILS
General
Product Identification Numbe
r
CE 0063 BP3254
Dimensions
(
h x w x d
)
M
m
835 x 458 x 485 890 x 458 x 670
Classification II2H3P
Gas Appliance Type B23; C13X,C23X,C33X,C43X, C53X, C63X,C83X
Boiler T
yp
e S-CB 60 80 100 120 150 180
Water content etc. Lt
r
3
,
9 5 6
,
5 8
,
3 10
,
4 12
,
9
Weight (empty) Kg 46 73 78 83 92 101
Gas connection ”R ¾” R ¾” R ¾” R ¾” R 1” R 1”
Co-axial flue connections m
m
80/125 80/125 100/150 100/150 100/150 100/150
Se
p
arate Flue Exhaust / Air Inle
t
80-80 80-80 100-100 100-100 130-130 130-130
Possible with Ada
p
tor
(
extra cost
)
mm 100-100 130-130
Power consum
p
tion W355 355 355 375 460 460
Protection class IP40 IP40 IP40 IP40 IP40 IP40
Central heatin
g
N
ominal in
p
u
t
(
Nett
)
80/60ºC kW 14-56 18-74 23-92 27-111 34-138 43-166
N
ominal in
p
ut
(
Gross
)
50/30ºC kW 15-61 20-82 25-102 30-123 38-154 48-184
Gas flow max.
(
G20
)
m³/h
r
5
,
9 7
,
9 9
,
811
,
8 14
,
7 17
,
6
Efficienc
y
at 80/60ºC %97 98 98 98 98 98
Efficienc
y
50/30ºC %109 109
,
5109
,
5109
,
5 109
,
5 109
,
5
Efficienc
y
40/30ºC RAL 61 %109
,
5110 110 110 110 110
N
ominal out
p
ut at 80/60ºC kW 55 73 90 109 136 163
N
ominal out
p
ut at 50/30ºC kW 15-60 20-80 25-100 30-120 36-150 45-180
N
orm efficienc
y
75/60ºC RAL-UZ61 107 107 107 107 107 107
NO x emission, RAL 61 mg/kWh <15 <15 <15 <15 <15 <15
CO emission, RAL 61 mg/kWh <20 <20 <20 <20 <20 <20
Table 1: Data
Boiler control includes:
Cascade control for up to 8 boilers ( requires flow temperature sensor at extra cost )see item G page 8
Remote run & fault indication
0-10 VDC control connection ( requires flow temperature sensor at extra cost )
Control for external calorifier primary pump ( pump not included ) via relay at extra cost ( see page 22)
Weather compensation control (with outside detector at extra cost)
Control for an external pump via relay at extra cost,( see page 22 )external pump not included.
Electronic Ignition.
Boiler output modulated between 25% and 100%,
Data
CO2- flue
g
as % 9
Dew
p
oint combustion
g
as °C 53
Tem
p
. Flue
g
as
@
ambient tem
p
20ºC °C 85
Flue resistance ca
p
abilit
y
* Pa 250* u
p
to 600*
PH value condensate 4 to 5
,
5
Available
p
ressure at 25ºC mw
k
2
,
5 3 1
,
5 1
,
5 1
,
5 1
,
5
Max. flow tem
p
. °C 90
Min./Max. Boiler Pressure
b
a
r
0.5
–
6
Sound level at Maximum Output dBA 46.0 47.0 48.0 49.0 50.0 50.0
Average Sound level dBA 32.0 33.0 33.0 34.0 35.0 35.0

Page 8 of 51
4. INTRODUCTION
Warning: For trouble free operation of the boiler, and to be assured of the full guarantee, the following
items are required:
A. An automatic air and dirt separator must be installed in the installation and a strainer in
the return also devices as shown on pages 5 or 6.
B. Minimum static water pressure should be more than 0.5 bar.
C. The system is flushed, water tested and additive utilised if required.
D. Boiler auto air vent cap must be open and all system air vents open.
E. Low and high water cut out pressure switches ( usually in the fill unit) connected in the
Boiler volt free control circuit in series with other controls on terminals 13 - 14 or by 0 volt
when using external 0 to 10 volt control by others.
F. Control of Boiler on/off must never be by interruption of the mains supply.
G. When using a common flue the inbuilt cascade control must be used.
These instructions are written for the installer of Strebel products and contain all necessary information on
the installation and adjustment of S-CB boilers. We suggest that you read the instructions before installation
to ensure that all work is done correctly. We suggest that you keep these instructions near the boiler.
4.1 Operation of the S-CB Boiler
The heating boilers from the Strebel S-CB series are central heating boilers with maximum high efficiency.
Such performance is reached by, among other things, using a special heat exchanger made of stainless steel.
The heat exchanger allows flue gases to cool down below condensation point, condensing the flue gases and
releasing extra heat. This has an immediate positive impact on the efficiency, exceeding 100%net calorific.
•S-CB flue gases have a low temperature (below 85°C), the boiler needs to have a high efficiency
approved stainless steel or plastic flue system .Aluminium flue systems are not allowed to be
connected to these boilers. Adequate drain points must be added to the flue system with a u trap.
4.2 Controls
The Strebel S-CB Boiler adjusts to the demand for heat by using flame modulation and external controls.
That is on the basis of 1) 0 to 10 volt control. 2) Strebel optimiser control 3) Built in weather compensation
with an outside detector. 4) RC or E-BUS .For RC or E-Bus system, see separate booklet.
The boiler control is equipped with:
Control for a DHW Cylinder with a diverter valve or a pump (pump via a relay both not supplied)
Connection for a Heating pump via a relay (pump and relay not supplied)
Connection for a room thermostat, on/off control, optimiser or 0 to 10 volt control (see 4.4.1).
4.3 Frost protection
Frost protection does not protect the system or system pumps. It protects the boiler.
Frost protect the system by fitting devices to link out any time controls. In a frost condition (at 7° Boiler
temperature) the Boiler internal pump starts. When the boiler water temperature falls down to 3°C, the burner
is also ignited. This operation will cease as soon as the boiler temperature has reached 10°C.
4.4 Cascade control
Using the integrated cascade control, a maximum of 8 boilers can be controlled in a cascade configuration.
The Cascade has in-built full logic step control. The Boiler will require a Flow temperature sensor and 2
wires to each boiler in a daisy chain. When using a common flue the cascade control must be used
4.4.1 0-10 VDC connection available
The boiler is equipped to take a 0-10 VDC signal from a controller by others (set at time of commissioning)
with which up to 8 boilers can be controlled in cascade, utilising the built in cascade manager. (0 Volt is
no heat demand.) The Boiler will require a Flow temperature sensor at extra cost.

Page 9 of 51
5. ACCESSORIES
Dependent on the choice of control and hydraulics etc, accessories are available from Strebel at extra cost.
See Page 50 for details
6. INSTALLATION OF THE STREBEL S-CB
6.1 Unpacking
The Strebel S CB includes the following documents and accessories:
•1 Installation and cascade instructions for the installer.
•User instruction (incorporated).
•1 suspension bracket.
•Fuses and 3 nuts for mounting the burner plate (attached to the front of the gas valve).
•1 siphon with tightening nut and gasket.
•Reducing couplings (where required) for flue gas discharge and air supply.
THE BOILER IS SET FOR NATURAL GAS G20.On delivery, immediately check that the Strebel S-CB is
complete and without any defects. Report any damage immediately to the supplier or Strebel Ltd.
.
.
1. After removing the carton, the easiest way to take the boiler off the pallet is as follows:
2. Lift the pallet including the boiler (at the side of the flue outlet) to a vertical position.
3. The boiler has a polystyrene block, which now supports the Boiler on the floor.
4. Push the Boiler a little forward, until the pallet is not touching the floor anymore.
5. The boiler stands now on the flow- and return pipes and the polystyrene block.
6. Take away the pallet (See also 6.3).
The boiler can now be lifted (unclip and remove the Boiler door before lifting) easily for mounting, by
putting a hand at the lower side of the boiler.
1
2
4 5
6

Page 10 of 51
6.2 Select the position for the Boiler
Select a position in the building with adequate access to the front, side and the bottom of the boiler for future
maintenance and servicing. The boiler must have at least 20 mm space at each side.
Boiler Type S-CB 60, 80, 100, 120
Co-axial flue is standard supply on 60kw to 100kw Boilers. Parallel flueing requires an adaptor at extra cost.
Parallel flueing is standard on the SCB 120 .Co-axial adaptor available at extra cost
Co-Axial
connection at the
rear.
Separate exhaust
and air inlet
connections are:
Flue exhaust at
the rear and air
inlet at the front
S
-
CB
Concentric Flue D
S-CB D
60 / 80 80/125 mm
100 100/150 mm
120 100/150 m
m
S-CB Parallel Flue
S-CB D D1
60 80 80
80 100 100
100 100 100
120 130 130

Page 11 of 51
Boiler Type S-CB 150 and S-CB 180
150kw and 180kw Boilers are supplied with parallel flue connections an adaptor is
available for co axial flue-ing at extra cost
6.2.1The installation area must have the following provisions:
•Items listed in 4 page 8 also see drawings 2.1 page 5 and 2.2 page 6.
•Electrical point with earth connection;
•Connection to the drains for condensation water or suitable condense removal device
•A sound wall or suitable mounting. The wall or frame used for mounting the boiler must be able to hold
the weight of the boiler.
•Both the air supply (if room sealed) and the flues are to be connected to the outside wall and/or the roof.
(see safety guidelines page 4)
•Install horizontal Flue parts under 1% fall in the direction of the boiler (one centimetre for every
linear metre) complete with extra drain points with a 60mm water trap.
•The installation area must be dry and frost-free and conform to relevant regulations.
•Installers are advised to choose a part of their building where slight noise emission will not cause
disturbance.
•A minimum of 15 mbar gas pressure (and or current regulations) all plant running.
890
S-CB
Parallel Flue Co- Axial Flue D
S-CB D D1
150 130 130 100 /150
180 130 130 130 /150
Air inlet Flue
D1 D

Page 12 of 51
6.3 Mounting the Boiler
Prepare the Boiler for mounting as in 6.1.Determine the positions for the flow and return pipes using the
suspension bracket or a suspension frame, if any. When marking the holes, ensure that the suspension bracket
or frame is level. Drill the holes for the flow and return pipes if required then hook the heating boiler onto the
bracket or place it upon the frame.
6.4 Air supply & flue types
When using multiple SCB Boilers on a common flue the inbuilt cascade control must be used. SCB
Boilers 60kw to 100kw use a co-axial flue. Twin pipe flue-ing utilises an adaptor at extra cost .Boilers 120.
150 and 180 kw use parallel i.e. one air inlet tube and one exhaust tube a co-axial adaptor is available at
extra cost. . All Boilers can be used in a room sealed application or, if the boiler room or fitting space
complies with the relevant ventilation requirements Boilers can be non room sealed I.E. exhaust only,
Providing ventilation as per current regulations is in place. See pages 10 and 11 for flue connections.
Install the horizontal flue parts under 1% fall in the direction of the boiler (one centimetre for every
linear metre). Adequate drain points should be installed throughout long horizontal exhaust runs and
at the base of any vertical flue exhaust run. 60 mm (minimum ) “u” traps should be utilized.
6.5 The air inlet and flue gas outlet system.
The Boiler is ( normally )room sealed, the casing is airtight with air entering through the air supply
connection only. Always ensure the casing is placed over the boiler when the boiler is in operation! The
available pressure for the inlet and flue system is 250
Pa, unless data from the table is being used.
N.B.! Install the horizontal flue parts under 1%
fall in the direction of the boiler (one centimetre
for every linear metre). Failing to do so may result
in water condensation building up in the flue gas
tube. In turn, this may cause failure.
The impact of the flue to the output
The table on the left shows the relationship between
the Boiler output and the resistance of the air inlet
and flue. Up to a resistance of around 250 Pa the
output will be approximately the same as the Boiler
data plate In the event of a greater resistance ( up to
maximum 600 Pa ) this will change the Boiler output
. The resistance and the change of output only affect
the maximum output and not the minimum.
Tip! Remember that possible output changes may
influence hot water production and
transmission/absorption calculations.
Resistance Decrease of in
p
u
t
u
p
to 250 Pa 0 %
300 Pa - 3 %
350 Pa - 4 %
400 Pa - 6 %
450 Pa - 7 %
500 Pa - 8 %
550 Pa - 9 %
600 Pa -10 %
40
60
80
100
120
140
160
180
0100 200 300 400 500 60
0
Pa
kW
A60
A80
A100
A120
A150
A180
180
150
120
100
80
60

Page 13 of 51
6.5.1 Strebel S-CB Flue/Air inlet Resistance table
The output of the boiler is affected by the resistance of the air inlet and flue system. At a resistance up to 250
Pa, the output will be as indicated on the name plate of the boiler. See page 12 for higher flue resistance.
Table 1; Resistance table
(
mm
)
Resistance inlet and outlet s
y
stem
[
Pa
]
Item Boiler S-CB 60 80 100 120 150 180
roof terminal 125/80 25 45 XX X X
outside wall terminal 125/80 15 30 XX X X
roof terminal 150/100 12 30 35 40 X X
Co-axial
Termina
ls
outside wall terminal 150/100 10 25 28 32 X X
strai
g
ht tube/
m
t
80 4 5
,
5 8 10 15 24
strai
g
ht tube/
m
t
100 1 3 3
,
54 6 9
strai
g
ht tube/
m
t
130 0
,
35 0
,
75 0
,
81 1
,
2 2
strai
g
ht tube/
m
t
150 X X 0
,
3 0
,
4 0
,
6 1
,
0
45° bend 80 2345 7.5 12
45° bend 100 0
,
6 1
,
5 1
,
72 2
,
2 4.5
45° bend 130 0
,
2 0
,
4 0
,
4 0
,
5 0
,
6 1
45° bend 150 X X 0
,
15 0
,
2 0
,
3 0
,
6
90° bend 80 45.5 810 15 24
90° bend 100 1 3 3
,
54 6 9
90° bend 130 0
,
35 0
,
7 0
,
81 1
,
2 2
(Twin )Air supply
90° bend 150 X X 0
,
3 0
,
4 0
,
6 1
,
2
strai
g
ht tube/
m
t
80 5 8 12 15 20 X
strai
g
ht tube/
m
t
100 2 3
,
546 9 12
strai
g
ht tube/
m
t
130 0
,
45 0
,
8 1
,
2 1
,
5 2 3
strai
g
ht tube/
m
t
150 X X 0
,
5 0
,
5 1 1.5
45° bend 80 2
,
546
,
58 14 X
45° bend 100 1 1
,
7 2 3
,
2 4.5 6
45° bend 130 0
,
2 0
,
4 0
,
6 0
,
8 1 1.5
45° bend 150 X X 0
,
2 0
,
4 0
,
8 1.8
90° bend 80 5 8 12 15 20 X
90° bend 100 2 3
,
546 9 X
90° bend 130 0
,
45 0
,
8 1
,
2 1
,
5 2 3
90° bend 150 X X 0
,
5 0
,
7 1
,
1 1.5
strai
g
ht tube/
m
t
125/80 8.5 11.5 X X X X
strai
g
ht tube/
m
t
150/100 2.5 4.5 58.0 15 20
45° Concentric bend 125/80 4.2 5.5 XX X X
45° Concentric bend 150/100 1.2 2.2 2.5 4 8 10
90° Concentric bend 125/80 8.5 11.5 16 21 X X
Co axial ( Twin) Flue gas discharge
90° Concentric bend 150/100 2.5 4.5 5 8 15 20
*Parallel Roof & wall terminal air inlet/exhaust resistance equals 1 meter straight length of same size
Strebel S-CB Example calculation - Boiler type: S-CB 60
S-CB 60 using a co-axial flue system 125/80, with through the roof terminal.
For the stated output the boiler has 250 Pa fan pressure
Roof terminal = 25 Pa Resistance 25 Pa subtracted from 250 Pa leaves 225 Pa
Each metre length of 125/80 flue has a resistance of 8.5 Pa. 225 divided by 8.5 =26.4
Therefore the above example allows a straight flue run of 26.4 metres.
Reduce this flue run by 1 metre for each 90 degree bend or ½ metre for each 45 degree bend.
See also sample parallel flue calculation on page 16
Install horizontal Flue parts under 1% fall in the direction of the boiler (one centimetre for every
linear metre).

Page 14 of 51
6.5.2 Single & Cascade resistance tables of air inlet and flue.
The output of the boiler is affected by the resistance of the air inlet and flue system (as a result of controlled
gas/air ratios in the Boiler). At a resistance up to 250 Pa, the output will be as indicated on the Boiler data
plate. Higher resistance of up to 600 Pa max can be overcome with reduced Boiler output (see page 12).
An under pressure, in the flue gas outlet, is not required, a positive pressure is created by the fan of the Boiler
which is specially designed for this purpose. As a result of this, the diameter of the common air inlet and flue
gas outlet is minimised; while the built in non return air valve prevents recirculation between the Boilers
when 2 or more are used on a common flue.
Table Resistance of the air inlet system
The stated Air inlet diameter is that used between the boilers and the roof or wall terminal.
Transmission
kW 80 mm Pa/m 100 mm Pa/m 130 mm Pa/m 150 mm Pa/m 180 mm Pa/m 200 mm Pa/m 250 mm Pa/m
60 4 1 0.35
90 7 2 0.6
120 10 4 1 0
,
4
150 15 6 1
,
50
,
6
180 24 9 2 1 0
,
5
210 12 2
,
51
,
40
,
6
240 15 3 1
,
80
,
7
270 18 4 2
,
20
,
8
300 21 5 2
,
60
,
9
330 25 7 3 1
,
10
,
8
360 8 3
,
41
,
30
,
9
390 9 3
,
81
,
51
420 10
,
55
,
31
,
71
,
2
450 12 5
,
82 1
,
3
480 13 6
,
32
,
31
,
4
510 14 6
,
52
,
61
,
5
540 15 7 2
,
91
,
8
570 16 8 3
,
32
,
1
600 18 9 3
,
62
,
30
,
65
630 20 10 3
,
92
,
40
,
7
660 22 11 4
,
22
,
50
,
75
690 23 12 4
,
62
,
60
,
8
720 25 13 5 3 0
,
85
750 27 14 5
,
43
,
50
,
90
780 28 15 5
,
84 0
,
95
810 30 16 6
,
24
,
21
840 17 6
,
64
,
31
,
1
870 18 7
,
04
,
31
,
2
900 20 7
,
54
,
51
,
3
930 21 8 4
,
71
,
4
960 22 8
,
54
,
91
,
6
990 23 9
,
05
,
21
,
8
1020 25 9
,
55
,
52
Resistance of the different parts of the inlet system: Standard Flue pipe can be used for the air inlet.
*Bend 90° : equal to 1 meter straight tube of the same diameter.
*Bend 45° : equal to 0,5 meter straight tube of the same diameter.
*Cascade T-piece on top of the boiler equal to 1 meter straight tube.
*Parallel Roof & wall terminal air inlet resistance is equal to 1 meter straight length of same size.
* See sample calculation page 16.
Install horizontal Flue parts under 1% fall in the direction of the boiler (one centimetre for every
linear metre).

Page 15 of 51
6.5.3 Single & Cascade Table Resistance of the Flue in Pa/m
SIZE 80m
m
100m
m
130m
m
150m
m
180m
m
200m
m
250m
m
Out
p
ut kW Pa/
m
Pa/
m
Pa/
m
Pa/
m
Pa/
m
Pa/
m
Pa/
m
60 5 2
90 8 4 1
120 15 6 1
,
50
,
6
150 26 9 2 1 0
,
5
180 12 3 1
,
50
,
6
210 15 4 2 0
,
8
240 20 5
,
52
,
51
270 25 7 3 1
,
20
,
8
300 8
,
53
,
51
,
50
,
9
330 10 4 1
,
71
,
1
360 11 4
,
52 1
,
3
390 12 6 2
,
31
,
5
420 13 7 2
,
51
,
7
450 15 8 3 1
,
9 X
480 17 9 3
,
52
,
1 X
510 19 10 4 2
,
3 X
540 21 11
,
54
,
52
,
5 X
570 23 13 5 2
,
8 0
,
8
600 27 14
,
56 3 0
,
9
630 28 16 6
,
33
,
3 1
,
0
660 30 17
,
56
,
53
,
7 1
,
2
690 19 7 4
,
0 1
,
4
720 20
,
57
,
54
,
3 1
,
5
750 22 8
,
24
,
6 1
,
6
780 23 8
,
44
,
9 1
,
7
810 24 8
,
75
,
2 1
,
8
840 25 9 5
,
6 1
,
9
870 26 9
,
56 2
,
1
900 27 10
,
16
,
4 2
,
2
930 28 10
,
66
,
8 2
,
3
960 29 12 7
,
3 2
,
4
990 30 13 8
,
0 2
,
5
1020 31 14 8,8 2,6
Resistance of the different parts of the inlet system:
Bends 90° : equal to 1 meter straight flue of the same diameter
Bends 45° : : equal to 0,5 meter straight flue of the same diameter.
T-piece on top of the boiler is equal to 1 meter straight flue .
Co axial flueing, roof and wall terminal see page 13
Parallel Roof & wall terminal flue resistance is equal to 1 meter straight length of same size
•See sample calculation page 16
Install horizontal Flue parts under 1% fall to the boiler (one centimetre for every linear metre).

Page 16 of 51
6.6 Example of a Flue Resistance Calculation
Boilers: 4 x 150 kW + 1 x 180 kW; Total 780 kW
Horizontal air inlet: 5 meter
Vertical air inlet to the roof: 8 meter
T-pieces over the boilers 4
Number of bends 90°: 2
Roof terminal: 1
Air inlet: Choosing a diameter of: 180 mm
Resistance
Horizontal duct , 5 meter 5 x 5.8 29.0 Pa
Vertical duct, 8 meter 8 x 5.8 46.4 Pa
Bends 90°:x 2 2 x 5.8 11.6 Pa
T-pieces: x.4 4 x 5.8 23.2 Pa
Roof terminal 5.8 5.8 Pa
Total 116Pa
Flue gas exhaust Choosing a diameter of: 180 mm
Resistance
Horizontal flue , 5 meter 5 x 8.4 42.0 Pa
Vertical flue, 8 meter 8 x 8.4 67.2 Pa
Bends 90°: x 2 2 x 8.4 16.8 Pa
T-pieces: x.4 4 x 8.4 33.6 Pa
Roof terminal 8.4 8.4 Pa
Total 168.0Pa
Total resistance of the system : 116 Pa+168Pa = 284 Pa
Total resistance is 284 Pa; higher than 250 Pa,(at which the Boiler output stays the same as stated on the
data plate) therefore according to the table on page 12, the output will be lowered by about 3%.
This means, that the total output will be 780 kW – 3% = 756 kW
6.7 Chosing a diameter of 150 mm for the whole 780 kW system,
Air inlet system:(uses flue material)
Choosing a diameter of: 150 mm Resistance
Horizontal duct, 5 meter 5 x 15 75 Pa
Vertical duct, 8 meter 8 x 15 120 Pa
Bends 90°: x. 2 2 x 15 30 Pa
T-pieces: x. 4 4 x 15 60 Pa
Roof terminal 15 15 Pa
Total 300Pa
Flue
Choosing a diameter of: 150 mm Resistance
Horizontal Flue, 5 meter 5 x 23 115 Pa
Vertical Flue, 8 meter 8 x 23 204 Pa
Bends 90°: x. 2 2 x 23 46 Pa
T-pieces: x. 4 4 x 23 102 Pa
Roof terminal 23 23 Pa
Total 490Pa
Total resistance: 300+490 = 790 Pa. It is clear, that the resistance is higher than the 250 Pa, even higher than
the maximum 600 Pa;the diameter of 150 mm is too small.

Page 17 of 51
6.8 Condense water drain
The condense water drain is next to the centre at the bottom of the boiler and has a ¾ inch hose discharge.
Connect this flexible hose to the drains via a tundish or oversize waste pipe. Also consider a waste trap.
N.B.!
Use only plastic parts with the condense water drain. Metal lines are not allowed.
Tip!
Blockage of this drain may cause damage to the boiler. The drain connection is correct when the condense
water can be seen flowing away, e.g. using a funnel. Any damage that may occur due to a blockage is not
covered by the warranty.
6.9 Central Heating
If plastic material for the flow and return from the radiators or under floor heating is being used and not
oxygen diffusion proof to DIN standard 4726/4729 a separation between the central heating water of the
boiler and the system will be required, e.g. using a plate heat exchanger. This will prevent contamination of
the boiler heat exchanger with magnetite. If the plastic material is not to the DIN standard failure to provide
such separation will void the warranty of any boiler parts relating to water.
6.9.1 Central Heating circuit
The S-CB has no pressure relief safety valve. This should be fitted in the flow of the system in close
proximity to the boiler (Boiler side of any valves). See pages 5 & 6.
The S-CB has no internal bypass. Low loss headers must be used to allow flow, even when all system valves
are closed.
Tip!
To prevent contamination of the S-CB heat exchanger, it is recommended to thoroughly flush the system
with clean running water prior to first use.
6.9.2 The expansion vessel
Please remember that the capacity of an expansion vessel is chosen or installed to match the capacity of the
central heating system and the static pressure. Fit the expansion vessel in the return of the central heating
system (see page 5 & 6 2.1 and 2.2) Expansion vessels and fill units available at extra cost from Strebel.

Page 18 of 51
LSV DOC
Low loss header
AAV
H3
H2
STRAINER
FILL
UNIT
L
ow
L
oss
H
eader
Hidden Detail
EXP
VESSEL
H1
D4
D1 Diameter of common
flow & return headers
Air & Dirt
seperator
6.9.3 Internal Pump
The pump has a speed regulator adjusted to the highest setting: Do not change this setting! The S -CB has a
built-in pump control with a standard 3-minute over run.
The pump will work at top speed when heat is required. When heat is no longer required, the pump will
continue to run for another 3 minutes. The pump and connected three-way valve for the calorifier or external
pump (if fitted) are also activated for one minute every 24 hours. The 24 hour cycle starts as soon as the
power supply to the boiler is activated.
6.10 Low loss header.
Low Loss Headers must be used with the S-CB Boiler
Typical Cascade Layout.
For Low Loss Header size,
Flow and Return size see table.
Low Loss Header & Common Flow/Return
.
Note to Design Engineer: See Quotation for equipment supplied.
OUTPUT H1 H2 H3 D4 D1
KW mm mm mm inch inch
60 330 370 465 3 1 1/2
80 340 380 480 3 1 1/2
100 345 390 510 4 2
120 360 405 565 4 2
150 400 450 610 4 2
180 445 505 665 5 2
240 445 505 665 5 2 1/2
300 560 620 725 6 2 1/2
360 680 780 865 8 2 1/2
420 780 850 980 10 4
480 780 850 980 10 4
540 780 850 980 10 4
600 780 850 980 10 4
Boiler Connections Group I
Type
S-CB Flow/Return Gas connection
60 1 1/2” 3 /4”
80 1 1/2” 3 /4”
100 1 1/2” 3 /4”
120 1 1/2” 3 /4”
Boiler Connections Group II
Type
S-CB Flow/Return Gas connection
150 2 “ 1”
180 2 “ 1”

Page 19 of 51
7. INSTALLATION INSTRUCTIONS FOR THE ELECTRICIAN
7.1 Connecting to the mains power supply
The console has an ON / OFF button to switch the Boiler on or off.
The electrical connections to the S-CB are made via discreet plugs and sockets which are located within the
boiler casing, on top of the control panel.
Connections must only be made using appropriate diameter multi strand flexible cables. Cable entry must
only be via the rubber glanded cable points located at the bottom rear of the appliance: the low voltage
cables are at the left side (top in the drawing below) and the 230 VAC cables are at the right hand side
of the boiler (bottom in the drawing below).
If the boiler is to be room sealed, then care must be taken to ensure the cable entries are reasonably air-tight.
7.2 Boiler Plug & Connector Strip
The stated items may be attached using the available plugs/sockets (use relays for pumps)
Interruption of the mains supply for on/off control must not be used
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
18 19 20 21 22 23 24 25 26 27 28 29 34 35 36
33536
Connector strip Strebel S-CB
Heating curve
When an outside temperature sensor has been connected, the boiler will respond to the program of weather
compensation (but not when 0 to 10 volt control is used)
Through the parameter menu the heating curve (see page 20) can be set: to do this, use the parameter menu
with the interface cable together with a laptop and the necessary software.
When the outside temperature sensor is connected, the cable terminals “13” and “14” should be bridged; or
an On/Off control should be used. For RC and E-BUS see separate data.
With the temperature button on the display (CH) this heating curve can be shifted with + and - 5°C.
The default for the heating curve of the main circuit is set to K-factor “3,5” See graph page 20
C = Common
HD = Heat Demand/Run
LO = Lock Ou
t
Outside
sensor Flow
Sensor
NOT
USED NOT
USED +
0 to 10 v
DC in
Boiler On/off
( low voltage)
SEE DATA for
RC or E-BUS
Cascade
Bus
Connection
C LO HD
See below
L1 N L2
Use for 3 way valve
on DHW. Use 22-
23 for D H W
Primary Pump
L1 N L2
NOT USED L1 N L2
Heating Pump
27 - 28
L N E
Mains connection
230 AC
Interruption of the
mains supply for
on/off control
must not be used
DHW
Sensor or
Thermostat

Page 20 of 51
Diagram Outside temperature versus Flow temperature and the K-factor
Plug Connection Description
1 - 2 Outside
Temperature
Sensor
When an outside temperature sensor is connected, the boiler will be weather
compensated. When no Roomstat or control is connected, the terminals “13 and
“14” should be bridged.
A remote room thermostat with or without time switch can be connected.
The RC or E –Bus (for RC and E-Bus see separate data), with or without built in
room compensation can be used,see other instructions.
When the outside temperature sensor is not connected, the boiler is controlled by the
roomstat or On/Off control (when connected to plug no. 13 and 14 )
3 – 4 Flow
temperature
sensor
In cascade the flow temperature sensor for the central heating circuit is connected to
these terminals and placed directly on the flow to the installation (after any low loss
header). This flow sensor can work in conjunction with or without an outside
temperature sensor and is required for 0 to 10 v control by others.
Outside tem
p
erature °C
30
2
0
4
0
50
60
7
0
80
1
0
25
30 1020 15 50-5 -10 -15
K=0,5
K=3,5 K=3 K=2,5 K=2
K=1,5
K=1
Flow temperature
°
C
K-F
actor
90
Outside tem
p
erature °C +
Flow Temperature
Outside Temperature + Outside Temperature -