Ferroli SIGMA User guide

cod. 3544071/2- 10/2004
SIGMA
wall mounted cast iron,
gas fired boiler for central heating
fan assisted, room sealed,
electronic flame ignition and control
INSTALLATION AND SERVICING INSTRUCTIONS
Sigma 60 - 100 GC N° 41-267-19

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INDEX PAGE
1. TECHNICAL CHARACTERISTICS .......................................................................................3
2. INSTALLATION...................................................................................................................6
3. COMMISSIONING AND TESTING...................................................................................20
4. ADJUSTMENT ..................................................................................................................21
5. GAS CONVERSION ..........................................................................................................22
6. MAINTENANCE AND CLEANING ..................................................................................23
7. REPLACEMENT OF PARTS ..............................................................................................25
8. FAULT FINDING ...............................................................................................................27
9. USER INSTRUCTIONS ......................................................................................................30
C.O.S.H.H.
Materials used in the manufacture of this appliance are non hazardous and no special precautions are
required when servicing.
IMPORTANT
Your "benchmark" Installation, Commissioning and Service Record Log Book will be enclosed in your
customer information pack. This record must be completed and left with the end user.
Ferroli is a member of the Benchmark initiative and fully supports the aims of the programme. Benchmark
has been introduced to improve the standards of installation and commissioning of central heating
systems in the UK and to encourage the regular servicing of all central heating systems to ensure
safety and efficiency.
CE MARK
CE mark documents that the Ferroli gas appliances comply with the requirement contained in European
directives applicable to them.
In particular, the appliances comply with the following CEE directives and the technical specifications
provided from them:
• Gas appliances directive 90/396
• Efficiencies directive 92/42
• Low tension directive 73/23 (modified from the 93/68)
• Electromagnetic compatibility directive 89/396 (modified from the 93/68)

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Fig. 1
Key
1 - Ø 22 mm flow
2 - Ø 22 mm return
3 - Ø 15 gas inlet
4 - Rear air inlet/flue outlet
5 - Top air inlet/Flue outlet
Front viewRight side view
Top view
325 35
207
5542
58
450
643
132,5 162,5105
25 25
200 250
450
115
200
360
115
1
2
3
3
4
26
60
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1. TECHNICAL CHARACTERISTICS
1.01 Introduction
The Sigma is defined as a “room sealed” boiler, all air required for combustion is taken from outside the room in which it
is installed. It is a new high performance gas fired heat generator, which is designed to provide indirect hot water and/or
central heating. The cast iron heat exchanger is suitable for use on fully pumped hot water/central heating systems,
which may be sealed or open vented. A special feature of this boiler is its built-in electronic flame ignition and control
unit making burner operation completely automatic and safe.
The main components are as follows:
Cast iron heat exchanger specifically shaped for high efficiency.
Ceramic fibre insulated combustion chamber
One stainless steel bladed burner specifically designed for this boiler.
Fan for discharge of combustion products and intake of combustion air.
Differential air pressure switch. For safety reasons, this ensures the burner ignites only when the fan is
functioning correctly.
Hermetically sealed compartment made from corrosion-resistant steel enclosing the above components.
Combination gas safety valve, complete with pressure stabiliser.
Central heating flow temperature adjustment thermostat.
Overheat safety thermostat.
Electronic control unit for automatic flame ignition and control.
Central heating flow temperature sensor.
Note: only for use on fully pumped systems.
1.02 Dimension

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Protection
level
IP 40
Boiler
water
contents
3,2
litres
Weight
62
kg
Model
15
Gas inlet
3
Ø
Return
2
Ø
2222
Flow
1
Ø
3
bar
Max. working
pressure
C.H.circuit
Connections Gas valve
Ø 1/2”
Honeywell
VK 4105 ASigma 60/100
Model
Sigma 60/100
G31-LPG
mbar
3720
G20-NG
mbar
Burner gas pressures
G31-LPG
Nominal
mbar
34,5
Minimum
mbar
13,5
Nominal
mbar
13,4
Minimum
mbar
5
Gas supply pressures
G20-NG
29,3
Max
kW Min kW
17,9 32,2
Max
kW Min kW
20,5 35,7
Max
kW Min kW
32,7
Model
Sigma 60/100
Heat
output
Heat
input
(net)
Heat
input
(gross)
G31-LPG
Ø
0,671,1
G20-NG
Ø
3,45
Max
2,17
Min
2,52
Max
1,60
Min
G20 m3/h-NG G31 kg/h-LPG
Injectors
(mm) Gas flow rates
N.B. • Maximum working temperature 82°C, adjustable between 60°C and 82°C.
1.03 Technical data

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1.04 General Layout and Main Components
Fig. 2
Gas in
C.H. inC.H. out
Flue out
Air in
Air in
C.H. in
C.H. out
Gas in
151
83
44
68
63
121
86
43
11
10
5
90
28
16
32
27
19
24
22
21
151
16
43
49
34
Flue out
Air in
Air in
C.H. in
C.H. out
Gas in
1.05 Boiler water flow diagram
Key
1 Fixing points
5 Room sealed compartment
7 Inlet gas-cock
10 Central heating flow outlet
11 Central heating return inlet
16 Fan
19 Combustion chamber
21 Gas injector
22 Burner
24 Spark and sensor electrode
27 Cast iron heat exchanger
28 Flue collector from heat exchanger
34 Central heating flow
temperature sensor
43 Air pressure switch
44 Gas valve
49 Safety overheat thermostat
63 Central heating temperature setting
68 Control box with P.C.B.
83 Full sequence automatic control
86 Automatic control reset switch
90 Flue outlet pressure test point
91 Air pressure test point
121 Boiler shut-down warning
132 Flue gas deflector
151 Drain tap
.1 .2
20
30
40
50
60
70
80
90
200
300
.3 .4 .5 .6 .7 .8 .9 2 31
100
10
Water flow rate (m3/h)
Pressure drop mm wg
Pressure loss diagram

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2. INSTALLATION
2.01 Important notices
Assembly, installation, first start up and maintenance must be carried out by competent persons only, in accordance
with all current technical regulations and directives.
Gas Safety (Installation & Use) Regulations: 1996
In the interest of safety, it is the law that all gas appliances are installed by a competent person in accordance with the
above Regulations, Building Regulations/Building Standards Scotland, Codes of Practice, current I.E.E. Regulations and
the byelaws of the Local Water Undertaking. Failure to comply with the Regulations may lead to prosecution; it is your
responsibility to ensure that the law is complied with.
This appliance must be installed strictly in accordance with these instructions and regulations:
The Gas Safety Regulations (Installations & Use) 1996.
The Local Building Regulations.
The Building Regulations.
The Buildings Standards (Scotland - Consolidated) Regulations.
British Standards Codes of Practice:
B.S. 5440 Part 1 2000 Flues
B.S. 5440 Part 2 1989 Air supply
B.S. 5449 1990 FORCED CIRCULATION HOT WATER SYSTEMS
B.S. 6798 1987 INSTALLATION OF GAS FIRED HOT WATER BOILERS
B.S. 6891 1989 GAS INSTALLATIONS
B.S. 7671 1992 IEE WIRING REGULATIONS
B.S. 4814 1990 SPECIFICATION FOR EXPANSION VESSELS
B.S. 5482 1994 INSTALLATION OF LPG
B.S. 7593 1992 TREATMENT OF WATER IN DOMESTIC HOT WATER CENTRAL HEATING SYSTEMS
Model Water Bye Laws
For Northern Ireland the rules in force apply
N.B. For Northern Ireland the rules in force apply.
Important - If the boiler is to be fitted in a timber framed building it should be fitted in accordance with
the institute of gas engineers publication IGE/UP/1. If in doubt advice should be sought from the Local Gas
Region of British Gas Plc.
2.01.01 Location of Boiler
The installation of the Sigma must be on a suitable non-combustible load bearing wall which will provide an adequate fixing
for the boiler mounting bracket assembly. The location should be in an area where the water pipes will not be subjected
to frost conditions. In siting the boiler the following limitations must be observed:
The boiler may be installed in any room or internal space, although particular attention is drawn to the requirements of the
current I.E.E. wiring regulations and in Scotland the electrical provisions of the building regulations applicable in Scotland,
with respect to the installation of the boiler in a room or internal space containing a bath or shower.
Where a room sealed appliance is installed in a room containing a bath or shower any electrical switch or
appliance control utilising mains electricity must be situated so that it cannot be touched by a person using
the bath or shower.
2.01.02 Air Supply
The room or compartment in which the boiler is installed does not require a purpose provided vent when using
the standard concentric flue.
2.01.03 Flue System
The boiler allows the flue outlet to be taken from the rear of the boiler, from either side or vertically.
It is absolutely essential, to ensure that products of combustion discharging from the terminal cannot re-enter
the building, or enter any adjacent building, through ventilations, windows, doors, natural air infiltration or
forced ventilation/air conditioning.

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Fig. 4a
Gas
Pump
Expansion
vessel
Cold water
1
3
2
Filling point
Note: A bypass must be fitted as far
as possible from the boiler if
thermostatic radiator valves
are fitted thoughout.
2.01.04 Gas Supply
If necessary the local Gas supplier should be consulted, at the installation planning stage, in order to establish
the availability of an adequate supply of gas.
An existing service pipe must not be used without prior consultation with the Local Gas supplier.
A gas meter can only be connected by the Local Gas supplier, or by a Local Gas suppliers Contractor.
Installation pipes should be fitted in accordance with BS6891-1988.
Appliance inlet working pressure must be 20mbar MINIMUM (Natural gas - G20) or 37 mbar MINIMUM (LPG - G31).
Pipework from the meter to the combination boiler must be of an adequate size, normally 22 mm.
Do not use pipes of a smaller size than the combination boiler inlet gascock connection.
The complete installation must be tested for gas soundness and purged as described in BS6981-1988. All pipework
must be adequately supported.
2.02 Water System (sealed systems)
Central heating
Detailed recommendations are given in BS6798, BS5449, BS6700 and CP342 Part 2. Pipework not forming part of the
useful heating suface should be insulated to prevent any heat losses or possible freezing (i.e. in roof spaces or ventilated
underfloor spaces). Drain taps should be positioned at the lowest point of the system in accessible locations to permit
the whole system to be drained down. The drain taps should be in accordance with BS2879. Copper tubing to BS2871,
Part 1 is recommended for water carrying pipework. Pipework in horizontal runs should have a gradient where possible
to facilitate the removal of air. Ensure that the boiler heat exchanger is not a natural point for air collection. A
typical sealed heating system illustrated in fig. 4.
Note: only for use on fully pumped systems.
Typical sealed fully pumped heating system

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Important - If thermostatic radiator valves are fitted throughout a bypass must be fitted to ensure a minimum flow rate
through the boiler of 6 l/min. The bypass should be fitted as far as possible from the boiler.
2.02.01 Safety valve
A safety valve complying with the requirements of BS 6750 Part 1 must be fitted close to the boiler on the flow pipe by
means of a horizontal or vertically upward connection with no intervening valve or restrictions and should be positioned
to facilitate testing. The valve should be pre-set and nonadjustable to operate at a pressure of 3 bar (45 Ibf/in2). It must be
arranged to discharge any water or steam through a pipe to a safe outlet position.
2.02.02 Pressure gauge
A pressure gauge of minimum range 0-4 bar (0-60 Ibf/in2) with a fill pressure indicator must be fitted to the system,
preferably at the same point as the expansion vessel in an easily visible position.
2.02.03 Venting
A method of venting the system during filling and commissioning must be provided by fitting automatic air
vents or by venting manually.
2.02.04 Expansion vessel
In a sealed system an expansion vessel complying with the requirements of BS 4814 must be fitted to the system
by means of a connection close to the inlet side of the circulating pump in accordance with the manufacturers
instructions, the connecting pipe being unrestricted and not less than 15 mm (1/2 in) nominal size. The volume
of the vessel should be suitable for the system water content and the nitrogen or air charge pressure should
not be less than the system static head.
Further details of sealed system design can be obtained from BS 5449: Part 1 and the British Gas publication entitled
Specifications for Domestic Wet Central Heating Systems.
2.02.05 Water treatment
If water treatment is used ferroli limited recommend only the
use of Fernox or Sentinel water treatment products, which must
be used in accordance with the manufacturers instructions. For
further information contact:
Fernox Manufacturing Co. LTD. Sentinel Division
Tandern house, Marlowe Way Betz Dearborn LTD
Croydon, surrey, CRO 4YS Widnes, Cheshire WA8 8ND
Tel: [phone] Tel: [phone]
Note - If the boiler is installed in an existing system any
unsuitable additives must be removed by thorough cleansing.
All systems should be cleansed according to B.S. 7593.
Note - In hard water areas treatment to prevent lime scale
may be necessary.
Note - It is important that the correct concentration of the
water treatment product is maintained in accordance with the manufacturers instructions.
2.03 Gas connection
Gas connection must be carried out using a rigid pipe.
The flow at the gas meter should be sufficient for the simultaneous use of all appliances connected to it. Connect
the gas supply to the boiler according to current regulations. The diameter of the gas cock leaving the boiler is not
the determining factor in choosing the diameter of the pipe between the appliance and the meter. This must be
selected in relation to length and pressure drop.
The whole of the gas installation including the meter should be inspected and tested for soundness and purged
in accordance with BS6891-1988.
VESSEL CHARGE
PRESSURE (bar)
INITIAL SYSTEM
PRESSURE (bar)
TOTAL WATER
CONTENT of SYSTEM
Litres
25
50
75
100
125
150
175
200
0.33
For syst. volumes other than
those given above, mult. the syst.
volume by the factor across.
0.5 1.0
EXPANSION VESSEL VOLUME (litres)
8.3
16.5
24.8
33.1
41.3
49.6
57.9
66.2
1.5
2.0
10.3
20.6
30.9
41.2
51.5
61.8
72.1
82.4
0.412
2.0
4.7
9.5
14.2
19.0
23.7
28.5
33.2
38.0
0.190
1.5
13.7
27.5
41.3
55.1
68.9
82.6
96.4
110.2
0.551
2.0
6.5
12.9
19.4
25.9
32.4
38.8
45.3
51.8
0.259
1.5
3.5
7.0
10.5
14.0
17.5
21.0
24.5
28.0
0.140
1.0
Sizing of expansion vessels:

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450
643
132,5 167,5 min105
25 25
5 min
250
255 min
200 min
855 min
Fig. 5
2.04 Wall Mounting
2.04.01 Drilling Template
115
82
Ø118
155
min. 138
200 min.643
200 min.
450
Minimum clearances and drilling template for standard
rear flue.
Fig. 6a
Drilling template for orizontal concentric flue.

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2.04.02 Wall mounting instructions for Rear Flue Application
1
Select suitable mounting position for
boiler. Refer to fig. 6 for dimensions and
minimum clearance. Using the template
or mounting plate mark flue outlet and
boiler mounting points.
Fig. 7
Drill four 10 mm holes 70 mm deep to
accept the wall plug. Using a core drill
cut hole for the flue.
Drill cut a 118 mm diameter hole if it
is possible insert the flue-pipe from
outside of the room; drill cut a 127 mm
diameter hole if to insert the flue-pipe
from inside of the room.
2
Fig. 8
Insert the plastic plugs.
3
Fig. 9
5a 5b
Ø 118
Fig. 11a Fig. 11b
4a 4b
Ø 127
Fig. 10a Fig. 10b
Insert flue-pipe from inside of the room (core drill 127 mm hole)...
... or insert flue-pipe from outside of the room (core drill 118 mm hole).

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11
Mark the aluminium flue pipe at the point it is flush with
the mounting plate. Add 40 mm to this mark and cut the
aluminium inner flue pipe at this point.
10
Insert the aluminium flue pipe into white plastic outer flue,
making sure the aluminium pipe sits fully and centrally
into the flue terminal.
Fig. 16 Fig. 17
40 mm
Cut the outer flue flush with the flange on the hanging
plate.
Through plate into air tube, drill two holes and fix in place
using two self tapping screws n° 6 x 6mm long.
89
Fig. 14 Fig. 15
67
Position the wall plate on the wall. Fix plate to wall with the
square gasket between the wall and the plate use the large
diameter washers for the bolts ad screws.
Gently pull back until wall seal is flush with the wall.
Fig. 12 Fig. 13

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Fig. 21a
2.05 Top outlet flue conversion
Take off the four screws which fix the top sealed chamber
cover, remove the cover and gasket.
Fig. 22a Fig. 22b
1
3
a
a
Fig. 21b
2
4
12 13 14
Install the inner metal flue "a" into the
adapter "b".
Lift boiler with flue pipe in place,
engage inner and outer flue, slide into
position.
Make sure the inner flue is fully engage
in the flue terminal, secure boiler with
two nuts and washers "a" and "b".
Fig. 18 Fig. 19 Fig. 20
Remove fan by pulling off electrical connections. Pull off
air pressure switch tubes from the air pressure switch.
Remove the two screws "a".
Pull fan
Rotate the cover and gasket through 90° and fit it to
the rear of the boiler to cover the original flue outlet.
Secure them both in place with the four screws removed
previously.

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9
10
Assembly the top outlet kit inserting
the correct restrictor.
(See section 2.07).
Fig. 27
Fig. 28
Refit wiring connections to fan and air
pressure switch tubes ensuring correct
orientation. I.E. red tube to air pressure
switch connection with red dot (+)
and clear tube to air pressure switch
connection with no paint marking (-).
Fit the fan into the boiler moving
like indicated. Secure with the screws
"b".
Boiler is fitted with rear outlet without restrictor. If it necessary to insert the restrictor for top outlet, identify
on 2.07 the correct restrictor.
Remove the two screws "a" from pipe
connection "b".
Remove pipe connection"b".
Remove fan mounting plate by undoing
the three fixing screws "c".
For top outlet
For rear outlet
cc
cd
dd
For rear
outlet
For top
outlet
Fig. 23
a
ab
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Fig. 25 Fig. 26
56
Fig. 24
Rotate the fan through 90° so that the fan nozzle points upward. Secure the fan
to the plate in the new position using screws in position "d".
1
2
b
b

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2Example of direct roof flue outlet
and wall air inlet with 2 pipe system
3Example of concentric flue Ø 100
with vertical outlet flue use.
Warning • Back exit with 2 pipe is not possi-
ble.
Fig. 32
Fig. 33
Note • Bear in mind that the two concentric
pipes must slope downwards away from the
boiler at a rate of about 3 mm/m to avoid
rainwater entering the boiler. Outside, the
pipes should protrude from the wall between
10 and 60 mm.
Warning • Back exit with coaxial bend is
not possible
1 Example of concentric flue Ø 100
with appliance bend use
2.06.01 Examples of top flue connection
Fig. 31
2.06 Top outlet Flue Connection
Three different connection are available from top of the boiler, using accessories as reported on fig. 30a, b e c and
on examples a next page.
Fig. 30
Vertical Connection, concentric bend
and two pipe separator can be
supplied on request.
Top outlet horizontal
concentric flue
Top outlet two
pipe system
Top outlet vertical
concentric flue
123
Fig. 30a Fig. 30b Fig. 30c

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2.07 Restrictor and max flue length
2.07.01 Concentric Flue System
First table below shows the maximum flue lengths available for boilers with concentric systems.
For correct calculation remember to include the reduction for bend and flue terminals listed on second table.
Reduction for bend
100 mm concentric bend 90°
100 mm concentric bend 45°
125 mm concentric bend 90°
125 mm concentric bend 45°
1 m
0,5 m
0,5 m
0,25 m
Maximum flue
length permissible
100 mm concentric
Vertical *Horizontal
125 mm concentric
Vertical *Horizontal
100 mm
concentric
back exit
Sigma 60/100 4 m 3 m 5 m 5 m 1 m
*For horizontal flueing the reduction for appliance bend are already included.
Sigma
60-100
A
B
C
Restrictor pipe
configuration
L2m
L2m
1m 2mL
L1m
Ø47
Ø43
Ø 47
Ø 43
No restrictorL1m
No restrictorL2m
3m
L3m No restrictor
Boiler is fitted with rear outlet without restrictor.
For instruction on changing restrictor for top outlet, refer to step 7-10 at pages 13.
L (max. 3 m.)
L (max. 1 m.)
Fig. 34 Fig. 35
To calculate the restrictor, identify your flue pipe configuration (A, B or C) and
choose the correct restrictor diameter from the restrictor table below.
L (max. 4 m.)
Fig. 36
AHorizontal concentric BBack concentric CVertical concentric

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Tab. 3
2.07.02 Two pipe flue system
1. Utilise the pipes and fittings flows resistance tables on the following pages and calculate the total flow resistance in
metres-air, by adding the flow resistances of the components in the whole air-flue system, based on their position
(vertical or horizontal, air inlet or flue outlet).
Please note that the same fitting, identified by a one code (i.e. 1 pipe diameter 80, code KWMA83A), can offer
different flow resistances if positioned as air inlet or flue outlet, if placed vertically or horizontally.
The flow resistance of the special two pipe flue-air adapters do not have to be included in the calculation as
they are already included in the maximum length calculation.
IMPORTANT: the pipes and fittings flow resistance (reduction) have been summarised on the following page. The
flow resistance values written refer only to Ferroli pipes and fittings.
2. Verify that the total flow resistance calculated is less or equal to 40 metre.
3. Choose the more suitable restrictor from table below.
DescriptionRef.
Connection for concentric pipe cod. KWMR52A1
N°of
pieces Length reduction
Total
Male - Female flue Ø 80 mm
3
4
Bend 80 mm
5
Air wall terminal outlet flue Ø806
Air wall terminal air Ø807
Air
Flue
Horizontal
Vertical
Horizontal
Vertical
//
1
/
2
5
1,5
2,5
5
2
19,0
1
1
/
1
5
1
1
1
1
Air
Flue
Total flow resistance 19,0 m:
use restrictor Ø47
Tab. 5
1 m
3
6
4
7
1
5 m
4
5
5
Example of calculation for wall inlet/outlet with 2 pipe system maximum total flue length: 40 metres
Fig. 37
Use restrictor:
Total flow resistance
0 - 4 m
4 - 12 m
12 - 25 m
25 - 33 m
33 - 40 m
Ø 43
Ø 45
Ø 47
Ø 50
No restrictor
Sigma 60/100

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Pipe and fittings reduction table (shown in Metres)

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Fig. 39
101 X4 X5
121 86
63
141 5
X8
GCP
JP
X3
Key
63. CH temperature setting
86. Reset switch
101. Main P.C.B.
121. Boiler shut-down warning (Led)
X3-X4-X5-X8. Connectors
JP. Link
Temp.
sensor
NTC 34
kOhm
1000 kOhm
185 kOhm
80 kOhm
Temp.
25°C
60°C
82°C
2.07.03 Terminal Position
Fig. 38
2.08 Electrical connection
The boiler must be connected to a single phase 230V 50Hz electricity supply with a 3 A max. fuse and a bipolar switch
with contact opening of at least 3 mm fitted between the boiler and the electricity supply. The boiler must always be
connected to an efficient earth installation. In the electrical box, there is a 3 pole terminal block for connecting the
boiler to the mains (230V 50Hz) and a 3 pole block for connecting a
circulating pump (not supplied). See Wiring diagram (fig. 41a) for the
connection of external control.
When the boiler is connected to an electricity main, it is essential TO
ENSURE CORRECT POLARITY (LIVE: brown cable, NEUTRAL: blue
cable, EARTH: yellow-green cable).
All wiring must conform to current I.E.E. regulations.
Note: If the power supply cable has to be replaced, use “0.75mm
(24/0.20) cable only to BS6500 with a maximum external diameter of
8 mm.
P
D, E
Q
Q
l
BC
A
G
F
L
J
HH
K
N
N
MM
Q
Directly below an opening, air brick, (0-7 kW)
opening windows, etc. (>7-14 kW)
(>14-32 kW)
(>32-70 kW)
Above an opening, air brick, (0-7 kW)
opening windows, etc. (>7-14 kW)
(>14-32 kW)
(>32-70 kW)
Horizontally to an opening, air brick, (0-7 kW)
opening windows, etc. (>7-14 kW)
(>14-32 kW)
(>32-70 kW)
Below gutters, soil pipes or drain pipes
Below eaves
Below balconies or car port roof
From a vertical drain pipe or soil pipe
From an internal or external corner
Above ground roof or balcony level
From a surface facing the terminal
(also see 6.1.2)
From a terminal facing the terminal
From an opening in the car port ( e.g. door,
window) into the dwelling
Vertically from a terminal on the same wall
Horizontally from a terminal on the same wall
From the wall on which the terminal is mounted
From a vertical structure on the roof
Above intersection with roof
Dimensions Terminal position
(kW input expressed in net)
Balanced flues room
sealed Open flues
Natural
draught Natural draught
Fanned
draught Fanned draught
Aa300 mm
600 mm
1500 mm
2000 mm
300 mm Not allowed 300 mm
Ba300 mm
300 mm
300 mm
600 mm
300 mm Not allowed 300 mm
Ca300 mm
400 mm
600 mm
600 mm
300 mm Not allowed 300 mm
D300 mm 75 mm Not allowed 75 mm
E300 mm 200 mm Not allowed 200 mm
F600 mm 200 mm Not allowed 200 mm
G300 mm 150 mmbNot allowed 150 mm
H600 mm 300 mm Not allowed 200 mm
I300 mm 300 mm Not allowed 300 mm
J600 mm 600 mm N/A 600 mm
K600 mm 1200 mm N/A 1200 mm
L1200 mm 1200 mm N/A 1200 mm
M1500 mm 1500 mm N/A 1500 mm
N300 mm 300 mm N/A 300 mm
ON/A N/A N/A 50 mm
PN/A N/A See Table 2
and Fig. 6b N/A
QN/A N/A See Table 2
and Fig. 4 150 mm
NOTE N/A = Not applicable
aIn addition, the terminal should not be nearer than 150 mm (fanned draucht) or 300 mm (natural draught) to an opening in the building fabric formed for the purpose of accommodating
a built-in element such as a window frame, (see Figure C2). Separation distances are linked to the rated heat inputs as shown.
bThis dimension may be reduced to 75 mm for appliances of up to 5 kW heat input.
A approved terminal guard (part. No. C2) should be screwed
to the wall centrally over the terminal, when the distance
is less than 2 m from the outside floor.

1 9
Sigma
101 X4 X5
63
121 86
141 5
16
49
43
NO NC
C
123456789101112
83
24
32
72
SwL L N PL PN
230V ~
50 Hz
W
Blue
BR
BL
YGYG
Blue
BR V G
Blue
BL BL W RW O P
BR Blue
X8
GCP
JP
Fully
pumped
X3
34
Blue
2.08.01 Schematic wiring diagram for fully pumped system
Key
16 Fan
24 Spark and sensor electrode
32 Central heating pump (not fitted)
34 Central heating flow temperature sensor
43 Air pressure switch
49 Safety thermostat
63 C.H. temperature adjustment
72 External controls
83 Full sequence automatic control on gas valve
86 Reset switch
101 Main P.C.B.
121 Boiler shut-down warning (Led)
Fig. 40a
If there are no external
controls fitted, connect the
SWL terminal to permanent
live in the junction box
Colors key
BR Brown
Blue Blue
BL Black
W White
O Orange
G Grey
R Red
V Violet
P Pink
YG Yellow-Green

20
Sigma
3. COMMISSIONING AND TESTING
3.01 Checks to be carried out before starting up for the first time
When firing the boiler up for the first time, it is good practice to check:
that the isolation valves between the boiler and central heating systems are open;
that the central heating system is well filled and vented;
that there are no gas or water leaks from the central heating system or boiler;
that the electric connections are correct and the earth wire of the boiler is connected to an efficient earthing
installation;
that there are no inflammable liquids or materials near the boiler;
that the central heating gas pressure and flow rate are as required.
3.02 Starting up the boiler
• Open the gas cock of the boiler.
• Vent air present in the pipe upstream of the gas valve.
• Turn on the switch (if present) or plug upstream of the boiler.
• Rotate the C.H. temperature adjustment knob above Min position.
• Set the room thermostat (if fitted) to maximum.
• At this point, the burner ignites and the boiler starts to function automatically, controlled by its control
and safety devices.
Note - If after completing the start-up procedure correctly, the burner fails to ignite and the boiler shut down warning
lights up, wait about 15 seconds then press the reset switch. The reset electronic control unit will repeat the start-up cycle.
If after a second attempt the burners still fail to ignite, consult the paragraph “Troubleshooting”.
Note - If there is a power failure while the boiler is in operation, the burners automatically go out and re-ignite
when the power returns.
WARNING
If the system is filled with very cold water, the boiler will automatically light due to the frost thermostat sensing the low
temperature. The boiler will not shut down, until the water temperature reaches 10°C.
3.03 Shutting down
To shut down the boiler for short periods
•Set the temperature adjustment knob to "Off" position.
To shut down the boiler for long periods
• Turn off gas supply.
• Turn off the electricity supply.
IMPORTANT
The boiler is protected by integral frost protection, but if the boiler is not to be used for a long period of
time, the system should be drained.
Note: The frost thermostat operates even if the temperature adjustment knob is in the OFF position and it is necessary
therefore, if the system is drained, for the external electrical and gas supplies to be isolated.
It is recommended that a label be affixed to the appliance to draw attention to the fact that the system
has been drained.
3.04 Checks and tests after first start-up
Check there are no leaks in the gas and water circuits.
Check correct boiler start up by carrying out start up and shut down tests using the boiler stat.
Check the integrity of the air-flue pipes during boiler operation.
Check that the gas consumption indicated on the meter corresponds to that given in Technical Data (paragraph
1.03).
Check that water is circulating correct. Balance the radiators to ensure that the flow and return differential
does not exceed 20°C.