Worcester 240 Combi BF User guide

Bosch Thermotechnik
240 Combi BF.
WALL MOUNTED COMBINATION BOILER FOR CENTRAL HEATING
AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
GCNUMBER47 31110
BOILER OUTPUT
Automatic Modulating Control
To Domestic Hot Water and Central Heating
Minimum 9.2 kW (31 ,400 Btu/h)
Maximum 24.0 kW (82,000 Btu/h)
IMPORTANT: THIS APPLIANCE IS FOR USE WITH NATURAL GAS ONLY
THESE INSTRUCTIONS APPLY IN THE UK ONLY
. '
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THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER

Contents
1. Installation Regulations .......... : ..................................... Page 2
2. General Information ...................................................... Page 2
3. Data Technical ................................................................ Page 4
4. Siting the Appliance ...................................................... Page 5
5. Siting the Flue Terminal ................................................ Page 6
6. Air Supply ....................................................................... Page 7
7. Sealed System ................................................................ Page 7
8. Open Vent Primary Water System ............................... Page 8
9. Domestic Hot Water ...................................................... Page 9
·1 . Installation R1egulations
1.1 Gas Safety (Installation and Use) ~egulations 1984
All gas appliances must be installed: by a competent person in
accordance with the above regulations. Failure to install appli·
ances correctly could lead to prosecution.
1.2 The manufacturers notes must not be taken,in any way,as
overriding statutory obligations.
1.3 The compliance with a Briti<>h Stnnrl;ml rlnAs nnt, nf itsAlf, r.nn·
fer immunity from legal obligations. In particular the installation
of this appliance must be in accordance with the relevant require·
ments of the Gas Safety (Installation and Use) Regulations 1 984 as
amended, current lEE Wiring Regulations, local Building Regula·
tions, Building Standards (Scotland)(Consolidation) and byelaws of
the local Water Company. Health and Safety Document No. 635
(Electricity at Work Regulations). It should be in accordance with
the relevant recommendations of the following British Standards.
BS 6798:1987 Specification for installation of gas fired hot water
boilers of rated input not exceeding 60 kW.
BS 5449:1990 Central Heating for Domestic Premises.
BS 5546:1990 Installation of gas hot water supplies for domes·
tic purposes.
BS 5440:1:1990 Flues and Ventilation for gas appliances of rated
input not
exceeding 60 kW: Flues.
BS 5440:2:1989 Flues and Ventilation for gas appliances of rated
input not
exceeding 60kW: Air Supply.
BS 6891 :1988 Installation of low pressure gas pipework installa·
tions up to 28 mm (R 1 ).
1.4 To ensure that the installation will perform to the highest
standards, the
system and components should conform to any
other relevant British Standards in addition tci those mentioned
in the instructions.
2. General Information
2.1 This appliance is not suitable for external installation.
2.2 The appliance controls are set to provide a maximum
output
of 24 kW for the domestic hot water and a central
heating
load of up to 16.1 kW.
2.3 The appliance has a permanent pilot.
2.4 PRINCIPLE APPLIANCE COMPONENTS See Fig. 1.
A low thermal capacity Gas to Water heat exchanger.
A Water to Water heat exchanger to provide domestic hot water.
Ft,dly modulating controls in the central heating and domestic
hot water
modes of operation.
An expansion vessel, pressure gauge and pressure relief valve.
Aby-pass for the central heating system.
Temperature safety cut·out controls.
2
10. Electrical ...... , .................................................................. Page 10
11. Installation ..................................................................... Page 14
12. Commissioning .............................................................. Page 17
13. Instructions to the User ................................................ Page 18
14. Inspection and Servicing .............................................. Page 19
15. Replacement of Parts .................................................... Pc;~ge 21
16. Short Parts List .............................................................. Page 28
17. Operational Flow Diagram ............................................ Page 29
18. Fault Finding ................................................................... Page 31
Awater flow regulator.
Astandard horizontal flue assembly giving flue lengths from
229 mm to 420 mm.
An optional extra extension flue kit to provide for flue lengths up
to 559 mm long.
An optional facia mounted programmer instead of the standard
Operating Switch.
2.5 ELECTRICAL SUPPLY
Main5 5upply: 2-1 OV ··, 50 I Iz, 150 wiltts. External fuse 3A.
Internal fuses: T2A (F1) and T315mA (F2).
2.6 GAS SUPPLY
The boiler requires 2.81 m' /h (99.3 ft'/hr) of gas. The gas meter
and supply pipes must be capable of supplying this quantity of
gas in addition to the demand from any other appliances being
served. The table below gives an indication of limiting gas pipe
lengths and the allowance to be made for fittings. Refer to
BS6891 for further information.
The meter governor should deliver a dynamic pressure of 20
mbar (Sin wg.) at the appliance.
The complete installation, including the gas meter, must be test-
ed for soundness and purged. Refer to BS 6891 .
TOTAL LENGTH OF
GAS SUPPLY PIPE (metres)
Pipe
Diameter
3 6 9
(mm)
Gas Discharge Rate (m3/h)
2.9
--
15
8.7
5.8 4.6
22
18.0 12.0
9.4 28
Note:
Each fitting used in the gas line from the meter is equivalent to a
length of straight pipe which must be added to the straight pipe
length to give the total length.
ie: Elbow = 0.5 metres, Tee = 0.5 metres, 90° Bend = 0.3 metres.
2.7 PACKING
The appliance and flue components are packed in separate car-
tons.
2.8 GENERAL INSTALLATION
The appliance is supplied for connection to a sealed system but
is suitable for use with an open vent system. The connections
are supplied as an optional kit.
The specified ventilation openings made into a wall or compart-
ment door must not be obstructed.
If the appliance is to be fitted into a compartment then the com-
partment must conform to the requirements of BS 6798: 1987:
Section 6.
Do not place anything on top of the appliance.
The clearances specified for servicing must be maintained.

Fig. 1. Appliance water flow diagram
Waterflow
manifold
[._
Central heating
by-pass adjuster
L__
Automatic air vent
Gas to Water
I h t h
ea exc anger
~-.
---
---
Boiler
I Sealed system
l expansion vessel
~ Circulating pump
Water to Water heat exchanger
tl-r-A#11
~
-c ----- Waterdiverter
r-
valve
14•---~
--l
~
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~~ ( ~
Pressure relief val
ve
- Domestic hot water o
ut
-- Mains cold water in
- Central heating return
'
-- Central heating flow
2.9 FLUE
The appliance has a room-sealed balanced flue system to the
rear.
The standard flue assembly length is from 240 mm to 420 mm.
An extention flue length from 420 mm to 559 mm is available.
A terminal guard, Type GC 393 545, is available from Tower Flue
Components, Vale Rise, Tonbridge, TN9 1 TB.
Do not allow the flue terminal fitted to the outside wall to
become obstructed or damaged.
2.1 0 CONTROLS
The electronic control system and gas valve modulate the heat
input in response to the central heating and domestic hot water
temperature settings between minimum and maximum.
The Operating Switch provides for the selection of domestic hot
water only (WATER) or central heating and domestic hot water
(HEATING & WATER) or OFF.
A facia mounted programmer is available as an optional extra. A
remote mounted programmer may be connected to the appli·
ance.
The integral facia displays indicate the status of the appliance.
There is provision for the connection of a mains voltage room
thermostat and/ or a frost thermostat.
The electronic controls prevent rapid cycling of the appliance in
the central heating mode.
3
2.11 SYSTEM NOTES
WARNING
Check that no dirt is left in either the gas and water pipework
as this could cause damage to the appliance. Thoroughly flush
the heating system and the cold water mains supply. Purge
the gas supply before finally connecting the appliance ..
The water pipe connections throughout a sealed system must
be capable of sustaining a pressure of upto 3 bar.
Radiator valves must conform to the requirements of BS2767
(10): 1972.
The relief valve discharge must be directed away from any elec·
trical components or where it would cause a hazard to the user.
A drain cock to BS 2879 must be fitted to the lowest point of the
system.
For circuit design purposes it is important that due note is taken
of the information given in Table 3 relating to the available
pump head.
2.12 SHOWERS, BIDETS, TAPS AND MIXING VALVES
Hot and cold taps and mixing valves used in the system must
be suitable for operating at a mains pressure of up to 10 bar.
Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a temper·
ature.
Hot and cold mains fed water can be supplied direct to an over·
rim flushing bidet subject to local Water Company requirements.
With all mains fed systems the flow of water from the individual
taps will vary with the number of outlets operated simultane·
ously and the cold water mains supply pressure to the property.
Flow balancing using 'Ball·o·Fix' type valves is recommended to
avoid an excessive reduction in flow or even starvation to indi·
vidual outlets. For further information contact Worcester Heat
Systems Ltd.
2.13 SAFETY CONSIDERATIONS
The appliance must not be operated with the boiler inner casing
cover removed.
Work must not be carried out on the appliance without the gas
and electricity supplies being switched off.
Checks must be made to ensure that the ventilation openings
made into walls and partitions are of the correct size and are not
obstructed.
2.14 OPERATION
Domestic Hot Water: With a demand for hot water the burner
will light at its maximum setting and then automatically adjust
its output to maintain the temperature rise of the delivered
water. When hot water is no longer required, the burner will
extinguish. The pump will continue to run for a short period to
dissipate the residual heat from the appliance.
Central Heating: With a demand for heating the burner will
light at its minimum setting and gradually increase to give the
maximum output. The output of the appliance is then
automatically adjusted
to maintain the temperature of the
system. The output can reduce down to a minimum of 9.2 kW. If
the system no longer requires even the minimum output to
maintain the desired room temperature the burner will
extinguish. The pump will continue to run to dissipate the
residual heat from the appliance. The appliance will remain off
for a fixed period of two minutes before re-lighting to
automatically meet the system requirements.
Domestic Hot Water and Central Heating: The appliance will
supply heat to the central heating system as required. A
demand
for domestic hot water at a tap or shower will override
the central heating requirement for the period of the domestic
hot water demand. When hot water is no longer required the
burner will extinguish and the appliance will return to the cen-
tral heating state and its normal mode of operation. The pump
will continue to run to dissipate the residual heat from the appli·
ance as necessary.

3. Technical Data
The Data Plate is fixed to the control box casing.
TABLE 1
TABLE 2 - Flue Details
NOMINAL BOILER RATINGS
mm inches
Output Input
Burner Setting
Gas Rate
Pressure
Wall Hole Size
Width 365 14.4
kW Btu/h
kW
Btu/h mbar. in.wg. m
3
!h
tt
3
!h
9.2
31,400
12.6
43,000 3.0
1.2 1.22
43.0
24.0
82,000
30.0
102,400 14.7
5.9 2.81
99.3
Height 265 10.5
Standard Flue -Minimum Length 240 9.5
Standard
Flue -Maximum Length 420 16.5
Extended
Flue -Maximum Length 559 22
TABLE3
AVAILABLE PUMP HEAD
Boiler Output Head Min. Flow Rate
Temp. rise across
Btu/h feet litres/min
gal/min
heating flow
kW
metres
and return
9.2
31,400 4.9 15.9 12.0
2.64
11 °( (20°F)
24.0
82,000
2.0 6.5
22.0
4.81
15"C (28°F)
TABLE4
SPECIFICATIONS
CENTRAL HEATING FLOW FITTING 22 mm Compression
CENTRAL HEATING RETURN FITTING 22 mm Compression
COLD WATER MAINS INLET FITTING 15 mm Compression
DOMESTIC HOT WATER OUTLET FITTING . 15 mm Compression
4VA1i.;A!ibi t~UMI~ i-l£1it) l
-~"*''!1""m~ ....... -"'....-.:., ... w·~. ""'""'/,.,.;...,.;.w.1f ....... r· """""Mi·vf'o.·.""1-W'r-~;.,....,!'-."~: Mt ....... tfi'""'~'l"''l-}~~
·· 1..~1 ~r 1ju · ·ut . :m~· . i ltl: Fitiw ~t~ . 1HfiJf:ji~ ~.~ i,(;(~si!
PKt:SSU~E Kt:d£YVALVt. u:l:J\RGEtrl'l~J.\11 """"''"d:,,,
1 !:l mm LompressiOn
CASING HEIGHT 900 mm (35.4 in.)
CASING WIDTH 450 mm (17.7 in.)
CASING DEPTH
360 mm (14.2 in.)
WEIGHT (including water) 48.7
kg (107lb.)
INSTALLATION WEIGHT
~
46.5 kg (1 02 lb.)
"
PACKAGED WEIGHT 49.6 kg (1 09lb.)
TABLE 5
SPECIFICATIONS
PRIMARY WATER CAPACITY
2.7litres (0.6 galls.)
MAXIMUM COLD SUPPLY PRESSURE
10 Bar (150 psi)
MINIMUM COLD SUPPLY PRESSURE (WORKING) FOR MAXIMUM HOT WATER FLOW
1.6 Bar (23.5 psi)
MINIMUM COLD SUPPLY PRESSURE (WORKING) TO OPERATE THE APPLIANCE
0.6 Bar (9 psi)
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE
Nominally 82°C (180°F)
MAXIMUM STATIC HEAD (PRIMARY)
25 metres (81 ft)
MIMIMUM STATIC HEAD (PRIMARY)
0.3 metres (1 ft)
OUTPUT TO DOMESTIC HOT WATER
Modulating 9.2-24 kW
(31 ,400-82,000 Btu/h)
OUTPUT TO CENTRAL HEATING
Modulating 9.2-24 kW
(31 ,400-82,000 Btu/h)
MAXIMUM DOMESTIC HOT WATER FLOW RATE FROM THE APPLIANCE
Nominally 8.5 litres/min (±15%)
(1 .87 gallons/min)
EQUIVALENT DOMESTIC HOT WATER FLOW RATE TO GIVE A TEMPERATURE RISE OF 35°C Nominally 9.8litres/min
(2.16 gallons/min)
4

4. Siting The Appliance
4.1 The appliance may be installed in any room although par·
ticular attention is drawn to the requirements of the current
I.E.E. Wiring Regulations and, in Scotland, the electrical provi·
sions of the Building Regulations applicable in Scotland, with
respect to the installation of appliances in rooms containing
baths or showers.
Where a room sealed appliance is installed in a room contain·
ing a bath or shower, any electrical switch or appliance control
using mains electricity must not be able to be touched by a
person using the bath or shower.
4.2 The appliance is not suitable for external installation.
4.3 The appliance does not require any special wall protection.
4.4 The wall must be capable of supporting the weight of the
appliance. See Table 4.
4.5 If the appliance is to be fitted in a timber framed building,
refer to the British Gas publication "Guide for Gas Installations in
Timber Framed Housing".
4.6 The following clearances must be available for installation
and for servicing. See Fig. 2.
Installation
Servicing
Above
100mm 100mm
In front
600mm 600mm
Below 230mm 230mm
Right hand side
5mm
5mm
Left hand side
5mm
Smm
4.7 The appliance can be installed in a cupboard used for airing
clothes provided that the requirements of BS 6798 and BS
5440:2 are strictly followed.
4.8 The airing space must be separated from the boiler space by
a perforated non-combustible partition. Expanded metal or rigid
wire mesh are acceptable provided that the major dimension is
less than 13 mm. See BS 6798:1987.
4.9 No combustible surface must be within 75 mm of the cas-
ing. See BS476:4.
4.1 0 The distance between the inner face of a cupboard door
and the cabinet front should not be less than 75 mm.
4.11 Always consider the possible need to disconnect the pipes
from the appliance after installation.
Fig. 2. Appliance casing dimensions and required clearances.
600mm
Space required in front
SIDE VIEW
for installation and servicing.
I
I
360 mm 1
I
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--------------
I
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FRONT VIEW
450mm
Fixing holes
1
r-- 413 mm CRS. _, 1
I ~-~0~:--f _________ _j I II
li I!
,-fl
.a_Lf,:
900m
~ 1 Space required below 5 mm i 1I
/). 1 for installation and servicing. Space required at left hand side -+t ~-+- . -.r ~
/) ________ ._j t for installation and servicing. !L ______________ _j l
Smm
m
Space required at right hand side
for installation and servicing.
5

Fig. 3. Appliance pipework connections.
,_ ...
·ao· :e-···.
- ii ::,..:;;.r -
-·
Central heating flow -+--""'
Central heating return
Mains cold water in --It+---
Pressure relief valve discharge .......j.---------- 306 mm --~
• I \'
. .
_, TIW!M.T\1111-
l_l ~ mm All~""""
Gas cock ---------405mm --------1~
5. Siting the Flue Terminal
See Fig. 4
5.1 The flue must be installed as specified in BS 5440:Part 1.
5.2 The terminal must not cause an obstruction nor the dis-
charge cause a nuisance.
5.3 Ifthe terminal is fitted within 850 mm of a plastic or painted
gutter
or within 450 mm of painted eaves then an aluminium
shield at least 750 mm long should be fitted to the underside of
the gutter or painted surface.
5.4 If a terminal is fitted less than 2 metres above a surface to
which people have access then a guard must be fitted. See Sec-
tion 2.9.
Fig. 4. Siting of the flue terminal.
MINIMUM SITING DIMENSIONS FOR POSITIONING THE BALANCED
FLUE TERMINAL.
A
6
5.5 The terminal guard must be evenly spaced about the flue
terminal and fixed to the wall using plated screws
5.6 In certain weather conditions a terminal may steam and sit-
ing where this could cause a nuisance should be avoided.
5.7 Take care to ensure that combustion product:; do not enter
ventilated roof voids.
TERMINAL POSffiON MIN. DISTANCE
A- Directly below an openable window or
other opening e.g. air brtck
300 mm (12in.)
B- Below gutters, soil pipes or drain pipes
300 mm (12in.)
c- Below eaves
300 mm (12in.)
D-Below balconies or car port roof 600 mm (24in.)
E- From vertical drain pipes and soil pipes
75mm(3in.)
F- From internal or external corners
600 mm (24in.)
G-- Above ground, roof or balcony level
300 mm (12in.)
H-From a surface facing a terminal 600 mm (24ln.)
I- From a terminal facing a terminal 600 mm (24ln.)
J- From an opening in a car port (e.g. door
window) Into dwelling 1200 mm (47in.)
K- Vertically from a terminal on the same wall
1500 mm (59in.)
L- Horizontally from a terminal on the same
wall
300 mm (12ln.)
M-From door, windoworairvent(achieve
where possible)
300 mm (12in.)

6. Air Supply
6.1 The appliance does not require a separate vent for combus-
tion air.
6.2 Installations in cupboards or compartments require perma·
nent vents for cooling purposes, one at high level and one at low
level, either direct to outside air or to a room. Both vents must
pass to the same room or be on the same wall to the outside air.
6.3 There must be sufficient clearance around the appliance to
allow proper circulation of ventilation air. The clearances required
7. Sealed System
See Figs. 5 and 6
7.1 The system must comply with the requirements of BS 6798
and BS 5449:1.
7.2 The appliance must not be operated without the system
being full of water, properly vented and pressurised.
7.3 Tht:! pressure relief valve operates at 3bar (45lb/in2 ). The dis-
charge must be directed away from electrical components or
where it might be a hazard to the user.
7.4 The pressure gauge indicates the system pressure which
must be maintained.
7.5 The 10 litre expansion vessel is charged to 0.5 bar and is
suitable for a static head of 5 metres (17 .Sft). The pressure can
be increased if the static head is greater than 5 metres (17.5ft).
7.6 With an initial system pressure of 0.5 bar, a system capacity
of about 104 litres can be accommodated. Refer to BS 707 4 Pt. 1
for more information. The charge pressure can be increased but
with a decrease in system volume.
Fig. 5. Sealed primary water system.
lockshield valve. Radiator valve.
lllllllll J 11111111
Note. A drain cock should be installed at
the lowest point of the heating circuk and
beneath the appliance.
7
for Installation and Servicing will normally be adequate for venti·
lation. See Section 4.6.
6.4 The minimum free areas required are given below.
Position of
Air from
Air direct
airvents the room
from outside
High Level
270 cm
2•
135 cm
2•
(42in2 .)
(21 in
2)
Low Level
270cm2•
135 cm
2•
(42in2 .)
(21 in
2
.)
6.5 Refer to BS 6798 and BS 5440:2 for additional information.
7.7 The filling point must be at low level. See Figs. 5 and 6.
7.8 Water loss must be replaced, See Fig 6. The connection
should
be made in the central heating return as close to the
appliance as possible. See Figs. 5 af)d 6
7.9
The make-up vessel must be fitted with a non-return valve.
7.1 0 Repeated venting loses water from the system. It is essen-
tial that this water is replaced and the system pressure main·
tained.
7.11 Connections to the mains water supply must not be made
without the authority of the local Water Company.
7. 12 The pump is set at maximum and must not be adjusted.
7.1 3 Connections in the system must resist a pressure of up to 3
bar.
7.14 Radiator valves must conform to BS 2767(10):1972.
7.15 Other valves used should conform to the requirements of
BS 1010.
7.16 To make use of the extra heating available from the appli·
ance at the end of any demand, it is recommended that a single
small radiator be left permanently open.
Sealed system
--expansion vessel
-· Water to Water
heat exchanger
Central heating
by-pass adjuster- '+t--T"H--'
Fill point-----'
Heating return
Heating flow.
Domestic hot water out
t
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Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Domestic
coldwater.
_.. British Standard
stop valve.
Fixed spindle type.
+- Water main.

Fig. 6. System filling and make-up.
Heating Return
Non return
valve
+-
Worcester Combi-Fill System
Non return
va-4!- ~ Hose union
1
1-----t..•--.f .... lll-..;...===:u ~=· •• ~ +-
!! !! Stop cock
u ,.
Test cock \l,m,;~
Temporary hose
8. Open Vent Primary Water System
See Fig. 7
8.1 The size of the flow and return pipework is given in Section
3 - Table 4. The components required to connect the appliance
to an open vent system are available as an optional extra kit.
8.2 The feed and expansion cistern should be arranged so that
there is a minimum static head of 0.3 metres (12in.) above the
top of the appliance or above the highest point in the heating
circuit, whichever is the higher. See Fig. 7.
8.3 The feed and vent pipe should be 22 mm diameter and rise
continuously from the appliance to the feed and expansion cis-
tern.
Fig. 7. Open vent water system.
S.H.-Minimum static head 300 mm 112 in. I
measured from the top surface of the
appliance or highest point in the heating
system to the water level in the feed and
expansion tank.
Feed and expansion tank
lockshield valve. Radiator valve.
lllllllll J
11111111
Note. A drain cock should be installed at
the lowest point of the heating circuit and
beneath the appliance.
8
Heating Return
Auto
air vent
1- .... 1-- Fill Point
' Heating Return
300mm (12inl min.
above the highest
point of the system.
8.4 A pressure relief Viilve is not required on an open vented sys·
tem. If the pressure relief valve is left in position then a discharge
pipe must be fitted which terminates in a position such that any
water or steam discharge does not cause a hazard to the occu-
pants or damage electrical components.
8.5 Air within the appliance will be expelled via the feed and
vent connection or dissipated into the rest of the system which
must be fitted with manual air vents at any high point.
8.6 The pump is set to maximum and must not be reset.
8.7 To make use of the extra heating available from the appli·
ance at the end of any demand, it is recommended that a single
small radiator be left permanently open.
Central heating
Sealed system
--expansion vessel
--Water to Water
heat exchanger
by-pass adjuster -'"l'f+---!-+--1---l
Fill point ---- .J
Heating return
Heating flow.
Domestic hot water out
I
Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Domestic
cold water.
,.. British Standard
stop valve.
Fixed spindle type.
-Water main.

9. Domestic Hot Water
9.1 The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
9.2 MAINS COLD WATER INLET. Devices capable of preventing
the flow of expansion water must not be fitted unless separate
arrangements
have been made. An expansion vessel connection
point (Rc'h) is provided adjacent to the flow switch within the
appliance.
A Zilmet Z160 expansion vessel is the preferred type. Athread
sealant compatible
with potable water must be used.
9.3 The final 600 mm of the mains cold water connection to the
appliance should be made in copper tube only.
9.4 The appliance is suitable for a mains pressure of up to 10
bar (150 lb/in').
9.5 The appliance is fitted with a mains supply isolating valve.
9.6 The maximum domestic hot water flow rate is 8.5
litres/min. (
± 15%) (1.87 gallons/min.).
9.7 In winter (when the mains inlet water temperature is lower)
a reduced flow rate at the taps will be required to achieve the
maximum hot water delivery temperature available in warmer
weather.
9.8 It is a requirement that long pipe runs to the taps or shower
should be insulated to prevent the rapid cooling of domestic hot
water after a tap or shower has been turned off. Refer to
BS5546: 1990.
9
9.9 Hot and cold taps and mixing valves used with this appli·
ance must be suitable for operating at a pressure of up to 10 bar
(1 SO lb/in').
9.10 No anti·syphonage arrangements are necessary except for
some loose head showers. See also Section 9.11 following.
9.11 Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a temper·
ature.
9.12 The head of a loose head shower must not fall closer than
25 mm (1 in.) above the top edge of the bath to prevent its
immersion in bath water. Alternatively the shower must be fit·
ted with an anti·syphonage device at the point of the flexible
hose connections.
9.13 The supply of hot and cold mains water direct to a bidet is
permitted, (subject to local Water Company requirements), pro·
vided that the bidet is of the over·rim flushing type. The outlet(s)
should be shrouded and unable to have any temporary hand
held spray attached. No anti·syphonage arrangements are nee·
essary.
9.14 AS the maximum temperature of the Water to Water heat
exchanger is limited by the control circuit, there is normally no
need for water treatment to prevent scale accumulation. In
exceptional circumstances a device to prevent scale formation
can be fitted.
Installation of a scale inhibitor assembly should be in accor·
dance with the requirements of the local Water Company. An
isolating valve should be fitted to allow servicing. The water
hardness
can be determined using a standard test paper or by
reference to the local Water Company.

10. Electrical
See Figs. 8, 9,10,11 and 12.
1 0. 1MAINS SUPPLY. 240 V - , SO Hz, 1 SO watts.
External Fuse 3A. Internal Fuses: T2A (F1) and T31 SmA (F2).
10.2 It must be possible to completely isolate the appliance.
1 0.3 Connection to the mains supply should be via a double
pole isolator with a contact separation of 3mm in aU poles and
supplying the appliance and controls only.
1 0.4 The appliance must be earthed.
1 0.5 Mains Cable. 0. 7S mm• (24 x 0.20 mm) to BS 6SOO Thble
16.
If a new cable is needed it must be connected into the terminals
marked L (Brown or Red lead), N (Blue or Black lead) and ;!<-
(Green/Yellow or Green) and be held securely in the cable clamp.
For access refer to Section 14. NOTE: Ensure the earth lead is
longer than the live and neutral leads.
10.6 The wiring between the appliance and the electrical supply
shall comply with current lEE Wiring Regulations and any local
regulations which apply.
10.7 If a room and/or frost thermostat is to be fitted refer to
Figs. 11 and 12. The thermostats must be suitable for use on
mains voltage.
1 0.8 A facia mounted programmer is available as an extra.
Instructions
are supplied with the programmer kit.
10.9 A time switch or programmer can be fitted externally to the
appliance.
10.10 SAFETY CHECK. After installation or in the event of an
electrical fault the electrical system shall be checked for short
circuits,
fuse failure, incorrect polarity of connections, earth
continuity and resistance to earth.
Fig. 8. Wiring Diagram - Control panel and facia.
(All components shown viewed from front of appliance)
A
TO
GAS VALVE
MAIN
~Fr:w~ fj-m~------- -----1
br e3X OX11 ~ 1
• • 410 3
F2 FUSE I
br1]1 4 I
bl
0
2X8 MAIN DRIVER BOARD I
r----;C;y 3 fiFt I
br : 1L tj FUSE
1
~:
bl I 2NX7 X1 v
• 3E 2 pk
I 4E X5 X4 X3 X2 3 I v
112 31 2312345123 4581234 5 81
gvt~rn!9J11~!tr1Jr~!ttr.r~r.r~
~ 'i~tVV%-J ~~~
~ ~ in I ;_ .:.: ~~ .. :.. ---'
OVERRUN ~ Iii DIVERTER H£ATING HOT WAml MODUREG
THERMOSTAT i j! VALVE SENSOR msOR REGULATOR
12 12 MICRO·SWITCH
MAINS
COLOUR CODE
br-brown bl-blue gy-green and yellow bk-black or-orange
r-red w-white y-yellow g-grey v-violet pk-pink
10

Fig. 9. Wiring Diagram - Components outside control panel.
(All components shown viewed from front of appliance)
~-- /~~-~--~__:-_-_-:.==== === =-= ~~~==:--i
I // "" I
1 r i :
I I I I
I
I
I
I
I
I
I
I
I COLOUR CODE
I ~ br-brown bl-blue gy-green and yellow bk-black or-orange
I ~ r-red w-white y-yellow g-grey v-v1olet pk-p1nk
l I ------:~
...L
....--· ---· --·----·-- ~ L.__..-
. --·-- ·---·--· L-.----
T·-·-
I I
I I
I I
I I
I ~
I
I
Pump
Overrun
Thermostat
or
----~
_____ _j I
---·-·==--~:
------·- I i
: I
I I
I I
I I
I I
/) I
-----~/ I
I
I
I
---------------------------1
Diverter Valve Micro-Switch
br
gy-4---
bl
11
l~bl
~llt=1 y
.If "L--
~~~~~~
Gas Valve
~~ Domestic Hot
~UW Water Sensor
r r
C F
Main Valve
Modureg
Regulator
I
I
I
I
I
I
I
I
I
I
I
- ....L

....
N
black
POWER ON
INDICATOR
L ~--- I------
l I .X11!PIN2t --------------
FROST THERMOSTAT IIF FITTED I
black
DEMAND
INDICATOR
:,:,:- ---------- -;,;INDRi~R-;,.u;;; l
I
FUSE F1
T2A
1---------_r::::::]_ lr--1
X4 !PIN 41 u X41PIN 51
RELAYRY1 I
XBIPIN 11
brown
XIO !PIN 31
white XIO !PIN 21
OPERATING SWITCH
lOR PROGRAMMER!
X4 !PIN 3!
MICRO SWITCH
w I
c
DHW
.
I
I
grey
X3 !PIN 31
L_ _______ _
XSIPIN 1)
brown
PUMP OVERRUN THERMOSTAT
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
L ~~z
_ ----------- X6!PIN3i
------------
Fig. 10. Functional flow diagram
Fig. 11 . Room thermostat
connections.
Remove link.
1 2 3 4 5
PUMP
Terminal X4 on
main driver board.
Honeywell room thermostat
T60608 (or similar.)
orange
brown
TRANSFORMER
violet
FUSE F2
T315 rnA
X31PIN 41
WATER DIVERTER VALVE
MICRO SWITCH •
_______ _j
red
XlWIN 51
CENTRAL HEATING SENSOR
DOMESTIC HOT WATER SENSOR
ELECTRONICS
ELECTRONICS
TEMPERATURE CONTROL POTENTIOMETER
_____ __J
brown
I •N
~----------------------------------------~N
~----------------------------------------------~~N
Fig. 12. Frost thermostat
connections. 1 2 3 4 5
Terminal X4 on
main driver board.
Honeywell frost thermostat
T 4160A (or similar.)

Fig. 13. Wall preparation.
9mm
~el
1:
I
2i.E
COL<'>
~~
5:
w
Wal mounting plate
Inside plaster
I
E
E
~
I
I
450mm
365 mm Wall aperture
348mm
--t=j- --o--
410mmCRS
U'J
a:
u
E
E
...
CD
"'
"'-
E
E
=
0.0
<0
Drill four holes
in wall to suit
No. 12 wall plugs
..,
.-

11. Installation
See figs. 2, 3, 13, 14 and 15.
1. Unpack the appliance and check the contents against the
enclosed
packing list.
. 2. Remove the cabinet:-
(a) Remove the cabinet front cover by lifting and pulling for-
ward.
(b) Remove the inner casing by unscrewing the four retaining
screws.
3. From the carton containing the flue kit, remove the flue
terminal, flue duct, air duct and the package containing:
4- No. 8 wall plugs. 1- Roll ducting tape.
4 -
No. 8 wood screws 1- Tube of silicone sealant.
Separate the
air and flue ducts from the terminal.
4. Unscrew the two M6 nuts from inside the boiler casing
holding the wall mounting plate onto the back of the boiler
and remove the plate. Retain the nuts for future use.
5. From the dimensions given in Fig. 13 and, using the wall
mounting plate as a guide, carefully mark the four mounting
holes and the position of the balanced flue duct. Make sure
the marking
is accurate as the eventual squareness of the
appliance
will depend on this.
6. Drill the four retaining holes 70mm (2.75 in.) deep. fit the
wall plugs supplied with the appliance.
7. Cut the 36.5 mm (14.4 in.) x 265 mm (10.5 in.) hole through
the
wall for the balanced flue air duct. Make good any plas-
ter or brickwork.
8. Screw the wall mounting plate into position using the four
No. 12 x 60 mm (2.5 in.) long screws provided with the appli-
ance.
9. Measure the distance from the inside edge of the mounting
plate to the outside of the wall W. See Fig. 13.
10. Fit the air ducts together and adjust the total length until it
corresponds with the W dimension. Using the ducting tape
provided
firmly tape the joint. See fig. 14.
11 . From the inside, push the assembled air ducts through the
aperture
with the flanged end of the duct on the inside.
12. Remove the two screws holding the flue hood in position
and remove the
flue hood.
1 3. Apply the silicone sealant in a bead approximately 10 mm
(0.38 in.) diameter around the balanced flue locating spigot
on the back face of the appliance. See Fig. 1 5.
14. Lift the appliance onto the mounting plate and locate the
two M6 studs on the back plate into the twci holes in the
back
of the casing. Locate the balanced flue spigot into the
balanced
flue air ducts. fasten the appliance with the two
M6 nuts retained from instruction 4.
15. From the outside, make good the gap between the air duct
and the
brickwork. Fit the flue terminal to the air duct and
mark the position
of the four fixing holes. Drill four holes 5
mm (0.19 in.) diameter x 30 mm (1.25 in.) deep in the wall
and fit the wall plugs provided.
16. Fix the flue terminal to the wall using the four No. 8 wood
screws.
NOTE: The flue terminal is not symmetrical and the narrow
air inlet gap is at the top. The top flange is marked TOP.
17. From inside the appliance enter the exhaust duct, plain end
first. Engage the exhaust duct over the front half
of the
exhaust duct attached
to the flue terminal. Slide in the
exhaust duct and secure the
flange with the screws but do
not tighten.
18. Engage the spigot on the flue hood into the exhaust duct and
slide into position on the heat exchanger. Fix into position
with the two screws at the front.
14
19. Tighten the screws from instruction 17.
Seal telescopic joint
with tape provided.
Fig. 15. Arrangement of balanced flue
and terminal.
10 mm 10.4 in.) diameter
continuous seam of
silicone sealant all
around. !See below.)
Telescopic flue duct.
Drill and plug wall.
Secure mounting plate
'...-----------..... with four screws.
10 mm (0. 4 in.) diameter
continuous seam of
silicone sealant all
around.

Sealed System:
Unscrew and discard the automatic air vent cap. See Fig. 16.
Open Vent System:
Undo the three screws securing the casing sealing plate. Discard
the plate and retain the gasket. See Fig. 17. Remove and discard
the automatic air vent. Fit the preformed pipe (optional extra)
using the three screws, washers and gasket. See Fig 18. Connect
the feed and expansion tank.
Remove the knock-out section in the top panel with a pair of
pliers.
Fig. 16. Automatic air vent.
Unscrew and discard the cap
Automatic air vent
(Sealed systems only!
1111111111 mmm
Feed and vent connection _:::_l~~r
!Open vent water system only)
Gas to Water heat exchanger
15
Fig. 17. Cover plate (Sealed Systems).
Appliance casing top panel
Cover plate fixing screws 131
Fig. 18. Pipe connection for open vent
systems.
Appliance casing top panel
Pre-formed feed and vent pipe
To Gas to Water heat exchanger

11.20 FINAL INSTALLATION
Check that all the water connections and the gas connection
have been tightened.
If a facia mounted programmer is to be fitted, unscrew the upper
two screws holding the facia panel in place and carefully lower
the facia. See Fig. 19.
Unplug the Operating Switch from the terminal X1 0 on the main
driver board. See fig. 8. Unscrew the four screws holding the
switch plate and remove the complete Operating Switch assem·
bly. Fit the programmer and tighten the four screws. Plug the
programmer
into terminal X10 on the main driver board.
Lower the control box as described in Section 14.3(d).
Connect the mains electrical supply to the appliance and con·
nect any room and/or frost thermostats. The electrical leads to
the room and frost thermostats must pass through the appropri·
ate holes in the control panel and be fixed with the cable clamps
provided. See Fig. 20. Refit the facia panel.
Test the gas supply pipework up to the appliance for soundness
as indicated in BS 6891.
Refer to Section 12 for a full description of the filling, venting
and,
with a sealed system, the pressurising of the system.
If the appliance is not to be commissioned immediately, replace
the cabinet front panel and control box. Check that the gas
supply, the
electrical supply and the water connections are all
turned off.
If the premises are to be left unoccupied during frosty condi·
tions, then commission the appliance as described in Section 12
and
leave it under the control of the frost thermostat or leave
operating continuously with the room thermostat set at 6°C.
16
Fig. 1 9. Appliance casing and control
equipment fixings.
-;L Top panel fixing screws 121
,.
Inner casing cover fixing screws 14)
• •
p c
Control box fixing screws 12)
Upper facia panel fixing screws 12)
l
I
I
-··
····~c
m·e
-·
-: __ ; ~,:
..... .._ .... " ...
-
Lower facia panel fixing screws 12)

Fig. 20. Electrical cable exists from control box.
ro
GAS VALVE
Earth MAINS ro ro
TO
WATER
DIVfRTER
VALVE
MICRO-SWITCH
ro ro ro
12. Commissioning
12.1 The appliance is despatched with the controls set to
provide a maximum output for domestic hot water of 24 kW
(82,000 Btu/h) and satisfy a central heating load of 16.1 kW
(54,900 Btu/h).
The controls can be reset to increase the heat load capability to
24 kW (82,000 Btu/h). Refer to Section 12.4- Central Heating. It
is not necessary to set the output below 16.1 kW (54, 900
Btu/h) as it is automatically modulated to satisfy lower heat
loads.
Domestic Hot Water System. Check that the mains water sup·
ply has been fully flushed out at installation.
Central Heating System. Check that the central heating system
has been fully flushed out at installation.
Gas Service . The complete system, including the meter, must
be inspected and tested for soundness and purged as indicated
in BS 6891.
12.2 APPLIANCE AND CENTRAL HEATING SYSTEM
PREPARATION
Remove the cabinet front panel.
Check that the electrical supply and the gas service to the appli·
ance are off. See Fig 3.
Check that all the water connections throughout the system are
tight.
Open the system valves at the appliance. See Fig 3. Open all the
radiator
valves, fill the system and vent each radiator in turn.
On sealed systems the automatic air vent, (fixed to the flow
manifold) will vent the appliance. Remove the boiler inner casing
cover to check that the air vent cap has been removed. See Figs
16 and 19. Replace the cover immediately.
Check that the pressure relief valve operates by turning the
knob anti-clockwise until it releases. Water sho1,.tld be expelled
from the discharge pipe. See Fig. 21. Lower the control box to
gain access. Refer to Section 14.3(d).
SEALED SYSTEMS ONLY
Set the Expansion Vessel Pressure
The charge pressure of the expansion vessel as despatched is
0.5 bar, which is equivalent to a static head of 5 metres (17 ft).
The charge pressure must not be less than the static head at the
point
of connection. See Fig. 5. A Schraider type tyre valve is fit·
ted to the expansion vessel to allow the charge pressure to be
17
PUMP PUMP
~-ll\JN
TltERMOSTAT
TO ROOM THERMOSTAT
I OPTIONAL I
CENTl\AL DOMESTlC GAS VALVE
HEATING HOT WATER MOOUREG
SENSOR SENSOR REGULATOR
TO FIIOST TltEAMOSTAT
IOPTlONALI
increased if necessary.
Set the System Pressure
Fill the system until the pressure gauge shows 2.5 bar (37
lb/ins') and check for water soundness. Release water from the
system using the relief valve test knob until the System Design
Pressure is obtained, up to a maximum of 1 .5 bar.
System Design Pressure in bar = Static Head of the System in
bar+ 0.3
Note: 1bar is equivalent to 10,2 metres (33.5 ft) of water.
Set the movable pointer on the pressure gauge to coincide with
the indicating pointer giving a permanent record of the set sys·
tern pressure.
If the pressure indicated on the pressure gauge is greater than
2.5 bar when operating at the maximum central heating tern·
perature, an extra expansion vessel must be fitted to the system
as close as possible to the appliance central heating return con·
nection.
The appliance (as despatched) can accommodate a system vol·
ume of about 104 litres. Refer to BS 7074 Part 1. If the system
volume is in excess of that accommodated by the expansion
vessel fitted to the appliance then an extra vessel must be fitted
as close as possible to the central heating return connection of
the appliance.
Any extra vessel fitted must be pressurised to the same figure as
the integral vessel. If the expansion vessel fails then the speci·
fied replacement must be fitted .
Fig. 21 . Pressure relief valve.
r Pressure gauge capillary connection
Pressure relief valve discharge pipe

12.3 PROGRAMMER
Any programmer fitted on the appliance should be set up at this
stage
following the instructions sent with the programmer. The
plug-in programmer will retain the setting for up to four weeks
following an interruption in the electricity supply.
12.4 APPLIANCE OPERATION
Check that the electrical supply to the appliance is off.
Set the Operating Switch (or Programmer) to OFF.
Remove the inner casing cover. Refer to Section 14.3(b).
Disconnect the electrical connections from the Modureg actua-
tor. Do not leave them unprotected. See Fig. 22. Turn on the gas
supply and reconnect the electricity
supply.
Push hard on the gas valve button and keep it pressed in. At the
same
time push the red igniter button. When it clicks the pilot
(see through the inspection window) should light. If the pilot
does not
light immediately, press the igniter button repeatedly
until
it does. When the pilot has lit continue to hold the gas
valve button in for a further 20 seconds, then release it slowly.
CAUTION: If the pilot does not stay alight, twist the gas valve
button in the direction of the arrow. Wait for three minutes and
repeat the operation
until the pilot is lit Continue to hold the
gas
valve button for thirty seconds. then release it slowly.
Test for gas soundness at the joint between the pilot pipe and
the burner
with leak detection fluid.
Observe the pilot flame. It should be about 20 mm long and
envelope the spark electrode
tip. It not, reler to Section 14.4.
See Fig. 25. If the pilot still does not light, contact Worcester
Heat Systems Service Department.
Replace the inner casing cover.
Reconnect the electrical connections to the gas valve. Loosen the
hurnRr prRssurR t.P.st point sr.rP.w and mnnP.r.t a pmssurR gau~;P.
See Fig 22.
Domestic Hot Water.
Switch on the electncity supply.
Set the Operating Switch (or Programmer) to WATER and fully
open a hot water tap.
The boiler should light at a burner pressure of between 14 and
15mbar (5.6 and 6.0 in. wg.). If the burner pressure is low, check
that the supply pressure at the gas valve inlet is at least 19
mbar (7.6 in. wg).
Note: The burner pressure is factory set and if (after checking
that the supply pressure
is sufficient) the correct pressure is not
obtained then Worcester Heat Systems Service Department
should
be contacted.
Gradually close the hot tap and check that the burner pressure
drops.
Fully open the tap and check that the burner pressure ris-
es. Fully close the tap and check that the burner goes off. The
pump will continue running until the appliance has cooled to a
preset temperature.
Set the Operating Switch (or Programmer) to OFF.
Central Heating
Check that all the radiator valves are open. Set the room thermo-
stat and the Central Heating Temperature Control to maximum.
On sealed systems check that the system is pressurised and set
to the required pressure as indicated on the gauge.
Set the Operating Switch (or Programmer) to HEATING &
WATER.
The burner will light.
The appliance will modulate its output from 9.2 kW (31 ,400
Btu/h) to the set output of 24 kW (82,000 Btu/h) over a period
of about two minutes.
Check the system to ensure that all the radiators are heating up
evenly.
Shut down all but one of the radiators and observe the burner
pressure
fall. Open all of the radiator valves and check that the
burner pressure
rises.
18
Balance the system so that the required temperature difference
across the central heating flow and return pipes is obtained. See
Table 3.
Adjust the central heating by-pass valve until the same tempera-
ture difference is obtained. See Fig 23. This should be carried out
with only a single radiator operating.
If thermostatic radiator
valves are fitted then one radiator should be left uncontrolled.
The bypass valve should never be fully closed.
If the heat load is in excess of 16.1 kW (54,900 Btu/h) then reset
the controls to the maximum
of 24 kW (82,000 Btu/h) by
carefully rotating the adjustment potentiometer to its
maximum position.
Access is gained to the adjustment point by
lowering the electrical control box. Indicate the new setting
pressure
on the data plate.
Set the room thermostat to minimum and check that the burner
goes out.
Reset the room thermostat to maximum and the burn-
er will relight and follow the nqrmal operating procedure.
Set the Operating Switch( or Prograr.1mer) to OFF.
Turn off the gas service cock and the electrical supply to the
appliance.
Drain the system while the appliance is still hot.
Refill, vent and, with a sealed system, re-pressurise as described
in Section 12.2.
Domestic Hot Water and Central Heating
Turn on the electricity supply to the appliance and open the gas
supply
cor.k at the appliance. Light the appliance as described in
the preceding notes.
Set the Operating Switch (cr Programmer) to HEATING &
WATER. If a programmer Is fitted, set the domestic hol water Lo
Continuous or 24Hrs and the central heating to ON. The burner
will light and heat will pass into the system. Turn on a hot water
tap and check that fully heated hot water is discharged from the
tap.
Close the tap and the burner will go off. The appliance will then
return
to the central heating mode and automatically balance
with the system requirements.
Set the Operating Switch (or Programmer) to OFF and the burner
will go out.
12. 5 COMPLETION OF COMMISSIONING
Disconnect the pressure gauge and tighten the test point screw.
Restart the appliance and check for gas soundness around the
test point
screw.
Refit the cabinet front panel.
If the appliance is being passed over to the user immediately,
refer to Section 13 -Instructions to the User and set the controls
to the user's requirements.
If the appliance is to be left inoperative, check that the Operating
Switch is set to OFF. Turn off the gas service cock and switch off
the electricity supply.
If there is any possibility of the appliance and system being left
inoperative during frosty conditions, drain the appliance and
system.
For short inoperative periods leave the boiler under the
control
of a frost thermostat or operating continuously under
the control
of a room thermostat set at 6°C.
13. Instructions To The User
13.1 Tell the user how to operate the appliance and hand over
the Users Instructions leaflet.
13.2 Tell the user what to do if the the heating system is not to
be used in frosty weather.
13.3 Tell the user the sealed system set pressure if applicable.
13.4 Tell the user of the importance of regular servicing. Worces-
ter Heat Systems Ltd offer a comprehensive maintenance con·
tract.

Fig. 22. Gas valve.
Electrical connections - Main valve ----"'""'-
{brown • blue • green/yellow)
Maximum pressure adjuster -----.._
Minimum pressure adjuster
Note. Turn the nuts clockwise
to increase and anti-clockwise
to""""'" <h""""" ~
Modureg cap
Modureg regulator head
Fig. 23. Central heating by-pass adjuster.
~~·
\ '
\ '
13.5 Set the system controls to the user's requirements.
13.6 If
an external programmer has been fitted which has a pro-
grammable domestic hot water facility then it is suggested that
this
be set to Continuous or the equivalent.
14. Inspection and Servicing
14.1 To ensure continued efficient operation of the appliance
it must be checked and serviced as necessary at regular inter-
vals. The frequency of servicing will depend upon the particu-
lar installation conditions and usage, but once per year should
·~~)--+--ii--:---+--- Pressure compensating tube
19
connection
--- Inlet pressure test point
generally be adequate. The extent of the service required by
the appliance is determined by the operating condition of the
appliance when tested
by fully qualified engineers.
Any service work must be carried out by competent engineers
such
as British Gas or Corgi registered personneL
14. 2
PRE-SERVICE INSPECTION
Check that the flue terminal and the terminal guard, (if fitted),
ilrP. r.lP.ilf.
If the appliance is in a compartment, check that the ventilation
openings in the compartment door or walls are clear. See Sec·
tion 6 - Air Supply.
Check the system and remake any joints or fittings which show
signs of leakage.
Refill, vent and, with a sealed system, re·pressurise as described
in Section 12. 2.
Operate the appliance and the system taking note of any faults.
Warning
Disconnect the electrical supply at the mains and turn off the
gas supply at the gas service cock on the appliance before ser-
vicing. See Fig. 3.
After completing the service always test for gas soundness as
indicated in BS 6891.
14. 3 DISMANTLE THE APPLIANCE
To carry out a full and comprehensive service of the appliance
remove the following parts to gain access to the components
which need to be checked or serviced.
(a) Cabinet Front PaneL Remove by lifting off the supports.
(b) Inner Casing Cover. Remove the cabinet front panel.
Unscrew the four screws securing the cover to the casing and lift
off. See Fig 1 9.
(c) Facia Panel. Check that the electricity supply to the appli·
ance is turned off. Remove the cabinet front panel as described
in Section 14.3(a). Unscrew the two upper screws as shown in
Fig 19 and lower the facia taking care not to damage the pres·
sure gauge capillary tube or electrical connections.

(d) Control Box. Remove the cabinet front panel as described in
Section 14.3(a). Unscrew the two screws as shown in Fig. 19,
Support the assembly and allow it to hinge down into the servic·
ing position. Make sure no damage is done to the pressure
gauge capillary tube or electrical wires.
(e) Flue Hood. Unscrew the two screws fixing the flue hood and
slide the flue hood assembly from the appliance. See Fig 24.
When refitting the hood ensure that the rear return passes
under the lip at the rear of the combustion chamber.
(~ Combustion Chamber Cover. Remove the the inner casing
cover. Unscrew the six screws securing the cover and remove
the cover. See Fig 24.
(g) Main Burner Assembly. Remove the combustion chamber
cover. Unscrew the pilot fixing screws. Pull off the electrode lead
and pull out the electrode. Undo the pilot pipe and remove the
pilot burner. See Fig 25. Unscrew the two screws and remove the
burner assembly by lifting the front of the burner and pulling
forward. See Fig 26.
14. 4 SERVICE OF COMPONENTS
Clean the Main Burner. Brush the blade tops and mixing tube
with a soft brush and check that all the flame ports are clear.
Remove any blockages with a non-metallic brush. Inspect the
injector and clean with a soft brush. Replace the injector if it
appears damaged. Do not use a wire brush or anything likely to
cause damage.
Clean the Pilot Burner Assembly. Brush with a soft brush.
Remove the pilot injector and clean by rinsing it in warm water.
Replace the spark electrode if it appears damaged. Fit the elec·
trade lead before replacing the electrode. When reassembling
see Fig. 25 for correct positioning of the spark electrode.
Clean the Gas to Water Heat Exchanger. Cover the main burner
manifold with a cloth. Clean the heat exchanger using a soft
brush. Remove the deposits from the bottom of the combustion
chamber. Do not distort any of the blades.
Combustion Chamber Insulation. Examine and replace any
pads that are damaged. See Section 15.6.
Controls. Remove any dust or deposits using a soft non-metallic
brush. Take care not to mishandle any component connections.
Reassemble the appliance in the reverse order.
Check that all components are in place and correctly fixed.
Leave the cabinet front panel to be fitted after checking the oper·
ation of the appliance.
14. 5 TEST THE APPLIANCE
On completion of the service and reassembly of the appliance,
check for gas soundness and the correct operation of the appli·
ance as described in Section 12 - Commissioning.
Refit the cabinet front panel and reset the controls to the users
requirements.
Fig. 24. Appliance components and fixings (upper assembly).
L Combustion chamber cover
and flue hood fixing screws 12).
0
Combustion chamber cover fixing screws 14)
Combustion chamber cover
0 0
20
1
~ Pump overrun thermostat
~Overheat thermostat
0
0
0