240 Combi BF. - Worcester, Bosch Group
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
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER
Contents
1.
2.
3.
4.
5.
6.
7.
8.
9.
Installation Regulations .......... :..................................... Page 2
General Information ...................................................... Page 2
Data Technical ................................................................ Page 4
Siting the Appliance ...................................................... Page 5
Siting the Flue Terminal ................................................ Page 6
Air Supply ....................................................................... Page 7
Sealed System ................................................................ Page 7
Open Vent Primary Water System ............................... Page 8
Domestic Hot Water ...................................................... Page 9
10.
11.
12.
13.
14.
15.
16.
17.
18.
Electrical ...... ,.................................................................. Page 10
Installation ..................................................................... Page 14
Commissioning .............................................................. Page 17
Instructions to the User ................................................ Page 18
Inspection and Servicing .............................................. Page 19
Replacement of Parts .................................................... Pc;~ge 21
Short Parts List .............................................................. Page 28
Operational Flow Diagram ............................................ Page 29
Fault Finding ................................................................... Page 31
A water flow regulator.
A standard 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.
·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 1984 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.
2.5 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 tested for soundness and purged. Refer to BS 6891 .
TOTAL LENGTH OF
GAS SUPPLY PIPE (metres)
9
Pipe
Diameter
(mm)
-
-
15
8.7
5.8
4.6
22
18.0
12.0
9.4
28
3
6
Gas Discharge Rate (m3/h)
2.9
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. General Information
2.1 This appliance is not suitable for external installation.
2.7 PACKING
The appliance and flue components are packed in separate cartons.
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 compartment door must not be obstructed.
If the appliance is to be fitted into a compartment then the compartment 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.
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
2.11 SYSTEM NOTES
Fig. 1. Appliance water flow diagram
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.
Gas to Water
heat exc hanger
Automatic air vent
I
~-.
Waterflow
manifold
[._
WARNING
---
--Boiler
I
Sealed system
l expansion vessel
~ Circulating pump
Water to Water heat exchanger
tl-r-A#11
~
L__
-c ----r-
Central heating
by-pass adjuster
Waterdiverter
valve
14•---~
- -l
~
I
I
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I
~~ ( ~
.
Pressure relief val ve
- Domestic hot water out
-
'
- - Mains cold water in
Central heating return
2.13 SAFETY CONSIDERATIONS
- - Central heating flow
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 central 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.
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.
Aterminal guard, Type GC 393 545, is available from Tower Flue
Components, Vale Rise, Tonbridge, TN9 1TB.
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.
Afacia 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
The Data Plate is fixed to the control box casing.
3. Technical Data
TABLE 1
TABLE 2 - Flue Details
NOMINAL BOILER RATINGS
Burner Setting
Input
Pressure
Output
kW
Btu/h
31,400
82,000
9.2
24.0
Btu/h
kW
mbar.
12.6
43,000
3.0
30.0
102,400
14.7
in.wg.
1.2
5.9
mm
Wall Hole Size
Gas Rate
m3!h
tt3!h
1.22
43.0
2.81
99.3
inches
14.4
Width
365
Height
Standard Flue - Minimum Length
Standard Flue - Maximum Length
Extended Flue - Maximum Length
265
240
420
16.5
559
22
10.5
9.5
TABLE3
AVAILABLE PUMP HEAD
Boiler Output
kW
Head
Min. Flow Rate
9.2
Btu/h
31,400
metres
4.9
feet
15.9
24.0
82,000
2.0
6.5
litres/min gal/min
2.64
12.0
22.0
4.81
Temp. rise across
heating flow
and return
11 °( (20°F)
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 .
. . . .-"'. .- :., .
-~"*''!1""m~
PKt:SSU~E
4VA1i.;A!ibi t~UMI~ i-l£1it)
15 mm Compression
.:m~·r·u:l:J\RGEtrl'l~J.\11
.
ltl: Fitiw ~t~ . 1HfiJf:ji~ ~.~ i,(;(~si!
""""''"d:,,,
w·~. ""'""'/,.,.;...,.;.w.1f.......
· ·1..~1 ~r 1ju ··ut
l
"""""Mi·vf'o.·.""1-W'r-~;.,....,!'-."~:
Mt.......tfi'""'~'l"''l-}~~
i
Kt:d£YVALVt.
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)
INSTALLATION WEIGHT
48.7 kg (107lb.)
~
PACKAGED WEIGHT
46.5 kg (1 02 lb.)
"
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
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE
0.6 Bar (9 psi)
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
EQUIVALENT DOMESTIC HOT WATER FLOW RATE TO GIVE A TEMPERATURE RISE OF 35°C
4
Nominally 8.5 litres/min ( ± 15%)
(1 .87 gallons/min)
Nominally 9.8litres/min
(2.16 gallons/min)
4. Siting The Appliance
Installation
100mm
600mm
230mm
5mm
5mm
Above
In front
Below
Right hand side
Left hand side
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.
Servicing
100mm
600mm
230mm
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 casing. 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.
I
I
I
I
--------------
I
I
I
I
I
450mm
1
~-~0~:--f
_________
1 Space required below
1 for installation and servicing.
/)________._j
t
I
_j
900m m
FRONT VIEW
I
I
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I
I
I
I
~
/).
I
I
360 mm
I
I
I
I
I
I
I
I
I
600mm
Space required in front
for installation and servicing.
I
I
I
I
SIDE VIEW
I
I
I
r--
Fixing holes
1
413 mm CRS. _ , 1
li
I!
.a_Lf,:II
I,-fl
i
5mm
Space required at left hand side -+t ~-+for installation and servicing.
1I
-.r ~
.
!L______________ _j l
Smm
Space required at right hand side
for installation and servicing.
5
Fig. 3. Appliance pipework connections.
...
-·
,_
Central heating flow
-
·ao·
. .:e-···.
ii
::,..:;;.r • I
\'
_, TIW!M.T\1111-
l_l ~ All~""""
-+--""'
mm
Central heating return
Mains cold water in - - I t + - - -
Pressure relief valve discharge
Gas cock
.......j.---------- 306 mm --~
---------405mm
--------1~
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 siting where this could cause a nuisance should be avoided.
5.7 Take care to ensure that combustion product:; do not enter
ventilated roof voids.
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 If the 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 Section 2.9.
Fig. 4. Siting of the flue terminal.
TERMINAL POSffiON
MINIMUM SITING DIMENSIONS FOR POSITIONING THE BALANCED
FLUE TERMINAL.
A
6
A-Directly below an openable window or
other opening e.g. air brtck
B- Below gutters, soil pipes or drain pipes
c- Below eaves
D-Below balconies or car port roof
E- From vertical drain pipes and soil pipes
F- From internal or external corners
G-- Above ground, roof or balcony level
H-From a surface facing a terminal
I- From a terminal facing a terminal
J- From an opening in a car port (e.g. door
window) Into dwelling
K- Vertically from a terminal on the same wall
L- Horizontally from a terminal on the same
wall
M-From door, windoworairvent(achieve
where possible)
MIN. DISTANCE
300 mm (12in.)
300 mm (12in.)
300 mm (12in.)
600 mm (24in.)
75mm(3in.)
600 mm (24in.)
300 mm (12in.)
600 mm (24ln.)
600 mm (24ln.)
1200 mm (47in.)
1500 mm (59in.)
300 mm (12ln.)
300 mm (12in.)
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.
6. Air Supply
6.1 The appliance does not require a separate vent for combustion 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
Position of
air vents
Air from
the room
Air direct
from outside
High Level
270 cm 2 •
(42in 2.)
135 cm 2 •
(21 in 2)
Low Level
270cm 2•
(42in2.)
135 cm 2•
(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 essential 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.
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 3 bar (45lb/in2). The discharge 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.
Sealed system
--expansion vessel
Domestic
coldwater.
-· Water to Water
heat exchanger
lockshield valve.
Radiator valve.
lllllllll J
Central heating
by-pass adjuster- '+t--T"H--'
Fill point-----'
11111111
Heating return
Heating flow.
Domestic hot water out
t
I
l
Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Note. Adrain cock should be installed at
the lowest point of the heating circuk and
beneath the appliance.
7
_.. British Standard
stop valve.
Fixed spindle type.
+- Water main.
Fig. 6. System filling and make-up.
Heating Return
Worcester Combi-Fill System
Heating Return
Non return
valve
Non return
va-4!- ~ Hose union
+1-----t..•--.f
. . lll-..;...===:u!!
u
~=·
!!,.
1•• +~
300mm (12inl min.
above the highest
point of the system.
Stop cock
\l,m,;~
Test cock
Auto
air vent
1-....1-- Fill Point
Temporary hose
'
Heating Return
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 occupants 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.
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 cistern.
Fig. 7. Open vent water system.
Feed and expansion tank
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.
Sealed system
--expansion vessel
Domestic
cold water.
--Water to Water
heat exchanger
lockshield valve.
Radiator valve.
lllllllll J
Central heating
by-pass adjuster -'"l'f+---!-+--1---l
Fill point -- -- .J
11111111
Domestic hot water out
Heating return
Heating flow.
,.. British Standard
stop valve.
Fixed spindle type.
I
Note. The mains cold inlet
connection to the appliance
must come before any other
connection from the cold supply.
Note. A drain cock should be installed at
the lowest point of the heating circuit and
beneath the appliance.
8
-Water main.
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.
9. Domestic Hot Water
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. A thread
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.
9.1
9
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 Atime 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.
1 0. Electrical
See Figs. 8, 9,10,11 and 12.
10. 1 MAINS SUPPLY. 240 V - , SO Hz, 1SO watts.
External Fuse 3A. Internal Fuses: T2A (F1) and T31 SmA (F2).
1 0.2 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.
10.5 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.
Fig. 8. Wiring Diagram - Control panel and facia.
(All components shown viewed from front of appliance)
~Fr:w~ fj-m~------br
•
e3X
• 410 3
br1]1
0 2X8
bl
r----;C;y
-----1
1
I
F2 FUSE
4
MAIN DRIVER BOARD
3
fiFt
br :
1L
tj FUSE
bl
2NX7
I
~
OX11
X1
• 3E
1 ~: v
2
4E
I
112
X5
31
X4
X3
2312345123
X2 3
4581234
III
5
pk
I
v
81
gvt~rn!9J11~!tr1Jr~!ttr.r~r.r~
~ 'i~tVV%-J ~~~
A
~ ~
MAINS
TO
GAS VALVE
MAIN
OVERRUN
THERMOSTAT
inI ;_ .:.: ~~ ..:.. ---'
~
Iii
DIVERTER
12
12
MICRO·SWITCH
i
j!
VALVE
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
H£ATING HOT WAml MODUREG
SENSOR msOR REGULATOR
Fig. 9. Wiring Diagram - Components outside control panel.
(All components shown viewed from front of appliance)
~-- /~~-~--~__:-_-_-:.====
I //
====-=
~~~==:--i
""
r
I I
1
I
I
I
iI :I
Pump
Overrun
Thermostat
I
I
I
I
I
I
or
I
I ~
I ~
I
l ...L
.
I
I
I
I
COLOUR CODE
----~
br-brown bl-blue gy-green and yellow bk-black or-orange
r-red w-white y-yellow g-grey v-v1olet pk-p1nk
_ _ _ _ _ _j
. ...--· ---· ------:~
--·----·-- ~ L.__..-
--·-- ·---·--·
T·-·-
---·-·==--~:i
------·-
L-.----
I
I
I
I
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I
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/) I
-----~/
I
I
I
I
: I
I I
I I
I
I ~
I
I
I
---------------------------1
l~bl
~llt=1
Main Valve
I
y
Modureg
~~~~~~
Regulator
"L--
.If
I
I
I
I
I
I
I
I
I
Gas Valve
br
gy-4--bl
~~ Domestic Hot
~UW Water Sensor
r
C
Diverter Valve Micro-Switch
11
r
F
I
- ....L
POWER ON
INDICATOR
DEMAND
INDICATOR
black
lL
~---
I
black
I--------------------
:,:,:- - - - - - - - - - - -;,;INDRi~R-;,.u;;; l
.X11!PIN2t
I
FUSE F1
T2A
1---------_r::::::]_
X4 !PIN 41
I
u
XBIPIN 11
lr--1
TRANSFORMER
X41PIN 51
X4 !PIN 3!
I
I
I
I
I
I
I
ELECTRONICS
FUSE F2
T315 rnA
MICRO SWITCH
cw
brown
DHW
.
XIO !PIN 31
white XIO !PIN 21
I
I
grey
X31PIN 41
X3 !PIN 31
violet
I
OPERATING SWITCH
lOR PROGRAMMER!
I
....
N
I
RELAYRY1
FROST THERMOSTAT IIF FITTED I
red
I
I
I
ELECTRONICS
XlWIN 51
WATER DIVERTER VALVE
MICRO
__
_ _SWITCH
_ _ _ _ j•
L_ _______ _
I
CENTRAL HEATING SENSOR
I
I
DOMESTIC HOT WATER SENSOR
XSIPIN 1)
brown
I
I
TEMPERATURE CONTROL POTENTIOMETER
brown
PUMP OVERRUN THERMOSTAT
I
L
_
orange
~~z
-----------
------------
Fig. 11 . Room thermostat
connections.
PUMP
1 2 3 4 5
Terminal X4 on
main driver board.
•N
_ _ _ _ _ __J
X6!PIN3i
Fig. 10. Functional flow diagram
I
brown
~----------------------------------------~N
~----------------------------------------------~~N
Fig. 12. Frost thermostat
connections.
1 2 3 4 5
Terminal X4 on
main driver board.
Remove link.
Honeywell room thermostat
T60608 (or similar.)
Honeywell frost thermostat
T4160A (or similar.)
Fig. 13. Wall preparation.
450mm
365 mm Wall aperture
9mm
~el
2i.E
COL<'>
~~
5:
1:
348mm
I
w
U'J
a:
u
E
...E =EE
"'
CD
E
E
0.0
<0
~
I
Wal mounting plate
Inside plaster
I
--t=j-
--o--
410mmCRS
"'-
Drill four holes
in wall to suit
No. 12 wall plugs
I
..,
.-
19. Tighten the screws from instruction 17.
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 forward.
(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.
1 - Tube of silicone sealant.
4 - No. 8 wood screws
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 plaster 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 appliance.
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.
13. 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. 15.
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.
Seal telescopic joint
with tape provided.
Fig. 15. Arrangement of balanced flue
and terminal.
Telescopic flue duct.
10 mm 10.4 in.) diameter
continuous seam of
silicone sealant all
around. !See below.)
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.
Drill and plug wall.
Secure mounting plate
' . . . - - - - - - - - - - - . . . . . with four screws.
10 mm (0. 4 in.) diameter
continuous seam of
silicone sealant all
around.
14
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. 17. Cover plate (Sealed Systems).
Appliance casing top panel
Cover plate fixing screws 131
Fig. 16. Automatic air vent.
Fig. 18. Pipe connection for open vent
systems.
Unscrew and discard the cap
Appliance casing top panel
Automatic air vent
(Sealed systems only!
Feed and vent connection
!Open vent water system only)
1111111111mmm
_:::_l~~r
Pre-formed feed and vent pipe
Gas to Water heat exchanger
To Gas to Water heat exchanger
15
11.20 FINAL INSTALLATION
Check that all the water connections and the gas connection
have been tightened.
Fig. 19. Appliance casing and control
equipment fixings.
,.
-;L Top panel fixing screws 121
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.
Inner casing cover fixing screws 14)
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.
p
•
•
c
Test the gas supply pipework up to the appliance for soundness
as indicated in BS 6891.
Control box fixing screws 12)
l
Upper facia panel fixing screws 12)
Refer to Section 12 for a full description of the filling, venting
and, with a sealed system, the pressurising of the system.
I
-··-·
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.
Lower facia panel fixing screws 12)
16
__ ;
m·e
I
····~c
-:
~,:
Fig. 20. Electrical cable exists from control box.
ro
Earth MAINS
GAS VALVE
ro
PUMP
ro
PUMP
~-ll\JN
TltERMOSTAT
TO ROOM THERMOSTAT
IOPTIONAL I
ro
TO
WATER
DIVfRTER
VALVE
MICRO-SWITCH
ro
ro
CENTl\AL DOMESTlC GAS VALVE
HEATING HOT WATER MOOUREG
SENSOR SENSOR REGULATOR
TO FIIOST TltEAMOSTAT
IOPTlONALI
increased if necessary.
12. Commissioning
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: 1 bar 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 .
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).
Fig. 21 . Pressure relief valve.
r
Pressure gauge capillary connection
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
Pressure relief valve discharge pipe
17
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 temperature 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.
1 2.3 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 actuator. 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.
Set the room thermostat to minimum and check that the burner
goes out. Reset the room thermostat to maximum and the burner 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.
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 rises. 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.
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.
Central Heating
Check that all the radiator valves are open. Set the room thermostat 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 &
13. Instructions To The User
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.
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. Worcester Heat Systems Ltd offer a comprehensive maintenance con·
tract.
18
Fig. 22. Gas valve.
Electrical connections - Main valve - - - - " ' " " ' {brown • blue • green/yellow)
Maximum pressure adjuster -----.._
·~~)--+--ii--:---+---
Minimum pressure adjuster
Note. Turn the nuts clockwise
to increase and anti-clockwise
Pressure compensating tube
connection
- - - Inlet pressure test point
to""""'" <h""""" ~
Modureg cap
Modureg regulator head
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),
Fig. 23. Central heating by-pass adjuster.
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 servicing. 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 19.
(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.
'
13.5 Set the system controls to the user's requirements.
13.6 If an external programmer has been fitted which has a programmable 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 intervals. The frequency of servicing will depend upon the particular installation conditions and usage, but once per year should
19
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.
(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.
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. 4 SERVICE OF COMPONENTS
14. 5
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.
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
1
0
0
Combustion chamber cover fixing screws 14)
Combustion chamber cover
0
0
0
20
~
Pump overrun thermostat
~Overheat thermostat
Combustion chamber cover
and flue hood fixing screws 12).
0
Fig. 25, Pilot burner assembly.
2 mm
Thermocouple
0
PILOT SHIELD REMOVED
FOR CLARITY
Fig. 26. Main burner fixings.
Fig. 27, Pilot burner settings.
Main burner
fixing screws 121
PILOT SHIELD REMOVED
FOR CLARITY
15.3 DRAINING THE APPLIANCE
Check that the eLectricity supply to the appliance is turned off.
Before removing any component holding water it is important
that as much water as possible is removed from the appliance.
(a) Central Heating Circuit. Turn off the central heating flow and
return valves at the appliance. See Fig 3. Fit a tube to the drain
tap on the Water to Water heat exchanger and open the tap
about one turn. See Fig 30. Close the drain tap when the flow
has stopped. Some water will remain in the expansion vessel,
pump, diverter valve and Gas to Water heat exchanger and
extra care must be taken when removing these components.
(b) Domestic Hot Water Circuit. 1l.irn off the mains cold supply
valve at the appliance and open the lowest hot water tap. See
Fig 3. A quantity of water will remain in the Water to Water
heat exchanger and the diverter valve and extra care must be
taken when removing these components.
15. Replacement of Parts ·
15.1 WARNING.
Switch off the electricity and gas supplies before replacing any
components. After the replacement of any components, check
for gas soundness where relevant and carry out functional
checks as described in Section 12 - Commissioning
15.2 COMPONENT ACCESS
To replace components it is necessary to remove one or more
sections of the cabinet and cover plates within the appliance as
described in Section 14.3. The facia panel and control box may
also need to be lowered as described in Section 14.3
21
15.4
the thermostat to its mounting plate on the Gas to Water heat
exchanger. Remove the front screw and thermostat.
Fit the replacement thermostat ensuring a layer of heat sink
compound is between the faces.
5. Combustion Chamber Insulation. See Fig 29
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 15.3(a).
Remove the inner casing cover, flue hood assembly, and Gas to
Water heat exchanger as described in Sections 14.3(b, and e),
and 15.4.(3), Remove the fibre insulation pads from the combus·
tion chamber side, rear, and front sections.
Fit the replacement pads in the reverse order taking care not to
damage them.
Open the valves, fill and re-pressurise the system as described in
Section 12.2.
6. Main Burner. See Fig. 26
Check that the electricity supply to the appliance is turned off.
Remove the burner assembly as described in Section 14.3(g).
Fit the replacement burner in the reverse order taking care not
to bend the pilot bracket on the main burner.
COMPONENT REPLACEMENT
1. Automatic Air Vent. (Sealed system installation only).
See Fig 16.
Remove the inner casing cover and flue hood assembly as
described in Section 14.3(b) and (e).
Drain the central heating circuit as described in Section 15.3(a).
Unscrew the assembly.
Fit the replacement assembly.
Open the valves and fill and re-pressurise the system as described
in Section 12.2.
2. Overheat Thermostat. See Fig. 24
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover as described in Section 14.3(b).
Lower the facia as described in Section 14.3(c).
Remove the two M3 screws holding the overheat thermostat to
the heat exchanger. Unscrew the overheat leads from the gas
valve. Push the grommet through the hole in the casing and
thread the lead assembly through the hole. Fit the replacement
overheat thermostat in reverse order ensuring a layer of heat
sink compound is under the thermostat head.
7. Pilot Burner. See Figs. 25 and 27
Unscrew the two screws and remove the pilot burner and pilot
shield from the main burner.
Remove the spark electrode cable and pull out the electrode.
Undo the pilot pipe, unscrew and remove the thermocouple.
Fit the replacement burner in the reverse order. Fit the electrode
lead before replacing the electrode. Check the pilot burner settings as shown in Fig. 27.
Make sure the pilot shield is in place.
3. Gas to Water Heat Exchanger. See Figs 16, 28 and 29.
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 15.3(a).
Remove the flue hood assembly, pump overrun thermostat,
overheat thermostat and main burner as described in Sections
14.3(e, f, and g), 15.4(4) and 15.4(6).
Unscrew the flow connectors at the heat exchanger and at the
bottom left of the inner casing and move the heat exchanger to
one side.
Unscrew the return connection at the bottom left of the inner
casing and manoeuvre the heat exchanger from the casing.
Carefully remove the left hand insulation pad and left hand com·
bustion chamber side panel.
Transfer the return pipe to the new heat exchanger leaving the
connector nut loose.
Fit the replacement heat exchanger in the reverse order ensuring
all the fibre washers are in place and a layer of heat sink com·
pound is on both the thermostats. Align the return pipe and
tighten the connection. Refit the side panel and the insulation
pad.
Open the valves and fill and re-pressurise the system as described
in Section 12.2.
Fig. 28. Gas to Water heat exchanger
connections.
Boiler return
i
4. Pump Overrun Thermostat. See Figs 9 and 24
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover and flue hood assembly as
described in Section 14.3(b) and (e).
Carefully remove the three wires from their connections and
make note of their positions. Loosen the rear M4 screw securing
Boiler flow connector screws
22
Fig. 29. Combustion chamber insulation.
Gas to Water heat exchanger
"
('5I
r
"I
I
I
I.
.I
@"':
I~
I
I
I
I
I
I
I
I
lo:••
.·~·"·
•
,~:~~--~::
....
~
'
:
I
I
Rear insulation pad
Side insulation pad
I
. ~:: ,«.
..,· ~-· -~
Side insulation pad
{
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
IJJI'I.
~I
;}i~
I
I
.I
~
:~
~
[l;.
-~~~
Main burner
Fig. 30. Appliance components (lower assembly).
PILOT GAS PIPE
THERMOCOUPLE
ELECTRODE LEAD
SPARK GENERATOR
(REO KNOB)
OVERHEAT
THERMOSTAT
LEADS
EXPANSION VESSEL
WATER
DIVERTER
VALVE
WATER TO WATER HEAT EXCHANGER
DRAIN COCK
GAS INLET
DOMESTIC HOT
WATER SENSOR
DOMESTIC HOT WATER FLOW
RESTRICTOR HOUSING
23
8. Main Burner Injector. See Fig. 25
Remove the main burner as described in Section 15.4(6).
Unscrew the brass injector at the back of the combustion cham·
ber.
Fit the replacement injector in the reverse order.
9. Spark Electrode. See Figs. 25 and 27
Check that the electricity supply to the appliance is turned off.
Remove the pilot burner assembly as described in Sections
14.3(b) and 15.7.
Pull the spark electrode out of the clip.
Fit the replacement electrode in the reverse order, checking that
the spark gap is 4 to 5 mm. Fit the electrode lead before replacing the electrode.
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Disconnect the pilot pipe. Unscrew and remove the black plastic
plug. Carefully pull off the two yellow wires from their termi·
nals. Remove the thermocouple connection and the white leads
from the gas valve. Remove the eight screws securing the valve
to the pipework and remove the valve from the appliance.
Fit the replacement gas valve in the reverse order ensuring the
sealing washers are correctly fitted.
'!Urn on the gas supply and check for soundness.
To replace the Modureg head only.
Pull off the electrical connections. Unscrew the two screws
securing the Modureg head to the main body and remove.
Fit the new Modureg head (Honeywell 3061) in the reverse order
ensuring that the gasket is in the correct position.
To set the burner pressure. See Fig. 22.
The minimum and maximum burner pressures must be set after
a new gas control has been fitted.
Follow the procedure desc,ribed in Section 12.4 - Appliance
Operation.
The maximum burner pressure must be set first, as any adjust·
ment of the maximum pressure influences the minimum pres·
sure setting.
Remove the the fixing scrl?w and rP.mnvP. the the Modureg cover.
The Modureg cap must be replaced immediately the adjust·
ments have been made to ensure the proper operation of the
gas control.
Start the appliance in the domestic hot water mode as described
in Section 12.4- Appliance Operation.
Adjust the maximum pressure adjustment nut to give a burner
pressure of 14.7 mbar. See Fig 22.
Switch off the appliance and turn off the electricity supply.
Remove a lead to the Modureg head.
Switch on the electricity supply to the appliance and re-light in
the domestic hot water mode. The burner pressure will remain
at the minimum setting.
'!Urn the minimum pressure adjustment screw until the burner
pressure is 2.8 mbar. See Fig.22.
Switch off the appliance and turn off the electricity supply. Refit
the lead to the Modureg head.
It should not be necessary to alter the central heating paten·
tiometer setting when the gas control is replaced and the mini·
mum and maximum burner pressures are set.
10. Pilot Burner Injector. See Fig 25
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover and pilot burner assembly as
described in Sections 14.3(b) and 15.7. Remove the injector (a
push fit inside the pilot assembly).
Fit the replacement injector in the reverse order.
11. Thermocouple. See Figs 25 and 27.
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover and pilot burner assembly as
described in Sections 14.3(b) and 15.7.
Unscrew the thermocouple at the gas valve. Remove the pilot
pipe cover plate and thread the thermocouple through the hole
in the casing. Fit replacement thermocouple in reverse order.
12. Spark Electrode Lead. See Fig. 25
Check that the electricity supply to the appliance is turned off.
Remove the inner casing cover as described in Section 14.3(b).
Carefully pull the lead from the spark electrode and withdraw
from the inner casing.
Fit the replacement lead in the reverse order. Loosen the pilot
assembly to refit the lead to the electrode.
13. Gas Valve. See Fig. 22.
Check that the electricity and gas supplies to the appliance are
turned off.
Fig. 31 . Circulating pump.
Fig. 32. Expansion vessel and pump
assembly.
24
Fit the replacement vessel in the reverse order.
Open the valves and fill and re-pressurise the system as described
in Section 12.2
18. Pressure Relief Valve. See Fig 21
Drain the central heating circuit as described in Section 15.3(a).
Lower the control box assembly as described in Section 14.3(d)
Undo the discharge pipe connection and unscrew the valve taking care not to distort the pipework.
Fit the replacement valve using a suitable thread sealing compound. Reconnect the discharge pipe.
Open the valves and fill and re-pressurise the system as described
in Section 12.2
14. Central Heating Sensor. See Fig. 30
Check that the electricity supply to the appliance is turned off.
Carefully pull off the two leads from the sensor. Loosen the two
M3 screws securing the sensor to the fitting and remove the sen·
sor
Fit the replacement sensor with a layer of heat sink compound
between the faces. Refit the leads.
15. Domestic Hot Water Sensor. See Fig. 30
Check that the electricity supply to the appliance is turned off.
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Carefully pull off the two leads from the sensor. Loosen the two
M3 screws holding the sensor to the fitting and remove the sen·
sor.
Fit the replacement sensor in the reverse order ensuring a layer
of heat sink compound is between the faces. Refit the leads.
16. Circulating Pump. See Fig 31
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 15.3(a).
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Undo the two union nuts and remove the pump from the
pipework. Support the pump and remove the electrical cover. Dis·
connect the electrical wires taking note of their positions.
Fit the replacement pump in the reverse order using new sealing
washers. Ease back the sleeved connector to allow the fitting of
the bottom washer.
Altematively replace the pump head only by removing Lhe four
Allen screws.
Open the valves and fill and re-pressurise the system as described
in Section 12.2
Note. The direction of flow should be downwards. The speed
should always be set to maximum.
17. Expansion Vessel. See Fig 32
Drain the central heating circuit as described in Section 15.3(a).
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Remove the gas valve as described in Section 15.13.
Undo the expansion vessel connection at the boiler flow connection and remove the vessel.
Fig. 33. Water diverter valve.
Water diverter valve micro-switch assembly
Fig. 34. Water to Water heat exchanger connections.
Boiler return pipe . . _
Water to Water heat exchanger
Boiler flow pipe
Mains cold water in
Drain point
25
22. Domestic Hot Water Flow Restrictor. See Fig 30
Check that the electricity supply to the appliance is turned off.
Drain the domestic hot water circuit as described in Section
15.3(b).
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Undo the water connection A and remove the fitting. The plastic
flow restrictor is located within the brass housing.
Fit the replacement flow restrictor and reassemble in the reverse
order ensuring the fibre washers are in place.
19. Water Diverting Valve Micro Switch Assembly. See Fig 33.
Check that the electricity supply to the appliance is turned off.
Lower the control box assembly as described in Section
14.3(d).
Using a pair of fine nosed pliers, pull the circlip off and remove
the micro switch assembly from the valve. Lower the facia as
described in Section 14.3(c). Carefully pull off the Molex connec·
tion from terminal X3 on the driver board. Remove the strain
relief bush to withdraw the switch and lead assembly from the
appliance.
Fit the replacement micro switch assembly in the reverse order.
20. Water Diverting Valve. See Fig 33
Check that the electricity supply to the appliance is turned off.
Drain the central heating and domestic hot water circuits as
described in Sections 15.3(a and b). Hang the control box assem·
bly in the servicing position as described in Section 14.3.(d).
Remove the micro switch assembly as described in Section 15. 4.
23. Pressure Gauge. See Fig 35
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 15.3(a).
Lower the facia panel as described in Section 14.3(c).
Remove the two screws securing the gauge to the facia panel.
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Disconnect the capillary at the pressure relief valve.
Fit the replacement gauge in the reverse order ensuring the fibre
washer is in place.
Open the valves and fill and re·pressurise the system as described
in Section ·12.2
19.
Undo all the water connections to the valve and remove from
the appliance.
Fit the replacement valve in the reverse order ensuring that the
filter and all fibre washers are in place.
Open the valves and fill and re·pressurise the system as described
in Section 12.2
Fig. 35. Facia (rear view in lowered position).
F====::::;;;;f
Indicator
\
lights~
0
0
Temperature control potentiometer
l:==v==
/0"
p~
Operating Switch
[]
w
~------------~~~~----~
~~----------------0~x
-,
Operating Switch plate (or programmer) fixing screws (4)
1----~
Pressure gauge fixing screws (2)
or
24. Operating Switch. See Fig. 35
Check that the electricity supply to the appliance is turned off.
Lower the facia panel as described in Section 14.3(c).
Remove the. leads from the rear of the switch making note of
their positions.
Squeeze together the two plastic retaining lugs to remove the
switch from the facia.
Snap in the replacement switch and reconnect the leads. Refer
to the wiring diagram, Fig. 8
25. Temperature Control Potentiometer. See Fig 35
Check that the electricity supply to the appliance is turned off.
Lower the facia as described in Section 14.3(c).
Pull the knob off the spindle. Unscrew the locknut and remove
the potentiometer from the facia panel. Remove the Molex plug
from terminal X1 on the driver board.
Fit the replacement potentiometer in the reverse order.
21. Water to Water Heat Exchanger. See Figs. 3, 30, 33 & 34.
Check that the electricity supply to the appliance is turned off.
Drain the central heating and domestic hot water circuits as
described in Sections 15.3(a and b).
Loosen the mains cold water inlet connection and locknut at the
appliance. See Fig.3.
Hang the control box assembly in the servicing position as
described in Section 14.3(d).
Undo connection A and remove the coupling.
Undo connection B and move the pipe to one side. Undo connections C, D and E. Loosen the two screws at the right hand fix·
ing bracket.
Protect the control box and carefully remove the heat exchanger as some water remains.
Transfer the boiler flow pipe (removed with the old heat ex·
changer) to the new heat exchanger using a new fibre washer..
Fit the replacement heat exchanger in the reverse order ensuring
all the fibre washers are in place.
Open the valves and fill and re·pressurise the system as described
in Section 12.2
26
Refit the facia panel and hang the control box assembly in the
servicing position as described in Section .14.3 (d).
Set the central heating operating pressure to maximum by turn·
ing the central heating potentiometer anti-clockwise as accessed
through an opening in the rear of the control box.
The adjustment is made using a thin flat-bladed screwpriver..
27. Piezo Spark Generator
Remove the cabinet front panel as described in Section 14.3(a).
Pull the spark electrode lead from the connection on the spark
generator. Unscrew the two MS screws and remove the spark
generator from the appliance. Fit replacement spark generator
in reverse order.
26. Main Driver Board. See Fig 8
Check that the electricity supply to the appliance is turned off.
Lower the facia panel as described in Section 14.3(c)
Carefully pull off all the Molex connectors. Disconnect the room
and frost thermostat connections (if fitted) from terminal X4.
Remove the Operating Switch (or programmer) plug from termi·
nal X10. Disconnect the mains supply leads at terminal X7.
Release the plastic catch in each corner of the driver board and
pull forward off the control panel.
Fit the replacement board in the reverse order ensuring it is
pushed firmly onto the four posts and clicks into place.
27
16. Short Parts List
Key
No.
GCNo.
Part
Manufacturer's Reference
No.
WHSPartNo.
41
378 581
Gas Valve
Honeywell·V4600N3061
1
ZAGAS181
114
378 585
Modureg Head (Gas Valve)
Honeywell·V7335A3008
1
ZAGAS185
33
378 025
Main Burner
Aeromatic·AC 23/053576
1
ZAGAS154
34
379 040
Main Burner Injector
Stereomatic 4.4mm Dia. '!ype 7
1
ZAGAS163
35
379 673
Pilot Burner
Honeywell·Q385A 2010
1
ZBGAS092
36
382 850
Pilot Burner Injector
Honeywell-45.004, 108·001 38/36A
1
ZBGAS016
37
386 575
Spark Electrode
Honeywell-45900413-004
1
ZBGAS093
38
324 887
Spark Electrode Lead
Vernitron 0. 7 PTFE
1
ZBGAS025
21
299 150
Gas to Water Heat Exchanger
Giannoni·PR 20/321
1
ZAGAS165
24
379 419
Automatic Air Vent
Intermes-02, 50, 010
1
ZMMIS055
53
299 199
Sensor and paste
Elmwood-6655·9428·4
2
SPK0039
94
299 202
System Pressure Gauge (with Washer)
Cewal
1
SPK0040
74
386 789
Pressure Relief Valve
Caleffi·3141, 3bar
1
ZCVLV018
50
378 034
Circulating Pump
Grundfos·UPS 15·60, 120CL, NOCL 50526613
1
ZAMAJ198
70
378 027
Expansion Vessel (Sealed System)
Inter Albion·MIS082/240
1
ZMMIS082
1
SSA6161/1
79
371 537
Water to Water Heat Exchanger
57
379 216
Diverter Valve
Giannoni·D2040
1
ZAGAS166
379 730
Driver Board
HoneywellW411 SB, 1226
1
ZAGAS228
97
I
90
386 227
CH Temperature Control Potentiometer
Omeg-OW20BU
1
SSAHAR002
93
386 778
Operating Switch
Arrow· 200400£83 9AA
1
ZDELE237
10
299151
Combustion Chamber Insulation (Complete)
122
371 539
Programmer Kit (Optional)
42
371 540
61
371 541
60
379 215
DHW Flow Restrictor
91
371 524
92
371 525
22
1
SPK0033
1
ZAMAJ164
Gasket Pack - Gas
1
SPK0022
Gasket Pack - Water
1
SPK0023
'!ype E, White 8litres/min. (± 10%)
1
ZBUNC138
Indicator Light - DEMAND
Neon (Green)- complete with plug
IMO Ref. N19L R/S-Green
1
SSAHAR081
Indicator Light - POWER ON
Neon (Amber)- complete with plug
IMO Ref. N19L R/S·Amber
1
SSAHAR082
SPK0088
ZBUNC229
WHS Single Channel Grey 490 488
299 277
Pump Overrun Thermostat plus paste
Thermodisc 60T1 3·.5001 03
1
MPMV 3326 Stainless Steel
1
59
378 416
Filter
115
299 032
Fuse Pack
40
390 210
Thermocouple
48
393 652
Spark Generator
Vernitron 0207
1
ZBGAS010
4
299 152
Limit Thermostat
Elmwood 2455RC, c/w lead
1
SSAHAR013
Honeywell Q309A2747
28
1
SPK0024
1
ZBGAS035
17. Operational Flow Diagrams
End of domestic hot
water Demand.
Note. The alpha references in these charts are to be used for cross- referencing when fault finding. See Section 18.
Operating SWitch off.
Operating SWitch and
room thermostat on.
Primary water
Frost thermoStat
on.
m
Central heating
temperature above set
temperature.
monitored by central
heating sensor
Main gas valve off.
EITHER
~·, Cmrtr.dbeatiO!
Demand.
~ ~.
18
Main Gas
valve
opens
Primary water
temperature
monitored by central
heating senSOt
II
DEMAND indicator off.
level
EITHER
m
.II
Main gas valve off.
Heat input modulated
to maintain Dow
ternperatl!re set by
Temperature Control
Potentiometer.
minutes.
m
Pump on, or continue
1. Central Heating Mode.
from pump overrun
mode.
Pump off, or continue
if pump overrun is
required.
I Da:::!~r II
-
II
.:.
II
Mains
gas
available
Depress
gas
valve
button
Repeatedly
press red
igniter button
until pilot
flame is
observed
After 20 seconds slowly
release gas valve button
(30 seconds if Dame has
previously extinguished}
f
J
Wait for 3 minutes?
I+-
FLAME
CONTINUES
FLAME EXTINGUISHED
Twist gas valve
button in the
direction of
the arrow
Pilot Dame
established
OU1
.m
r - -....-
Wait for domestic hot
water temperature to
fall below set level
Operating Switch ON
and tap on.
Tap off.
Operating Switch OFF.
(Pump remains on).
m
Pump on, or continue
Domestic hot water
Signal
I
from
flow switch.
(Overrides central heating
Monitor primary water
via central heating
sensor and continue
into central heating
mode.
Domestic hot water
temperature rises above
pre·set leveL
from pump overrun
mode.
Hot water
Demand.
I
• I temperature monitored
by domestic hot
water senSOJ:
VALVE
mode and pump overrun
funct1on.)
ON
EITHER
II
water temperature at
factory pre-set level.
-
Hot water
Demand
satisfied.
r+
DEMAND indicator off.
.....
Main gas valve and
pilot valve off.
YES
.....
Is there a central
heating Demand?
NO
~
Automatic start
up sequence
IJ
~
!
DEMAND
indicator
iUuminated
SEE DETAILED SEQUENCE ABOVE.
2. Domestic Hot Water Mode.
Pilot
lit
No Demand and
primary water
temperature above
6o•c.
Pump on until primary
water temperature
falls below 6o•c.
Gas to Water heat
II
l1'!1
1!1
3. Pump Overrun Function.
Iii
exchanger excess
temperature causes
boiler overheat
thermostat to trip.
Gas valve shuts
down but pump
and indicator lights
remain on
(If Demand still exists)
4. Overheat Protection.
~ Pump off, or continue
into overrun mode.
, This Fault Finding Chart is tope used in conjunction with the Operational
Flow Diagrams in Section 17. To find the fault, locate the point on the flow
diagram at which the appliance has failed, eg, letter B. Then read the
corresponding section in the fault finding chart, eg. Failure at point B.
Note: Each section assumes that the appliance operates correctly up to
that point.
Notes. 1. All voltage measurements are with respect to neutral unless otherwise stated. 2. Before changing any component indicated in the chart, it is
essential that the associated wiring is checked for continuity, condition and correct routing. 3. Preliminary electrical system checks are the first electrical
checks to be carried out during a fault finding procedure. On completion of the Service/Fault Finding task which has required the breaking and remaking
of electrical connections, check-(a), EARTH CONTINUITY, (b), SHORT CIRCUIT CHECK, (c), POLARITY and (d), RESISTANCE TO EARTH.
1 8. Fault Finding
NO
Switch on the mains electrical
supply. Is the STANDBY indicator
illummated?
Cherk the mains electrical supply
and external wirtng
Is there a240V supply to terminal
X7pin 1?
YES
Cherk connections at the gas valve
Repair or replace as required.
Start of pilot lighting test
Sat operator SWitch or programmer
(If fitted) to off. Tum the room thermostat (II ntted) to
mm. Rlllow the manual operanon of the lighting
sequence to point ACiln apilot flame be observed?
n
lsthereagas·="'·
and check pressure
~
YES
~
+
r
~r
YES
Has the
overheat
thennostat
tnppW?
-NO
Is the pilot
flame
height 18
20mm?
' the primary
water temperature
lessthan95'C?
~
-NO
Check the p1lot i7ector for
blockage.Replace necessary
and ensure the pilot
adjustment serew is
correctly set by screwing
mfully and then unscrewing
two revolutions
Wait for the temperature to fall below
95'Cto reset the thermostat
ched: for cononuity across the devce.
Does continurty occu~
t
UGHTINGTEST
I
I
-=-1
Replace the
thermocouple
YES
Replace the
gas valve
31
A
Replacethe
overheat
thennostat
I
YES
Check the soundness of the
ECOconnectionsatthe
thermocouple and gas valve
{improve if necessary).
Rlllow procedure 5mthe
mult1meter handbock. Does
theclosedCJJtUitvoltage
exceedBmV'
I
Replace Injector
NO
YES
D1scon~ect the overheat thermostat and
t
END OF PILOT
NO
YES
is
c...,.
J
Re~acelgniter
0
I
YES
YES
Cherk condition of
Igniter leads and
connections Does the
igniterproduceaspark?
Ensure gas has bled
through the system
l
fiameremamestablished'
NO
1----
Jsthep1lotinjector
free from any blockage?
l
J
YES
Check that the p~ot adjustment screw is
correctly set by screwing it mfully clockwise
and tllen unscrewmg two revolutions. Does
the lngmter produce a spark?
FollowthemanualprocedurelopointBDoesthepilot
Tum on gas supply
NU
Supplytotheboiler
I
'
I
START OF CENTRAL HEATING TEST
Set the Operating Switch (or
programmer) to HEATING &WATER
and set the temperature control
potentiometer and room
thermostat (if fitted) to maximum.
Does the DEMAND indicator
illuminate?
Refer to section STANDBY indicator
light does not illuminate.
Is the STANDBY indicator still
illuminated?
YES
YES
Replace the Operating Switch (or
programmer).
Replace the room thermostat.
Replace the flowswitch.
Is there a 240V supply at pin 2on
terminal X5?
YES
Replace the pump overrun
thermostat.
YES
YES
,....f----------1 Remove the plated screw in the
Replace the pump.
centre of the pump and turn the
shaft with a flat bladed screwdriver.
Does the pump now run?
Refer to failure at
point AandB
burner Ignite?
Is there a 240v supply at
pin 1on terminal X8
YES
NO
Is there approx 24V ac
across the test pins on the
driver board?
NO
Transformer is faulty.
Replace the driver board
YES
Check connections to gas
valve or replace gas valve
32
NO
Check the connections at
Remove the C.H. molex plug
1---+1 the central heating sensor
from terminal X2.
or replace the sensor
Is the sensor resistance
between 1.5 and 25 kohms
across the white leads?
Does the gas pressure remain at 2.2
mbar for approximately two
minutes and then increase to the
set level over the next one minute?
Note. The system load must be
greater than 9kW and in acool
state for this to be possible.
YES
Does the gas pressure settle to
maintain aconstant flow
temperature set by the temperature
control potentiometer? (If the
burner pressure is correctly
balanced to the system load).
YES
Does the DC voltage across the gas
valve Modureg terminals remain at
aconstant low voltage for
approximately two minutes and
then gradually increase over the
next one minute? Note. The voltage
values are not important.
Replace the main driver board.
YES
Remove the Molex plug from
terminal X1. Measure the resistance
as follows: Between purple and
yellow pins ·10 kohms between
purple and pink pins · between zero
and 10kohms depending on the
setung of the temperature control
potentiometer. Is this correct?
Replace the temperature control
potentiometer on the facta paneL
YES
Remove the left hand Molex plug
from terminal X2.ls there a
resistance of between 1.5 and 25
kohms across the two white pins?
jReplace the main driver board: ·. · ·1
L
Gradually tum off the radiators one
by one so that the burner shuts
down as the system temperature
rises above the set levei.Does the
output drive at pin 1on terminal
XS drop from 240V to OV during the
shutdown?
The overheat thermostat has
activated. Has the voltage across the
modureg terminals dropped below
5Vdc? Wait for the temperature to fall
below we to reset the thermostat.
Relight the pilot
YES
Replace the main driver board.
33
Replace the central heating sensor.
Nb
NO
START OF DOMESTIC HOT WATER TEST
Set the Operating Switch (or
programmer) to WATER. Turn a
domestic hot water tap on fully.
Does the DEMAND indicator
illuminate?
Is the STANDBY indicator still
illuminated?
Refer to section STANDBY Indicator
light does not illuminate.
YES
YES
Replace the Operating Switch (or
programmer).
Investigate and rectify low flow rate.
Replace the pump overrun
thermostat.
YES
..,.1----------1 centre
Remove the plated screw in the
of the pump and turn the
Replace the pump.
shaft with a flat bladed screwdriver.
Does the pump now run?
j Refer to failure at point E.
34
Slowly reduce the domestic hot
water flow rate so that the gas
pressure reduces and settles. Does
the domestic hot water temperature
stabilise at 55·60°C?
Does the DC voltage across the
Modureg terminals decrease as the
flow rate reduces?
Remove the domestic hot water
Molex plug from terminal X2. Is
there a resistance of 1.5 to 25
kohms across the red pins?
Replace the domestic hot water
sensor.
YES
YES
Replace the main driver board.
Further reduce the domestic hot
water flow rate so that the
appliance shuts down as the
domestic hot water temperature
rises above the set level. Does the
burner re·ignite if the flow is
increased again?
The overheat thermostat has
activated. Atlow the overheat
thermostat and repeat this test.
YES
Does the DEMAND indicator light
go out immediately?
Replace the flow switch.
YES
YES
START OF PUMP OVERRUN TEST
With no central heating or domestic
hot water demand and with
primary water above 60°C
(approx.), does the pump operate?
Refer to section STANDBY Indicator
does not illuminate.
Is the STANDBY indicator light
illuminated?
YES
YES
Replace the pump overrun
thermostat.
When the primary temperature
drops below 60°C (approx.), does
the pump stop?
,Replace the pump overrun
·thermostat.
YES
OVERHEAT PROTECTION TEST
[
Does the burner shut down if the
Gas·to.Water heat exchanger water
exceeds 100°C
Replace the system overheat
thermostat.
35
~~~O~CESTER
Bosch Thermotechnik
Worcester Heat Systems Limited, Cotswold Way, Wamdon, Worcester I'W/4 9SW.
Telephone: (0190$) 754624 Fax: .(01905) 754619
This booklet is accurate at the date of printing but will be superseded and should be disregarded if specifications and/or appearances are changed in the interests
of continued improvement.
All goods sold are subject to our official Conditions of Sale, a copy of which may be obtained on application.
8 716 115 057a
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