Worcester Highflow 4.5 OF User guide

.......-~ ~ ~ORCESTER---
Highflow 4.5 OF
FLOOR STANDING COMBINATION BOILER FOR CENTRAL
HEATING AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
GC NUMBER 41 311 41
BOILER OUTPUT
To Hot Water On/Off Control
Maximum 22.9 kW (78,000 Btu/h)
To Central Heating On/Off Control, Range Rated
Minimum 8.8 kW (30,000 Btu/h)
Maximum 22.9 kW (78,000 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
~---------~~~ORCESTER __________ ~
Bosch Group

' CONTENTS
I. GenerallnformatJon II.
Electrical
2. Technical Data 12. Removal of Cabinet
3.
Dimensions and Wall Preparation 13. lnstallatJOn
4. Siting the Appliance
14. Commissioning the Appliance
5. Flue
15. Users Instructions
6. Arr Supply
16. Routine Cleamng and Inspection
7. System Considerations
17. Replacement of Parts
8. Sealed Primary System
18. Short Parts List
9.
Open Vent Pnmary Systems 19. Fault Fmdmg
10. Domestic Water Supply
1. GENERAL INFORMATION
See Fig. 1
1. THE HIGHFLOW 4.5 INCORPORATES:
(a) An open flued low thermal capacity boiler having a maximum
heat output of 22.9 kW (78,000 Stu/hi
(b) A heatbank having a nominal capacity of 92litres (21 gallons)
of circulating primary
hot water and positioned at the side of
the appliance. Acopper finned water to water heat exchanger
is fitted into the heat bank. Secondary mains supply domestic
hot
water passes through the heat exchanger.
{c) Adiverting valve to direct the boiler output either to domestic
hot
water or central heating as required.
{d) Two mtegral circulating pumps.
(e) A multifunctional gas valve and electrical control system to
individually control
the domestic hot water and central
heating.
(f) Boiler and hot water temperature control thermostats
providmg control for central heating and domestic hot water.
(g) An Operating Switch for selection of water only or central
heating
and water. A programmer kit is available as an
optional extra
(h) An expansion vessel, pressure gauge, pressure release valve
and auto air vent to enable the appliance to be connected to a
sealed
water system.
{i) An electronic pump delay control board which enables the
central heating pump to run on for a period of about 5 minutes
after each operating cycle.
2. THE HEATING SYSTEM
The appliance
is supplied for connection to a sealed system.
IMPORTANT: The pipe connections made throughout the
system must be capable of sustaining a pressure of up to 3 bar.
when the appliance is fitted to an existing installation and that
system ts upgraded to a sealed system then the water connec-
tions must be checked and replaced if necessary
If thermostatic radiator valves are to be fitted to the system
then they must conform to the requirements ofBS 276 7:1972.
Acombined cold feed
and vent pipe connection is availablefor
use when the boiler is fitted to an open vented system. See Fig.
2. Provision is made in the top panel for access.
INSTALLATION REQUIREMENTS
The installation of this appliance must be in accordance with the
relevant requirements of the Gas Safety (Installation and Use)
Regulations, local Building Regulations, Building Standards
(Scotland) {Consolidation), current lEE wiring regulations and bye
laws of the local water undertaking. It should be in accordance
with the relevant recommendations of the following British
Standards and Codes of Practiceo BS 6798:1987, BS 5449:1:1990,
BS 5546:1:1990, BS 5440:1:1990, BS 5440:2:1989 and BS 6891.
Gas Safety (Installation and use) Regulations 1984: It is the law that
all gas appliances are installed by a competent person, in
accordancewith the above regulations. Failure to install appliances
correctly could lead to prosecution. It is in your interest, and that of
safety,
to ensure compliance with the law.
The
manufacturers notes must not be taken, tn any way, as
overriding statutory obligations.
3.
2
NATURAL GAS SUPPLY
The boiler requires 2.8 m3 /h (98.5 ft
3
/hr) ofgas.The gas meter
and supply pipes must be capable of supplyrng this quantity
of gas in addition to the demand from any other appliances
being served.
It is recommended that a 22 mm dia. supply
pipe is used up to the appliance. Under no circumstances
should the size of the gas supply pipe be less than that of the
applianceinletconnection(22 mm diameter). The meter outlet
governor
must ensure a nominal pressure of20 mbar (8 in.wg.)
at the appliance. The complete installation, including the
meter, should be inspected and tested for soundness and
purged in accordance with the recommendations of BS 6891.
Fig. 1. Appliance water flow diagram.
Flow- -- ----
regulators
Comb1ned cold feed
and vent p1pe
I Open vent pnmary
systems onlyl
Bmler heat exchanger
Bo11ersec110n
lrrnnnuuu,
Bumer
:3ealed system

4. INSTALLATION WARNING:
CARE SHOULD BE TAKEN TO ENSURE THAT NO FOREIGN
MATTER IS LEFT IN EITHER THE GAS OR WATER PIPEWORK AS
THIS COULD CAUSE DAMAGE TO THE APPLIANCE
5. SAFETY VALVE
The safety valve may be removed and sealed if the boiler is
fitted to an open vented system. The safety valve drain
connection must be directed away from any electrical
components_ See Section 13.8
6. ELECTRICAL SUPPLY
Mains supply 240V- 50 Hz, 240 watts. External Fuse 3 amps.
7. CONTROLS
All controls includedwith the applianceare specified in Section
18-Short Parts List, included m th1s booklet. There is pro-
vision for a room thermostat and frost thermostat to be con-
nected to the appliance. See Section 11-Elt•c!rical
Thermostatic radiator valves can be used in the system but a
suitable by-pass is recommended with this type of controL
When using a sealed primary system, particular care should
be exercised
that only radiator valves of high quality to BS
2767,10 should be f1tted.
B. DRAINAGE
Adrain cock to drain
water from the boiler and the heat bank
is fitted in the prpe connecting the primary heat bank to the
sealed
system pressure vessel. A drain cock should also be
fitted to the lowest point of the
system
9. MAINS COLD WATER SUPPLY PRESSURE
If the mains supply pressure to the appliance is expected to be
low, it
is recommended that a 22 mm diameter supply pipe is
used from the rising main to the appliance
10. SHOWERS, BIDETS, TAPS AND MIXING VALVES
Standard hot and cold taps and mixing valves used with the
appliance
must be suitable for operating at mains pressure.
The use ofa thermostatically controlled showervalve
will give
added comfort and safeguard against flow of water at too high
a temperature.
If a loose head shower is fitted then the hose
rnusl be fixed to prevent the shower head falling closer than
25 mm
(1 m_) above the top edge of the bath to prevent it being
immersed
in the bath water. Alternatively an anti-syphonage
device
must be fitted. Hot and cold mains fed water can be
supplied
to an over rim flushing bidet, but is subject to local
Water Authority requirements.
3
11. APPLIANCE OPERATION
See Fig. 1.
The appliance output is range rated for central heating from
8.8
kw (30,000 Btu/h) to 22.9 kW (78,000 Btu/h). The output
is preset at 15 kW (51 ,200 Btu/h). If this output is not suitable
it should be adjusted to
match the central heating require-
ment. The domestic hot water output is preset at 22.9 kW
(78,000 Btu/h) and must not be adjusted. See Section 14-
Commissioning the Appliance.
The control
system ensures the heatbank is maintained at the
temperature set by the hot water temperature control ther-
mostat
With the Operating Switch (or Programmer) in the heating and
hot
water mode, priority will be given to satisfy the heatbank.
Hot
water will automaticallybe diverted to the central heating
system, the
temperature being regulated by the central
heating
temperature control thermostat.
With
the Operating Switch (or Programmer) in the domestic
hot
water mode, no heat will pass into the central heating
system. Domestic
hot water may be drawn off at a nominal
rate of
21 litres/min. (4.5 gal/min.) governed by two pre-set
flow restrictors located in the cold water inlet manifold.
The appliance includes a domestic hot
water pump and a
central heating pump. With the appliance
in the domestic hot
water mode both pumps are energised. The domestic hot
water pump circulates primary water around the heat bank
and the centralheating pump circulatesprimary water around
the
heat bank and the boiler
With the appliance
in the central heating mode the domestic
hot
water pump is de-energised and the central heating pump
is energised. Primary water then circulates around the boiler
and the central heating system.
In the eventof an unacceptable rise in temperature oftheheat·
bank due to continuous operation of the burner a high limit
thermostat is fitted which will shut down the boiler. This over-
heating is caused by a tap not being turned off properly and
allowing a very small flow of
water past the heat bank control
thermostat ph1al
An overheat thermostat is fitted to the flow pipefrom the boiler
section. In the event of a malfunction, thE! gas pilot circuit will
be interrupted which will completely shut off the gas valve
12. PACKAGING
The appliance is despatched in one package

2. TECHNICAL DATA
NOTE: THE DATA PLATE IS POSITIONED BEHIND THE FRONT PANEL ON TOP OF THE ELECTRICAL COVER
Table 1
NOMINAL BOILER RATINGS (1 0 minutes after lighting)
OUTPUT INPUT BURNER SETIING GAS RATE
PRESSURE
kW Blu/h kW Btu/h mbar
in_wg m3
/h
ft' /h
8.8
30,000 12 1 41,300
2.5 1 0
1.15
40.7
11 37.500
14.9
50.800 4.0 1.6
1.42
500
13
44.350 17.5
59,700 s 8
23
1_67 58.8
15 51,200
19.9 67,900 7.0 2.8 1.90
66.9
17 58,000 22.5
76,800
9.0 3.6 2 1s 75 7
19
64,800 24 8 84,600 11.0 44 2 37 83 3
22 9
78,000 29.3 100,000 14.3 57 2.80
98.5
DOMESTIC HOT WATER
22.9 78,000 29 3 100,000 14.0 5.62 2.80 98.5
Note: The Pressure test point 1s located on the gas valve {See Fig. 13 ).
Table 2
SPECIFICATIONS
CENTRAL HEATING FLOW 28
mm Copper tube
CENTRAL HEATING RETURN
28 mm Copper tube
COLD WATER MAINS INLET 22
mm Copper tube
DOMESTIC HOT WATER OUTLET 22
mm Copper tube
GAS INLET 22
mm Copper tube
HEIGHT
860 mm (33.9 in 1
WIDTH
685 mm (27 in.)
DEPTH
600 mm (23.6 in.)
WEIGHT
(DRY)
1 55 kg (340 lbs.)
PRIMARY CAPACITY
981itres (21.6 galls.)
MAXIMUM STATIC HEAD
25 metres (81 ft)
MINIMUM STATIC HEAD 1 metre {39 in.)
CIRCULATING PUMPS (2)
Grundfoss UPS 15·60
EXPANSION VESSEL
12\itres charged 0.5 bar
MAXIMUM OUTPUT TO HEATING
22.9 kW (78,000 Btu/h)
OUTPUT TO DOMESTIC HOT WATER
22.9 kW (78,000 Btu/h:
MAXIMUM DOMESTIC HOT WATER FLOW RATE
Nominally 21litres/min. (4.5 gal/min.)
GAS RATE (after 10 min.) 2.8 m3
/h (98.52 ft
3
/h)
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE
82°C (180°F)
NOTE. Appliance static head is measured from the top surfaceof the appliance or the highest point in the heating system to the top of the water
level in the feed and expansion tank. See Fig_ 7
Table 3
AVAILABLE PUMP HEAD
BOILER OUTPUT HEAD
MINIMUM FLOW RATE
TEMPERATURE RISE
ACROSS HEATING
kW
Btu/h
metres
feet
litres/min
gal/min
FLOW AND RETURN
8.8
30,000
5 1 16.6
11.5
2.5
11
37.500
4.7 1s s 14.5 3.2
13
44,350
4.3 14.1
17.0 3.8
15
51,200
38
12.6
19.5
4.3 11
°( (20°F)
17
58,000
33
10.9
22 s
49
19
64.800
2.2 7.2
24.8
54
22.9
78,000
1.7 5.5
30.0
6.6
4

3. DIMENSIONS AND
WALL PREPARATION
Fig. 2. Appliance dimensions and pipework connections.
l---600mm i23.6tn) -~~
685mm i27tnl
320mm 11
f-- 253 mm (10 in.)
-j
225mm I
2.6tnl
8.9tnl
Jinl1 185mm 17
Rear view
rl
80mml3.1
'"'
6tnl
""ll r
A ... -+• i
.--
-·
. BI-TcTo l
.G ____ E
BOILER
c "
'"
HEAT BANK
0
~
M
E E
~
E
:c
f
f-- 40mm(1
T
I <
~-
'"
"'
-
E E
E
~
" l
c
'"
~
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E
E
0
~
E
E
WJ
172 mm
16 Btn I
NOTE: ALL DIMENSIONS ARE NOMINAL
A VENT AND FEED 122 mm Copper)
B CENTRAL HEATING FLOW 128 mm Copper)
C CENTRAL HEATING RETURN (28 mm Copper)
Fig. 3. Installation and servicing clearance
r600mmi236io( l
I'
II
I
l1
II
II
D DOMESTIC HOT WATER OUT (22 mm Copper)
E DOMESTIC COLD WATER IN i22mm Copper)
F GAS INLET l22 mm Copper)
G SAFETY VALVE(~ mm Copper)
I
I
I
I
I
I I
0
=
~
~
E
E
0
----l
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--'~"---------'.- -- _ _J
II
II
II
l1
II
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jj_
600mm {24in)
I. .I
SPACE REQUIRED FOR
INSTALLATION AND SERVICING
5
5mm (0.2io) ---ft_
SPACE REQUIRED FOR
SERVICING
25mm 11m.)
SPACE REQUIRED AT LEFT
HAND SIDE FOR INSTALLATION.
70 mm {2.8m.)
SPACE REQUIRED AT RIGHT
HAND SIDE FOR INSTALLATION

4. SITING THE APPLIANCE
IMPORTANT
The appliance must not be installed in a bedroom orbed-sitting room
or in a room contaimng a bath or shower.
The appliance may
be installed in any other room although particular
attention is drawn to the requirements of the current I.E. E. Wiring
Regulations and, in Scotland, the electrical provisions of the Building
Regulations applicable m Scotland. with respect to the installation
of Lhe appliance in a room containing a bath or shower.
1. The appliance is floor standing. The floor must be firm and
level.
2. Siting must allowfor the proviston of an open flue termination.
See Section 5-Flue
3. If the appliance is to be fitted in a timber frame building then it
must be fitted in accordance with the British Gas publication
"Guide for Gas Installations in Timber Framed Housing".
5. FLUE
The appliance must be connected to a flue conforming to BS71 5
and incorporate a suitable adapter.
The appliance flue outlet has an mternal diameter of 144mm. The
flue pipe fitted
to the boiler must have an internal diameter of
1
25 mm (5 in.). If the outside diameter of the flue pipe is greater than
1 44 mm then an adapter must be fitted.
An acceptable means of disconnection e.g. a slip or split socket,
must be incorporated in the installation immediately above the
draught diverter.
The appliance
must be connected to a flue wh1ch will provide a
consistent up-draught
without undue cooling of the flue gases. The
requirements of BS 5440:1 should be followed.
Horizontal flue runs
should be avoided and the flue should
terminate in accordance with the relevant recommendations given
in BS 5440:1 The flue must be fitted with a term mal which has been
tested and found satisfactory by British Gas. The terminal must not
be installed w1thm 600mm (24 in.) of an openable wmdow, air vent
Or any other ventilation opening.
F.x1sting ch1mneys may be suitable but must be swept first and
usually require an approved liner to be fitted. If in doubt regarding
the suitabillty of a flue, consult the local Gas Region for advice.
!f the flue is required to be taken through the wall behind the boiler
then
adequate space should be allowed for a suitable flue bend to
be fitted Right
angle bends must not be used.
When the flue is taken through a ceiling and into the roof space or
room above. it must be provided with a sleeve of non-combustible
material suff1cient to allow an
a1r space between the sleeve and the
flue of 25 mm (1 in.) mm1mum. Asuitable non-combustible sleeve
or plate
must be fitted to centre the flue and maintain the 25 mm
6
4. The following clearances must be left to allow for seJVicing
and ventilation:
(a) Above the appliance,
(b) In front of the appliance,
(c) Left·hand sideo
(Viewed from front)
(d) Right·hand sideo
(Viewed from front)
Servicing
450 mm (18 in.)
Ventilation 5
mm {0.2 in.)
Servicing
600 mm (24 in.)
Ventilation
150 mm (6 in.)
SetVicing
25 mm {1.0 in.)
Ventilation 5 mm {0.2 in.)
Servicing 70
mm (2.8 in.)
Ventilation
70 mm {2.8 in.)
If a standard work surface is
fitted
then the gap should
be 1 00 mrn (4 in.)
Take care to ensure that adequate space is available at
either side to manoeuvre the appliance during installation.
This is left
to the discretion of the installer.
5. Refer to Sections 2, 3, 5, 6 and 7 for additional information.
(1 in.) air gap. The space between the plate or sleeve and the flue
pipe
should be filled with mineralwool or similarnon·combustible,
non conducting materials
IMPORT
ANT: It is ESSENTIAL to ensure, in practice, that products
of combustion discharging from the terminal cannot re-enter the
building or any other adjacent building through ventilators,
windows, doors or other sources of natural air infiltration or
forced ventilation or air conditioning. If this eventuality should
occur, the appliance MUST be turned off immediately and the
local Gas Region called in to investigate.
6. AIR SUPPLY
The appliance must have clearance at the right hand side for air
movement of at least 70 mm (2.8 in.) or 100 mm (4 in.) if a work
surface
has been fitted above the appliance. See Section 4.
The appliance must not be boxed in tightlywith kitchen cupboards
etc. Air supply must be provided in accordance with BS 5440:2.
1. If the appliance is installed in a room, then the room must have
a permanent air vent direct to outside air, or to an adjacent
roomwhich itself has a permanent air vent directto outside air.
The minimum effective
area of the air vent(s) required is
1 DO cm
2 (15 in2).
2. If the appliance is installed in a cupboard or compartment,
permanent air vents are required in the cupboard or compart·
ment, one at high level, and one at low level, either direct to
outside air or to a room. Both high and low level air vents must
commumcate with the same room or must both be on the
same wall to the outside air. The minimum effective areas are
given
in Table 4. Where the cupboard or compartment is

ventilated to a room, the room itself must have an air vent
dtrect
to the outside air of a minimum effective area of 1 DO em'
(15 in.'). Details of essential features of cupboard/compartment
design, including airing cupbaord installation, are given
in BS
6798:1987
3. If there is any type of extract fan fttted m the premises. spiltage
of the products from the appliance flue could occur when the
fan is operating unless an adequate air inlet area from outside
is provided.
4. A spillage test as detailed in BS 5440:1 must be carried out and
any remedial action taken to ensure the installation meets
these standards
Table 4
Position
Air from Air direct
Air Vents room from outside
H1gh Level
264 em' 132 em'
(41 in')
(20.5 in 'I
Low Level
528 cm
1 264
cm
1
(82 m.') (41 in.')
Additional information in respect of air supply and installation data
is given in BS 6798 and BS 5440:Part 2.
7. SYSTEM CONSIDERATIONS
1. For circuit design purposes it is most important that the flow
rate and pressure drop across the appliance corresponding to
the system
temperature differential and maximum heating
output chosen, should be as given
in Table 3
2.
The appliance includes a central heating circulating pump and
no other circulatmg pump IS required. When fitting a room or
frost thermostat refer to Section 11--Eiectrical.
The appliance
will operate sat1sfactonly on a two pipe small bore or microbore
system
3. The
heatbank contains two finned copper heat exchangers
which provide domestic hot water A control system
is incor-
porated that gives priority to the domestic hot water and the
central heating
will be turned off when a demand for hot water
IS made. For large quantities of hot water the Hot Water Tem-
perature Control Knob should be set at maximum and after use
a
few minutes may be reqmred to re-heat the heatbank. The
central heating will remain off during this period
4. The appliance IS supplied suitable for direct connection to a
sealed system
5.
It is essential that the fittings and joints in a sealed system are
capable
of maintaining the chosen system pressure.
It is generally advisable to fit a by-pass to all systems.
8. SEALED PRIMARY SYSTEM
See Figs. 5 and 6
1. GENERAL
The installation must comply with the requirements of BS
6798:1987 and BS 5449:1 For sizes of flow and return pipe
work refer to Section
2- Technical Data and Fig. 2
The open end
of the combined feed and vent pipe must be
sealed
IMPORTANT: The pipe connect10ns made throughout the
system must be capable of sustaining a pressure of up to 3 bar
When the appliance
is fitted to an existing installation and that
system
is upgraded to a sealed system then the water con-
nections must be checked and replaced if necessary
2. SAFETY VALVE
The spring loaded safety valve is set to operate at 3 bar
(45 p.s.i.). The discharge pipe must be so arranged that the
discharge of
water or steam from the tundish pipe cannot
create a hazard to occupants of the premises or cause
7
damage to electrical components and wiring. See Section 13
-Installation.
The safety valve complies with
the general requirements of
BS759.
3. PRESSURE GAUGE
A pressure gauge fitted to the appliance covers the range 0-4
bar (0-60 p.s.i.)
4. THE EXPANSION VESSEL
The appliance incorporates a 12 litre diaphragm type expan-
sion vessel charged to 0.5 bar. The expansion vessel is charged
with air and
is fitted wtth a Schraider type valve. The charge
pressure
!S therefore adjustable by using a tyre pump and
pressure gauge and should be increased
if necessary.
The charge pressure must not be less than the static head at the
point
of connectiOn (i.e. height of the top point of the system
above the expansion vessel)
The vessel as supplied is, therefore, SUitable for systems with a
static heat
of 0.5 bar whtch 1S equivalent to 5 metres (17ft.)
5.
SYSTEM VOLUME
The expansion vessel accommodates differing system volumes
depending upon the initial charge pressure and pre-pressurisa-
tion of the system
if any. Reference should be made to Table 5
to
establish the approximate system volume that can be
accommodated under different conditions with the standard
expansion vessel.
If it is found that the system volume is in
excess of that catered for by the expansion vessel supplied,
then an extra vessel can be added as close to the return con-
nection of the appliance as possible so that the total expansion
volume
is sufficient Refer to BS 5449:1 and BS 6798:1987 for
further information.
Table 5
TOTAL SYSTEM VOLUME IN LITRES (Gallons)
Initial System Initial Charge Pressure (bar)
Pressure (bar) 0.5 1 0
15
0.5
156
- -
(35)
1.0
96
122.5 -
(21) (27)
15
51.5 69.5 85
(11.5) (155) (185)
2.0 24 32.5
395
(5.5) (7)
(9)
NOTE. Because of the increased primary· capacity of this appliance
care should be exercised over the correct sizing
of the expansion
vessel
In order to check that the standard vessel (or standard vessel
together with any supplementary vessel) capacity
is adequate, first
ensure that with the system cold the initial system pressure is
correctly set. Allow the system to heat fully with the hot water and
central heating thermostats set to maxtmum.
Check that the system
pressure has not exceeded 2.6 bar If the system pressure has
exceeded 2.6 bar a supplementary vessel should be fitted as
described previously or
if one has already been fitted then this
should be increased
1n size.
6.
MAKE·UP
Provision must be made for replacing water lost from the
system either from a make-up vessel mounted
in a position
h1gher than the top point of the system and connected through
a non-return valve to the
system on the return side on the
heating circuit.
See Fig. 5. Or, where access to a make-up vessel
would be difficult, provision
for make up can be made by pre-
pressurisation of the system.
The
appliance must not be operated without the system
being full of water and properly vented. Repeated venting
will reduce the quantity of water in the system. It is essential
that this water is replaced and the system pressure main-
tained.

7. MAINS CONNECTION
Connection to the mains water supply or to a water storage
cistern supplying domestic water even through a non return
valve must not be made without the approval of the local
Water
Authonty.
8. FILLING
The system should be fitted with a filling point at low leveL
Methods offilling and making up sealed systems aredescribed
in
BS 5449:Part 1 Two methods of filling a sealed system are
shown in Fig. 6
9. VENTING
The
automatic air vent fitted to the appliance is fitted with a
protective black plastic screw
cap_ This should be removed
and discarded. Air will now automatically be vented from this
point during fil!ing. See Fig. 29.
The heating system should be fitted with manual air vents at
all h1gh pomts.
1 0. COMMISSIONING
For a complete description of the commissioning procedure
refer to Section 14-Commissioning the Appliance.
(a) Flush the whole system with cold water and fill until the
pressure gauge registers 1 .5 bar (21 .5 p.s.i.). Clear any air locks
and check for water soundness
(b) Check the operation of the safetyvalve. Release water from the
system until the initial system design pressure is obtained,
taking into account any difference in height between the
pressure gauge and the point at which the pressure vessel is
connected.
NOTE: The initial system design pressure should be 0.3 bar(4.5
p.s.i.) plus the static head of the system. Total pressure must
not exceed 1. 5 bar {21.5 p.s. i.).
(c) Light the boiler and heat the system to maximum working
temperature. Check for water soundness. Turn off the appli-
ance and drain the system while it is still hot.
(d) Refill and vent the system. Adjust to the initial system design
pressure. Any
set pointer on the pressure gauge should be set
to coincide with the indicating pointer.
Fig. 5. Sealed primary water system.
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Ill"
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--- i-- ---- _____ ....!._ --r--~- ------ .J ____ ..,
I I I
--~-------------...1-------------..,
I
I I
'I I
I
NOH: A DRAIN COCK SHOULD BE
I
INSTALLED AT THE LOWEST
I
POINT OF THE SYSTEM AND
I
BENEATH THE BOILER
I
I
I
I
~~J:~Hl:l! II ~
Jl\11~!;0~~
f----
11. SYSTEM BY-PASS
A suitable by-pass designed to give the minimum flow rate
corresponding to the heating output US!~d must be fitted. See
Table 3.
A suitable position for
the by·pass is shown in Fig. 5. The by·
pass should be connected in 22 mm dfameter pipe at least
2 metres (7 ft.) from the appliance and fitted with a suitable
valve
to provide adjustment.
To adjust the by-pass, the boiler should be operated on central
heating with the system by-pass and radiator valves set fully
open for at least 45 minutes. With the aid of a contact
thermometer, balance the heating system and restrict the by-
pass by the minimum amount necessary to givea temperature
rise across the flow and return pipe of 11 °C (20°F).
12. PUMP
The central heating pump has been set at MAXIMUM and
must not be adjusted.
SPHERICAL PLUG BALL
VALVEFORA~CE
SERVICING
""
DOMESTIC COLD WATER
TO TAPS, SHOWER
ANOW.C
I
r-"---
BRITISH STANDARD
STOP VALVE FIXED
SPINDL£TYPE
:
MAIN
~--2m(7ft1 MIN.--
r--,
I
I -
DOMESTIC
HEATING RETURN
:
HOT
I I
WATER
HEATING FLOW
_1_ __ ~---,
I ! : e
I
I
lfl
F
AUT0~1TIC 1
1
I I
j
SUPPLEMENTARY
EXPANSION VESSE
I I I
AIR VENT
I
Refer tro Section 8
'
Paragraph 5.
I
FLOW RESTAICTORS
BOILER
I
• I
0
HEAT
0
~
BANK
~
~
~
~
~~
~
EXPAJSION
~a?
~
PRfSSURf 1
~*
'!'
GAUGE
VESSEL
APf'LIANCE
I
CASING
I
------------------~
8

Fig. 6. System filling and make-up.
Heating Return
Non return
valve
+-
Non return
valve
~ Hose un1on l
t--...y<llt--r--{..-0..--.. ----, ,. ~
See Fig. 7
!J f! Stop cock
::eo==~/'
Test cock
Temporary hose
9. OPEN VENT PRIMARY
SYSTEM
1. For sizes of flow and return pipework refer to Section 2-
Technical Data and Fig_ 2
2. FEED
AND EXPANSION CISTERN
The feed and expansion pipe must rise continuously from the
appliance avoiding any horizontal runs.
The cistern
must be arranged to provide a minimum static
head of 1 metre (39 in.} above the top of the appliance or above
the highest point in the heating circuit whichever is the greater.
3. SAFETY VALVE
A safety valve is not required on an open vented system. If
preferred. it may be removed from the appliance and the
tapping blanked off. If the valve is left in position, a discharge
pipe
must be fitted which terminates in a position such that if
water or steam is discharged itwould not cause a hazard to the
occupants of the premises or damage the electrical com-
ponents and wiring. See Fig. 5
Fig. 7_Open vent water system.
EXPANSION
TANK
4.
Heating Return
Auto
air vent
..... ....., .... _ Fill Point
' Heating Return
FILLING AND VENTING
300mm 112m) min.
above the highest
pomt of the system
An auto air vent {which initially requires the top to be loosened)
is fitted to the top of the insulated heat exchanger adjacent to
the boiler. See Fig. 29. Air should be released as necessary from
this
point during filling. Any other air within the appliance will
be expelled via the feed and vent connection or dissipated into
the restof the system. The heating system should be fitted with
manual air vents at any high point
5. SYSTEM BY-PASS
A suitable by-pass
must be fitted, designed to give the
minimum flow rate indicated in Table 3 corresponding to the
heating output used. A suitable position for the by-pass is
shown in Fig. 5_ The by-pass should be connected in 22 mm
diameter pipe at least 2 metres (7ft.) from the appliance and
fitted with a suitable valve to provide adjustment.
To adjust the by·pass, the boiler should be operated on central
heating with the by-pass and radiator valves set fully open for
at least 45 minutes. With the aid of a contact thermometer,
balance the heating system and restrict the by-pass by the
minimum amount necessar~ to give a temperature rise across
the flow and return pipes of 11 °( (20°F)
6. PUMP
The central heating pump has been set at MAXIMUM and
must not be adjusted
DOMESTIC COLD WATER
TOT APS. SHOWER
h ANDWC
-------
1"-~~~-="t---- --- -j- --
T-
--
-,
I
STATIC
HEAD
L_
- r--------., ,.--------.,
,J llllllll,
.J 1111111 L
1..-------..1 I '
._ _______ ...
'
~
* * *
--- i--- --- _____ ...~__ -T---- ______ _.L ___ - •
I I I
--~---------------L-------------,
I
I
I
NOTE: A DRAIN COCK S'lOULD BE
I
INSTALLED AT THE LOWEST
I
POINT Of THE SYSTEM AND
I
BENEATH THE BOILER.
I
I
I
I
I
I
Jlllllll
II II;:;~~
I
I
I
l I
I
LOCKSHIELD I
VALVE
'
SPHERICAL PLUG BAll
VALVE FORA~ANCE
COMBINED
SERVICING \:-,.
FEED AND
VENT
~
~--2m171t1MIN.--
-,
I
HEATING RETURN
:
I
HEATING HOW
I
I
I l
I
r-
BRITISH STANDARD
STOP VALVE FIXED
SPINDLE TYPE
I
MAIN
DOMESTIC
HOT
WATER
-----
I
I
I
I
~-t
I
lfl ll
AUTOMATIC
MINIMUM ST A Tl
CHEADTOBE 1m
FROM THE TOP
I I I
AIR VENT
I
HOW RESTRICTORS
BOILER
•
HEAT
:;;
BANK
~
-~
~
PRESSUR£ J. EXPA;SION
~~
~
GAUGE VESSEL
APPLIANCE
CASING
9
13ft) MEASURED
SURFACE OF TH E APPLIANCE OR
OINT IN THE THE HIGHEST P
HEATING SYSTE M TO THE TOP OF
EL IN THE FEED
NTANK
THE WATER LEV
AND EXPANSIO

10. DOMESTIC WATER SUPPLY
See Figs. 5 and 7.
NOTE: The following mstructions are general installation recom-
mendations and reference should be made to the local Water
Authority before fitting any of these appliances. In the event of
difficulty please contact the manufacturer
1. MAINS COLD WATER INLET
Connection is made as shown in Figs 5 and 7.
Devices capable of preventing the flow of expansion water
should not be fitted unless separate arrangements for
expansion water are made_ The final600 mm (23.6 in.) of the
mains cold water connection to the appliance should be made
in copper only
2. HOT WATER SUPPLY AND FLOW REGULATION
The appliance 1s fitted w1th two water flow regulators
The
maximum flow of domestic hot water available through
the appliance is limited to 21 litres/min. (4.5 gal./ min.).
NOTE: The flow regulators contained within the flow regulator
housing are plastic. Do not heat the housing during soldering
operations on adjacent joints, e.g. remove and replace after
soldering
11 . ELECTRICAL
See Figs. 8, 9. 10 and 11
NOTE. Sw1tch off the mains supply before removing the control box
cover
ro gain access to the electrical terminal stnp:
(a) Remove the cabinet top panel by snatching squarely upwards
(b) Release the five pozi·drive screws securing the cover of the
electncal control box and remove.
ROOM AND FROST THERMOSTATS
If the room or frost thermostat 1s to be fitted, it should be w1red into
the appliance terminal strip
as shown in Fig. 8. One or both of the
blankmg plugs must be removed from the electncal cover and the
cable
passed through the hole. A Heyco cord strain rel!ef bush
(packed c,eparately with these mstructions) must be used to retain
the cables at
th1c, point. The cables should be routed neatly away
from hot sur!aces to a convenient ex1t pmnt from the cabinet.
MAINS WIRING
The
method of connectiOn to the appliance must facilitate the
complete !solation of the appl!ance, preferably via a 3 amp fused
thrce·pin plug
and unswitched shuttered socket outlet, both
complymg with the requirements of BS 1363. Alternatively con·
nection may be made via a double pole isolator with a contact
separation of 3 mm in all poles and supplying the boiler and
controls only
Mains Cable: 0.75
mm
2 (24 x
0.20 mm) to BS 6500 Table 16.
Temperature rated at 100°C.
Should the factory fitted mains cable need to be replaced then the
new cable must be connected into the terminals marked l, Nand
+at the left hand side of the appliance terminal strip. The cable
should then be passed through the cable clamp located in the left
hand side of the electrical cover and clipped to the two cable
retaining clipsfixed
to the left hand sidepanel.Care should be taken
that the cable is clipped neatly into place.
NOTE. Ensure that the earth wire is longer than the live and neutral
conductors so that they become taut before the earth
10
3. TAPSANDVALVES
Hot and cold taps and mixing valves used with this appliance
must be suitable for operating at mains pressure
4. SHOWERS (FIXED HEAD TYPE)
No anti·syphonage arrangements are necessary
5. SHOWERS (LOOSE OR FLEXIBLE HEAD TYPE)
If a loose head shower with flexible hose is to be used over a
bath, the hose must be fixed so that the head cannot fall closer
than 25 mm (1 in.) above the top edge of the bath in order
that the head is prevented from being immersed in bath water~
Alternatively the shower must incoprorate or be fitted with an
anti·syphonage device at the point of the flexible hose con·
nections.
6. BIDETS
The
supply of hot and cold mains water direct to a bidet is
permitted provided 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 necessary
7. USE IN HARD WATER AREAS
If the appliance is used in any area where the temporary
hardness exceeds 200 ppm a Worcester 'In·Line' scale
inhibitor(available from
Worcester Heat Systems Ltd.) must be
fitted into the cold supply to the appliance
Installation
should be strictly in accordance with the require·
ments of the local Water Authority. An isolating valve to
facilitate serv1cing may be incorporated.
The external wiring between the appliance and the electrical supply
shall comply with current lEE Wiring Regulations, and any local
regulations which apply. The
appliance must be earthed.
SAFETY CHECK
In the event of an electrical fault after installation of the appliance,
preliminary electrical
system checks shall be carried out (i.e. earth
continuity, polarity and resistance to earth, etc.), as described in the
British Gas Multimeter Handbook.
Fig. 9. Room thermostat
and frost thermostat connections.
ROOM THERMOSTAT CONNECTIONS
REMOVE UNK -c
ri,J
t
HONEYWELL ROOM
THERMOSTAT 6160
OR SIMILAR.
FROST THERMOSTAT CONNECTIONS
A SUIT ABLE 2-POLE
FROST THERMOSTAT
I
I I
240V-.. 50Hz
BOILER MAINS
SUPPLY

Fig. 10. Functional flow diagram-Hot water mode.
SUPPLY l
240V~
50 Hz
FUSE
be
3A
DHW HIGH LIMIT
THERMOSTAT
-- -----
OPERATING SWITCH
'
'
'
114 : hi
TL
1
be
m
ROOM THERMOSTAT
hi
~
PUMP DELAY TIMER BOARD
hi
I eLu
'
'"
CENTRAL HEATING PUMP
IL,
-·
T10
e be
bl
hi
7J
be
m '
r---
-----------------------
'
I
e
L_-
'
w
\\ ~!
'
T2
gTJ
m ' g .
J'
T12 : W
w :
~
e
pk
. -~
•
l
DOMESTIC HOT WATER
CONTROL THERMOSTAT
----------
PROGRAMMER IIF FITTED)
'
T9
I
~
f-.
::.(9=~
DOMESTIC HOT WATER
pk HIGH LIMIT THERMOSTAT
T4
lbk T5
bt
......
T7
g
be
bl
v~
I
f,A\ IOLfNOIO CENTRAL H[ATI~G
bl
I ~J\!V
bl
CONTROL RELAY
I I
1\IJPO~[S\OF~
r ,.
hv
T8
I9
~
bt I
V\
bl
,.
w I
~'''["TING '0•\L'o'[
p w
~
4l
10
I
J-
w
11
7 ..
lE~ T~AL H[ATING
~m
••
-(JNTR~II THfR~Q\TAT
T6
be
bl
N
N
N
N
N
N
N
.~ y ru: ~
hk
~12
8
Vv_.l
Tl~r
N
. ..::..
w
m:
'
be
e
------
- -- _j
COL OUR CODE
hi BLUE
bk BLACK
br BROWN
y YELLOW
pk
DOMESTIC HOT WATER PUMP
bt
pk PINK
or ORANGE
VIOLET
w WHITE
T13
""
I
pk
r RED
g y GREEN YELLOW
GREY
PURPlE
GAS SOIE~OID DOMES! C HU. w•HR
hi
bl
~
N
N
Fig. 11. Functional flow diagram-Central heating mode.
SUPPLY
240V- L
50 Hz
-
FUSE
bt
TL
3A
DHW HIGH LIMIT ~~
THERMOSTAT i
oPe-RATING sw,TcH --: I • I
bt
~-.t
T~ : bl
ROOM THERMOSTAT
~: br
r-----
w '
T2 +* lJ T3
g T\1 ' g - •
Ill
T12 ; W
~ Jj
'1:
rl"k
'
I
"'
- -----
___ _j
•
l
DOMESTIC HOT WATER
CONTROL THERMOSTAT
------ --
PROGRAMMER IIF FITTED I '
I I-f-
DOMESTIC HOT WATER
hi
PUMP DELAY TIMER BOARD
hi
., .
-~
~
• Ls
-·
CENTRAL HEATING PUMP
T '
T10
be
bl
m
bl
__________________________ .,....
g
T7
lu
bl
--~
~,A> \Cl!NOIC C!NlRAl H! 4TI~G
bl
~v"
l bl
CONTROL RELAY
louPPR!'i\00~
1 .. I.!.
se I
T8
bt bl
9
e-vv--e
, ..
UJ
DIVfRliNG;~·.y[
p w
6•
T9
10
.~J
w
3
..
i
~
~~
ck
HIGH LIMIT THERMOSTAT
11
J.
nm
CE~TR4lH!ATING
• .:-. g Tll:
. ..::...
w
T12 :
'
bt
i
-------
______ _)
'--
co
LOUR CODE
bl BlUE
bk BLACK
br BROWN v YELLOW
T4
lbk~
/
bk
pk
DOMESTIC HOT WATER PUMP
bt
pk PINK
or ORANGE.
VIOLET
w WHITE
be
~
12 8
lT!L, n~f
pk
r REO
g y GREEN·YELLOW
11
CIINTR-JllH!RMOSW
T6
"'
Vv
I
-.
I I
GAl S01 f~OI~ 00'.'(\TI( ><01 WAHR
GREY
PURPLE
bl
bl
bl
~
~
----
N
N
N
N
N
N
N
N
N
N

W
y
c=J( be
,----,
rr---]' ~
\'l__.
'~,_ -I I CE'IJTRAL HEATI'IIG
lco.r PUMP
~'
bl br 9Y
DOMESTIC HOT
WATER PUMP
14
13
L ___ _
SUPPLY L N
240V-
I
I
50 Hz
DHWHIGH
LIMIT
I THERMOSTAT
I@
I
I
I
I
I
I
I
be
I
I
I
I
I
I
gy
I
_L
EARTH
E
I Fllgnlll
~~~~~IX
I ~ NTRALHEATING
I PUMP DELAY co~~ROL THERMOSTAT
MESTIC HOT WATER TIMER BOARD
I ggNTROL THERMOSTAT
L_________
bk SLACK
V YElLOW
pk PI~K
or ORANGE
v VIOLET
w WHITE
g GREY
p PURPLE
PLUG~N
TERMINAL
STRIP
iii~JI=I
~~'
w~._;J~ '='
PROGRAMMER OPERAnNG
IALTERNATM TO
SW1TCifl

I
12. REMOVAL OF THE CABINET
See Fig_ 12
NOTE. It is necessary to remove the cabinet top panel, front
panel, left
and right hand side panels and lower grille to aid
installation
{a) Remove the appliance top panel by snatching squarely
upwards to release the clips.
(b) Remove thefront panel by pulling firmly at the base and lifting
upwards and outwards.
Fig. 1 2. Cabinet and control panelfixing screws.
(c) Undo the five pozi·drive screws holding the lower front grille
kick strip to the side panels and base frame.
(d) Remove the two thermostat knobs and release the three pozi·
drive screws securing the control box and facia panel to the
sidepanels. Lift the controlbox and facia and rest the assembly
on top of the boiler. Take care not to stretch any electrical
cables or thermostat capillaries.
(e) Remove the three screws remaining at the top of each of the
panels one in the left hand and two in the right hand panel.
Draw
the side panels slightly forward and release them from
the securing lugs in the base plate. Disengage the wiring from
the left hand panel location clip.
S1de panel bracket ---------.,----T,
Control box cover panel
I I I
I 0 0
' ' '
' ' '
t t
'--- - ~'<,;;::::::±::!::::.
I
I
Lett hand s1de panel -- +---
I
L __ _
Control box and fac1a -------
r---
1
I
I
I
I
I
I
I
I
Facia panel --_I_--
r---~--1------ Righthands1depanel
I I I
t I I
: I
I I
t :
I
t
' '
I I I 1
.. ___ .1_ __ ..1.. __ _,__
•
--- Facia rear cover
----Temperature controls
mounting bracket
: • • I
I : : : ~
L _ __._ ______ _,__- ---- _._ _ _.__-- --
Lower front panel
13. INSTALLATION
See Figs, 2, 3, and 12.
NOTE: Refer to Section 4-Siting the Appliance, for space required
for installing
the appliance and for minimum clearances for
servicing
the appliance.
Aknock-out panel is provided in the cabinet top panel to facilitate
vertical pipe connections.
The following description covers
one method of installation. If
connections are made in a different way then the space required for
installation
may be greater.
Compression fittings may be used on all water connections to
facilitate easier installation and servicing of the appliance.
It 1s most important that the pipework is routed so as not to
obstruct access to the circulating pumps, diverting valve or heat
exchanger {heat bank).
1. Check
that the proposed position of the boiler is firm and level.
No special floor protection is required. Do not place the boiler
in
its final position at this stage.
2. Remove the cabinet top, front, lower grille, left hand and right
hand side panels_ See Section 12
13
NOTE: Rest the control box and facia assembly at the top right
hand side of the boiler.
3. Remove
the cabinet left hand side panel support strap by
removing the two rearMS screwssecuringit to the boilerinner
casing.
4. Make
the gas connection to the end of the gas supply pipe at
the right hand side of the appliance.
5.
Fit a 22 mmelbowtotheprimaryfeed pipe sothatitsoutlet will
face upwards through the cabinet top panel cut-out.
6.
Fit a 15 mm elbow to the domestic cold water inlet manifold
and a 22 mm elbowto the domestic hot water outlet manifold.
The outlets may face upwards through the cabinet top panel
cut-out or
towards the left hand side of the appliance.
7.
Fit a 28 mm x 28 mm compression fitting elbow to the central
heating flow and return pipes. The outlets may face upwards
through the cabinet top panel cut-out or towards the left hand
side of the appliance.
8. Sealed Systems Only
Fit a 22 mm copper pipe to the outlet of the tundish pipe to
lead any possible discharge from the safety valve away
from the boiler.
(On open vent systems the safety valve may be removed
and the connection capped. Take care not to damage the
p1pe).

The d1scharge pipe from the tund1sh must be continued in 22
mm copper p1pe, and laid to a continuous fall to avoid the
retention of any discharge water within the pipework. A fall in
excess of 1 in 200 will be satisfactory.
The pipework should have a resistance to flow of water not
greater than that of a straight pipe 9 metres long.
The termination of the discharge pipe must be visible, but in a
localion
not readily accessible to persons.
Discharges at low level are acceptable provicUng that a wire
cage or similar is positioned to prevent contact, while
maintaining visibility.
9. Move the appliance mto its correct position with the rear of the
appliance base plate parallel with the wall or skirtmg board.
10. Connect the gas pipe to the gas inlet on the appliance at the
left hand side. The connection must be close to the side of the
appliance
14. COMMISSIONING THE
APPLIANCE
After the appliance has been finally connected and the heating
system nushed out (See Section 1. Paragraph 4-Installation
Warnmg), check that the electricity supply is off, the gas service
cock is o!f. the appliance thermostat control knobs are turned to
maximum and the system controls are calling for heat
1. Open all radiators and lockshield valves and fill the system
Vent as necessary. See Section 9, Paragraph 4. Checkfor water
soundness
2. Sw1tch the electrical supply on at the mains socket.
NOTE: Immediately mains electncity is applied to the boiler
the pump delay timer is energised causmg the central heating
pump to run for about 5 minutes. This occurs whether or not
the controls are calling _for heat. The pump will subsequently
only run m the course of the normal operation of the boiler
3. Position the Operatmg Switch to HEATING & WATER If a
programmer is fitted, switch to the ON programme. Leave
the system to work 1n a cold stdlc for about 20 minutes,
venting dS necessury. Position the Operatmg Switch or
programmer to OFF
4. Turn the gas on at the gas service cock
5. Push hard on the grey gas valve button and keep it pressed m
At the 'iame time, separately push in the red 1gniter button.
When 1t clicks. the pilot(seen through the observation window}
should light. If the pilot does not light immediately, press the
1gniter button repeatedly until1t does. When the pilot lights,
contmue to hold the gas valve button in for a further 15
seconds. then release it slowly
NOTE. If the pilot does not stay ul1ght.. twist the gas valve
button m the direction of the arrow. Wait for three minutes and
repeat operation 5 until the pilot IS lit. Continue to hold the gas
valve button in for a longer period, then release it slowly. Check
the pilot flame length is as mdicated in Fig. 19. If 1t is not, then
adjust the pilot throttle. clockw1se to reduce the size or anti-
clockWISP to increase the s1ze of t.he pilot flame. See Fig. 13
NOTE:l he m1mmum recommended thermocouple output is
SmV closed c1rcuit
6. Loosen the burner pressure test point screw one turn and
connect a pressure gauge See F1g. 13.
7. Position the Operating Switch to HEATING & WATER or, if a
programmer is fitted, switch to ON programme. Check the
main burner 1gnites smoothly.
8. lest for gas soundness around the boiler gas components
us1ng leak detect1on fluid. Refer to Section 16, Paragraph 7c
for details of the method of checking the burner manifold
joint for gas soundness_
lUrn off the boiler and replace the boiler inner casing cover
immediately after checking the gas soundness. Check the main
burner through the observation window.
14
11. Check the gas pipework up to the appliance gas service cock
for gas soundness in accordance with BS6891.
1 2. Connect the water system pipes at the rear of the appliance.
13. Thoroughly flush the whole of the water system with cold
water. Fill the system, vent the boiler and check for water
soundness.
14. Connect the first section of the flue to the socket on top of the
boiler. See Section 5 - Flue. Properly seal the flue pipe into the
socket. Complete the installation of the flue. DO NOT OPERATE
THE APPLIANCE WITHOUT THE FLUE FULLY CONNECTED.
15. Connect the mains lead as described in Section 11 -Electrical.
For
frost and room thermostat connections refer also to
Section 11.
1 6. Reassemble the appliance leaving off the cabinet front panel
until the commissioning has taken place. See Section 14. Push
the wiring back into the locating clip on the left-hand side
panel.
~.E T PRE,,cql
"FS"Ptl•'l
l.WV l.lCTRICAI
Si.•PPL Y PI II~
TO IOIGH;LOW
~UIHvlliD
A Ar.- HJ',lMf~·l S·:,Rf>N f[JR [lfJMf <;TIC 11:1 I WAIT II
I•IIGII• GAS i'fl( SSURl S( liiNb
8 ACJUSTMf~ T SCREW fOR Hf A'l~f, 11 [J'/ill,AS
PRfSSIIRf
\FTIII<~
l PlASII[lAf'
> (l THRJT':E
"'
Check the burner setting pressures. See Section 2- Technical
Data
ADJUSTING DHW (HIGH) GAS PRESSURE
Refer to Fig. 13
(a) Allow the boiler to fire for at least 10 minutes before making
any adjustments.
(b) Turn the DHW thermostat to maximum. Turn the HEATING
thermostat OFF
(c) If DHW service gas pressure needs adjustment refer to
TECHNICAL DATA. Using a 10mm bladE width screwdriver, turn
the screw 'A' clockwise to increase and counter-clockwise to
decrease pressure until the des1red setting is achieved.
(d) Check several times if main burner ignites smoothly, by
operating the OHW thermostat, before proceedmg to check the
HEATING (LOW) gas pressure.
ADJUSTMENT OF HEATING (LOW) GAS PRESSURE Refer to Fig.13
(e) Turn the DHW thermostat to OFF. Set the HEATING thermostat
to maximum
(f) If the HEATING gas pressure requm:~s adjustment refer to
TECHNICAL DATA
(g) Using a small screwdriver turn the screw 'B' clockwise to
increase and counter-clockwise to decrease pressure until the
desired settmg IS achieved
(h) Operate the HEATING thermostat several times to ensure the
main burner ignites smoothly before checking that gas valve
switches from HIGH to LOW correctly.

(i) Using the DHW and HEATING control thermostats switch the
boiler
from HIGH to LOW and back several times to ensure
correct gas pressures.
Replace the plastic cap 'C'.
9. Position the Operating Switch to OFF, or, if a programmer is
fitted, set select button toOFF. Disconnect the pressure gauge
and retighten thetest point
screw. Test for gas soundnessaround
screw.
1
0. Check the operation of the flame failure device to ensure that
it will shut off the gas to the main burnerwithin 60 seconds. To
do this, switch off the electricity supply at the mains and turn
off the gas supply at the gas cock. After 60 seconds, check for
the correct operation of the flame failure device by turning the
gas back on atthe gas cock and attempting to re-light the pilot
without depressing the gas valve button.
If the pilot can be lit
in this way, turn off thegas supply and contactWorcester Heat
Systems
Ltd. Service Dept.
11 . Position the Operating Switch to HEATING & WATER or, if a
programmer
is fitted, set select button to OFF. Re-light the
appliance and allow it to operate, venting as necessary.
NOTE: It will take about 15 minutes for the heat bank to be
satisfied before the central heating system
will receive heat.
Check for water soundness.
Important:
The complete appliance must be checked for water
leaks. Should any leaks be found they must be rectified before
proceeding further. Check
for spillage from the down draught
diverter outlet at the right hand side
of the appliance. Refer to
BS 5440, Part 2, 1978.
12. Position the Operating Switch to
OFF, or, if a programmer is
fitted, set select button to OFF. Switch the electrical supply off
at mains. Turn the pilot gas off at the gas valve as described
in paragraph 5. While the water is still hot, drain the water at
the drain points on the appliance and
in the system.
13.
Refill the appliance and system (see Instruction 1) and repeat
Instructions 2 and
3.
14. Light the pilot (see Instruction 5) and repeat Instruction 7.
15. Check for correct operation of the user controls including the
room thermostat
(if fitted) and leave set to the customers
requirements.
16.
Refit the cabinet front panel.
15. USERS INSTRUCTIONS
Hand the Users Operating Instructions to the user or purchaser for
retention and instruct in the efficient and safe operation of the
appliance and the heating and hot water system.
Advise the user or purchaser
of the precautions necessary to pre-
vent damage to the heating and hot water system and to the
building
in the event of the heating system remaining inoperative
during frost conditions.
Inform the user
of the system pressure on a sealed system instal-
lation and advise them not to operate the unit if a significant drop
in pressure is observed on the pressure gauge indicating a loss of
water from the system.
Finally advise theuser or purchaser
that for continuedefficient and
safe operation
of the appliance it is important that adequate
servicing
is carried outat intervals recommended by the Local Gas
Region_
Worcester Heat Systems Limited will be pleased to discuss and
offer a comprehensive maintenance contract.
Set the system controls to the users requirements.
15
16. ROUTINE CLEANING AND
INSPECTION
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 installa-
tion conditions and usage, but in general,once peryearshould be
adequate.
It is the law that any service work must be carried out
by a
competent person such as British Gas or other Corgi
registered personnel.
1. The following should
be carried out at periods not
exceeding one year.
(a) Carry out a pre-service check noting any operational faults.
(b) Clean the burner.
(c) Clean the burner and pilot injectors.
(d) Inspect the heat exchanger and clean if necessary.
(e) Check the condition of the spark electrode and thermocouple.
(f) Check the condition of the combustion chamber insulation.
(g) Check that the flue terminal is unobstructed and that the flue
system, including the flue canopy assembly, is sealed cor-
rectly.
(h) If the appliance has been installed in a compartment check
that the ventilation areas are clear.
(i) Check that the pipe connections throughout the system
remain capable
of sustaining apressure of up to 3bar. Remake
or replace any fittings which show evidence
of water leakage.
SOME OF THE SERVICING POINTS ARE COVERED MORE FULLY IN
THE FOLLOWING INSTRUCTIONS.
2. PRE-SERVICE CHECK
(a) Remove the cabinet front and top panels as described in
Section 12, paragraphs (a) and (b).
(b) Operate the appliance and system, noting any faults which
may need to be corrected during the service.
WARNING: Disconnect the electrical supply at the mains
before commencing any servicing.
Turn off the gas at the gas
service cock. After completing any service work always test for
gas soundness and check the function of the controls.
Fig. 14.
Flue hood 'J' bolt fixings

3. REMOVE THE BOILER INNER COVER, FLUE HOOD,
COMBUSTION CHAMBER FRONT PLATE, BURNER
AND PILOT ASSEMBLY
(a) Remove the boiler inner casing cover
(See Fig. 23.)
Remove
the six MS screws and washers holding the inner
cover onto the boiler casing. Remove the inner cover.
(b) Remove the flue hood
(See Fig. 14.)
Slacken the wing nuts securing the 'j' bolts until the 'j' sections
can be manipulated to pass upwards through their location
brackets.
Lift the flue hood clear of the heat exchanger and remove from
the casing. Gently prise upwards at the front sides to disengage
if necessary. Take care not to disturb the overheat thermostat
connections.
(c) Remove the combustion chamber front plate
Remove by releasing the six MS fixing screws.
(d) Remove the burner and pilot assembly
(See Fig. 17 .)
Disconnect the thermocouple nut at the pilot burner assembly
and ease the thermocouple from the assembly.
Carefully pull
the electrode lead off the connector tab at the
electrode.
Disconnect
the pilot tube within the combustion chamber at
the adaptor.
Release the two extended MS screws securing the burner
manifold block at the front.
Carefully remove
the burner and pilot assembly.
NOTE: The '0' ring in the burner manifold block which seals
with
the gas manifold flange should be removed and retained
for reassembly.
4. CLEANING THE BURNER ASSEMBLY
(See Fig. 17 .)
(a) Disconnect the pilot pipefrom the pilot burner and remove the
pilot injector which fits loosely between the pipe and burner.
(b) Release the screw and carefully dismantle the lint arrester
assembly, see Section 17-Instructions 2 and Figs. 15 and 16.
(c) Carefully remove the main injector from the burner and check
that there is no blockage or damage.
(d) Brush the burner blades and check that the flame ports are
clear.
Do not use a brush with metallic bristles.
Fig. 15.
Lint arrester assembly
Main burner injector
16
Fig. 16. Lint arrestor assembly
(e) Inspect the pilot burner and ignition electrode. Ensure that
they are clean and in good condition. Check that the spark gap
is 3-4mm (0.14 in.). See Fig. 19.
(f) Check that the thermocouple tip is not burned or cracked. If it
shows any sign of damage a new thermocouple must be fitted.
(g) Clean the lint arrester gauze to remove any lint or fluff. Do not
use a brush with metallic bristles.
(h) Reassemble the burner components in the reverse order, not
forgetting the pilot and main burner injectors. Thread sealing
compound must not be used to seal the injectors. Do not fully
tighten
the pilot pipe at this stage.
5. CLEANING THE HEAT EXCHANGER
(See Fig. 26.)
(a) Cover the pilot gas inlet adaptor and the main gas inlet within
the combustion chamber.
(b) Using a suitable brush, clean the inside surface of the heat
exchanger and the fins.
(c) Clean the flue duct.
(d) Remove any deposits which fall to the bottom of the boiler
casing.
(e) Check the condition of the rear, sides and front combustion
chamber insulation.
NOTE: The insulation used on the inside surfaces of the
combustion chamber is delicate. Take great care not to abrade
this insulation when cleaning the heat exchanger. Do not
attempt to clean the insulation which should be replaced if
there are any signs ofdeterioration. See Section 17-Replace-
ment of Parts, Instruction 9.
6. RE-ASSEMBLE THE APPLIANCE
Re-assemble the appliance in the reverse order to the dis-
mantling procedure.
(a) Replace the flue hood on to the heat exchanger ensuring that
the hood is properly located on the heat exchanger.
(b) Locate the 'J' bolts in the side brackets, ensuring that they are
hooked into the bracket, and hand tighten. Do not over
tighten.
(c) Inspect the '0' ring seal. Replace the seal if there are any signs
of deterioration.
(d) Refit the '0' ring into the burner foot. Replace the burner and
pilot assembly and fit the burner location bracket into the
bracket in the combustion chamger.
(e) Secure the burner manifold with the extended MS screws.
(f) Connect and tighten the pilot feed pipe at the adaptor. Fully
tighten the connection at the pilot assembly.
(g) Reconnect the thermocouple.

(h) Reconnect the piezo igniter lead to the electrode.
(i) Check that all joints are tisht.
(j) Replace the combustion chamber front plate.
(k) Brush any dust or deposits from the gas control and associated
pipework.
(I) Reassemble the cabinet in the reverse order to its removal. Do
not fit the boiler inner casing cover, facia or the cabinet front
panel
at this stage.
7. TEST THE APPLIANCE AND INSTALLATION
(a) Turn on the gas at the gas service cock and reconnect the
electrical supply.
(b) Refer to the lighting instructions on the appliance front panel.
(c) Carefully light the boiler and check for gas soundness (includ·
ing the burner manifold connectiorr within the combusion
chamber) in accordance with BS 6891. It is necessary to
operate the boilerfor a short period with the boiler innercover
casing removed.
The action must be undertaken with great
care. Turn off the boiler and replace the boiler inner casing
cover immediately after checking the gas soundness. Check
the main burner through the observation window.
(d) With the centralheating off, check that the domestic hot water
operates correctly. When the priority thermostat is satisfied,
switch the central heating on and check that the water
diverting valve operates and supplies hot water to the central
heating circuit.
(e) Set the Operating Switch (or programmer) to OFF.
(f)
Loosen the burner pressure test point one turn and connect
a pressure gauge. See Fig. 24. Set the Operating Switch to
WATER & HEATING (or programmer to HW-24 hrs, CH-24
hrs). Set the Hot Water Temperature Control Knob to off and
the Central Heating Temperature Control Knob to maximum.
If necessary, adjust the gas pressure at the governor on the
gas valve. See Section 14-Commissioning the Appliance.
(g) Set the Operating Switch to WATER (or programmer to
HW -ON). Set the Central Heating Temperature Control
Knob to off and the Hot Water Temperature Control Knob to
maximum. Check the burner pressure. See Technical Data,
Table 1. Should
the pressure require adjustment, contact
Worcester Heat Systems Service Dept.
(h) Set the controls to OFF. Disconnect the pressure gauge and
retighten the test point screw. Relight and test for gas
soundness around the test point screw.
(i)
Before leaving the site the service engineer should check that
no flammable material is left inside the appliance casing and
that the ventilation requirements remain at the required
17
Thermocouple Burner fixing screws (2 off)
standard. See Section 7.
(j) If the appliance is fitted in a cupboard check that the cupboard
ventilation remains adequate. See Section 6
(k) Refit the facia, cabinet front panel and top panel.

17. REPLACEMENT OF PARTS
WARNING: Disconnect the electrical supply at the mains and turn
off the gas service cock before commencing any further work.
After
replacement of components, check for gas soundness and
carry out the functional checks as described in Section 14-Com-
missioning the Appliance.
COMPONENT ACCESS
To replace appliance parts it is necessary to remove one or more
sections of the cabinet and cover plates within the appliance as
described below_
(a) Cabinet Top Panel
Snatch squarely upwards to release the clips.
(b) Cabinet Front Panel
Pull firmly at the base to release the clips and lift upwards and
out
(c) Facia Panel
Remove the six pozi-drive screws and the plug-in terminalstrip
connection. See
Fig. 12. Remove the remaining screw in the
right hand side panel to allow the removal of the facia.
(d) Control Box and Facia
Remove
the cabinet top and front panels. Release the three
pozi-drive screws and rest the assembly on the appliance. See
Fig. 12. Release the remaining screw in the right hand side
panel to allow the removal of the control box and facia.
(e) Boiler Inner Casing Cover
Remove the six slotted hexagon head screws and washers. See
Fig. 23.
(f) Combustion Chamber Panel
Remove the six slotted hexagon head screws.
(g) Cabinet Lower Front Panel
Remove the five pozi-drive screws securing the panel. See
Fig. 12.
(h) Control Box Cover
Remove the five pozi-drive screws. See Fig. 12.
(i) Control Box
Remove
the facia panel. Remove the single pozi-drive screw in
the top of the left hand side panel. See Fig. 12. Support the box
so that undue strain is not placed upon the electrical cable and
thermostat capillaries.
(j) Left Hand and Right Hand Cabinet Side Panels
Remove the cabinet top, front and lower front panels and the
control box and facia. Remove the three screws remaining at
the top of each of the panels, one in the left hand and two in the
right hand panel. See Fig. 12. Draw the panels slightly forward
to release them from the securing lugs in the b_ase plate and lift
away from the appliance.
COMPONENT LOCATION
The following components can be replaced if the cabinet top panel,
cabinet front panel, inner casing and combustion chamber cover
are removed. See 17(a), (b), (e) and (f) preceding.
1: Main Burner
2: Main Burner Injector
3: Lint Arrestor Assembly
4: Pilot Injector
5: Spark Electrode
6: Pilot Shield
7: Pilot Burner
8: Thermocouple
9: Electrode Lead
1 0: Combustion Chamber Insulation.
The following
components can be replaced if the cabinet front panel
is removed. See 17(b) preceding.
11 : Piezo Generator
1
2: Pressure Gauge
18
The following components can be replaced if the cabinet front
panel, lower front
panel and the inner casing are removed. See
17(b),
(e) and (g) preceding.
Check that the electrical supply and the gas service cock are shut
off.
1 3: Domestic Hot Water Pump
14: Gas Valve
1 5: Pilot Filter
16: Sealed
System Expansion Vessel.
The following components can be replaced if the cabinet top panel,
front
panel and inner casing are removed. See 17(a), (b) and (e)
preceding.
1
7: Overheat Thermostat
The following components can be replaced if the cabinet top panel,
cabinet front panel, facia and the control box cover are removed.
See 17(a), (b), (c) and (h) preceding.
Check that the electrical supply has been disconnected.
19: Domestic Hot Water High Limit Thermostat
20: Central Heating Control Thermostat
21: Domestic Hot Water Control Thermostat
22: Operating Switch
23: Control Relay
24:
Programmer (if fitted)
25:
Suppressor
26: Pump Delay Timer Board.
The following
components can be replaced if the cabinet top panel
is removed. See 17(a) preceding.
Check that the electrical supply has been disconnected.
27: Central Heating Pump
28: Flow Regulators
29: Safety Valve.
The following component can be replaced if the cabinet top panel,
cabinet frontpanel, control box cover, inner casing, control box and
facia and combustion chamber cover are removed. See 17(a), (b),
(d),
(e), (f) and (h) preceding.
Check that the electrical supply has been disconnected.
30: Diverting Valve.
The following component can be replaced if the cabinet top panel,
cabinet frontpanel, control box and facia are removed. See 17(a), (b)
and (d) preceding.
31:
Automatic Air Vent
The following components can be replaced if the cabinet top panel,
cabinet front panel, lower front panel, inner casing, combustion
chamber cover, control box and facia are removed. See 17(a), (b),
(d),
(e), (f) and (g) preceding.
32: Heat Bank
33: Heat Exchanger.
1. THE MAIN BURNER
Fig. 17.
(a) Disconnect the thermocouple nut at the pilot burner assembly
and ease it from the assembly.
(b) Carefully pull the electrode lead off the connector tab at the
electrode.
(c) Disconnect the pilot tube within the combustion chamber at
the adaptor.
(d) Release the two extended MS screws securing the burner
manifold block at the front of the chamber.
(e) Carefully remove the burner and pilot assembly from the
combustion chamber by lifting and pulling.
(f) Remove the pilot assembly by removing the two screws and
nuts. Remove the main injector.

(g) Reassemble in the reverse order. Ensure that the 0-ring is
located in the end of the burner manifold.
(h) Check the gas soundness of the connection between the
burner manifold and the gas line. See Section 16-Routine
Cleaning and Inspection.
2- THE MAIN BURNER INJECTOR
Fig. 18.
(a) Remove the burner. See Instruction 1 preceding.
(b) Remove the lint arrestor assembly.
(c) Remove the main injector from the burner.
(d) Fit the new main injector and re-assemble the main burner
assembly in the reverse order.
3. THE LINT ARRESTER ASSEMBLY
(a) Remove the main burner. See Instruction 1 preceding.
(b) Remove the MS screw securing the lint arrester assembly and
lift the rear frame away from the burner.
(c) Remove the clip beneath the arrester assembly and lift away
the side frames to left and right.
(d) Lift the front frame up and away from the burner mixing tube.
(e) Clean the gauze by shaking, washing in soapy water or brushing
with a non-metallic brush. Take care not to damage the gauze
or its assembly housing.
4. THE PILOT INJECTOR
Remove the main burner assembly. See Instruction 1
preceding.
(a) Disconnect the thermocouple nut at the pilot burner assembly
and ease it from the assembly.
(b) Disconnect the pilot pipe from the pilot burner. Slacken the
pilot tube conrjection at the adaptor within the combustion
chamber and move the pilot pipe away from the pilot
assembly.
(c) The pilot injector may now be removed. It may be necessary to
carefully ease the injector free.
(d) Fit a new pilot injector and reassemble in the reverse order.
5. THE SPARK ELECTRODE
Fig. 20.
Remove the main burner assembly. See Instruction 1
preceding.
(a) Release the hexagon nut securing the spark electrode to the
pilot assembly and remove.
(b) Fit a new spark electrode. Check that the spark gap is 3-4 mm
(0.14 in.). See Fig. 19.
6. THE PILOT SHIELD
Fig. 21.
Remove
the main burner assembly. See· Instruction 1
preceding.
(a) Remove the two M4 screws and nuts securing the pilot shield
to the pilot bracket.
(b) Fit a new pilot shield and reassemble in the reverse order.
7. THE PILOT BURNER
Fig. 20.
Remove the main burner assembly. See Instruction 1
preceding.
(a) Remove the spark electrode, pilot shield and injector as
previously described.
(b) Remove the remaining M4 screw from the pilot bracket and
remove the pilot burner.
(c) Fit a new pilot burner and reassemble in the reverse order.
Check that the pilot assembly is fitted above the mounting
bracket on the main burner.
8. THE THERMOCOUPLE
Fig. 17.
(a) Disconnect the thermocouple nut at the pilot bracket and ease
the thermocouple from the assembly.
19
Fig. 19. Pilot head/electrode position.
3 to 4 mm 10.1~- in.)
-~--
PILOT FLAME LENGTH
13 to 18 mm 10.5 in. to 0.75 in.)
(b) Release the thermocouple from its connection at the right
hand side of the gas valve.
(c) Remove the sealing cover and gasket from the boiler base by
releasing the MS screw.
(d) Remove the thermocouple from the boiler. To prevent the risk
of
damage, remove the electrode lead before removing the
thermocouple
(e) Reassemble in the reverse order using a. new thermocouple.
Avoid sharp bends in the thermocouple lead and ensure that
it follows the same route as the original. Check that the
thermocouple is seated correctly against the gasket where it
enters the burner compartment. Fit a new gasket if necessary.
9. THE ELECTRODE LEAD
Fig. 22.
(a) Carefully pull the lead off the connector tab at the electrode
and at the piezo unit.
(b) Remove the lead and fit a replacement.
1 o. THE COMBUSTION CHAMBER INSULATION
Fig. 17.
(a) Cover the burner and pilot with a clean cloth to prevent any
loose matter falling onto the assembly.
(b) Remove the flue hood as described in Section 16 (3b)-Routine
Cleaning and Inspection.

(c) Drain the boiler.
(d) Loosen, but do not completely remove, the two MS screws at
the top
of each side of the combustion chamber securing it to
the inner casing.
(e) Release the union connections at the heat exchanger and
carefully manoeuvre the heat exchanger out
of the inner
casing taking care not to mislay the fibre washers.
(f) Remove and discard the insulation and fit the replacement
pads.
Do not forget the pad fitted to the combustion chamber
front cover.
(g) Refit the heat exchanger ensuring that it is correctly
positioned.
Do not forget the union washers.
NOTE. Do not forget to remove the cloth from the burner and
pilot assembly.
(h) Refit the combustion chamber cover.
(i) Tighten the combustion chamber fixing screws.
(j) Reassemblethe appliance in the reverse orderchecking that all
the components have been fitted correctly.
11. THE PIEZO GENERATOR
Fig. 22.
(a) Carefully pull the lead off the connector tab at the piezo
generator
(b) Remove the two MS fixing screws and remove the piezo
generator
(c) Fit a new generator and reassemble in the reverse order checking
that the overheat thermostat leads are not trapped by the
generator bracket.
12. THE PRESSURE GAUGE
Fig. 30.
(a) Isolate the boiler and drain off the central heating and
domestic hot water systems.
(b) Unscrew the pressure gauge from the heat bank.
(c) Fit a new pressure gauge.
(d) Open all the radiator valves and refill the system, venting as
necessary.
The appliance is fitted with an automaticair vent on
the heat bank.
20
1 3. DOMESTIC HOT WATER PUMP
Fig. 30.
Check that the electrical supply has been disconnected.
(a) Turn off the isolating valves mounted on the inlet and outlet of
the pump.
(b) Undo the two union nuts and remove the pump. Discard the
sealing washers.
(c) Support the pump and remove the two screws holding the
electrical cover onto the pump and disconnect the electrical
leads. Note the wire positions.
(d) Fit the replacement circulating pump using new sealing
washers.
NOTE. The direction flow indicator on the pump should point
upwards towards the top
of the appliance. The replacement
pumpshould be setatmaximumiffitteci with a speed adjuster.