Bosch Appliances 24I RSF Boiler User Manual

Bosch Group
24i RSF
WALL MOUNTED COMBINATION BOILER FOR CENTRAL HEATING
AND MAINS FED DOMESTIC HOT WATER
INSTALLATION AND
SERVICING INSTRUCTIONS
GC NUMBERS
N.G. 47 311 37 L.P.G. 47 311 38
BOILER OUTPUT
To Domestic Hot Water – Modulated Control
Minimum 7.5 kW (25,600 Btu/h)
Maximum 23.4 kW (80,000 Btu/h)
To Central Heating – Modulated Control\
Auto Range Rated
Minimum 7.5 kW (25,600 Btu/h)
Maximum 23.4 kW (80,000 Btu/h)
THESE INSTRUCTIONS APPLY IN THE UK ONLY
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER
This appliance must be installed by a competent person in accordance
with the Gas Safety (Installation and Use) Regulations 1994
Contents
1. Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
2. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
3. Data Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
4. Siting the Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5
5. Siting the Flue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6
6. Air Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6
7. Sealed System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 7
8. Open Vent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 7
9. Hot Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 8
.........................................................
10. Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 9
11. Installing the Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 11
12. Commissioning the Appliance . . . . . . . . . . . . . . . . . . . . Page 16
13. Instructions to the User . . . . . . . . . . . . . . . . . . . . . . . . . . Page 18
14. Inspection and Service. . . . . . . . . . . . . . . . . . . . . . . . . . . Page 18
15. Replacement of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 20
16. Conversion Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . Page 23
17. Operational Flow Diagrams. . . . . . . . . . . . . . . . . . . . . . . Page 24
18. Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 26
19. Component Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 34
1. Installation Regulations
2. General Information
1.1 Gas Safety (Installation and Use) Regulations, October 1994
all gas appliances must be installed by a competent person in
accordance with the above regulations. Failure to install
appliances 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 British Standard does not, of itself,
confer immunity from legal obligations. In particular the
installation of this appliance must be in accordance with the
relevant requirements of the following;
Gas Safety (Installation and Use) Regulations 1994 as amended.
Current IEE Wiring Regulations BS 7671.
Local Building Regulations.
Building Standards (Scotland)(Consolidation).
Bylaws of the local Water Company.
Health and Safety Document No. 635 (Electricity at Work
Regulations).
The British Gas Material and Installation Specification for central
heating and hot water
It should be in accordance with the relevant recommendations of
the following British Standards.
BS6798:1987 Specification for installation of gas fired hot water
boilers of rated input not exceeding 60 kW.
BS5449:1990 Central Heating for Domestic Premises.
BS5546:1990 Installation of gas hot water supplies for domestic
purposes.
BS5440:1:1990 Flues and Ventilation for gas appliances of rated
input not exceeding 60 kW: Flues.
BS5440:2:1989 Flues and Ventilation for gas appliances of rated
input not exceeding 60kW: Air Supply.
BS6891:1988 Installation of low pressure gas pipework
installations up to 28mm (R1).
BS7593:1993 Central Heating system cleansing and flushing.
BS5482:PART 1 Domestic Butane and Propane gas burning
installations in permanent dwellings.
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 to those mentioned
in the instructions.
1.5 The appliance complies with the Essential Requirements of
the Gas Appliance Directive and other Directives currently
applicable.
1.6 This appliance contains no asbestos products.
There is no potential hazard due to the appliance being
electrically unsafe.
There are no substances used that are a potential hazard in
relation to the COSHH Regulations 1988.
1.7 The advice and instructions given in this document covers, as
far as possible, the foreseeable situations which may arise. Contact
Worcester Heat Systems Technical Helpline for advice on specific
installations.
2.1 This appliance is not suitable for external installation.
2.2 The appliance controls are set to provide a maximum output
of 23.4 kW for the domestic hot water and central heating load.
2.3 The control circuit provides direct burner ignition. A pilot is
not used.
2.4 PRINCIPAL APPLIANCE COMPONENTS.
See Fig. 1.
A low thermal capacity Gas to Water heat exchanger
incorporating an integral Hot Water heat exchanger to provide
domestic hot water.
Fully modulating controls in the central heating and domestic
hot water modes of operation.
An expansion vessel, pressure gauge and pressure relief valve.
A fixed by-pass for the central heating system.
A Temperature safety cut-out control.
A water flow regulator.
A standard telescopic horizontal flue assembly giving flue
lengths from 127mm to 350mm.
Optional extra extension flue kits to provide for flue lengths up to
2500mm.
An optional vertical flue kit to provide for flue lengths up to
3000mm including vertical flue terminal.
Optional facia mounted mechanical programmer.
Fig. 1. Water flow diagram.
Bi-thermal
gas to water
heat
exchanger
Automatic
air vent
Sealed
system
expansion
vessel
Domestic
water flow
switch
Circulating
pump
Pressure
relief valve
Fixed
by-pass
Safety
discharge
2
Domestic
hot water
out
Domestic C.H.
C.H.
cold
flow
return
supply
2.5 ELECTRICAL SUPPLY
Mains supply: 230V ~, 50 Hz, 180 watts.
External fuse: 3A., Internal fuses: 2AT HRC(F1), and 1 AF (F2).
2.6 GAS SUPPLY
The boiler requires 2.76 m3/h (97.5 ft3/hr) of natural gas with a
calorific value of 37.78 MJ/m3 (1014 Btu/ft3) or 1.07 m3/h (37.8
ft3/hr) of propane with a calorific value of 95.65 MJ/m3 (2568
Btu/ft3). The meter governor should deliver a dynamic pressure
of 20 mbar (8in w.g.) at the appliance, equivalent to a pressure of
about 19-19.5 mbar at the gas valve on natural gas or 37.0 mbar
(14.8in w.g.) at the appliance for propane.
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 complete installation, including the gas meter, must be
tested for soundness and purged. Refer to BS 6891.
Gas
Discharge
Rate
Gas Discharge
Rate 3
(m /hr)
(m3/hr)
Total length of gas supply pipe
(metres)
3
6
9
12
Propane
1.5
–
–
–
8.0
5.2
4.2
3.6
15.9
8.8
8.5
7.2
Natural Gas
8.7
5.8
4.6
–
18.0
12.0
9.4
–
2.11 SYSTEM NOTES
IMPORTANT
Check that no dirt is left in either the gas or water pipework as
this could cause damage to the appliance. The heating system
should be flushed and treated in accordance with the
recommendations of BS 7593:1992. Thoroughly flush cold water
mains supply and 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 up to 3 bar.
Radiator valves must conform to the requirements of BS
2767:1991.
The relief valve discharge must be directed away from any
electrical 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, section 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 mains pressure.
Thermostatically controlled shower valves will guard against the
flow of water at too high a temperature.
Hot and cold mains fed water can be supplied direct to an overrim 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
simultaneously 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 to
individual outlets.
2.13 SAFETY CONSIDERATIONS
The appliance must not be operated in a waterless condition.
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 unobstructed and the correct
size.
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 of the delivered water.
When hot water is no longer required, the burner will extinguish.
The fan and pump may 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 a
controlled temperature rise. When the required heating
temperature is achieved 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 7.5 kW. If
the system no longer requires even the minimum output to
maintain the desired room temperature the burner will
extinguish. The fan and pump may continue to run to dissipate
the residual heat from the appliance. The appliance will remain
off for a fixed period 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
appliance will return to the central heating state and its normal
mode of operation. The fan may continue to run to dissipate the
residual heat from the appliance as necessary.
2.15 DOMESTIC SUPPLY
Devices capable of preventing the flow of expansion water must
not be fitted unless separate arrangements have been made.
Pipe size
(Ømm)
15
22
28
22
28
Note: Each fitting used in the gas line from the meter is
equivalent to a length of straight pipe which must be added to
the straight pipe length to give the total length.
i.e.: Bend = 0.5 metres, Tee = 0.5 metres, 90° Bend = 0.3
metres.
2.7 PACKING
The appliance and flue components are packaged separately.
2.8 GENERAL INSTALLATION
The appliance is for connection to a sealed system only.
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 7.
Do not place anything on top of the appliance.
The clearances specified for servicing must be maintained.
2.9 FLUE
The appliance has a multi-directional fanned flue system.
The standard telescopic flue assembly length is from 127mm to
350mm.
Extension flue lengths available are from 350mm to 2500mm.
An optional vertical flue kit to provide for flue lengths up to
3000mm including vertical flue terminal.
A terminal guard, Type K2, GC 393 553, 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.
A kit for internal fixing of the flue is available separately.
2.10 CONTROLS
The electronic control system and gas valve modulate the heat
input in response to the domestic hot water temperature and
central heating setting between minimum and maximum.
The Central Heating Temperature control knob provides for the
selection of domestic hot water only (Turned fully anti-clockwise)
or central heating and domestic hot water (Turned clockwise).
A facia mounted programmer is available as an optional extra. A
remote mounted programmer may be connected to 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 inner casing cover.
3. Data Tables
Table 1
kW
Btu/h
7.5
23.4
(25,600)
(80,000)
NOMINAL BOILER RATINGS
BURNER SETTING
INPUT (Net).
PRESSURE
kW
Btu/h
m bar.
in. wg.
NATURAL GAS
9.60
(32,750)
1.0
0.4
26.05
(88,890)
13.6
5.4
7.5
23.4
(25,600)
(80,000)
9.60
26.05
OUTPUT
GAS RATE
3
m /h
ft3/h
1.01
2.76
35.7
97.5
0.39
1.07
13.9
37.8
PROPANE
(32,750)
(88,890)
3.5
35.0
1.4
14.0
Table 2.
FLUE DETAILS
HORIZONTAL FLUE (Side or Rear)
FLUE DIAMETER
WALL HOLE DIAMETER
WALL HOLE DIAMETER (using internal flue fitting kit)
STANDARD FLUE – MINIMUM LENGTH
STANDARD FLUE – MAXIMUM LENGTH
EXTENDED FLUE – MAXIMUM LENGTH
mm
100
110
150
127
350
2500
inches
3.9
4.25
5.9
5.0
14.0
98.4
Table 3
AVAILABLE PUMP HEAD
BOILER OUTPUT
kW
7.5
23.4
Btu/h
(25,600)
(80,000)
HEAD
Metres
6.0
2.6
MIN. FLOW RATE
Feet
19.7
8.5
L/min.
9.8
30.5
Gal/Min.
2.2
6.7
TEMPERATURE RISE
ACROSS HEATING
FLOW AND RETURN
11°C (20°F)
Table 4
SPECIFICATIONS
CENTRAL HEATING FLOW FITTING
CENTRAL HEATING RETURN FITTING
COLD WATER MAINS INLET FITTING
DOMESTIC HOT WATER OUTLET FITTING
GAS INLET FITTING
PRESSURE RELIEF VALVE DISCHARGE FITTING
OVERALL HEIGHT (including flue turret)
CASING HEIGHT
CASING WIDTH
CASING DEPTH
WEIGHT(including water)
INSTALLATION WEIGHT
PACKAGED WEIGHT
PRIMARY WATER CAPACITY
MAXIMUM COLD SUPPLY PRESSURE
MINIMUM COLD SUPPLY PRESSURE (working) for max. hot water flow
MINIMUM COLD SUPPLY PRESSURE (working) to operate appliance
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE
OUTPUT TO DOMESTIC HOT WATER
OUTPUT TO CENTRAL HEATING
MAXIMUM DOMESTIC HOT WATER FLOW RATE (from the appliance)
EQUIVALENT DOMESTIC HOT WATER FLOW RATE TO GIVE A TEMP RISE
OF 30°C (SPECIFIC RATE)
4
22mm Compression
22mm Compression
15mm Compression
15mm Compression
Rc 1⁄2inch
15 mm Copper Tube
960mm (37.8 inches)
800mm (31.5 inches)
450mm (17.7 inches)
360mm (14.2 inches)
44 kg
39 kg
44 kg
3.0 litres
10 Bar (150 psi)
0.9 bar
0.1 bar
Nominally 82°C (180°F)
Modulating 7.5 to 23.4 kW
Modulating 7.5 to 23.4 kW
Nominally 8.0 ± 15% litres/min
Nominally 11.2 litres/min
4. Siting The Appliance
Fig. 2. Appliance casing dimensions and
required clearances.
4.1 The appliance may be installed in any room although
particular attention is drawn to the requirements of the current
IEE Wiring Regulations BS 7671 and, in Scotland, the electrical
provisions 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 containing
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 The following clearances must be available for installation
and for servicing. See Fig. 2. (note the clearances at the front are
for a removable panel e.g. a door).
4.6 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.
Above
180mm
In front
0 mm
In front to a fixed surface
600mm
Below
200mm
Right-hand side
10 mm
Left-hand side
10 mm
20mm*
225mm
Side view
360mm
Front view
450mm
600mm*
200mm*
10mm*
10mm*
* Space required for installation and servicing
Notwithstanding the instructions given in BS 5440:2, this appliance
may be fitted in a compartment with no vents as long as the
minimum clearances stated in Section 6: Air Supply, are maintained.
4.7 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 13mm. See BS 6798:1987.
4.8 No combustible surface must be within 75mm of the casing.
See BS476:4.
4.9 Always consider the possible need to disconnect the pipes
from the appliance after installation.
4.10 LPG Installation: The appliance shall not be installed in a
room or internal space below ground level when it is
intended for use with LPG. This does not preclude the
installation into rooms which are basements with respect to
one side of the building but open to ground level on the
opposite side.
5
800mm
180mm
5. Siting The Flue
6. Air Supply
See Fig. 3.
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
discharge cause a nuisance.
5.3 If the terminal is fitted within 850mm of a plastic or painted
gutter or within 450mm of painted eaves then an aluminium
shield at least 750mm 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.
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 products do not enter
ventilated roof voids.
6.1 The appliance does not require a separate vent for
combustion air.
6.2 The appliance can be fitted in a cupboard with no vents for
cooling but the minimum clearances must be increased to those
given below (note the clearances at the front are for a removable
panel e.g. a door).
Above the Turret
20mm
In front
250mm
Below
200mm
Right-hand side
75mm
Left-hand side
75mm
6.3 If the appliance is to be fitted in a cupboard or compartments
with less clearance than those above (minimum clearances given
in Section 4. Siting The Appliance) then permanent vents for
cooling are required. 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.
6.4 The minimum free areas required are given below.
POSITION OF
AIR VENTS
AIR FROM
THE ROOM
HIGH LEVEL
270cm
LOW LEVEL
270cm
AIR DIRECT
FROM OUTSIDE
2
2
135cm
2
2
135cm
6.5 Refer to BS 6798 and BS 5440:2 for additional information.
Fig. 3. Siting of the flue terminal.
A
L
G
B,C
K
L
D
K
F
F
HI
A
F
J
TERMINAL POSITION
A– directly below an openable window or
other opening e.g. air brick.
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.
E
G
M
MIN. DISTANCE
TERMINAL POSITION
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, window or air vent (achieve
where possible).
300mm (12in.)
75mm (3in.)
25mm (1in.)
25mm (1in.)
25mm (1in.)
25mm (1in.)
300mm (12in.)
600mm (24in.)
6
MIN. DISTANCE
1200mm (47in.)
1200mm (47in.)
150mm (6in.)
300mm (12in.)
150mm (6in.)
7.7 The filling point must be at low level. See Fig. 4.
7.8 Water loss must be replaced. See Fig 4. The connection
should be made in the central heating return as close to the
appliance as possible.
7.9 Repeated venting loses water from the system. It is essential
that this water is replaced and the system pressure maintained.
7.10 Connections to the mains water supply must not be made
without the authority of the local Water Company.
7.11 The pump is set at maximum and must not be adjusted.
7.12 Connections in the system must sustain a pressure of up to
3 bar.
7.13 Radiator valves must conform to BS 2767:10.
7.14 Other valves used should conform to the requirements of
BS 1010.
7.15 The appliance is fitted with a fixed internal by-pass. But it is
advisable to keeps one radiator permanently open.
7. Sealed System
See Figs. 4.
7.1 The system must comply with the requirements of BS 6798
and BS 5449.
7.2 The appliance must not be operated without the system
being full of water, properly vented and pressurised.
7.3 The 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 8 litre expansion vessel is charged to 0.5 bar and is
suitable for a static head of 5 metres (17.5ft). 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 up to 100 litres can be accommodated. For system capacities
greater than this an extra expansion vessel must be fitted. Refer
to BS 7074 Pt. 1 for more information. The charge pressure can
be increased but with a consequent decrease in system volume.
8. Open Vent System
The appliance is NOT suitable for connection to an open vented
system.
Fig. 4. Sealed primary water system.
Automatic
air vent
Expansion
vessel
Mains cold
water
Radiator
valve
Hot water
out
Lockshield
valve
Heating
return
Heating
flow
British Standard
stop valve.
Fixed spindle type
Water main
NOTE: A drain cock should be installed at
the lowest point of the heating circuit and
beneath the appliance.
Filling Loop Detail
Heating Return
Non-return Non-return
Valve
Valve
Hose union
Stop cock
Test cock
7
Temporary Hose
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
temperature.
9.12 The head of a loose head shower must not fall closer than
25mm (1in.) above the top edge of the bath to prevent its
immersion in bath water. Alternatively the shower must be fitted
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),
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.
9.14 LIME SCALE. In temporary hard water areas (more than
350mg/litre or 200ppm calcium bicarbonate) it is
recommended that a proprietary scale reducer is fitted in the
mains cold water connection to the appliance. Consult the
local water company for additional advice.
Installation of a scale inhibitor assembly should be in
accordance with the requirements of the local Water
Company. An isolating valve should be fitted to allow
servicing. The water hardness can be determined by
reference to the local Water Company.
9.15 NOTE: HOT WATER ONLY.
If required the appliance may be used for Hot Water only
before the Central Heating is connected. A 22mm copper bypass pipe at least 4 meters long must be connected between
the Central Heating Flow and Return, but it is advisable to
connect a small radiator instead.
IT IS NOT RECOMMENDED TO USE THE BOILER IN THIS
CONDITION FOR EXTENDED PERIODS.
9. Hot Water Supply
9.1 The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
9.2 MAINS COLD WATER INLET. Devices capable of preventing
the flow of expansion water must not be fitted unless
separate arrangements have been made.
A mini expansion vessel kit is available which contains the
necessary parts for fitting an internal expansion vessel to the
appliance.
See Section 19 COMPONENT PARTS LIST.
A thread sealant compatible with potable water must be
used. An external expansion vessel may be fitted on the
mains cold water connection to the appliance.
9.3 The final 600mm 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/in2).
9.5 The appliance is fitted with a mains supply isolating valve.
9.6 The maximum domestic hot water flow rate is 8.0 litres/min
(±15%) (1.8 gallons/min).
9.7 In winter (when the mains inlet water temperature is lower) a
reduced flow rate at the taps may be required to achieve the
type of hot water delivery temperature available in warmer
weather.
9.8 It is suggested 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.
9.9 Hot and cold taps and mixing valves used with this
appliance must be suitable for operating at mains pressure and
temperatures of 65°C.
Fig. 6. 230V programmer connections.
Fig. 5. 230V room thermostat connections.
RN
RI
CN
RL
CI
CL
X2
Motor
8
Live
Switched live
Neutral
Live
Neutral
Remove link
Switched live
X2
Remove link
conjunction with a programmer.
Important: To provide external frost protection the appliance
must have the Central Heating Temperature Control Knob set to
supply heating (the appliance may then be left with the central
heating turned off on the programmer).
Connection must be made at X2 terminals RI and CL. For advice
on external frost thermostats contact Worcester Heat Systems
Technical Helpline
10.11 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.
10. Electrical
10.1 MAINS SUPPLY.
230 V ~, 50 Hz, 180 watts.
External Fuse: 3A. Internal Fuses: 2AT HRC(F1), and 1.AF (F2).
10.2 It must be possible to completely isolate the appliance.
10.3 The following connection alternatives must be used:
A 3 amp fused three-pin plug and unswitched shuttered socket
outlet (both complying with the requirements of BS 1363) or a
double pole isolator with a contact separation of 3mm in all
poles and supplying the appliance and controls only.
10.4 The appliance must be earthed.
10.5 Mains Cable. 0.75mm2 (24 x 0.20mm) to BS 6500 Table 16.
The mains cable must be connected into the terminal X1,
marked L (Brown or Red lead), N (Blue or Black lead) and the
earth stud and be held securely in the cable clamp. For access
undo the three bottom screws and remove the facia access cover.
See Fig. 7.
10.6 The wiring between the appliance and the electrical supply
shall comply with current IEE Wiring Regulations and any local
regulations which apply.
10.7 If a room thermostat and/or external programmer is to be
fitted refer to Figs 5 and 6. The devices must be suitable for use
with mains voltage.
10.8 A facia mounted mechanical programmer is available as an
optional extra. Instructions are supplied with the programmer kits.
10.9 A time switch or programmer can be fitted externally to the
appliance.
10.10 The boiler provides automatic frost protection, the use of
a frost thermostat is not recommended. However if an external
frost thermostat is considered necessary then it must be used in
Fig. 7. Mains electricity connections.
230V
N
L
X1
X2
ue
Bl
Brown
Blue
Gr
ee
n/y
ello
w
Brown
Strain relief clamp
Green/yellow
Programmer and room thermostat
strain relief clamps
Fig. 8. Wiring diagram.
Flame sense
electrode
Spark
electrode
Spark
transformer
Flow
switch
X3
X6
2 Yellow
2 Orange
Mains in
2 Blue
2 pink
2 Red
Link
Blue
Brown
Link
Blue
Brown
X2
Brown
Blue
X1
X4
Blue
Brown
X5
DHW
sensor
Brown
White
Green
Air
pressure
switch
Fan
Gas
valve
Main
Reg
3 COM
Pump
CH
sensor
9
1 NC
2 NO
Safety
limit
stat
CH control POT
DHW temp. sensor
CH temp. sensor
X6 Pins 3 & 4
Flow signal
Outputs
X6 Pins 19 & 20
Air pressure switch
X6 Pins 1 & 2
Overheat stat
X6 Pins 15 & 16
X6 Pins 8 & 9
Modulating
valve
X6 Pins 5,6 & 7
Fig. 9. Functional flow diagram.
Inputs
FAN
X4 Pin 3
X4 Pin 1
LOW VOLTAGE
ELECTRONICS
(Microcontroller)
RL1
PUMP
X3 Pin 1
Mains
indicator
X3 Pin 2
RL3
X5 Pin 3
GAS VALVE
F2 1.25AT
X5 Pin 1
RL4
ROOM STAT
6
5
FULL SEQUENCE
CONTROLLER
4
3
MAINS
PROGRAMMER/CLOCK
2
N
X2 1
Flame sense
Optional links
F1 2ATHRC
X1
3 2 1
L N
10
Spark
X5 Pin 2
N
N
Technical Helpline.
Flue components
1. Turret clamping ring.
2. Flue turret assembly
3. Flue terminal assembly
4. Extension air duct
5. Extension flue duct
6. In-line 90° flue bend
7. In-line 45° flue bend
8. Vertical flue adapter
The flue must be installed as specified in BS 5440 Part 1.
NOTE: READ THIS SECTION FULLY BEFORE COMMENCING
INSTALLATION
11.2 GENERAL FITTING.
Check that the appliance carton contains:- Appliance, Installers
Instruction Pack, Appliance Wall Plate, Users Information Pack,
Installer Hardware Pack and an appliance template.
Check that the position chosen for the appliance is in accordance
with the instructions given in Sections 4 and 5.
Hold the template to the wall. Check that the template is
horizontal. See Fig. 10.
Mark the position of the fixing holes and the position of the flue
hole centre line onto the wall. See Fig. 10.
11. Installing The Appliance
The appliance is only suitable for fitting to a sealed system.
11.1 FLUE OPTIONS.
The standard flue length is from 127mm to 350mm measured
from the appliance casing to the outer wall.
Extension flue kits, a vertical take-off adapter, 45° and 90° flue
bends are available to increase the length and redirect the flue as
follows.
Horizontal balanced flue:
a) From 127mm to 2500mm straight flue.
b) From 127mm to 1750mm when a 90° flue bend is
required.
c) From 127mm to 1000mm when two 90° flue bends are
required.
A 90° flue bend is equivalent to 750mm of straight flue. A 45°
flue bend is equivalent to half a 90° bend.
Refer to Figs. 21 and 22 to determine whether extension kits,
90° flue bend, 45° flue bend, or adapters are required.
The maximum number of 90° flue bends allowed is two.
Fig. 10. Appliance mounting plate and flue position.
Mounting wall
Rear flue hole
110mm dia.
(150mm dia. for
internal fixing)
166mm
60mm
Mounting
plate
Fixing holes Mounting
(alternatives) plate
Mounting wall
222mm
Appliance
casing
Appliance
casing
Side flue position
Rear flue position
740mm
Side wall
Rear flue hole
110mm dia.
(150mm dia. for
internal fixing)
400mm
Side Flue – Extend the flue hole centre line from Fig. 11 along the
appropriate wall. Check that it remains horizontal and mark a
horizontal line. Measure 222mm from the junction of the walls
and mark a vertical line which will then give the position of the
flue hole.
Drill the two fixing holes 60mm deep for No. 12 size plugs. Cut
the flue duct hole at 110mm diameter (150mm dia. for internal
fitting). Ensure that the hole is horizontal through the wall. Fit
the wall mounting bracket.
Drill the two fixing holes 60mm deep for No. 12 size plugs. For
the boiler retaining screws.
Fix the wall plate and check that it is horizontal before tightening
the 2 screws.
Hang the appliance on the wall plate and screw the appliance to
the wall using the screws provided.
Fig. 11. Marking out the side flue position.
Side flue hole
110mm dia.
(150mm dia. for
internal fixing)
Mounting wall
22
2m
m
Sid
ew
all
166mm
11
Measure and cut the extension ducts to length ensuring that the
cuts are square and free from burrs. Always check the
dimensions before cutting the ducts.
All extension duct dimensions refer to the straight lengths. The
socketed ends must not be removed or included in any
measurement.
Connect the gas, water and pressure relief valve connections to
the appliance. The primary system should be flushed and
treated in accordance with the recommendations of
BS7593:1992.
Fig. 12. Appliance pipework connections.
Fig. 14. Side flue.
Make
good
(A)
(B)
100mm
(C)
36.5mm
40mm
(D)
(E)
Appliance side panel
(F)
A
B
C
D
E
F
Safety Relief
CH Flow
DHW Out
Gas Inlet
Mains Cold Water In
CH Return
=
=
=
=
=
=
External
wall face
50mm
95mm
160mm
225mm
290mm
355mm
L
If the air and flue duct assembly is to be fitted from inside the
room then the ducts must be adjusted to length, assembled and
inserted through the wall at this stage before fitting the flue
turret to the appliance. Refer to Section 11.3 following for the
assembly of the air and flue ducts.
Remove the fan. See Section 14.3(e).
11.3 AIR AND FLUE DUCT PREPARATION AND ASSEMBLY
Check the contents of the standard flue kit against the packing
list. Similarly check the extension kits if applicable.
Remove all the packing from the flue and terminal assembly.
The standard flue kit accommodates a flue assembly up to
350mm long measured from the appliance casing to the outer
wall face. See dimension L, Figs.13 and 14.
When dimension L is greater than 350mm extension flue
assemblies will be required.
It will not be necessary to cut either the ducts attached to the
turret or the terminal unless L = 350 to 450mm.
11.4 EXTERNAL FITTING OF THE DUCT ASSEMBLY
Measure distance L.
Side flue duct length = L + 184mm. See Fig. 14.
Rear flue duct length = L + 181mm. See Fig. 13.
Do not cut either the turret or the terminal assembly ducts
unless L = 350 to 450mm.
1. Should L = 350 to 450mm then cut the terminal assembly
ducts reducing the length of the ducts to 200mm. Then cut each
extension duct to 200mm (See Fig. 15). Assemble the flue as
described below ensuring the correct length (L+184mm for side
flues or L+181mm for rear flues).
Fig. 15. 350-450 Special.
Rear flue L + 181mm
Side flue L + 184mm
Fig. 13. Rear flue.
Turret assembly
with full
standard
duct
lengths
Make
good
Terminal assembly
reduced to 200mm
Fixing screws
Flue extension
duct length
200mm
Appliance casing
L = 350mm-450mm
40mm
Rear face of appliance
and face of mounting
wall
External
wall face
L
12
Air
extension
duct
length
200mm
Fig. 16. Standard flue assembly.
Fig. 18. Flue turret fixing.
Flue turret
Rear flue L + 181mm
Side flue L + 184mm
Turret
assembly
Fixing screw
Terminal
assembly
Appliance casing
L
Flue Gas
Test Point
2. If L is within the range 127mm to 350mm then the flue can
be telescopically adjusted to the correct length (L+184mm for
side flues or L+181mm for rear flues). The ducts are then fixed
by drilling a pilot hole through the hole in the air duct and screwing
the self tapping screw provided into the two ducts (See Fig. 16).
3. If L is within any of the following ranges it will not be
necessary to cut the extension ducts:
0.88m to 1.10m, 1.63m to 1.85m or 2.38m to 2.50m.
Each extension must be connected to the first section of flue or
the previous extension by firstly fitting the inner flue ducts
together and pilot drilling and fixing. (See Fig. 17). Then the outer
air ducts can be similarly fixed using the pair of screws provided.
The flue terminal section can then be telescopically adjusted and
fixed as before (See Fig. 16) ensuring the correct length
(L+184mm for side flues or L+181mm for rear flues).
Reset button
Turret clamping
ring
4. In the event of L not falling within any of the above ranges
it will be necessary to cut the FIRST extension length. The air
and flue duct lengths should both be reduced to the same
length: L – 240mm where one extension is used; L – 990mm with
two extensions and L – 1,740mm with three. (See Fig. 17). The flue
can then be assembled ensuring that the cut extension is fitted to
the turret duct assembly first and that the flue is adjusted to the
correct length of (L+184mm for side flues or
L+181mm for rear flues) (See Fig. 16).
5. Finishing the flue
Apply the plastic tape provided to the last section of flue where it
will be sealed to the external brickwork.
From inside, push the assembly through the wall, align the flue
turret with the socket on the appliance, push the turret down to fully
engage it and clamp in place with the turret clamping ring. See Fig.
18.
Make good the internal and external brickwork or rendering.
Refit the fan and replace the inner casing cover.
Fig. 17. Extensions.
Rear flue L + 181mm
Side flue L + 184mm
Turret
assembly
Fixing screws
Fixing screw
Extensions of equal length
Appliance casing
Shorten first extension fitted
to the turret assembly
L = 450mm-2500mm
13
Terminal
assembly
11.5 INTERNAL FITTING OF THE DUCT ASSEMBLY
The rubber sealing gasket and the clamping ring are available from
Worcester Heat Systems.
Measure and cut the ducts as previously described for external
fitting (Section 11.4). Fix the ducts to the terminal and fit the rubber
sealing gasket and clamp to the terminal. Centralise the gasket and
tighten the clamping ring. See Fig. 19. Slide the flue centering ring
onto the air duct and tighten the screw. See Fig. 20. Fix the ducts
and terminal assembly to the flue turret as described in Section 11.4
preceding.
Fig. 20. Duct and terminal assembly for
internal fitting of the flue.
Flue centring ring
Flue terminal
Fig. 19. Terminal assembly for internal
fitting of the flue.
Rubber sealing
gasket
Flue duct
Air duct
Rubber
sealing
gasket
Flue terminal
provided into the two ducts. (See Fig. 21).
The length Y is the distance between bends the ducts must be
cut to Y – 162mm. The swaged ends must be removed from the
extension tube and only the air duct needs fixing. See Fig. 21.
Z is the final flue length from the last elbow to the outside face of
the external wall. The first duct sections fitted to the elbow must
have unswaged ends. The length of the air ducts should be Z –
196mm. The inner flue duct must be 30mm longer than the air
duct. If Z – 196mm is less than 160mm then the terminal section
will need to be shortened to the same length as the extension flue
section fitted to the elbow (length Z – 100). If flue extensions are
needed to attain the required length care must be taken to ensure
that the last section of flue is longer than 260mm.
Each extension must be connected to the previous section of flue
or bend by firstly fitting the inner flue ducts together and pilot
drilling and fixing as above (See Fig. 21). Then the outer air ducts
can be similarly fixed using the pair of screws provided. The flue
terminal section can then be telescopically adjusted and fixed as
before (See Fig. 21), ensuring the correct length of Z – 41.
The silicon sealant supplied should be applied to the flue ducts
which engage into elbows. See Fig. 21.
From inside, push the assembly through the wall
Align the flue turret with the socket on the appliance, push the
turret down to fully engage it and clamp in place with the turret
clamping ring. See Fig. 18.
Make good the internal and external brickwork or rendering.
Refit the fan. Do not use any sealant on the joint. Replace the
inner casing cover.
Clamping ring
Apply the plastic tape provided to the last section of flue where it
will be sealed to the external brickwork.
Push the assembly through the wall so that the gasket flange is
against the outside face of the wall. See Fig. 20.
Align the flue turret with the socket on the appliance, push the
turret down to fully engage it and clamp in place with the turret
clamping ring. See Fig. 18.
Refit the fan and replace the inner casing cover.
Seal the gap around the duct with the flexible seal provided and
make good. See Fig. 20.
11.6 FLUE BENDS
See Figs 21 and 22.
Measure distances X, Y and Z as appropriate.
Side flue duct length = X + 63mm. See Fig. 21.
Rear flue duct length = X + 60mm. See Fig. 21.
Cut the flue and air ducts which are to make up the first section
X such that both the assemblies are of equal length (either X +
63mm or X + 60mm). Extensions will be necessary to allow X to
be larger than 250mm.
Any extension ducts are fixed by drilling a pilot hole through the
hole in the duct or elbow and screwing the self tapping screw
Fig. 21. Flue bends.
Z
56mm
Y Ð 162mm
Z Ð 41mm
Y
X
56mm
Side flue X + 63mm
Rear flue X + 60mm
14
11.7 VERTICAL ADAPTER
Measure and fit the flue as in Section 11.6 Flue bends except the
first section length is measured from the case top and the ducts
are cut to X – 168mm. The minimum length for X is 190mm. See
Fig. 22.
11.8 FINAL INSTALLATION
Check that all the water and gas connections have been
tightened.
If a facia mounted programmer is to be fitted follow instructions
with the programmer..
Remove the facia bottom panel as described in Section 14.3(c).
Connect the mains electrical supply to the appliance at terminal
X1. See Fig. 23. Connect any room and/or frost thermostats. The
electrical leads must pass through the appropriate space in the
control panel and be fixed with the cable clamps provided. Refit
the facia panel.
Test the gas supply pipework up to the appliance for soundness
as indicated in BS 6891.
Refer to Section 12 for a full description of the filling, venting and
the pressurising of the system.
If the appliance is not to be commissioned immediately, replace
the cabinet front panel. 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 conditions,
then drain the appliance and system. For short inoperative
periods, leave the appliance under the control of the built in frost
thermostat or the remote frost thermostat (if fitted) or leave
operating continuously with the room thermostat set at 6°C.
Fig. 22. Vertical adaptor with
horizontal flue.
Y-162
90¡
90¡
Z-41
X-168
Vertical flue adaptor required
for upwards section
Appliance
TOTAL STRAIGHT FLUE LENGTH
X + Y + Z or X + Z
2500mm with one bend
1750mm with two bends
1000mm with three bends
Fig. 23. Mains electricity connections.
230V
N
X1
L
X2
Blue
Brown
Strain relief clamp
Green/yellow
15
Programmer and room thermostat
strain relief clamps
12. Commissioning The Appliance
Fig. 25. Appliance components and fixings
(upper assembly).
12.1 SUMMARY
The appliance is dispatched with the controls set to provide a
maximum output for domestic hot water and central heating of
23.4 kW (80,000 Btu/h). The appliance automatically modulates
to satisfy lower heat loads.
Domestic Hot Water and Central Heating Systems. Check that
both the mains water supply and central heating systems have
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
appliance are off.
Check that all the water connections throughout the system are
tight.
Open the system valves at the appliance. Open all the radiator
valves, fill the system and vent each radiator in turn.
Remove the inner casing cover as described in section 14.3(b).
See Fig 24.
Flue hood
Fan assembly
fixing screws (4)
Overheat
thermostat
Auto air
vent
Combustion
chamber
cover fixing
clips (2)
Burner fixing
screws (2)
Fig. 24. Appliance casing and control
equipment fixings.
Inner casing
cover
screws (4)
Flue Gas
Test Point
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
system pressure.
If the pressure indicated on the pressure gauge is greater than
2.6 bar when operating at the maximum central heating
temperature, an extra expansion vessel must be fitted to the
system as close as possible to the appliance central heating
return connection.
The appliance (as dispatched) can accommodate a system
volume of about 100 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 specified
replacement must be fitted.
Side casing
fixing
screws (4)
Facia panel
fixing
screws (2)
Fig. 26. Pressure relief valve.
Bottom facia
panel fixing
screws (3)
The automatic air vent will vent the appliance. Check that the air
vent cap has been removed. See Fig. 25.
Check that the pressure relief valve operates by turning the knob
anti-clockwise until it releases. Water should be expelled from
the discharge pipe. See Fig. 26. Lower the control box to gain
access. Refer to Section 14.3(c).
Set the Expansion Vessel Pressure
The charge pressure of the expansion vessel as dispatched is 0.5 bar,
which is equivalent to a static head of 5 metres (17ft). The charge
pressure must not be less than the static head at the point of
connection. A Schraider type tyre valve is fitted to the expansion
vessel to allow the charge pressure to be increased if necessary.
Set the System Pressure
Fill the system until the pressure gauge shows 2.5 bar (37
lb/ins2) and check for water soundness. Release water from the
system using the relief valve test knob until the initial System
Design Pressure is obtained, up to a maximum of 1.5 bar.
Initial System Design Pressure (bar) = Expansion Vessel Charge
Pressure +0.3 (bar).
Pressure relief
valve.
(Turn knob
anti-clockwise
to test).
16
12.3 PROGRAMMER
Any programmer fitted on the appliance should be set up at this
stage following the instructions sent with the programmer.
12.4 APPLIANCE OPERATION
Turn off the gas and electricity supplies to the appliance.
Undo the two screws and hinge down the facia.
Loosen the burner pressure test point screw and connect a
pressure gauge. See Fig. 27.
Central Heating
Check that all the radiator valves are open.
Check that the system is pressurised and set to the required
pressure as indicated on the gauge.
Set any Programmer to HEATING & WATER.
Turn on the gas and electricity supplies.
Set the room thermostat and the Central Heating Temperature
Control to maximum.
The burner will light.
The appliance will modulate its output between 7.5 and 23.4 kW
over a period of about twenty 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.
Balance the system so that the required temperature difference
across the central heating flow and return pipes is obtained. See
Table 3, Section 3 Data Tables.
Set the room thermostat to minimum and check that the burner
goes out. Reset the room thermostat to maximum and the
burner will re-light after a short anti-cycle delay and follow the
normal operating procedure.
Check for proper ignition of the burner after a break in the gas
supply. Turn off the gas service cock and wait for 60 seconds. The
burner will go out but sparking from the electrode will continue
for 10 seconds when the appliance will enter a “lockout” state.
Carefully open the gas service cock, interrupt the mains power
supply to the appliance for a few seconds to reset the controls
and observe the burner re-light and follow the normal sequence
of operation.
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 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 cock at the appliance.
Set the Central Heating temperature control knob to demand
and any programmer to HEATING & WATER. If a programmer is
fitted, set the domestic hot water to Continuous or 24 Hrs 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 after a
short delay fully heated hot water is discharged from the tap.
Close the tap and the burner will go off. After a short time the
appliance will then return to the central heating mode and
automatically balance with the system requirements.
Set the Central Heating Temperature Control Knob to OFF and the
burner will go out.
12.5 COMPLETION OF COMMISSIONING
Disconnect the pressure gauge and tighten the test point screw.
Restart the appliance and check for gas soundness around the
test point screw.
Refit the cabinet front panel.
If the appliance is being passed over to the user immediately,
refer to Section 13 - Instructions to the User and set the controls
to the users requirements.
If the appliance is to be left inoperative, check that the Central
Heating Temperature Control 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. If the premises are to be left unoccupied during frosty
conditions, then drain the appliance and system. For short
inoperative periods, leave the appliance under the control of the
built in frost thermostat or the remote frost thermostat (if fitted)
or leave operating continuously with the room thermostat set at
6°C.
Fig. 27. Gas valve.
Main gas valve
connections
(Black : blue : brown :
green/yellow)
Minimum
pressure
adjuster
Maximum pressure
adjuster
Note: Clockwise to
increase and anticlockwise to
decrease the
pressure
Burner pressure
test point
Inlet pressure test
point
Electrical connections Ð
modulator (Blue : Blue)
Modulating
solenoid
Domestic Hot Water.
Set any Programmer to HEATING & WATER.
Turn on the gas and electricity supplies.
Set the Central Heating temperature control knob to Off.
A tap should be opened to create a hot water demand then a
continuous ignition spark will occur until the burner is alight and
sensed by the control circuit. The burner will light and remain at
its maximum setting. The burner pressure should be between
13.4 and 13.8 mbar on Natural gas (33.0 and 35.0 mbar on
Propane). If the burner pressure is low, check that the supply
pressure at the gas valve inlet is at least 19 mbar for Natural gas
(37 mbar for Propane).
Test for gas soundness at the joint between the burner and the
gas valve with leak detection fluid.
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
fan may continue running until the appliance has cooled.
17
13. Instructions To The User
14. Inspection And Service
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 heating system is not to be
used in frosty weather.
13.3 Tell the user the sealed system set pressure.
13.4 Tell the user of the importance of regular servicing.
Worcester Heat Systems Ltd. offer a comprehensive maintenance
contract.
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.
14.1 SERVICING
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
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), are
clear.
If the appliance is in a compartment, check that the ventilation
openings in the compartment door or walls are clear. See Section
6 - Air Supply.
Check the system and remake any joints or fittings which show
signs of leakage.
Refill, vent and re-pressurise as described in Section 12.2.
Operate the appliance and the system taking note of any faults.
Measurement of the Flue Gases
For consistency of results of the flue gas measurements it is
necessary to have a constant output and for the appliance to be
at equilibrium.
Turn on a tap to create a hot water demand.
Wait until the appliance reaches thermal equilibrium (approx. 10
minutes).
Remove the test point sealing screw on the appliance top panel.
See Fig. 30.
Connect to the test point with a piece of tubing.
Expected measurements should be between:
For Natural Gas:
Fig. 28. User controls.
Reset button
Mains indicator
System
pressure
gauge
C.H. temperature control
and on/off knob
Equivalent flue
length (metres)
Carbon
Dioxide (%)
Carbon
Monoxide (%)
0.5
6.9
0.0008
1.0
7.0
0.0009
1.5
7.1
0.0010
2.0
7.3
0.0012
2.5
7.4
0.0013
Equivalent flue
length (metres)
Carbon
Dioxide (%)
Carbon
Monoxide (%)
0.5
7.9
0.0017
1.0
8.0
0.0020
1.5
8.2
0.0024
2.0
8.5
0.0030
2.5
8.8
0.0035
For Propane:
When calculating the equivalent flue length a flue bend is
equivalent to 750mm of straight flue.
After taking the measurement replace and tighten the sealing
screw.
IMPORTANT
Disconnect the electrical supply at the mains and turn off the
gas supply at the gas service cock on the appliance before
servicing.
After completing the service always test for gas soundness as
indicated in BS 6891.
18
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.
(d) Bottom panel. Unclip and remove the appliance bottom
panel.
(e) Fan. Remove the inner casing cover. Carefully unplug the
electrical connections and pull off the sensing tubes. Unscrew
the four fixing screws and remove the fan assembly. See Fig. 30.
(f) Combustion Chamber Front. Remove the inner casing cover.
Undo the spring clips fixing the combustion chamber front. See
Fig. 30.
(g) Flue Hood Assembly. Remove the fan assembly. Remove the
combustion chamber front. Lift and slide the flue hood assembly
from the appliance. See Fig. 30. When refitting the hood ensure
that the rear return edge passes under the lip at the rear of the
combustion chamber.
(h) Burner Assembly. Remove the combustion chamber front.
Pull off the two spark electrode leads and disconnect the flame
sense lead. Undo the burner fixing screws. Lift up and remove
the burner assembly from the appliance. See Fig. 31.
Fig. 29. Appliance casing and control
equipment fixings.
Inner casing
cover
screws (4)
Side casing
fixing
screws (4)
Fig. 31. Burner and electrode assembly.
Facia panel
fixing
screws (2)
Injector
Bottom facia
panel fixing
screws (3)
(a) Cabinet Front Panel. Remove by lifting off the supports.
(b) Inner Casing Cover. Check that the electricity supply to the
appliance is turned off. Remove the cabinet front panel. Unscrew
the four screws securing the cover to the casing and lift off. See
Fig. 29.
(c) Facia Panel. Check that the electricity supply to the appliance
is turned off. Remove the cabinet front panel. Unscrew the two
upper screws as shown in Fig. 29. and hinge down the facia
taking care not to damage the pressure gauge capillary tube or
electrical connections.
Spark electrode
14.4 SERVICE OF COMPONENTS
Clean the Fan. Any dust or fluff should be removed with a soft
brush or by blowing. Take care not to distort the pressure
sensing device.
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. Replace the spark and sense electrodes if they
appear damaged.
Clean the Gas to Water Heat Exchanger. 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. Remove any dust or deposits using a
soft brush.
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 operation
of the appliance.
14.5 TEST THE APPLIANCE
On completion of the service and reassembly of the appliance,
check for gas soundness and the correct operation of the
appliance as described in Section 12 - Commissioning.
Refit the cabinet front panel and reset the controls to the users
requirements.
Fig. 30. Appliance components and fixings
(upper assembly).
Flue hood
Flue Gas
Test Point
Fan assembly
fixing screws (4)
Overheat
thermostat
Auto air
vent
Combustion
chamber
cover fixing
clips (2)
Burner fixing
screws (2)
19
2. Air Pressure Switch. See Fig. 34.
Check that the electricity supply to the appliance is turned off.
Remove the cabinet front panel as described in Section 14.3 (a)
and lower the facia. Section 14.3(c).
Carefully pull off the sensing tubes and the electrical connections
from the switch. Remember to note their positions.
Unscrew the two screws behind the Air Pressure Switch and
remove the switch from the appliance.
Fit the replacement switch in the reverse order ensuring that the
electrical connections have been made to the correct terminals
on the switch. Check that the sensing tubes are fitted correctly.
3. Fan. See Fig. 30.
Check that the electricity supply to the appliance is turned off.
Remove the fan assembly as described in Section 14.3(e).
Fit the replacement fan in the reverse order.
4. Overheat Thermostat. See Fig. 30 and 32.
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 off the two wires from the thermostat head.
Undo the retaining nut on the top of the appliance and remove
the retaining clip from the heat exchanger. Carefully withdraw
the thermostat from the appliance.
Fit the replacement thermostat in the reverse order ensuring that
some heat sink compound is between the thermostat and the
heat exchanger.
5. Gas to Water Heat Exchanger. See Fig. 32.
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit and domestic circuits as
described in Section 15.3 (a) and (b).
Remove the inner casing cover, fan, flue hood assembly,
combustion chamber front, overheat thermostat, automatic air
vent and combustion chamber side insulation as described in
Sections 14.3 (b, e, f and g), 15.4 (1) and 15.4 (4).
Fit the replacement heat exchanger in the reverse order ensuring
that all the fibre washers are correctly fitted and a layer of heat
sink compound is on the thermostat.
Open the valves and fill and re-pressurise the system as
described in Section 12.2.
15. Replacement Of Parts
15.1 IMPORTANT
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 may also need to be
hinged down as described in Section 14.3 (c).
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. Open the pressure relief valve,
make sure that the dust cap on the auto air vent is removed. See
Fig. 30. Close the pressure relief valve when the flow has
stopped. Some water will remain in the expansion vessel, pump
and Gas to Water heat exchangers and extra care must be taken
when removing these components.
(b) Domestic Hot Water Circuit. Turn off the mains cold supply
valve at the appliance and open the lowest hot water tap. A
quantity of water will remain in the Gas to Water heat exchanger,
extra care must be taken when removing this component.
15.4 COMPONENT REPLACEMENT
1. Automatic Air Vent. See Figs. 30. and 32.
Remove the inner casing cover as described in Section 14.3 (b).
Drain the central heating circuit as described in Section 15.3 (a).
Unscrew air vent from the heat exchanger.
Fit the replacement assembly ensuring thread sealant is applied
and the dust cap is removed.
Open the valves and fill and re-pressurise the system as
described in Section 12.2.
Fig. 32. Combustion chamber.
Heat
exchanger
Auto air
vent
Overheat
Thermostat
Hot water heat
exchanger
connections
Central heating
heat exchanger
connections
Cut-outs in
combustion
chamber sides
Pump bulk
head
connector
20
Restart the appliance in central heating mode and adjust the
minimum adjustment screw on the gas valve to give a pressure
of 1.0 mbar on natural gas or 3.5 mbar on propane. See Fig. 33.
After completing the adjustments, check the minimum and
maximum pressures and re-adjust as necessary. Once this has
been done the clear cap should be re-fitted to the adjuster and
the retaining screw tightened. Coat the screw with paint or nail
varnish to prevent user adjustment.
6. Combustion Chamber Insulation.
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, fan, flue hood assembly, burner,
and Gas to Water heat exchanger as described in Sections 14.3
(b, e and f), and 15.4 (5). Remove the fibre insulation pads from
the combustion chamber side, rear, and front sections.
Fit the replacement pads in the reverse order taking care not to
damage them.
Open the valves and fill and re-pressurise the system as
described in Section 12.2.
7. Burner. See Fig. 31.
Check that the electricity and gas supplies to the appliance are
turned off.
Remove the burner assembly as described in Section 14.3 (h).
Fit the replacement burner in the reverse order taking care not to
damage the electrode leads.
8. Burner Injector. See Fig. 31.
Remove the burner as described in Section 14.3 (h).
Unscrew the brass injector from the manifold.
Fit the replacement injector in the reverse order.
9. Spark Electrode Assembly. See Fig. 31a.
Remove the combustion chamber front as described in 14.3 (g)
Carefully pull off the two electrode leads,
Undo the M4 extended nut and remove the spark electrode
assembly from the burner.
Fit the replacement electrode in the reverse order, checking that
the spark gap is 3.5 to 4.5mm.
Fig. 27. Gas valve.
Main gas valve
connections
(Black : blue : brown :
green/yellow)
Minimum
pressure
adjuster
Maximum pressure
adjuster
Note: Clockwise to
increase and anticlockwise to
decrease the
pressure
Burner pressure
test point
Fig. 31a. Spark electrode assembly.
Inlet pressure test
point
3.5-4.5mm
2.5-5mm
Modulating
solenoid
Electrical connections Ð
modulator (Blue : Blue)
12. Central Heating Sensor. See Fig. 34.
Check that the electricity supply to the appliance is turned off.
Hinge the facia assembly in the servicing position as described in
Section 14.3(c and d).
Carefully pull off the two leads from the sensor.
Pull off the sensor and spring retaining clip from the pipe.
Fit the replacement sensor in reverse order with a layer of heat
sink compound between the faces. Refit the leads.
10. Flame Sensor. See Fig. 31.
Remove the burner as described in sections 14.3(h) and 15.4(8).
Undo the M3 screw and remove the sense electrode from the
burner.
Fit the replacement electrode in the reverse order, checking that
the sense gap is 5 to 6mm.
11. Gas Valve. See Figs. 33. and 34.
Check that the electricity and gas supplies to the appliance are
turned off.
Hinge down the control box assembly in the servicing position
as described in Section 14.3(d).
Whilst supporting the valve unscrew the plug retaining screw
and carefully pull off the electrical solenoid plug connection and
the two modureg leads.
Undo the 8 manifold screws and remove the gas valve. See Fig. 34.
Fit the replacement gas valve in the reverse order ensuring the
“O” rings are correctly fitted.
Turn on the gas supply and check for soundness.
To set the burner pressure. See Fig. 33.
The minimum and maximum burner pressures must be set after
a new gas control has been fitted.
The maximum burner pressure must be set first, as any
adjustment of the maximum pressure influences the minimum
pressure setting.
Start the appliance in the domestic hot water mode as described
in section 12.4. - Appliance Operation.
Adjust the maximum pressure adjustment screw on the gas
valve to give a burner pressure of 13.6 mbar on natural gas, for
propane the maximum pressure adjustment must be increased
to maximum clockwise, this should give 33.0 - 35.0 mbar.
End the demand and reset the appliance by interrupting the
mains electricity supply. (Otherwise there is a four minute anticycle delay at the end of a demand).
Fig. 34. Gas valve pump and air pressure
switch.
Air pressure switch
Top gas valve
connection (4 bolts)
Gas
valve
Pump
connecting tubes
Red
pipe
Pressure gauge
Central Heating
connection
Sensor
Gas valve
Lower pump
electrical
Air pressure
connection
connections
switch
21
13. Domestic Hot Water Sensor.
Check that the electricity supply to the appliance is turned off.
Hinge the facia assembly in the servicing position as described in
Section 14.3(c and d).
Carefully pull off the two leads from the sensor.
Undo and remove the clamping screw.
Pull off the sensor and spring retaining clip from the pipe.
Fit the replacement sensor in the reverse order ensuring a layer
of heat sink compound is between the faces. Refit the leads.
14. Circulating Pump. See Figs. 32 and 34.
Check that the electricity supply to the appliance is turned off.
Drain the central heating circuit as described in Section 15.3(a).
Hinge the facia assembly in the servicing position as described in
Section 14.3(c).
Undo the two union nuts and the pipe to the expansion vessel,
remove the pump from the pipe-work. Support the pump and
remove the electrical cover.
Disconnect the electrical wires taking note of their positions.
Fit the replacement pump in the reverse order using new sealing
washers.
(Alternatively replace the pump head only by removing the four
Allen screws on the pump, remove the head and support whilst
removing the electrical connections. Refit the new head).
Open the valves and fill and re-pressurise the system as
described in Section 12.2
Note: The direction of flow should be upwards. The speed should
always be set to maximum.
15. Expansion Vessel.
Drain the central heating circuit as described in Section 15.3(a).
Isolate the gas supply at the mains.
Then either fit a separate expansion vessel on the central heating
return to the appliance or replace the existing vessel as
described below.
Drain the domestic circuit as described in Section 15.3(b).
Disconnect the flue system at the boiler.
Disconnect the appliance pipework at the appliance entry points
ensuring precautions are taken to cope with any water
remaining in the appliance.
Remove the appliance from the wall.
Disconnect the expansion vessel from the appliance by undoing
the fitting nut at it’s base.
Fit the replacement vessel in the reverse order.
Open the valves and fill and re-pressurise the system as
described in Section 12.2
16. Pressure Relief Valve. See Fig. 35.
Drain the central heating circuit as described in Section 15.3(a).
Hinge down the facia assembly as described in Section 14.3(c)
Remove the Bottom panel as described in Section 14.3(d)
Undo the discharge pipe connection and remove the valve
retaining clip. Remove the valve taking care not to distort the
pipework.
Fit the replacement valve in reverse order. Reconnect the
discharge pipe.
Open the valves and fill and re-pressurise the system as
described in Section 12.2
17. Water Flow Switch. See Fig. 36.
Check that the electricity supply to the appliance is turned off.
Drain the domestic hot water circuit as described in Section
15.3(b).
Remove the two upper screws and hinge down the facia panel as
described in Section 14.3(c).
Undo the two union nuts securing the “T” piece and remove the
housing from the pipework.
Disconnect the electrical connection.
Fit the replacement water flow switch in the reverse order
ensuring new fibre washers are fitted to the new switch body.
Fig. 36. Water Flow Switch. (Side View)
Flow Restrictor
Water Flow Switch
ÒTÓ Piece
Fig. 35. Pressure relief valve.
18. Domestic Hot Water Flow Restrictor. See Fig. 36.
Remove the water flow switch as described in Section 15.4-17.
Undo the two union nuts securing the “T” piece and remove the
housing from the pipework.
The plastic flow restrictor is located within the “T” piece on the
water flow switch.
Fit the replacement flow restrictor and reassemble in the reverse
order ensuring the fibre washers are in place.
19. Pressure Gauge.
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 two upper screws and hinge down the facia panel as
described in Section 14.3(c).
Prize back the retaining clips securing the gauge to the facia
panel remove wire clip and unplug the gauge from the pump
inlet pipe.
Fit the replacement gauge in the reverse order ensuring the “O”
ring is in place.
Open the valves and fill and re-pressurise the system as
described in Section 12.2
Pressure relief
valve.
(Turn knob
anti-clockwise
to test).
22
20. Control Board.
Check that the electricity supply to the appliance is turned off.
Undo the 3 screws and remove the facia bottom panel.
Remove the two upper screws and hinge down the facia
assembly.
Carefully pull off all the connectors. Disconnect the mains supply
lead at terminal X1 and the earth connection at the back.
Remove the four corner screws on the back of the facia and
separate the metal back panel from the plastic facia.
Remove and retain the brass nut and washer.
Release the six pillars on the control board and pull the control
board forward off the back panel.
Fit the replacement board in the reverse order ensuring it is
pushed firmly onto the six pillars and clicks into place. Special
care should be taken with the brass post and nut to ensure a
good earth contact. (Check earth continuity between the
incoming earth and the appliance chassis).
Refit the facia panel and hinge the control box assembly in the
servicing position as described in Section 14.3 (c).
21. Gauze filter. See Fig. 37.
Remove the water flow switch as described in section 15.4-17.
Undo the lower union nut on flow switch housing.
Undo the nut on the isolating valve and remove the mains water
inlet pipe. Carefully extract the filter from the valve end of the
pipe.
Replace the filter and refit the pipe in reverse order.
22. Flue flow sensor. See Fig. 38.
Check that the electricity supply to the appliance is turned off.
Remove the fan assembly as described in Section 14.3(e).
Unscrew the single central retaining screw and withdraw the
sensor from the fan.
Fit the new sensor ensuring the correct orientation and carefully
tighten the retaining screw.
Refit the fan assembly in reverse order.
Fig. 37. Gauze Filter.
Gauze Filter
Isolating Valve
Fig. 38. Flue flow sensor.
Positive
16. Conversion Instructions
5. Refit the end cap ensuring the bracket is in the correct
orientation.
6. Refit the burner to the appliance and re-assemble the
inner casing.
7. Follow the dismantling instructions to remove the gas
valve and refit the new valve. See Installation Instructions:
Section 15.4.11 Replacement of Parts, Component
Replacement, Gas Valve.
8. Turn on the gas and electricity supplies and following
the commissioning procedure confirm gas soundness and
correct boiler operation.
9. Set the gas pressure to the required rate for the new gas
type as specified on the data plate. When this is done refit
the cap to the adjuster and seal its retaining screw with
paint or nail varnish.
10. Turn off the boiler and when cool peel off the arrow
from the data plate and re-stick it against the gas type for
which the appliance is now converted.
11.Replace the boiler front panel.
These instructions should be used when converting appliances from natural gas to LPG and vice versa.
Only components supplied by Worcester Heat Systems
should be used.
Only competent persons should attempt the conversion.
Conversion from Natural Gas to LPG should not be
carried out on appliances installed in a room or internal space below ground level.
1. Ensure the gas service cock is turned OFF and the electrical supply is isolated.
2. Refer to section 14.3 Dismantle the Appliance to
remove the boiler front panel and inner casing. Follow the
dismantling instructions to remove the burner.
3. Remove the injector and replace with the injector from
the kit.
4. Remove the nut, end cap and bracket from the end of
the burner.
4.1 For conversion to Natural gas remove the internal
gauze.
4.2 For conversion to LPG fit the gauze into the burner
body.
The conversion is now complete.
Parts List
Item No.
Description
Natural Gas to LPG Kit
7 716 192 131
8 716 140 209
Stereomatic 2.78mm
1.
Burner Injector
2.
Burner Gauze
8 716 142 601
Remove Gauze
3.
Gas Valve
8 716 142 430
8 716 142 413
23
LPG to Natural Gas Kit
7 716 192 132
8 716 140 224
Stereomatic 4.3mm
24
Pump on
Water flow
temperature
monitored by central
heating sensor
Escape pause by
resetting the mains
electricity supply
OFF-ON
Is fan in
overrun mode?
YES
NO
Wait (pump on
in central
heating mode)
FAIL
Air pressure
switch test
PASS
AUTOMATIC START-UP SEQUENCE
Internal
"Autofrostat"
demand
CENTRAL HEATING
DEMAND
Operating Switch
(or programmer)
and room
thermostat on
End of a domestic
hot water overrun
1. Central Heating Mode
Fan ON
Sense air
pressure
Wait
(fan or fan and
pump on)
ABSENT
AUTOMATIC
START-UP
SEQUENCE
Anti-cycle delay
PRESENT
Burner pressure
1.0 mbar for 60
seconds.
Main gas valve
OFF
Main valve
opens
Initiate
sparking
17. Operational Flow Diagrams
Ignition Time out (after 9secs)
ABSENT
Sense
flame
Stop
sparking
Burner pressure
automatically
adjusted for range
rating and then
modulated to
maintain set flow
temperature
6
Central heating
temperature 5°C
above set point
Ignition
Lock-out
Wait
(fan or fan and
pump on)
PRESENT
CENTRAL
HEATING
DEMAND
SATISFIED
EITHER
Operating Switch
(or programmer)
OFF
Fan overrun
4 minutes
Continue
pump overrun
for 6 secs pump
pulse after
2 miniutes.
Gas valve OFF
Room thermostat
OFF
25
Inhibit operations
for approximately
1 second. 6 second
delay before reignition from any
other demand.
Run pump
Burner pressure
at 1.0 mbar
4°C to 8°C
6
Above 8°C
At the set point
change to a wide
band proportional
control
Return to normal
OFF state
Pump OFF
Is the central
heating mode
interrupted?
Wait for hot water
temperature to
drop to factory
pre-set level
Burner never to be
extinguished
irrespective of the
rate of temperature
rise
Monitor central
heating sensor
Below 4°C
Commence normal central
heating mode until heating
temperature reaches 20°C
Domestic hot water
temperature
monitored by hot
water sensor
Burner pressure adjusted
based on the temperature
rise over the previous
minute. Aiming at 4°C
rise/minute.
6. Central Heating ramp control
Internal
"Autofrostat"
Demand
No demand and
primary
temperature below
6°C monitored by
the central heating
sensor
3. "Autofrostat" Function
HOT WATER
DEMAND
(Overrides all other
overrun modes
and functions)
Signal from the
flow switch
2. Domestic Hot Water Mode
AUTOMATIC
START-UP
SEQUENCE
Gas valve OFF.
Fan remains ON
End of demand or central
heating temperature above
70°C monitored by the
central heating sensor
Fan on for
4 minutes
6 second pump pulse with a
2nd 6 second pump pulse 2
minutes later.
5. Fan Overrun Function
End of hot water demand
with no central heating
demand. Hot water
thermistor above 40°C
No demand and central
heating temperature above
50°C monitored by the
central heating sensor
Fan overrun
4 minutes
Pump pulse 6
seconds then 2
minutes later
2nd pulse
Gas valve OFF
Pump on until
primary temperature
drops to 50°C
HOT WATER
DEMAND
SATISFIED
Operating
Switch (or
programmer
OFF)
4. Pump Overrun Function
Modulate heat
input to maintain
hot water
temperature at the
factory pre-set
level
Hot water
temperature above
70°C
CH control POT
DHW temp. sensor
CH temp. sensor
X6 Pins 3 & 4
Flow signal
Outputs
X6 Pins 19 & 20
Air pressure switch
X6 Pins 1 & 2
Overheat stat
X6 Pins 15 & 16
X6 Pins 8 & 9
Modulating
valve
X6 Pins 5,6 & 7
18. Fault Finding
Inputs
FAN
X4 Pin 3
X4 Pin 1
LOW VOLTAGE
ELECTRONICS
(Microcontroller)
RL1
PUMP
X3 Pin 1
Mains
indicator
X3 Pin 2
RL3
X5 Pin 3
GAS VALVE
F2 1.25AT
X5 Pin 1
RL4
ROOM STAT
6
5
FULL SEQUENCE
CONTROLLER
4
3
MAINS
PROGRAMMER/CLOCK
2
N
X2 1
Flame sense
Optional links
F1 2ATHRC
X1
3 2 1
L N
26
Spark
X5 Pin 2
N
N
Fault in
Domestic Hot Water
Fault in
Central Heating
Is mains LED flashing?
YES
GO TO
CHECK D
YES
NO
NO
Is mains LED
illuminated?
NO
GO TO
CHECK C
NO
Is mains LED
iluminated?
YES
YES
Is control knob
set for demand?
Is mains LED flashing?
NO
Turn control knob
fully clockwise
NO
Ensure link is fitted at
X2 pins 5 & 6
NO
Set room stat to
call for heat
NO
Ensure link is fitted at
X2 pins 2 & 3
YES
Is a room thermostat
fitted?
YES
Is room thermostat
calling for heating?
YES
Is programmer fitted?
GO TO
CHECK O
YES
Is programmer calling
for heat?
YES
NO
Set clock to call for heat
YES
Is pump running?
NO
GO TO
CHECK F
YES
GO TO
CHECK E
YES
Has overheat
thermostat tripped?
YES
Has overheat
thermostat tripped
NO
NO
GO TO
CHECK K
GO TO
CHECK K
27
No mains LED
Is mains present at
X1 pins 1 & 3?
NO
Connect mains
supply
YES
Is F1 (2ATHRC) OK?
NO
Replace fuse
YES
Is F2 (1.25AT) OK?
NO
Replace fuse
YES
Faulty PCB
Replace
Flashing mains LED
Remove X6
Is resistance between
pins 3 & 4 between
690ohms & 33k
NO
YES
Is resistance between
pins 19 & 20 between
690ohms & 33k
YES
Open circuit
NO
Short circuit
YES
NO
GO TO
CHECK H
Faulty
Replace thermistor
Faulty
OK
GO TO
CHECK I
OK
Faulty PCB
Replace
28
GO TO
CHECK H
OK
Faulty
Replace harness
Faulty
GO TO
CHECK J
OK
Overheat Thermostat Check
The overheat thermostat can be
reset by pressing the reset button,
but if it trips immediately or on a
regular basis a serious problem has
occurred therefore contact your
installer
Reset thermostat
Does button hold in?
NO
Is capillary broken?
YES
YES
Is capillary firmly
ATTACHED
to exchanger?
NO
Replace overheat
thermostat
ATTACH to heat
exchanger
YES
GO TO
CHECK I
Pump Check
Is pump connector
secure on the PCB (X3)?
NO
Secure Connector
YES
Is mains present at the
pump connector
(X3 pins 1 & 2)?
NO
GO TO
CHECK O
YES
Faulty pump
Fan Check
Is fan connector
secure on the PCB (X4)?
NO
Secure Connector
YES
Is mains present at the
fan connector
(X4 pins 1 & 2)?
NO
GO TO
CHECK L
YES
Mains at fan
NO
Faulty Harness
YES
Faulty fan
29
NO
Ensure appliance is
cool and retest
Thermistor Check
Remove connectors
from thermistor
YES
Is resistance between
terminals of thermistor
between 690ohms & 33k
NO
Faulty thermistor
YES
Thermistor OK
Harness Continuity Check
Remove appropriate
connectors
YES
Is continuity observed
between each end of
wire in question?
NO
Faulty harness
or connector
YES
Harness OK
Harness Short Check
Remove appropriate
connectors
YES
Is short circuit
observed between pair
of wires in question?
NO
Faulty harness
YES
Harness OK
30
Ignition Check
Is fan running?
NO
GO TO
CHECK G
NO
GO TO
CHECK E
NO
Is sparking present at
the electrodes?
YES
Does sparking occur?
GO TO
CHECK L
Faulty PCB
Replace
YES
Does ignition occur?
NO
YES
YES
Are ignition leads
connected both
ends securely?
Are leads breaking
down?
YES
Replace leads
NO
YES
Is flame sense
electrode in flame?
NO
YES
Is lead secure
both ends?
NO
YES
GO TO
CHECK I
HARNESS OK
Faulty PCB
Replace
Does gas pressure
modulate?
NO
Connect ignition leads
securely
NO
Ignition coil faulty
replace PCB
YES
GO TO
CHECK M
Does burner continue?
NO
GO TO
CHECK N
YES
Ignition OK
31
Ensure flame sense
electrode in flame at
minimum burner
pressure
Secure lead
L
Air Pressure Switch Check
Remove BROWN and
WHITE terminals
from air pressure
switch
With no demand, is a
short-circuit observed
at exposed APS
terminals?
NO
Air pressure switch
faulty
YES
Reconnect the
WHITE & BROWN
wire and remove the
GREEN wire. Initiate
a demand.
Does the fan run?
NO
YES
Fan or fan cable
faulty
YES
With fan running
disconnect BROWN
wire. (DO NOT touch
chassis with it). Is a
short circuit observed
across exposed APS
terminals?
Is there mains 230V
at fan connector X4
pins 1 and 3?
NO
Air pressure switch
faulty
YES
APS OK
Gas Valve Check
Is gas pressure present
at input to gas valve?
NO
Ensure gas supply
YES
Is live output present at
X5 pins 1 & 2 relative to
neutral at pin 3?
NO
Faulty board
Replace
NO
Faulty gas valve
Replace
YES
Is gas pressure present
at input to burner?
YES
Gas valve OK
32
NO
PCB faulty
N
Modulating Valve Check
Is minimum pressure
observed at burner at all
times?
YES
Remove X6, measure
resistance between
pins 15 & 16
NO
GO TO
CHECK I
NO
Is resistance
nominally 125ohms
YES
Is pressure at burner
always the same?
YES
NO
With pressure above
minimum, remove Modureg
Lead. Does pressure drop to
minimum?
NO
Faulty modulating valve .
Replace gas valve
Reconnect X6 and measure
voltage across modulating
valve during operation
YES
Gas valve OK
YES
Does voltage
go above 6.25V
NO
Faulty PCB.
Replace
Flow Switch Check
Remove X6
Close all taps to set no
domestic flow
Is open circuit observed
at X6 pins 1 & 2?
NO
Faulty flow switch.
Replace
NO
GO TO
CHECK I
YES
Open a tap fully to set
domestic flow
Is short circuit observed
at X6 pins 1 & 2
YES
Flow Switch OK
33
HARNESS OK
Faulty flow switch.
Replace
19. Component Parts List
Key
No.
1
G.C. No.
E01-579
E01-580
2
E01-591
E00-741
3
E01-892
E01-893
4
E01-596
5
375 697
6
E01-612
E01-930
7
E01-598
8
E01-599
9
E01-600
10
E01-601
11
299-506
12
375 699
13
E01-602
14
E01-603
15
E01-604
16
E04-582
E01-900
299-495
18
E01-605
19
324-822
20
299-363
21
E01-606
22
E01-607
23
E01-886
24
299-357
25
E01-610
ACCESSORIES
299-360
E01-940
E01-941
E05-341
FLUE OPTIONS
E01-942
E01-943
E01-944
E01-945
E01-946
E01-058
E01-059
Part
Manufacturer’s Reference
Aeromatic
AC23/053586
Aeromatic
AC23/053587
Stereomatic O 4.3mm
Stereomatic O 2.78mm
SIT
SIT
Huba 605.99484
Buccleuch
Buccleuch
Qty
Burner Assembly Natural Gas
Burner Assembly LPG
Injector Natural Gas
Injector LPG
Gas Valve Natural Gas
Gas Valve LPG
Air Pressure Switch
Spark Electrode Assembly
Flame Sensor
Flame Sensor Harness
Ignition Harness
Gas to Water Heat Exchanger
Insulation Pack
Auto Air Vent
Pressure Gauge
Pressure Relief Valve
Pump with Harness
Expansion Vessel (8Ltr) 389mm Dia
PCB Boiler Control
Temperature Thermistors
CH Thermistor Clip
DHW Thermistor Clip
DHW Flow Regulator
Gauze Filter
Flow Sensor
Fan Assembly
Safety Temperature Limiter
Flow Switch Assembly
Fuse Pack
Gasket Pack
WHS
WHS
SIFAN
Ranco LM7
SIKA
WHS
WHS
Mechanical Programmer Kit
Gas Conversion Kit
Gas Conversion Kit
Mini Expansion Vessel Kit
Deihl
NG to LPG
LPG to NG
Including new pipe and Expansion Vessel
7 716 192 002 0
7 716 192 131 0
7 716 192 132 0
7 716 192 188 0
Telescopic Horizontal Flue Kit
Extension Flue Kit
Vertical Flue Kit
Vertical Flue Adaptor
Internal Fixing Kit
Flue Elbow Kit
Flue Elbow Kit
127-350 mm
750 mm
7 716 191 005 0
7 716 191 006 0
7 716 191 015 0
7 716 191 016 0
7 716 191 019 0
7 716 191 013 0
7 716 191 014 0
Buccleuch
Giannonni
WHS
Intermes
Cewal
Caleffi 3141 3bar
Grundfos 15 60 special
Winkelman Panhof
Pactrol
Elmwood
Telescopic Flue
90 deg.
45 deg.
34
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
WHS
Part No.
8 716 142 604 0
8 716 142 611 0
8 716 140 224 0
8 716 140 209 0
8 716 142 413 0
8 716 142 430 0
8 716 142 414 0
8 716 142 100 0
8 716 120 345 0
8 716 120 126 0
8 716 120 236 0
8 716 142 905 0
7 716 192 216 0
8 716 140 504 0
8 716 142 300 0
8 716 142 404 0
8 716 143 107 0
8 716 142 502 0
8 716 146 300 0
8 716 142 384 0
8 716 148 313 0
8 716 148 303 0
8 716 141 052 0
8 716 148 401 0
8 716 141 000 0
8 716 120 993 0
8 716 142 307 0
8 716 120 971 0
7 716 192 206 0
7 716 192 218 0
9
8
14
3
21
1
15
22
4
13
12
7
11
10
20
23
23
25
24
2
35
6
19
18
16
Bosch Group
Worcester Heat Systems Limited, Cotswold Way, Warndon, Worcester WR4 9SW.
Telephone: (01905) 754624. Fax: (01905) 754619.
Technical Helpline (0990) 266241.
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.
PUBLICATION 8 716 145 028C 11/98