Bosch 24I RSF 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

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.

2. General Information1. Installation Regulations

2

1. Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . Page 2 10. Electrical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 9

2. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2 11. Installing the Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 11

3. Data Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4 12. Commissioning the Appliance . . . . . . . . . . . . . . . . . . . . Page 16

4. Siting the Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5 13. Instructions to the User . . . . . . . . . . . . . . . . . . . . . . . . . . Page 18

5. Siting the Flue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6 14. Inspection and Service. . . . . . . . . . . . . . . . . . . . . . . . . . . Page 18

6. Air Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6 15. Replacement of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 20

7. Sealed System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 7 16. Conversion Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . Page 23

8. Open Vent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 7 17. Operational Flow Diagrams. . . . . . . . . . . . . . . . . . . . . . . Page 24

9. Hot Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 8 18. Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 26

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19. Component Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 34

Contents

Fig. 1. Water flow diagram.

Bi-thermal
gas to water
heat
exchanger

Automatic
air vent

Domestic
water flow
switch

Pressure
relief valve

Safety

discharge

Domestic
hot water

out

Domestic

cold

supply

C.H.

return

Sealed
system
expansion
vessel

Circulating
pump

Fixed
by-pass

C.H.

flow

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/m

3

(1014 Btu/ft3) or 1.07 m3/h (37.8

ft

3

/hr) of propane with a calorific value of 95.65 MJ/m3(2568

Btu/ft

3

). 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.

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.

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.

3

Total length of gas supply pipe Pipe size

(metres) (Ømm)

36912

Propane

Gas Discharge

1.5 – – – 15

Rate

8.0 5.2 4.2 3.6 22

(m

3

/hr)

15.9 8.8 8.5 7.2 28

Natural Gas

8.7 5.8 4.6 – 22

18.0 12.0 9.4 – 28

Gas

Discharge

Rate

(m3/hr)

The data plate is fixed to the inner casing cover.

3. Data Tables

4

NOMINAL BOILER RATINGS

OUTPUT INPUT (Net).

BURNER SETTING

GAS RATE

PRESSURE

kW Btu/h kW Btu/h m bar. in. wg. m

3

/h ft3/h

NATURAL GAS

7.5 (25,600) 9.60 (32,750) 1.0 0.4 1.01 35.7

23.4 (80,000) 26.05 (88,890) 13.6 5.4 2.76 97.5

PROPANE

7.5 (25,600) 9.60 (32,750) 3.5 1.4 0.39 13.9

23.4 (80,000) 26.05 (88,890) 35.0 14.0 1.07 37.8

Table 1

AVAILABLE PUMP HEAD

BOILER OUTPUT HEAD MIN. FLOW RATE

TEMPERATURE RISE

ACROSS HEATING

kW Btu/h Metres Feet L/min. Gal/Min. FLOW AND RETURN

7.5 (25,600) 6.0 19.7 9.8 2.2
11°C (20°F)

23.4 (80,000) 2.6 8.5 30.5 6.7

Table 3

SPECIFICATIONS

CENTRAL HEATING FLOW FITTING 22mm Compression
CENTRAL HEATING RETURN FITTING 22mm Compression
COLD WATER MAINS INLET FITTING 15mm Compression
DOMESTIC HOT WATER OUTLET FITTING 15mm Compression
GAS INLET FITTING Rc

1

⁄2inch
PRESSURE RELIEF VALVE DISCHARGE FITTING 15 mm Copper Tube
OVERALL HEIGHT (including flue turret) 960mm (37.8 inches)
CASING HEIGHT 800mm (31.5 inches)
CASING WIDTH 450mm (17.7 inches)
CASING DEPTH 360mm (14.2 inches)
WEIGHT(including water) 44 kg
INSTALLATION WEIGHT 39 kg
PACKAGED WEIGHT 44 kg
PRIMARY WATER CAPACITY 3.0 litres
MAXIMUM COLD SUPPLY PRESSURE 10 Bar (150 psi)
MINIMUM COLD SUPPLY PRESSURE (working) for max. hot water flow 0.9 bar
MINIMUM COLD SUPPLY PRESSURE (working) to operate appliance 0.1 bar
MAXIMUM CENTRAL HEATING FLOW TEMPERATURE Nominally 82°C (180°F)
OUTPUT TO DOMESTIC HOT WATER Modulating 7.5 to 23.4 kW
OUTPUT TO CENTRAL HEATING Modulating 7.5 to 23.4 kW
MAXIMUM DOMESTIC HOT WATER FLOW RATE (from the appliance) Nominally 8.0 ± 15% litres/min
EQUIVALENT DOMESTIC HOT WATER FLOW RATE TO GIVE A TEMP RISE Nominally 11.2 litres/min

OF 30°C (SPECIFIC RATE)

Table 4

FLUE DETAILS

HORIZONTAL FLUE (Side or Rear) mm inches

FLUE DIAMETER 100 3.9
WALL HOLE DIAMETER 110 4.25
WALL HOLE DIAMETER (using internal flue fitting kit) 150 5.9
STANDARD FLUE – MINIMUM LENGTH 127 5.0
STANDARD FLUE – MAXIMUM LENGTH 350 14.0
EXTENDED FLUE – MAXIMUM LENGTH 2500 98.4

Table 2.

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.

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.

4. Siting The Appliance

5

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

Fig. 2. Appliance casing dimensions and

required clearances.

Side view

360mm 600mm*

20mm*

200mm* 10mm*

* Space required for installation and servicing

Front view

450mm

10mm*

225mm

180mm

800mm

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).

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.

6.5 Refer to BS 6798 and BS 5440:2 for additional information.

6. Air Supply5. Siting The Flue

6

L

L

K

K

F

F

G

A

M

EJF

HI

D

G

A

B,C

Fig. 3. Siting of the flue terminal.

TERMINAL POSITION MIN. DISTANCE TERMINAL POSITION MIN. DISTANCE

A– directly below an openable window or I– From a terminal facing a terminal 1200mm (47in.)

other opening e.g. air brick. 300mm (12in.) J– From an opening in a car port (e.g. door
B– Below gutters, soil pipes or drain pipes. 75mm (3in.) window) into dwelling. 1200mm (47in.)
C– Below eaves. 25mm (1in.) K– Vertically from a terminal on the same
D– Below balconies or car port roof. 25mm (1in.) wall. 150mm (6in.)
E– From vertical drain pipes and soil pipes. 25mm (1in.) L– Horizontally from a terminal on the same
F– From internal or external corners. 25mm (1in.) wall. 300mm (12in.)
G– Above ground, roof or balcony level. 300mm (12in.) M– From door, window or air vent (achieve
H– From a surface facing a terminal. 600mm (24in.) where possible). 150mm (6in.)

Above the Turret 20mm
In front 250mm
Below 200mm
Right-hand side 75mm
Left-hand side 75mm

POSITION OF AIR FROM AIR DIRECT

AIR VENTS THE ROOM FROM OUTSIDE

HIGH LEVEL 270cm

2

135cm

2

LOW LEVEL 270cm

2

135cm

2

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.

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.

The appliance is

NOT suitable for connection to an open vented

system.

8. Open Vent System

7. Sealed System

7

Fig. 4. Sealed primary water system.

Automatic
air vent

Expansion
vessel

Hot water
out

Water main

Heating
return
Heating
flow

Radiator
valve

Lockshield
valve

Mains cold

water

British Standard
stop valve.
Fixed spindle type

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

Valve

Non-return

Valve

Test cock

Hose union

Stop cock

Temporary Hose

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/in

2

).

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.

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

8

Fig. 5. 230V room thermostat connections.

Fig. 6. 230V programmer connections.

RN RI

X2

Remove link

Neutral

Switched live

Live

RL

CN

Motor

CI

X2

Neutral

Switched live

Live

CL

Remove link

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

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

9

Fig. 7. Mains electricity connections.

Brown

Strain relief clamp

Blue

Brown

Green/yellow

Green/yellow

Programmer and room thermostat

strain relief clamps

230V

X1

X2

NL

Blue

Fig. 8. Wiring diagram.

Safety

limit
stat

DHW
sensor

CH

sensor

Gas
valve

Pump

Main

Reg

Flow
switch

Air

pressure

switch

Spark

transformer

Mains in

2 pink

2 Blue

2 Red

2 Yellow

2 Orange

Brown

Blue

Blue

Brown

Blue

Brown

Brown

Blue

Link Link

X1

X2

X3

X6

X5 X4

Flame sense
electrode

Spark
electrode

Fan

Brown

White

Green

3 COM

1 NC

2 NO

10

Fig. 9. Functional flow diagram.

F1 2ATHRC

F2 1.25AT

Optional links

SparkFlame sense

Outputs Inputs

Mains
indicator

Modulating

valve

Overheat stat

X6 Pins 8 & 9

X6 Pins 15 & 16

X6 Pins 5,6 & 7

X6 Pins 1 & 2

X6 Pins 19 & 20

X6 Pins 3 & 4

Flow signal

CH temp. sensor

DHW temp. sensor

CH control POT

Air pressure switch

MAINS
PROGRAMMER/CLOCK

FULL SEQUENCE

CONTROLLER

GAS VALVE

LOW VOLTAGE

ELECTRONICS

(Microcontroller)

ROOM STAT

X1

X2

321

1

2

3

4

6

5

RL1

X3

Pin 1 X3 Pin 2

X4 Pin 3

X5 Pin 3

X5 Pin 2X5 Pin 1

X4 Pin 1

FAN

PUMP

RL3

RL4

N

N

N

N

L

Technical Helpline.

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.

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.

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.

11. Installing The Appliance

11

Fig. 10. Appliance mounting plate and flue position.

Fig. 11. Marking out the side flue position.

Mounting wall

Rear flue hole
110mm dia.
(150mm dia. for
internal fixing)

Side flue hole
110mm dia.
(150mm dia. for
internal fixing)

Appliance
casing

Mounting
plate

Fixing holes
(alternatives)

Mounting wall

Mounting
plate

222mm

Side wall

166mm

740mm

400mm

Rear flue position Side flue position

60mm

Appliance
casing

Rear flue hole
110mm dia.
(150mm dia. for
internal fixing)

Mounting wall

Side wall

222mm

166mm