Glow-worm Hideaway 120B Instructions For Use Manual

Hepworth Heating Ltd.,

Nottingham Road, Belper, Derbyshire. DE56 1JT

General/Sales enquiries:

Tel: [phone] Fax: [phone]

One Contact Local Service

Customer Services:
Tel: [phone]
Fax: [phone]

221765B.11.00

All replacement parts
All labour charges
All call-out charges

Thank you for installing a new Glow-worm appliance in your home.

Glow-worm appliances' are manufactured to the very highest standard so we are pleased

to offer our customers' a Comprehensive First Year Guarantee.

In the centre pages are to be found your Guarantee Registration Card, which we recommend you complete and

return as soon as possible.

If this card is missing you can obtain a copy or record your registration by telephoning the Heatcall Customer

Service number 01773 828100.

Our Guarantee gives you peace of mind plus valuable protection against breakdown by covering the cost of:

Guarantee Registration

Balanced Flue Boiler

This is a Cat I2H Appliance

BS 6332
BS 5258

Reference in these instructions to British Standards and Statutory

Regulations/Requirements apply only to the United Kingdom.

For Ireland the rules in force must be used.

The instructions consist of three parts, User, Installation and Servicing Instructions, which includes the Guarantee Registration

Card. The instructions are an integral part of the appliance and must, to comply with the current issue of the Gas Safety

(Installation and Use) Regulations, be handed to the user on completion of the installation.

T o be left with the user

Instructions for Use

Installation and Servicing

G.C. No. 41 313 28

REGISTER YOUR GLOW-WORM APPLIANCE

FOR 1ST YEAR GUARANTEE PROTECTION

CALL 0208 247 9857

120B

Hideaway

1388

❏

✔

❏

✔

❏

✔

2

221765B

Important Information

Introduction 3
Lighting the Boiler 4

General Data 1 5
Water Systems 2 7
Flue and Ventilation 3 8
Installation 4 9
Casing Location / Fitting 5 12
Electrical Wiring 6 14
Commissioning 7 15

Servicing 8 17
Replacement Parts 9 18
Fault Finding 10 21
Spare Parts 11 24

CONTENTS DESCRIPTION SECTION PAGE No.

INSTRUCTIONS

FOR USE

INSTALLATION

INSTRUCTIONS

SERVICING

INSTRUCTIONS

Testing and Certification

This boiler is tested and certificated for safety and performance. It is therefore important that no alteration is made to the boiler, without
permission, in writing, from Hepworth Heating Ltd.

Any alteration not approved by Hepworth Heating Ltd., could invalidate the certification, boiler warranty and may also infringe the
current issue of the Statutory Requirements, see Section 1.4.

CE Mark

This boiler meets the requirements of Statutory Instrument No. 3083 The boiler (Efficiency) Regulations, and therefore is deemed
to meet the requirements of Directive 92/42/EEC on the efficiency requirements for new hot water boilers fired with liquid or gaseous
fuels.

Type test for purposes of Regulation 5 certified by: Notified body 0086.
Product/productioncertifiedby: Notified body 0086.
The CE mark on this appliance shows compliance with:

1. Directive 90/396/EEC on the approximation of the laws of the Member States relating to appliances burning gaseous fuels.

2. Directive 73/23/EEC on the harmonization of the Laws of the Member States relating to the electrical equipment designed
for use within certain voltage limits.

3. Directive 89/336/EEC on the approximation of the Laws of the Member States relating to electromagnetic compatibility.

INFORMATION FOR THE INSTALLER AND SERVICE ENGINEER.

Under Section 6 of The Health and Safety at Work Act 1974, we are required to provide information on substances hazardous to
health.

CERAMIC FIBRE/INSULATION PADS, GLASSYARN.

These can cause irritation to skin, eyes and the respiratory tract. If you have a history of skin complaint you may be susceptible to
irritation. High dust levels are usual only if the material is broken. Normal handling should not cause discomfort, but follow normal
good hygiene and wash your hands before eating, drinking or going to the lavatory. If you do suffer irritation of the eyes or severe
irritation to the skin seek medical attention.

THERMOSTATS

These contain very small amounts of xylene in the sealed phial and capillary. If broken, under normal circumstances the fluid does
not cause a problem, but in case of skin contact, wash with cold water. If swallowed drink plenty of water and seek medical attention.

3

221765B

Instructions for Use

General Information

Please read these instructions and follow them carefully for the
safe and economical use of your boiler.

The boiler is automatic in operation, once the pilot has been lit
and the controls set.

Glow-worm Hideaways are central heating boilers, to provide
heating and if required, an indirect domestic hot water supply.

Important Notice

This boiler is for use only on G20 gas.

Gas Safety (Installation and Use) Regulations

In your own interests and that of safety, is the law that ALL gas
appliances are installed by a competent person in accordance
with the current issue of the above regulations.

Warning

Make sure that nothing obstructs the rear side grille or clearances.
See page 4 for minimum clearances.

Boilers Installed in a Compartment

If the boiler is fitted in a compartment, cupboard etc., do not
obstruct the purpose built compartment vents or the grille on the
boiler.

Do not use the compartment for storage purposes.

Maintenance

To ensure the continued efficient and safe operation of the boiler
it is recommended that it is checked and serviced as necessary
at regular intervals. The frequency of servicing will depend upon
the particular installation conditions and usage, but in general
once a year should be enough.

It is the law that servicing must be carried out by a competent
person.

If this appliance is installed in a rented property there is a duty
of care imposed on the owner of the property by the current
issue of the Gas Safety (Installation and Use) Regulations,
Section 35.

To obtain service please call your installer or Heatcall (Glow­worm’s own service organisation) using the telephone number
given on the front panel.

Please be advised that the ‘Benchmark’ logbook should be
completed by the installation engineer on completion of
commissioning and servicing.

All CORGI Registered Installers carry a CORGI ID card, and
have a registration number. Both should be recorded in your
boiler Logbook. You can check your installer is CORGI registered
by calling CORGI direct on :- 01256 372300.

Boiler Electrical Supply

WARNING. This boiler must be earthed.
The boiler must only be connected to a 230V~50Hz supply

protected by a 3A fuse, maximum.
All wiring must be in accordance with the current issue of

BS7671.
Heat resistant flexible cable having a conductor size of 0.75mm

2

,

to the current issue of BS6500 Table 16 must be used.

To Connect an Electrical Plug

The standard colours of three core flexible cable are,
Brown - live, Blue - neutral, Green and Yellow - earth.
As the markings on your plug may not correspond with these

colours, continue as follows:
The Blue cable must be connected to the terminal marked “N”

or “Black”.
The Brown cable must be connected to the terminal marked “L”

or “Red”.
The Green and yellow cable must be connected to the terminal
marked “E” or “Green” or the earth symbol

.

To Light the Boiler

WARNING. If the pilot light goes out for any reason, do not
attempt to relight until 3 minutes have elapsed.

Remove the door by pulling forwards with the fascia at the top.
Lift up to disengage from the bottom side lugs.

Refer to diagram 1 to identify controls.
Check that the mains electrical supply to the boiler is switched

OFF.

SETTING
POINT

GAS
CONTROL
KNOB 'A'

THERMOSTAT
CONTROL
KNOB 'B'

GAS CONTROL KNOB
= OFF
= PILOT/IGNITION
= MAIN BURNER

E

9009

PIEZO IGNITION
BUTTON 'C'

Diagram 1

SETTING
POINTS

4

221765B

Instructions for Use

Push in slightly and turn gas control knob “A” clockwise until
is against its setting point.

Turn thermostat control knob “B” anticlockwise until “O” is
against its setting point.

Push in slightly and turn gas control knob “A” anticlockwise until

is against its setting point, then depress fully and hold in.

Push in and release piezo ignition button “C” until the pilot
burner lights.

Air may be present in the supply pipe so the lighting of the pilot
may need to be repeated until all the air has been expelled.

When the pilot is alight, view through window “E”, keep gas
control knob “A” fully pushed in for about 15 seconds, then
release.

If the burner fails to stay alight, wait 3 minutes, then repeat the
lighting procedure only now keep control knob “A” pushed in for
a little longer before releasing.

Press in and turn gas control knob “A” anticlockwise until

is

against its setting point.
If the gas control knob “A” is turned to

, a safety lock prevents
it being turned on again for a short period. No attempt should
be made to relight the pilot until 3 minutes have elapsed.

Make sure that the pilot is alight and stable then switch on the
electrical supply.

Set any system controls to “ON” or “HIGH”.
Turn the boiler thermostat knob “B” clockwise until “MAX” is

against its setting point and the main burner will light. Adjust
thermostat to required setting between “MIN” and “MAX”.
“MAX” is about 82

o

C (180oF).

Refit the door by locating the hooked runner at the bottom into
the slot in the side panels and pushing onto the studs.

To Turn the Boiler Off

For short periods, turn the boiler thermostat control knob “B”
anticlockwise to “O”. The pilot will stay alight. To relight the
main burner turn thermostat control knob “B” clockwise to the
desired setting between “MIN” and “MAX”.

For longer periods, depress slightly and turn gas control knob
“A” fully clockwise until

is against its setting point. Turn
thermostat control knob “B” anticlockwise to “O”. Isolate the
boiler from the electrical supply. Follow full lighting procedure
to relight. Refer also to “Protection Against Freezing”.

Gas Leak or Fault

If a gas leak fault exists or is suspected the boiler must be turned
off, including the electrical supply and must not be used until the
fault has been put right. Advice/help should be obtained from
the local gas undertaking or your installation/servicing company.

Protection Against Freezing

If the boiler is to be out of use for any period of time during severe
weather conditions we recommend the whole system including
the boiler, be drained off to avoid the risk of freezing up. If an
immersion heater is fitted to the hot water cylinder make sure it
is switched off.

Sheet Metal Parts

WARNING. This boiler contains metal parts (components) and
care should be taken when handling and cleaning, with particular
regard to edges.

Cleaning

Keep the casing clean by wiping it occasionally with a damp
soapy cloth and dry with a polishing cloth.

Do not use abrasive cleaners.

Replacement Parts/Boiler Identification

If replacement parts are required apply to your local supplier.
Please quote the name of the boiler and its serial number which
can be found on the data label, positioned on the boiler top, to
the rear of the inclined flueway cleaning door.

Clearances

Minimum clearances must be left around the boiler as shown in
diagrams 1.3, 1.4 and 1.5.

5

221765B

General Data

ABCDE✝FG H J K L M N P
mm 474 214 558 294 359 533 3 300 445 121 156 664 398 398
in. 1811/1681/222 111/2141/8211/8113/4171/243/461/8261/8155/8155/

8

RANGE RATING

NOMINAL

kW

HEAT INPUT
(GROSS)

Btu/h

37.0 40.55 44.13

126,250 138,370 150,560

min medium max

BURNER

mbar

SETTING
PRESSURE

in.w.g

(HOT)

9.8 11.7 13.8

3.9 4.7 5.5

NOMINAL

kW

HEAT
OUTPUT

Btu/h

29.31 32.24 35.17

100,000 110,000 120,000

205746

INJECTOR

GENERAL DIMENSIONS - given in millimetres (Approx. inches)

Diagram 1.1

1071

✽ Refer to BOILER CASING
HEIGHT diagram

M

D

C

C

L

✝ A SPECIAL TOP CASING
TO SUIT 600mm (23

5

/

8

in.)

WORKTOPS IS AVAILABLE

WATER CONNECTIONS

Rc1 (1in. B.S.P.T.)

WATER CONNECTIONS Rc1 reduced
with DISTRIBUTOR TUBE to
Rc

3

/

4

(

3

/

4

in. B.S.P.T.) (pumped return)

GAS CONNECTION

Rc

1

/

2

(

1

/

2

in. B.S.P.T.)

✝ F(MIN.)

L

H

A

L

C

B

✽

N

P

C

L

E

J

K

G(MIN.)

G(MIN.)

Important Notice

This boiler is for use only on G20 gas.
Wherever possible, all materials, appliances and components

used shall comply with the requirements of applicable British
Standards.

Where no British Standard exists, materials and equipment
should be fit for their purpose and of suitable quality and
workmanship.

1.1 Data

Weight of boiler 147.0kg (324lb)
Water content 11.7litre (2.57gall)
Gas connection Rc1/2

1

/2inBSP
Water connection Rc1 1 in BSP
Electrical supply 230V ~ 50Hz fused 3A
Burner Aeromatic (2 off)

All dimensions are given in millimetres, except as noted.
The Seasonal Efficiency Domestic Boilers UK (SEDBUK)

is 72.0%.
The value is used in the UK Government’s Standard Assessment

Procedure (SAP) for energy rating of dwellings. The test data
from which it has been calculated have been certified by B.S.I.

1.2 Range Rating

This boiler is range rated and may be adjusted to suit individual
system requirements.

The Tables give the appropriate settings and ratings.
The boiler heat input is factory preset to its maximum rating.

This should be adjusted to suit individual system requirements.
The arrow indicator, from the loose items pack, should be stuck

on the data label to indicate the setting.

1.3 Sheet Metal Parts

WARNING. When installing or servicing this boiler, care should
be taken to avoid any possibility of personal injury when
handling sheet metal parts.

1.4 Statutory Requirements

The installation of this boiler must be carried out by a competent
person in accordance with the relevant requirements of the
current issue of:

Manufacturer’s instructions, supplied.
The Gas Safety (Installation and Use) Regulations, The Building

Regulations, The Bye-laws of the Local Water Company, The
Building Standards (Scotland) Regulations, (applicable in
Scotland), The Health and Safety at Work Act, Control of
Substances Hazardous to Health, Electricity at Work Regulations
and any applicable local regulations.

Detailed recommendations are contained in the current issue of
the following British Standards and Codes of Practice:

BS6798, BS5440 Part 1 and 2, BS5546, BS5449 Part 1,
BS6700, BS6891, BS7478, BS7593, BS7671.

Manufacturers instructions must in not be taken as overriding
statutory requirements.

6

221765B

BOILER CASING HEIGHT(S)

Diagram 1.2

MAX.900 (35

1

/

2

in.)
MID. 890 (35in.)
MIN. 860 (34in.)

MAX.867 (34

1

/

8

in.)

MID. 857 (33

3

/

4

in.)

MIN. 827 (32

1

/

2

in.)

BOILER
WITH TOP
CASING

BOILER
WITHOUT
TOP CASING

BOILER CASING ALTERNATIVE
HEIGHT POSITIONS

MIN.

MAX.

MIN.

MAX.

MID.

MID.

To
floor
level

FLOOR
LEVEL

0982

General Data

Diagram 1.4

MINIMUM CLEARANCES
UNDER WORKTOP, FIXTURES

0865

10
(

3

/

8

in.)

10
(

3

/

8

in.)

3 (

1

/

8

in.)

BOILER

WITH

TOP

CASING

BOILER

WITHOUT

TOP

CASING

CUPBOARD

CUPBOARD

CUPBOARD

10 (

3

/

8

in.)

WORKTOP OR FIXTURE

10
(

3

/

8

in.)

1387

WORKTOP

10
(

3

/

8

in.)

10
(

3

/

8

in.)

BOILER

BOILER

5
(

3

/

16

in.)

CUPBOARDS

Diagram 1.3

MINIMUM CLEARANCES
LEVEL WITH WORKTOP

494 MIN.

(19

7

/

16

in.)

494 MIN.

(19

7

/

16

in.)

1.5 B.S.I. Certification

This boiler is certificated by B.S.I. for safety and performance.
It is, therefore, important that no alteration is made to the boiler,
without permission, in writing, from Hepworth Heating Ltd.

Any alteration not approved by Hepworth Heating Ltd., could
invalidate the B.S.I. certification, boiler warranty and could also
infringe the Statutory Requirements.

1.6 Gas Supply

The gas installation shall be in accordance with the current
issue of BS6891.

The supply from the governed meter must be of adequate size
to provide a steady inlet working pressure of 20mbar (8in wg) at
the boiler.

On completion test the gas installation using the pressure drop
method and suitable leak detection fluid, purge in accordance
with the current issue of BS6891.

1.7 Electrical

WARNING. This boiler must be earthed.
The electrical installation must be carried out by a competent

person.
All external components shall be of the approved type and shall

be connected in accordance with the current issue of BS7671
and any local regulations which apply.

Connection of the boiler and any system controls to the mains
supply should be through an unswitched shuttered socket outlet
and 3A fused 3 pin plug both to the current issue of BS1363.
Alternatively, a 3A fused double pole isolating switch may be
used, having a minimum double pole contact separation of
3mm, serving the boiler and system controls only.

Heat resistant flexible cable of at least 0.75mm

2

(24/0.20mm)
to BS6500 Table 16, must be used for all connections within the
boiler casing.

1.8 Boiler Location

This boiler is not suitable for outside installation.
The boiler may be installed in any room, although particular

attention is drawn to the requirements of the current issue of
BS7671 with respect to the installation of the boiler in a room
containing a bath or shower. Any electrical switch or boiler
control utilising mains electricity should be so situated that it
cannot be touched by a person using the bath or shower. The
electrical provisions of the Building Standards (Scotland)
Regulations are applicable to such installations in Scotland.

The boiler must stand on a level floor, conforming with the local
authority requirements and building regulations. The base
temperature is within the requirements of BS5258. The boiler
may be stood on a wooden floor but a metal base plate is
required to protect plastic tiles and similar floor coverings.

Suitable clearance needs to be available at the sides of the
boiler to facilitate direct connection of pipework and making
good around the flue assembly. The actual clearance required
will vary with site conditions.

The casing can be fitted to the boiler at various heights. The top
casing can be discarded, if preferred, when fitting the boiler
under a worktop or fixture. See diagram 1.2.

When the boiler is to be installed level with work surfaces etc.,
minimum clearances should be provided as shown in diagram

1.3. Work tops which overhang the cupboard sides almost in
contact with the casing top, require a larger minimum air gap.
Flush sided fixtures require the same overall minimum space
but can have a reduced air gap on one side.

Boilers to be installed under work tops or fixtures, with or without
the casing top fitted, should be positioned to provide minimum
clearances as shown in diagram 1.4.

To facilitate minimum clearances it may be necessary to modify
the kitchen units or fixtures, depending upon which type of
connections are used.

A front access clearance should be provided as shown in
diagram 1.5.

The minimum gap behind the top casing is as shown in diagram

1.1. The boiler can be sited further away from the wall if required
to align with kitchen units etc. Refer to Section 3.5.

Combustible wall material must be 25mm (1in) away from flue
components. Refer to Section 3.5.

7

221765B

FRONT CLEARANCE

Diagram 1.5

0906

700 (27

1

/

2

in.)

BOILER

WALL OR
FIXTURE

1 General Data

2 Water Systems

Diagram 2.1

0869

27metre
Max.

PUMP

To Heating
Circuit

INDIRECT
CYLINDER

22mm VENT

15mm COLD FEED

REFER TO BS 5546

28mm

Distributor tube in
pumped return
connection

BOILER
C

L

DRAIN OFF
COCK

Diagram 2.2

FULLY PUMPED SYSTEM
(DIAGRAMMATIC)

0870

1 metre
MIN.
27metres
MAX.

PUMP

To Heating
Circuit

TO INDIRECT
CYLINDER

22mm VENT

15mm
COLD FEED

Distributor tube in
pumped return
connection

BOILER
C

L

DRAIN OFF
COCK

A special top casing, part No. 424820, can be purchased to
enable the boiler casings to be arranged flush with 600mm (23

5

/

8

in) deep work tops and kitchen units.

Where the installation of the boiler will be in an unusual location,
special procedures are necessary, the current issue of BS6798
gives guidance on this.

A compartment used to enclose the boiler must be designed
and constructed specifically for this purpose. An existing
cupboard or compartment modified for the purpose may be
used. Details of essential features of cupboard design are
given in the current issue of BS6798.

If the boiler is to be installed in a compartment, make sure that
nothing will obstruct the openings/vents in the compartment.

1.9 Heating System Controls

The heating system should have installed: a programmer and
room thermostat controlling the boiler.

Thermostatic radiator valves may be installed in addition to the
room thermostat.

2.1 Water Pressure Head

This boiler shall only be connected to a cistern supply, with a
minimum head of 1 metre (3ft) and a maximum of 27 metres
(90ft) and having an open vent in the system.

The boiler must not be connected to a sealed water system.

2.2 Inhibitor

Attention is drawn to the current issue of BS5449 and BS7593
on the use of inhibitors in central heating systems.

If an inhibitor is to be used in the system, contact should be
made with an inhibitor manufacturer so they can recommended
their most suitable product.

When using in an existing system take special care to drain the
entire system, including the radiators, then thoroughly cleaning
out before fitting the boiler, whether or not adding an inhibitor.

2.3 Gravity Domestic and Pumped Heating

It is recommended that a cylinder thermostat is used to prevent
the stored water temperature becoming unnecessarily high.

The primary flow and return must be 28mm. The
installation must comply with the current issue of BS5546 and
BS6700, see diagram 2.1.

If the above conditions cannot be met, it is suggested that a fully
pumped system be used.

Fully Pumped System

Where a single pumped, flow and return is taken from the boiler,
refer to diagram 2.2.

2.5 Circulation Pump

The pump should be set to give a temperature difference of
11oC (20oF) across the system. At the appropriate flow rate the
resistance through the boiler can be found from the pressure
loss graph, diagram 2.3.

If possible use a pump with integral valves, if not fit valves as
close as possible each side of the pump.

Note: If the pump is to be fitted inside the boiler casing a heat
shield kit is required. Kit No. 425839.

Note: For further information, see The Building Regulations
1991 - Conservation of fuel and power, 1995 edition - Appendix
G, table 4b.

8

221765B

2 Water Systems

3 Flue and Ventilation

PRESSURE LOSS OF BOILER

Diagram 2.3

1370

1.0

0.8

0.6

0.4

0.2

0

30

20

10

0

0

10

20 30

40 50

FLOW RATE (LITRES/MINUTE)

WATER PRESSURE LOSS

(metre HEAD OF WATER)

WATER PRESSURE LOSS

(INCHES HEAD OF WATER)

1.2
40

012345678 109

FLOW RATE (GALLON/MINUTE)

2.6 Cylinder

For all systems supplying domestic hot water the cylinder must
be indirect and to the appropriate British Standard.

2.7 Safety Valve

A safety valve need not be fitted to an open vented system.

2.8 Draining Tap

A drain tap must be provided at the lowest points of the system
which will allow the entire system, including the boiler and
domestic hot water cylinder to be drained. Drain taps shall
comply with the current issue of BS2879.

3.1 Flue

Detailed recommendations for flues are given in the current
issue of BS5440 Part 1.

The boiler must be installed so that the flue terminal is exposed
to the external air. It is important that the position allows the free
passage of air across it at all times.

3.2 Terminal Positioning

The minimum acceptable spacings for the terminal to
obstructions, other terminals and ventilation openings are given
in diagram 3.1.

Car port or similar extensions of a roof only, or roof and one wall,
require special action with regard to openings, doors and
windows under the roof. Care is required in protecting plastic
roofs. If the car port consists of a roof and two or more walls
seek advice form the local gas undertaking.

Where the terminal is within 850mm (34in) below plastic guttering,
or within 450mm (18in) of painted eaves or gutter an aluminium
shield 1.5 metres (5ft) long should be fitted to the underside and
immediately beneath the guttering.

The air inlet/products outlet duct and the terminal of the boiler
must not be closer than 25mm (1in) to combustible material.

3.3 Timber Frame Buildings

If the boiler is to be installed in a timber frame building it should
be fitted in accordance with the Institute of Gas Engineers
document IGE/UP/7/1998. If in doubt seek advice from the local
gas undertaking or Hepworth Heating Ltd.

3.4 Terminal Guard

A terminal guard is required if persons could come into contact
with the terminal or the terminal could be subject to damage.

If a terminal guard is required, it must be positioned to provide
a minimum of 50mm clearance from any part of the terminal and
be central over the terminal.

A suitable guard is available from

Tower Flue Components Ltd.,
Morley Road,
Tonbridge,
Kent.
TN9 1RA

reference type “F”

3.5 Flue Duct Length

The flue lengths quoted below allow the minimum rear clearance
of 3mm (1/8inch) behind the boiler, although the boiler can be
installed further away from the inside wall. In such cases any
extra clearance behind the boiler must be added to the wall
thickness to obtain the flue duct length.

Check the wall thickness/flue duct length where the boiler is
fitted. Flues available are:
Standard pack - 280 to 410mm (11 to 16inches).
Short pack - 150 to 280mm (6 to 11inches)

The short flue pack, part No.425504 is available to order.
Standard pack is part No.424886.

3.6 Room Ventilation

The boiler is room sealed and does not require the room or
space containing it to have permanent air vents.

9

221765B

Under Car Port etc.

H,I

J

D

F

K

A

A

F

G

E

A
G

G

B,C

B,C

F

F

K

K

K

C

L

L

G

G

3 Flue and Ventilation

1112

A DIRECTLY BELOW AN OPENABLE mm

WINDOW, AIR VENT, OR ANY
OTHER VENTILATION OPENING 300

B BELOW GUTTER,DRAIN/SOIL PIPE 300
C BELOW EAVES 300
D BELOW A BALCONY OR CAR PORT 600

E FROM VERTICAL DRAIN PIPES

AND SOIL PIPES 75

F FROM INTERNAL OR EXTERNAL

CORNERS 600

G ABOVE ADJACENT GROUND OR

BALCONY LEVEL 300

H FROM A SURFACE FACING

THE TERMINAL 600

I FACING TERMINALS 600
J FROM OPENING (DOOR/WINDOW)

IN CARPORT INTO DWELLING 1200

K VERTICAL FROM A TERMINAL 1500
L HORIZONTALLY FROM A TERMINAL 300

MINIMUM SITING DIMENSIONS FOR
BALANCED FLUE TERMINALS

Diagram 3.1

FROM
OUTSIDE

COMPARTMENT AIR VENT TABLE

COMPARTMENT
VENTILATION
REQUIREMENTS

203cm2 31in2203cm231in

2

VENTILATION
FROM ROOM
OR SPACE

406cm262in2406cm262in

2

HIGH LEVEL LOW LEVEL

VENT AREA VENT AREA

4 Installation

POSITION MINIMUM

SPACING

3.7 Cupboard/Compartment Ventilation

Where the boiler is fitted in a cupboard or compartment, the high
and low level permanent air vents must have effective areas in
accordance with the Compartment Air Vent Table.

Both the high level and the low level air vents must communicate
with the same room, or must both be on the same wall to outside
air.

Before fixing the boiler make sure that the location selected is
in accordance with the requirements of Section 1.8.

4.1 Unpacking

Remove the packaging and then the boiler from its pallet by
removing the screws.

The boiler casing panels are packed separately within the main
carton. They are designed to enable gas and water connections
to be made before fitting the casing.

The casing brackets, distributor tube and loose items, in a
plastic bag, are packed in the corner fitment.

4.2 Casing Brackets

Fit the two upper and two front casing brackets as shown in
diagram 4.1 using eight of the No.8 screws.

Push the captive nuts, supplied loose, on to the casing brackets
as shown in diagram 4.1.

4.3 Planning Water Connections - Gravity
Domestic and Pumped Heating.

It is important that all connections are made as shown in
diagram 4.2.

Heating flow, either one of the two upper front connections may
be used.

Domestic gravity flow, any one of the three remaining upper
connections may be used.

Heating return, the water distributor tube MUST be fitted into
either one of the front lower connections on all installations, see
diagram 4.3. The distributor tube is packed in the top fitment.

Domestic gravity return, any one of the three remaining lower
connections may be used for the gravity domestic hot water
return.

10

221765B

CASING BRACKETS FITTING

Diagram 4.1

4 Installation

0888

FRONT
CASING
BRACKET

No.8 SCREW (8)

CAPTIVE
NUT

UPPER CASING
BRACKET

CAPTIVE
NUT

DISTRIBUTOR TUBE

Diagram 4.3

1277

UPPER
MARKER

UPPER MARKER must
lie between the two outer
NOTCHES

DISTRIBUTOR
TUBE
must be in pumped
return connection

BOILER

Diagram 4.2

WATER CONNECTIONS - GRAVITY
DOMESTIC, PUMPED HEATING

ALTERNATIVE
HEATING
RETURN
With distributor
tube (not
shown)

ALTERNATIVE
HEATING FLOW
(Thermostat
phial and pocket
must be adjacent
to heating flow
connection)

DOMESTIC
GRAVITY
RETURN TO
ANY OF THE
3 REMAINING
LOWER CONNECTIONS

1309

DOMESTIC GRAVITY
FLOW TO ANY OF THE
3 REMAINING UPPER
CONNECTIONS

Fit plugs into all unused connections.
NOTE, if only limited clearance is available it is recommended

that the front tappings are used.

4.4 Planning Water Connections - Fully
Pumped Systems

It is important that all connections are made as shown in
diagram 4.4.

Flow, either one of the two upper front connections may be
used,

Return the water distributor tube MUST be fitted into the return
connection on all installations, see diagram 4.3. The distributor
tube is packed in the top fitment.

4.5 Thermostat Pocket

Fit the thermostat phial pocket, supplied in the top fitment, into
the front tapping adjacent to the heating flow connection and
plug the other front pocket connection.

Carefully unwind the thermostat capillary, insert phial fully into
the pocket and secure with the location washer behind the
retaining split pin, supplied in the loose items pack, see diagram

4.5.

4.6 Pump Within Boiler Casing

If the pump is to be fitted inside the boiler casing, see diagram

6.2, ensure that a heat shield kit is obtained and fitted
(Kit No. 425839).

The kit contains a flueway cleaning door with heat shield
(attached).

4.7 Positioning/Connecting Boiler

If the boiler casings are to fit flush with any kitchen units, the
distance the boiler is away from the wall must be measured and
dimension “G” increased by this amount, see diagram 1.1.

Having selected the position of the boiler, mark out and cut a
hole through the wall where the boiler is to be installed, to the
dimensions shown in diagram 4.6, after checking that sufficient
clearances will be left around the boiler as described in Section

1.8 “Boiler Location”, refer also to Section 3.5 “Flue Duct
Length”.

Fit the distributor tube, see diagram 4.2 or 4.4 for position, see
diagram 4.3 for alignment. Fit appropriate fittings and plugs into
the boiler connections.

IMPORTANT NOTE, do not route any pipes across the front of
the boiler thermostat pocket, the controls, burner supply pipe,
combustion chamber cover or flueway cleaning door. The gas
supply pipe should be run along the left-hand side of the boiler.

If the flue duct length necessitates the use of the flue extension
kit, that is 410 to 610mm (16 to 24inches) this will need to be
assembled before positioning the boiler. Read the separate
instructions supplied with the kit in conjunction with Section 4.8
“Balanced Flue Terminal”.

When suitable installation clearances are available, position
the boiler in readiness to connect pipework.

If suitable clearances are not available it will be necessary to
preplumb the gas and water connections before positioning the
boiler.

When the front tappings are used it is essential that any
pipework of fittings be assembled as shown in diagram 4.7., that
is, do not stick out more than shown.

11

221765B

4 Installation

Diagram 4.5

SECURING THE
THERMOSTAT PHIAL

1870

THERMOSTAT
CAPILLARY

LOCATION
WASHER

PHIAL
POCKET

RETAINING
SPLIT PIN

Diagram 4.4

WATER CONNECTIONS
FULLY PUMPED SYSTEMS

1310

ALTERNATIVE
FLOW
(Must be adjacent
to THERMOSTAT
PHIAL POCKET)

ALTERNATIVE
RETURN
With distributor
tube (not shown)

;;;

;;;

;;;

;;;

;

Diagram 4.6

PREPARED HOLE IN
THE WALL DIMENSIONS

BALANCED
FLUE DUCT
FROM BOILER

360
(14

1

/

4

in.)

485
(19 in.)

PREPARED
HOLE IN
THE WALL

3 (

1

/

8

in.)

MIN.

1384

360
(14

1

/

4

in.)

When using a rear tapping with Rc1 (1inch BSP) fittings for
28mm o.d. pipework it is recommended that a short nipple and
a R thread (BSP) copper elbow is used. If the pipework is
required to run back to the wall make sure that it will clear the
boiler air duct and, if working to minimum clearance does not
stick out too far from the boiler, see diagram 4.8.

Make the water connections to the system pipework.
Make the connection to the gas supply at the union gas service

cock. Test the complete gas installation for soundness and
purge in accordance with the current issue of BS6891.

When the boiler is finally positioned with the balanced flue duct
sticking out into the prepared hole in the wall and pipework
connected, make good to the inside of the wall face around the
boiler flue assembly.

4.8 Balanced Flue Terminal

Take the balanced flue assembly from its carton and remove the
four screws to release the outer baffle, see diagram 4.9.

Remove the four outer wire guards then pull off the inner baffle/
flue duct assembly.

Place the air duct assembly into the prepared hole, from the
outside, engaging it over the boiler air duct. Slide it until the wall
plate contacts the outer wall surface.

Cut and fix four pieces of the yellow tape provided into the four
corners at the joint in the air duct, running the tape on the inside
of the duct about 25mm (1inch) along the joint from the corners.
Fix four further pieces along the joints overlapping the corner
tapes, to make a good seal.

Cement around the wall plate to make good and provide a
weatherproof seal.

Refit the inner baffle/flue duct assembly over the boiler flue duct
and slide in until the baffle contacts the wire guards.

Seal the flue duct joint on the inside using the semi-transparent,
heat resistant, tape provided, in a similar way to the air duct
sealing procedure, making sure that a good seal is made at the
corners.

Refit the wire guards, outer baffle and secure with the screws
previously removed.

12

221765B

4 Installation

5 Casing Location / Fitting

Diagram 4.7

PIPEWORK CASING
CLEARANCES

57 MAX.
(2 1/4 in.)

'A'

VIEW ON ARROW 'A'

57 MAX.
(2 1/4 in.)

1524

BOILER

Diagram 4.8

REAR CONNECTION
PIPEWORK (28mm)

1525

57 MAX.
(2 1/4 in.)

VIEW ON
ARROW 'B'

'B'

BOILER

57 MAX.
(2 1/4 in.)

FOR
MINIMUM
CLEARANCE

Diagram 4.9

TERMINAL AND AIR DUCT ­STANDARD OR SHORT

1280

BOILER
AIR DUCT

WALL
PLATE

INNER BAFFLE/
FLUE DUCT
ASSEMBLY

AIR DUCT
ASSEMBLY

WIRE GUARDS

SCREW (4)

OUTER
BAFFLE

5.1 Side Vent Grille

One side vent grille is supplied with the boiler and can be fitted
at the rear of the left or right-hand side casing. The grille is fitted
on the opposite side to any pipework connections.

If required, fit the grille, using plastic pegs at the top and bottom,
see diagram 5.1, prior to fixing the side casing. The plastic pegs
are a tight fit, so they are best pushed home with a flat faced tool.

Discard the grille if water connections are made on both sides
of the boiler or if the boiler is screened by fixtures.

5.2 Side Casings

Fit each side casing by locating the lugs into the appropriate
slots in the boiler plinth, see diagram 5.2, depending on the
required casing height, see diagram 1.2.

Secure the side casings to the casing brackets at the front and
top.

13

221765B

SIDE VENT GRILLE

Diagram 5.1

SIDE VENT GRILLE
(If required, will fit to
left or right side casing)

PLASTIC PEG

SIDE CASING
(R.H. SHOWN)

0885

5 Casing Location / Fitting

TOP CASING FITTING

Diagram 5.3

STRAP FITTING (No top casing)

Diagram 5.4

0909

PEG POSITIONS IN TOP CASING
A = FRONT EDGE FLUSH
B = 10mm (3/8 in) FRONT OVERHANG

AB

AB

SIDE CASING

DOOR

BOILER SHOWN WITH
ROLLED EDGE FLUSH

SIDE CASING

DOOR

BOILER SHOWN WITH
SQUARE EDGE FLUSH

AB

AB

No.8 SECURING
SCREW

SIDE CASING
(R.H.)

CAPTIVE
NUT

STRAP fitted when no
top casing

B

A

B

A

SIDE
CASING
(L.H.)

TOP CASING

PLASTIC PEG (4)

0914

SIDE CASINGS FITTING

Diagram 5.2

MAX.

MIN.

MID.

MAX.

SIDE
CASING
(L.H.)

MAX.
MID.

MIN.

MIN.

BOILER PLINTH

FRONT
CASING
BRACKET

MID.

No. 8 SCREW
(4)

UPPER
CASING
BRACKET

LOCATING
LUG AND SLOTS

0886

5.3 Top Casing

The top casing can be fitted in four alternative positions, that is,
with either a rolled or square front edge, flush with the door or
overhanging it by 10mm (3/8inch).

Select either a rolled or square front edge and for a flush fitting
top casing, fit four plastic pegs into holes “A” as shown in
diagram 5.3. For overhanging top casing, fit four plastic pegs
into holes “B”. The plastic pegs are a tight fit so they are best
pushed home with a flat faced tool.

Fit the top casing by engaging the pegs in to the holes in the side
casings and then make sure that they are fully engaged by
pushing the pegs down.

For boilers fitted under work tops, not using the casing top, the
strap should be fitted as diagram 5.4.

14

221765B

6 Electrical Wiring

MAINS INLET
CONNECTOR

Diagram 6.1

0878

N

L

CABLE
CLAMP

COVER

SLOTS

LUGS

E

6.1 Control Box Cable Connection.

WARNING. This boiler must be earthed.
Remove the screw and cover from the mains inlet connector,

supplied loose, see diagram 6.1.
Using heat resistant flexible cable of a suitable length and rating

as stated in Section 1.7 “Electrical” connect the three wires to
the appropriate terminals in the connector.

Engage slots and lugs, replace cover and secure with screw.
Connect the mains inlet connector to the control box and use

three of the cable clips, from the loose items pack, pushed onto
the edge of the right-hand panel in position CB as shown on
diagram 6.2 to ensure the cable does not touch any hot
surfaces.

6.2 Pump Cable Connection

Heat resistant cable as above must be used if the pump is to be
fitted inside the casing.

Support the cable in a similar manner to Control Box Connection,
only fit clips to the casing at P or AP as diagram 6.2.

6.3 System Controls

The electrical installation must be made in accordance with the
current issue of BS7671.

The electrical isolator must isolate both the appliance and
system controls.

6.4 Testing

Checks to ensure electrical safety should be carried out by a
competent person.

In the event of an electrical fault after installation of the boiler,
preliminary system checks must be carried, that is, earth
continuity, polarity and resistance to earth, as described in the
British Gas Multimeter Instruction Book or equal publication.

AP

AP

P

P

CB

CB

CB

CB

230

(9)

25

(1)

230

(9)

230

(9)

9016

CABLE CLIP POSITIONS

Diagram 6.2

Fit 4 control
box feed cable
clips at positions
CB

Alternative pump
cable clips (if feed is
on the left hand side)
at positions AP

Fit 2 pump cable
clips at positions P

15

221765B

7 Commissioning

Please ensure the “Benchmark” logbook is completed and left
with the user.

7.1 Preliminaries

With the pump removed the whole of the system should be
thoroughly flushed out with cold water.

Refit the pump and fill the system. Examine for water soundness
and vent all air from the system and pump. Make sure that all
valves are open.

7.2 Initial Lighting, Testing and Adjustment

CAUTION. The following procedure should be carried out by a
competent person.

Identify the boiler controls by reference to diagram 7.1.
Check that the gas service cock “K” is closed, indicator slot

vertical.
Make sure that the thermostat phial is fully inserted in the phial

pocket “J” and is securely located by the retaining split pin.
Check that the mains electrical supply is switched off.
Set thermostat control knob “B” to “O”.
Remove the burner pressure test point screw “G” and connect

a suitable pressure gauge.
Open gas service cock “K”, indicator, horizontal.

Turn gas control knob “A” to'

' pilot/ignition position and

depress.
At the same time push and release piezo ignition button “C” until

the pilot burner lights, view through window “E”. At this stage air
may be present in that gas pipes, so this operation may need to
be repeated several times. When the pilot burner lights, keep

control knob “A” fully pushed in for about 15 seconds. If the pilot
burner fails to stay alight, repeat the lighting procedure only now
keep the control knob pushed for a little longer.

If the gas control knob “A” is turned to'

'a safety lock prevents

it being turned on again until 3 minutes have elapsed.
Make sure that the pilot is alight and stable, see diagram 7.2 for

the approximate flame length. Switch on the electrical supply.
Set any remote controls so that they are calling for heat. Turn

control knob “A” to ' ' main burner position. Set the thermostat
control knob “B” between “MIN and “MAX”, the main burner will

light. “MAX” is about 82

o

C (180oF).

Test for gas soundness around boiler gas components with a
suitable leak detection fluid.

Ten minutes after lighting, check the burner setting pressure
and adjust, if necessary, as follows, remove cover “F”, see
diagram 7.1 and turn adjustment screw anti-clockwise to
decrease, see Data Table or refer to “L” Data Label for setting
pressure. After adjusting replace cover.

If any doubt exists, the gas rate should be checked at the meter.
This should be in the range of :- HIDEAWAY 120B 3.5m

3

/h to

4.2m3/h (125 to 148 ft3/h)
Stick the self-adhesive arrow indicator, from the loose items

pack, to the data label against the rating the boiler is going to be
set to.

Allow the water system to reach maximum working temperature
and examine for water soundness. The system should then be
turned off and drained rapidly, whilst still hot, to complete the
flushing process.

The system should then be filled again, vented and examined
for water soundness.

Diagram 7.1

BOILER COMPONENTS

L

J

J

H

M

K
(Shown
closed)

E

9017

B

C

A

F

N

G

SETTING
POINT

SETTING
POINT

K
(Shown
open)

= OFF
= PILOT/IGNITION
= MAIN BURNER

A GAS CONTROL KNOB H CONTROL BOX
B TERMOSTAT CONTROL J PHIAL POCKET
C PIEZO IGNITION BUTTON (alternative positions)
E VIEWING WINDOW K GAS SERVICE COCK
F GOVERNOR ADJUSTMENT L DATA LABEL

COVER M GAS CONTROL VALVE

G BURNER PRESSURE N PILOT ADJUSTMENT

TEST POINT SCREW

16

221765B

7 Commissioning

PILOT FLAME DIMENSION

Diagram 7.2

PLINTH / DOOR FITTING

Diagram 7.3

FLAME
DIMENSION

SPARK GAP
DIMENSION

0937

Pilot shield
omitted
for clarity

13 (1/2 in.)
APPROX.

3-4mm.
(1/8 in.)

PILOT
BURNER
ASSEMBLY

VIEWING
WINDOW

1356

VIEW 2

VIEW 1

VIEW 2

PLINTH
FRONT

LOWER
HOOK

VIEW 1

UPPER
HOOK

DOOR
FASCIA

STUD

7.3 Operational Checks

Check operation of the flame failure device as follows, with the
main burner alight, turn the gas valve control knob “A” fully

clockwise to its stop'

' , this will extinguish the main and pilot
burners. The safety device should close before 60 seconds
have elapsed, a click from the gas valve will indicate it has
closed.

Remove the pressure gauge and refit the pressure test point
screw “G”, make sure that a gas tight seal is made.

Turn thermostat “B” to “O” then relight the pilot burner as
Section 7.1.

Relight the main burner.
Check that the boiler thermostat and all automatic controls are

operating correctly.
Do not attempt to adjust the thermostat calibration screw.
Relight the main burner and check for gas soundness with a

suitable leak detection fluid.

7.4 Completion and User Information

Instruct and demonstrate the efficient and safe operation of the
boiler, heating and hot water system.

Hand the Instructions for Use to the user, for their retention,
making sure that they are understood.

Advise that to ensure the efficient and safe operation of the
boiler it is recommended that it is checked and serviced at
regular intervals. The frequency of servicing will depend upon
the installation conditions and usage, but in general once a year
should be enough.

It is that law that any servicing must be carried out by a
competent person.

Draw attention, if applicable, to the current issue of the Gas
Safety (Installation and Use) Regulations, Section 35, which
imposes a duty of care on all persons who let out any property
containing a gas appliance.

Fit the plinth front by locating the sides over the boiler plinth then
lowering to engage the upper and lower hooks, see diagram

7.3.
Fit the door by locating the hooked runner at the bottom into the

slots in the side casings and pushing on to the studs on the side
casings.

Reminder - Leave these instructions and the “Benchmark”
logbook with the user.

17

221765B

8 Servicing

ACCESS TO FLUEWAY Diagram 8.3

0908

FLUEWAY
CLEANING
DOOR

SELF­TAPPING
SCREW (4)

Before commencing any servicing, turn off the gas supply at the
gas service cock, see diagram 8.1 and isolate the electrical
supply to the boiler.

Always test for gas soundness after completing any servicing or
replacement of parts.

8.1 Gain Access to the Boiler

Pull the door forward at the top to disengage studs and lift to
release from the slots, see diagram 7.3.

Lift the plinth front up and forwards to withdraw, see diagram

7.3.
If the top casing is removed during servicing care must be taken

not to damage or lose any plastic pegs when replacing it. Refer
to Section 5.3 “Top Casing” when refitting.

8.2 Boiler Flueways

Unscrew the union nut securing the gas service cock to the gas
valve, see diagram 8.1.

Remove the mains inlet connector by pulling downwards, see
diagram 8.1

Remove split pin on the thermostat phial pocket and withdraw
the phial and capillary, see diagram 4.5.

Remove the five screws retaining the combustion chamber
cover and burner assembly, see diagram 8.2.

Ease the gas service cock away from the gas valve and unhook
the pipe support bracket from the tie bar to enable the assembly
of cover, control box, gas valve and burners to be withdrawn
forwards.

Remove graphite coated nut to release baffle tray and remove
from combustion chamber, taking care not or damage the
insulation material in the sides of the chamber.

Remove the self-tapping screws which retain the flueway
cleaning door and lift door clear, see diagram 8.3.

Remove the baffles from the heat exchanger, see diagram 8.6.
Place a sheet of paper in the combustion chamber to catch any

flue debris.
Access for flueway cleaning is made through the cleaning door

and combustion chamber apertures.
Thoroughly clean boiler flueways and fins from top and bottom

with a suitable stiff brush. Remove any debris from the base of
the combustion chamber.

Check that the flueways are clear, view with the aid of a mirror
or reflector.

8.3 Burners and Injectors

Refer to Section 8.2 for instructions on how to remove cover,
burners and controls assembly.

Remove the two screws and nuts securing each burner support
bracket to the combustion chamber cover, see diagram 8.4.

Remove the graphite coated nuts on supply feed pipe at the rear
of the burner to release the burners, taking care not to damage
the pilot burner and shield when removing.

Remove the nuts, washers and burner end caps, see diagram

8.5.
Remove the distributors from inside the burners then clean the

burners and components thoroughly with a vacuum cleaner.
Check that the main burner injectors are not blocked or damaged.

Clean or renew as necessary. Do not clean with a wire or sharp
instrument, see diagram 8.4.

8.4 Service Checks

Inspect the thermocouple and pilot burner, clean or renew as
necessary.

ACCESS FOR SERVICING

Diagram 8.2

9018

GRAPHITE
COATED NUT

TIE
BAR

SECURING
SCREW (5)

BAFFLE
TRAY

PIPE
SUPPORT
BRACKET

COMBUSTION
CHAMBER
COVER

Diagram 8.1

ISOLATION OF
GAS AND ELECTRICITY

9012

GAS
SERVICE
COCK
(turn off)
(shown
closed)

MAINS INLET
CONNECTOR
(pull downwards)

18

221765B

8 Servicing

9 Replacement Parts

6039

Diagram 8.4

REMOVAL OF BURNER

COMBUSTION CHAMBER
COVER

SUPPLY
PIPE

MAIN
BURNER (2)

INJECTOR (2)

GRAPHITE
COATED NUT (2+2)

SCREW
(2+2)

BURNER
SUPPORT
BRACKET (2)

BURNER SERVICING

Diagram 8.5

6040

BURNER

WASHER

SECURING
NUT

BURNER
END CAP

Diagram 8.6

6143

BAFFLES

HEAT EXCHANGERS

Check the condition of the insulation panels in the combustion
chamber, renew if necessary.

Check the condition of the seals on the cleaning door and the
combustion chamber cover, renewing if necessary.

8.5 Re-assembly

Make sure that the baffle tray is replaced and secured with the
graphite coated nuts, previously removed.

Make sure that the thermostat phial is fully inserted into the phial
pocket and secured, with the location washer behind the
retaining split pin, see diagram 4.5.

Make sure flueway baffles are positioned as diagram 8.6

8.6 Operational Checks

Light the boiler and carryout the operational checks as described
in Sections 7.2 and 7.3.

Before removing or replacing any parts, turn the gas off at the
gas service cock, see diagram 8.1 and isolate the electrical
supply to the boiler.

ALWAYS test for gas soundness after replacing any gas
carrying component.

Unless stated otherwise replacement of parts is in the reverse
order to removal.

9.1 Gas Valve

Gain access to boiler, see Section 8.1.
Disconnect the gas valve plug, thermocouple nut and pilot tube

connections at the gas valve, see diagram 9.1.
Support the valve and remove the four right-hand flange screws

to disconnect the gas valve from the burner supply pipe.
Ease the gas service cock union out and remove the valve

taking care not to damage the “O” ring seal at the flange.
Inspect the condition of the “O” ring seal and renew if necessary.
Remove the union half and refit into the replacement valve on

the inlet, left-hand side. Use a little jointing compound, on the
external thread only, to ensure gas soundness.

It will be necessary to purge air from the gas line after changing
the gas valve, refer to Section 7.2.

9.2 Injectors

Gain access to the boiler as Section 8.1
Unscrew the injectors from the manifold and renew as necessary.
When replacing the injectors use a little jointing compound, on

the external thread only, to ensure gas soundness.
Replace thermostat phial as Section 8.5.

9.3 Thermocouple

Gain access to the boiler as Section 8.1.
Disconnect the thermocouple by unscrewing nuts at the gas

valve and pilot burner, see diagrams 9.1 and 9.2. Withdraw the
thermocouple.

When replacing tighten the thermocouple nut only a quarter turn
beyond finger tight.

9.4 Pilot Burner

Gain access to the boiler as Section 8.1.
Remove the cover and burner controls assembly, as Section 8.2.
Disconnect the ignition lead at the electrode, see diagram 9.2.
Disconnect the thermocouple nut at the pilot burner.
Disconnect the pilot tube nut, ease out the tube and injector

which is hooked on to the pilot tube.

19

221765B

9 Replacement of Parts

PILOT ASSEMBLY

Diagram 9.2

0935

PILOT
INJECTOR

PILOT
TUBE

PILOT
BURNER
ASSEMBLY

PILOT
SHIELD

SPARK
ELECTRODE

SECURING SCREW (2)
AND NUT (2)

THERMOCOUPLE

IGNITION LEAD
(CLEAR END)

INSULATION PANELS

Diagram 9.3

SIDE
INSULATION
PANEL

1281

SCREW

REAR
INSULATION
PANEL

CLIP

BAFFLE
TRAY

GRAPHITE
COATED NUT

Remove the nut retaining the spark electrode and remove.
Remove the two screws and nuts securing the pilot burner and

shield to the combustion chamber cover.
Hook pilot injector over pilot tube olive when refitting.
Check that the pilot flame length is as shown in

diagram 7.2.
Replace thermostat phial as Section 8.5.

9.5 Spark Electrode

Gain access to the boiler as Section 8.1.
Disconnect the thermocouple nut and withdraw thermocouple

from pilot burner, see diagram 9.2.
Disconnect the nut retaining the spark electrode and remove.
When re-assembling check that spark gap is as shown in

diagram 7.2

9.6 Insulation Panels

Gain access to the boiler as Section 8.1.
Remove the burner assembly as Section 8.2.
Remove the two screws retaining each side insulation panel

within the combustion chamber and remove panel, see diagram

9.3.
Release the rear insulation panel upper clips and lift panel out.
Refit thermostat phial as Section 8.5.

9.7 Boiler Thermostat

Follow the relevant instructions in Section 8.1.
Remove the mains inlet connector by pulling downwards, see

diagram 8.1.
Remove the retaining split pin from the phial pocket then

withdraw the phial and capillary, see diagram 4.5.
Pull off the thermostat control knob.
Gain access to inside of the control box by removing the

securing screw located at the top of control box and unhooking
at the bottom, see diagram 9.4.

Remove the two screws which secure the boiler thermostat to
the control box, see diagram 9.4.

Tilt the thermostat so that the electrical connections can be
removed.

Withdraw boiler thermostat from control box complete with
capillary tube and phial.

Refer to diagram 9.5 to connect electrical connectors.
Replace the thermostat phial as the relevant part of Section 8.5.
Make sure that the capillary is positioned so that it passes

through the cut out in the control box, see diagram 9.4.

9.8 Piezo Unit

Pull door forward at the top to disengage the studs and lift to
release from slots, see diagram 7.3.

Remove mains inlet connector by pulling downwards, see
diagram 8.1.

Gain access to inside of the control box by removing the
securing screw located at the top of control box and unhooking
at the bottom, see diagram 9.4.

Disconnect the ignition lead at the piezo unit.
Note: To ease the removal of the piezo unit it is advisable to

temporarily remove the boiler thermostat from the control box.
Depress the retaining tabs and remove the Piezo unit.

9.9 Ignition Lead

Gain access to the boiler as Section 8.1.
Disconnect the ignition lead at the piezo unit, see diagram 9.4

and section 9.8.

9013

Diagram 9.1REMOVAL OF GAS VALVE

GAS
VALVE
PLUG

GAS
VALVE

GAS
OUTLET
FLANGE
SCREW
(4)

PILOT TUBE

NUT

THERMOCOUPLE
NUT

20

221765B

9 Replacement of Parts

Disconnect the lead at the spark electrode, see diagram 9.2.
When reconnecting lead make sure that the clear end is fitted

to the spark electrode.

9.10 Electrical Control Box

Gain access to the boiler as Section 8.1.
Disconnect the mains inlet connector, see diagram 8.1.
Remove the retaining split pin from the phial pocket then

withdraw phial and capillary, see diagram 4.5.

Disconnect the gas valve plug from the valve, see diagram 9.1.
Release the control box by removing the securing screw located

at the top of control box and unhooking at the bottom, see
diagram 9.4.

Pull the ignition lead off piezo unit, see diagram 9.4.
When refitting control box make sure the thermostat capillary is

positioned so that it passes through the cut out in the control
box, see diagram 9.4.

Refit thermostat phial, refer to Section 8.5.

7995

ELECTRICAL
CONNECTORS

ELECTRICAL
CONTROL BOX
COVER

COVER
SECURING
SCREW (4)

ELECTRICAL
CONTROL BOX

THERMOSTAT
SECURING
SCREW (2)

THERMOSTAT
CONTROL KNOB

PIEZO
UNIT

HOOK

IGNITION LEAD
(BLACK END)

CUT-OUT FOR
CAPILLARY

SECURING SCREW

THERMOSTAT
AND CAPILLARY

Diagram 9.4

CONTROL BOX

Diagram 9.5

CONTROL BOX AND GAS VALVE WIRING

6284

CHASSIS
EARTH

230V~ 50Hz

MAINS SUPPLY

FUSED AT 3A

BLUE

BLACK

GREEN / YELLOW

BROWN

C

THERMOSTAT

GAS VALVE

N

E

NL

VIEW OF PLUG
WHEN REMOVED

L

GREEN/
YELLOW

N/C

21

221765B

10 Fault Finding - Electrical

Diagram 10.2ELECTRICAL FAULT FINDING

1526

START
Isolate electricity supply at the external isolator. Remove the mains inlet connector and cover to expose
supply cable connections. Reconnect inlet connector, restore power. Is there 220 to 240V between 'L' and 'N'?

Isolate electricity supply to the unit at the
external isolator. Remove the control box cover.
Check continuity of red cable between terminal
'L' in the inlet connector and Thermostat terminal 'C'.
Is there continuity?

Check that all remote time or temperature
controls are calling for duty.

Turn boiler thermostat to maximum. Connect
ohmmeter across thermostat terminals 'NC' and 'C'.
Is there continuity?

Faulty cable, renew.

Faulty thermostat, renew

Faulty cable, renew.

Faulty cable, renew.

Turn boiler thermostat OFF.
Is continuity interrupted?

Connect ohmmeter and check the continuity
of brown cable between terminal 'L' on gas
valve plug and terminal 'NC' at thermostat.
Is there continuity?

Connect ohmmeter between terminal 'N' in
inlet connector and gas valve plug terminal 'N'.
Is there continuity?

Disconnect ohmmeter and reconnect gas valve plug.
Restore power to unit. Does burner light?

Boiler in order. Isolate electricity supply and
refit mains inlet connector cover.

Carry out preliminary electrical system checks to make sure that the electricity supply is available at the boiler.
Check that any remote time or temperature controls are calling for duty. Make sure that the system is filled,
the gas supply is available and the pilot is lit.

NO

NO

NO

NO

NO

NO

Faulty gas valve, renew.

NO

YES

YES

YES

YES

YES

YES

YES

FUNCTIONAL FLOW WIRING

Diagram 10.1

4708

BLUE

N

N

L

VIEW OF
PLUG
WHEN
REMOVED

E

BROWNBLACK

THERMOSTAT

N/C

C

GAS VALVE

CONTROL SOLENOID

L

10.1 Electrical

IMPORTANT, the preliminary electrical system checks as
contained in the British Gas Multimeter Instruction book or
similar publication, are the first checks to be carried out during
a fault-finding procedure. On completion of the service fault­finding task which has required the breaking and remaking of
electrical connections then checks, earth continuity, polarity
and resistance to earth must be repeated.

Refer to functional flow diagram 10.1 electrical fault finding
chart, diagram 10.2 and wiring diagram 9.5.

22

221765B

Closed Circuit Voltage (millivolts)
DIAGNOSIS GRAPH FOR

THERMOCOUPLE CIRCUIT

Open Circuit Voltage (millivolts)

0246810121416182022

9

11

13

15

17

19

21

23

25

27

29

ABC

10 Fault Finding - Thermocouple

Diagram 10.4

1546

Diagram 10.3THERMOCOUPLE FAULT FINDING

Disconnect appliance thermocouple from the multifunctional control. Check that all
connections are clean and in good condition. Fit test meter interrupter into the magnet unit.
Fit appliance thermocouple into the test meter interrupter.

NO

YES

Hold down control tap in ignition position. Ignite burner, allowing thermocouple to attain
operating temperature. Measure the OPEN CIRCUIT voltage.

Is

voltage

greater

than

15mV?

Faulty thermocouple.
Replace.

Note the open circuit reading then measure the CLOSED CIRCUIT voltage. Note this voltage.
Referring to the diagnosis graph, mark the open circuit voltage on the VERTICAL axis,
and the closed circuit voltage on the HORIZONTAL axis. Note the point where these
two values intersect on the graph.

THERMOCOUPLE
CIRCUIT IS
SATISFACTORY

In

which

area of the

graph is the

intersect

Faulty thermocouple.
Replace.

Faulty magnet unit in gas tap.
Replace multifunctional control.

B

A

C

6042

10.2 Thermocouple

To test the thermocouple a meter with a range of 0 to 30mV is
required together with a thermocouple interrupter similar to the
Minitest 6 Multimeter and interrupter.

Refer to thermocouple fault finding chart, diagram 10.3 and
diagnosis graph, diagram 10.4.

10.3 Pilot

Refer to pilot fault finding chart, diagram 10.5.

23

221765B

PILOT WILL NOT LIGHT
START HERE

Check gas line-open all cocks,
rectify any blockages, purge out
any air. Does pilot light?

Apply match to pilot burner instead
of pressing piezo unit button.
Does pilot light?

Undo tubing nut at pilot burner.
Turn gas valve knob to Pilot/Ign.
Press gas valve knob.
Does gas flow freely?

Rectify blockage in pilot injector,
or renew pilot injector.

Undo tubing nut at pilot outlet
of gas valve. Press gas valve knob.
Does gas flow freely?

Change blocked pilot tube.

Change gas valve.

Does pilot stay alight when
gas valve knob is released?

PILOT SATISFACTORY

Does pilot flame envelop
thermocouple?

Check aeration. If necessary - Clean
pilot, rectify blockage in pilot
injector, or replace.

Check thermocouple circuit using
Thermocouple and Boiler Overheat
Cut-Off fault finding.

On pressing piezo unit button is
there a spark across electrode
gap?

Pull ignition lead off electrode.
Hold end of lead close to pilot
burner and operate piezo unit.
Is there a spark across gap?

Pull ignition lead off piezo unit.
Using blade of a screwdriver, touch
unit chassis and leave approx.
4mm gap from connection tag on
piezo unit. Operate piezo.
Is there a spark across gap?

Change
piezo unit.

Change
ignition lead.

Check electrode gap. Reposition,
or replace electrode as necessary.

NO YES

NO

YES

NO

YES

NO

YES

NO

YES

NO

YES

NO

YES

NO

YES

NO YES

10 Fault Finding - Pilot

Diagram 10.5BOILER PILOT FAULT FINDING

0905

24

221765B

11 Spare Parts

Because of our constant endeavour for improvement, details may vary slightly from those shown in these instructions.

When ordering spare parts please quote the part number and
description, stating the model and serial number, from the data
label “L”, see diagram 7.1.

If ordering from British Gas also quote the GC number of the
part and appliance.

9014

3

5

8

9

10

4

7

6

12

1

2

11

Diagram 11.1

Key No Part No Description GC No

1 203377 Gas control valve 394151
2 205746 Injector (2) *** ***
3 203414 Pilot burner 312 426
4 203508 Injector - pilot 395 674
5 202407 Thermocouple c/w nut 392 850
5 202415 Thermocouple c/w nut
6 202571 Thermostat c/w screws
7 204687 Control knob assy - thermostat
8 202713 Piezo unit
9 WW4609 Ignition lead assembly 136 464
10 202605 Spark electrode 395 720
11 208302 Sight glass 312 419
12 212031 “O” ring - gas valve 312 602