Glow-worm 18-30sxi User Manual

0020008155A.02.05

Instructions for Use

Installation and Servicing

To be left with the user

18sxi

12041

G.C. No. 41-047-72

30sxi

G.C. No. 41-047-62

High Efficiency

Condensing

System Boiler

Glow-worm, Nottingham Road, Belper, Derbyshire. DE56 1JT

www.glow-worm.co.uk

Guarantee Registration

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 Guarantee.
This product is guaranteed for 24 months from the date of installation or 30 months from the date of
manufacture, whichever is the shorter, for parts. In addition this product is guaranteed for 12 months
from the date of installation or 18 months from the date of manufacture, whichever is the shorter, for
labour.
The second year of the parts guarantee, from the beginning of the 13th month onwards after installation
or manufacture, is conditional upon the boiler having been serviced by a CORGI registered gas installer,
in accordance with the manufacturer's recommendations. We strongly recommend regular servicing of
your gas appliance, but where the condition is not met, any chargeable spare parts or components
issued within the applicable guarantee period still benefit from a 12 month warranty from the date of
issue by the manufacturer.

We recommend you complete and return as soon as possible your guarantee registration card.

If your guarantee registration card is missing you can obtain a copy or record your registration by
telephoning the Glow-worm Customer Service number 01773 828100.

For customer service call:

01773 828100

Technical helpline: 01773 828300

For General and Sales enquiries:

Tel. [phone]

Fax: [phone]

To register your Glow-worm appliance call:

0800 073 2142

0020008155A

2

Contents

The instructions consist of three parts, User, Installation and Servicing Instructions. 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.

CONTENTS DESCRIPTION SECTION PAGE No.

Important Information 4

INTRODUCTION

General Information 5
Manual Handling 5

INSTRUCTIONS

FOR USE

INSTALLATION

INSTRUCTIONS

SERVICING

INSTRUCTIONS

Appliance Safety Devices 7
Maintenance and Servicing 7
Operating the Boiler 8

Technical Information 1 9
Boiler Location and Ventilation 2 12
Flue Location and Ventilation 3 13
Heating System 4 15
Domestic Hot Water System 5 16
Installation Preparation 6 17
Gas/Water & Appliance Connection 7 19
Safety Discharge Valve and
Condensate Connections 8 20
Flue Preparation Telescopic and Standard Flue 9 22
Electrical Connections 10 25
Commissioning 11 27

Servicing 12 30
Fault Finding 13 34
Replacement of Parts 14 38
Spare Parts 15 48

3 0020008155A

Important Information

WARNINGS

Gas Leak or Fault

Turn off the gas emergency control valve immediately. Eliminate all sources of ignition, i.e.smoking, blowlamps, hot air guns

etc. Do not operate electrical lights or switches either on or off. Open all doors and windows,ventilate the area.

Sheet Metal Parts

This boiler contains metal parts (components) and care should be taken when handling and cleaning,

Under no circumstances must the User interfere with or adjust sealed parts.

with particular regard to edges.

Sealed Components

Gas Category

This boiler is for use only on G20 natural gas, but the 30sxi
may be converted for use on G31 gas (Propane L.P.G.).

Gas safety (Installation and use) Regulations

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

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
Glow-worm.

Any alteration not approved by Glow-worm, could invalidate
the certification, boiler warranty and may also infringe the
current issue of the Statutory Requirements.

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 0087.

Product/production certified by: 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.

Control of Substances Hazardous to Health

The adhesives and sealants used in this appliance are cured
and give no known hazard in this state.

Insulation Pads / Ceramic Fibre

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 to the eyes or severe irritation to the
skin seek medical attention.
The insulation is composed of non-combustible material.

Electrical Supply

The boiler must be earthed.

All system components shall be of an approved type and shall
be connected in accordance with the current issue of BS7671
and any applicable local regulations.

External wiring must be correctly earthed, polarised and in
accordance with the relevant standards.

In GB this is BS 6891.

In IE this is the current edition of I.S.813 "Domestic Gas
Installations".

The boiler must be connected to a permanent 230V ac, 50Hz
supply.

Connection of the whole electrical system of the boiler, including
any heating controls, to the electrical supply must be through
one common isolator.

Isolation should be by a double pole switched fused spur box,
with a minimum gap of 3mm for both poles. The fused spur box
should be readily accessible and preferably adjacent to the
appliance. It should be identified as to its use.

Alternatively, an unswitched shuttered socket outlet and 3A
fused 3 pin plug, both to the current issue of BS1363 may be
used provided that they are not used in a room containing a bath
or shower.

o

Wiring to the boiler must be PVC 85
than 0.75mm2 (24/0.20mm).

C insulated cable, not less

0020008155A

Sealed System

Draining, refilling and pressurising MUST be carried out by a
competent person.

4

General Information

General Note

This condensing system boiler is designed to provide central
heating from a sealed water system with a fully indirect cylinder.
The central heating water temperature can be adjusted on the
boiler.

Once the controls are set the boiler operates automatically.

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

Water Treatment

In the case of an existing installation, it is ESSENTIAL that prior
to installing the new boiler the system is thoroughly flushed. For
optimum performance after installation of a new system, the
boiler and its associated central heating system should also be
flushed. Flushing should be carried out in accordance with
BS7593: 1992 using a cleanser such as Sentinel X300 or X400,
Fernox Superfloc or Salamander corrosion guard cleaner.

For long-term corrosion protection, after flushing, an inhibitor
suitable for stainless steel exchangers should be used, refer to
the current issue of BS 5449 and BS 7593 on the use of
inhibitors in central heating systems. Examples are Sentinel
X100 Fernox or Salamander corrosion guard inhibitor.

Compartment or Cupboard Installations

If the boiler is fitted into a compartment or cupboard it does not
require ventilation openings.

Do not use the compartment or cupboard for storage.

Condensate Drain

The condensate drain, see section 8.2, must not be modified or
blocked.

Pluming from flue terminal

Like all condensing boilers this appliance will produce a plume
of condensation from the flue terminal in cool weather. This is
due to the high efficiency and hence low flue gas temperature
of the boiler. It is normal and not a fault indication.

Cleaning

The boiler casing can be cleaned using a mild liquid detergent
with a damp cloth, then a dry cloth to polish.

Do not use any form of abrasive or solvent cleaner as you may
damage the paintwork.

Electrical Supply

If the mains electricity and gas are to be turned off for any
long periods during severe weather, it is recommended that
the whole system, including the boiler, should be drained to
avoid the risk of freezing. Make sure that, if fitted, the
immersion heater in the cylinder is switched off.

Clearances

If fixtures are positioned close to the boiler, space must be
left as shown in diagram 2.1. Enough space must also be
left in front of the boiler to allow for servicing.

Manual Handling

IMPORTANT: With regards to the Manual Handling Operations,

1992 Regulations, the following lift operation exceeds the
recommended weight for a one man lift.

General recommendations when handling

Clear the route before attempting the lift.

Ensure safe lifting techniques are used – keep back straight –
bend using legs.

Keep load as close to body as possible.

Do not twist – reposition feet instead.

If 2 persons performing lift, ensure co-ordinated movements
during lift.

Avoid upper body/top heavy bending - do not lean forward/
sideways.

Recommend wear suitable cut resistant gloves with good grip
to protect against sharp edges and ensure good grip.

Always use assistance if required.

Removal of carton from delivery van

Recommend 2 person lift or 1 person with use of sack truck. If
1 person is performing lift, straddle the load, tilt and place carton
into position on truck. Recommend secure appliance onto truck
with suitable straps. Ensure safe lifting techniques are used –
keep back straight – bend using legs. Keep load as close to
body as possible. If 2 persons performing lift, ensure co­ordinated movements during lift. Always use assistance if
required.

Carriage of carton from point of delivery to
point of installation – ground floor

Recommend 2 person lift or 1 person with use of sack truck. If
1 person is performing lift, straddle the load, tilt and place carton
into position on truck. Recommend secure appliance onto truck
with suitable straps. Ensure safe lifting techniques are used –
keep back straight – bend using legs. Keep load as close to
body as possible. If 2 persons performing lift, ensure co­ordinated movements during lift. Clear the route before
attempting the lift. If removing boiler from truck straddle the load
and tilt forwards to facilitate secure grip. Ensure safe lifting
techniques are used – keep back straight – bend using legs. Do
not twist – reposition feet instead. Take care to avoid trip
hazards, slippery or wet surfaces and when climbing steps and
stairs. Always use assistance if required.

5 0020008155A

Manual Handling

Carriage of carton from point of delivery to
point of installation – first or higher floor,
cellar.

Recommend 2-person lift or 1 person with use of sack truck. If
1 person is performing lift, straddle the load, tilt and place carton
into position on truck. Recommend secure appliance onto truck
with suitable straps. Ensure safe lifting techniques are used –
keep back straight – bend using legs. Keep load as close to
body as possible. If 2 persons performing lift, ensure co­ordinated movements during lift. Avoid upper body/top heavy
bending - do not lean forward/sideways. Clear the route before
attempting the lift. If removing boiler from truck straddle the load
and tilt forwards to facilitate secure grip. Ensure safe lifting
techniques are used – keep back straight – bend using legs. Do
not twist – reposition feet instead. Take care to avoid trip
hazards, slippery or wet surfaces and when climbing steps and
stairs. Always use assistance if required.

Carriage of carton from point of delivery to
point of installation – roofspace.

Recommend 2-person lift. Ensure co-ordinated movements
during lift. Avoid upper body/top heavy bending - do not lean
forward/sideways. Clear the route before attempting the lift.
Take care to avoid trip hazards, slippery or wet surfaces and
when climbing steps and stairs. When transferring appliance
into roofspace, recommend 1 person to be in roofspace to
receive the appliance and other person to be below to pass up
and support appliance. Ensure safe lifting techniques are used
– keep back straight – bend using legs. Keep load as close to
body as possible. Always use assistance if required. It is
assumed safe access, flooring and adequate lighting are
provided in the roof space. It is recommended a risk assessment
of the roof space area be carried out before moving the
appliance into the area to take into account access, stability of
flooring, lighting and other factors, and appropriate measures
taken.

Unpacking of appliance from carton.

Recommend 2 persons unpack appliance from carton. Always
keep working area clear. Recommend cut base end of carton
and open carton flaps, then tilt boiler forwards from its side onto
its base and remove carton by sliding up over the boiler. Ensure
safe lifting techniques are used – keep back straight – bend
using legs. Keep load as close to body as possible. Always use
assistance if required. Dispose of packaging in a responsible
manner. Recommend wear suitable cut resistant gloves with
good grip to protect against sharp edges and ensure good grip
when handling appliance outside packaging.

Positioning of Appliance for Final Installation
– no obstructions.

Recommend 2 persons lift appliance to position into place. Fit
bracket securely onto wall before lifting appliance into position.
Obtain firm grip on front and sides of appliance, lift upwards,
ensure stable balance achieved and lift upwards to position in
place on bracket. Ensure safe lifting techniques are used – keep
back straight – bend using legs - when lifting load from floor
level. Do not twist – reposition feet instead. Keep boiler as close
as possible to body throughout lift to minimise strain on back.
Ensure co-ordinated movements to ensure equal spread of
weight of load. Always use assistance if required. Recommend
wear suitable cut resistant gloves with good grip to protect
against sharp edges and ensure good grip when handling
appliance.

Positioning of Appliance for Final Installation
– above worktop, foreseeable obstructions
etc.

Recommend 2 persons lift appliance to position into place. Fit
bracket securely onto wall before lifting appliance into position.
Obtain firm grip on front and sides of appliance, lift upwards,
onto worktop if practicable. Ensure stable balance achieved
and lift upwards to position in place on bracket. If 2 persons
positioning onto bracket obtain firm grip at front and sides/base
of boiler. Ensure co-ordinated movements during 2 person lifts
to ensure equal spread of weight of load. Ensure safe lifting
techniques are used – keep back straight – bend using legs ­when lifting load from floor level. Do not twist – reposition feet
instead. Keep boiler as close as possible to body throughout lift
to minimise strain on back. Avoid upper body/top heavy
bending - do not lean forward/sideways. Always use assistance
if required. Recommend wear suitable cut resistant gloves with
good grip to protect against sharp edges and ensure good grip
when handling appliance.

Positioning of Appliance for Final Installation
– within compartment etc. restricting
installation.

Recommend 2 persons lift appliance to position into place,
space permitting. Fit bracket securely onto wall before lifting
appliance into position. Obtain firm grip on front and sides of
appliance, lift upwards, onto worktop if practicable. Ensure
stable balance achieved and lift upwards to drop into place onto
bracket. If 2 persons positioning onto bracket obtain firm grip at
front and sides/base of boiler. Ensure co-ordinated movements
during 2 person lifts to ensure equal spread of weight of load. If
1 person positioning onto bracket recommend obtain firm grip
supporting base of boiler. Ensure safe lifting techniques are
used – keep back straight – bend using legs - when lifting load
from floor level. Do not twist – reposition feet instead. Keep
boiler as close as possible to body throughout lift to minimise
strain on back. Always use assistance if required. Recommend
wear suitable cut resistant gloves with good grip to protect
against sharp edges and ensure good grip when handling
appliance.

Positioning of Appliance for Final Installation
– in roof space restricting installation.

Recommend 2 persons lift appliance to position into place,
space permitting. Fit bracket securely onto wall before lifting
appliance into position. Obtain firm grip on front and sides of
appliance, lift upwards, ensure stable balance achieved and lift
upwards to position into place onto bracket. If 2 persons
positioning onto bracket obtain firm grip at front and sides/base
of boiler. Ensure co-ordinated movements during 2 person lifts
to ensure equal spread of weight of load. If 1 person positioning
onto bracket recommend obtain firm grip supporting base of
boiler. Ensure safe lifting techniques are used - keep back
straight – bend using legs - when lifting load from floor level. Do
not twist – reposition feet instead. Keep boiler as close as
possible to body throughout lift to minimise strain on back.
Always use assistance if required. Recommend wear suitable
cut resistant gloves with good grip to protect against sharp
edges and ensure good grip when handling appliance. It is
recommended a risk assessment of the roof space area be
carried out before moving the appliance into the area to take into
account access, stability of flooring, lighting and other factors,
and appropriate measures taken.

0020008155A

6

Appliance Safety Devices - User Instructions

Electrical Supply Failure Reset Switch

The boiler will not work without an electrical supply.

Normal operation of the boiler should resume when the electrical
supply is restored.

Reset any external controls, to resume normal operation of the
central heating.

If the boiler does not resume normal operation turn the mains
reset switch off and on. If the boiler does not resume normal
operation after this the overheat stat may have operated.

Overheating Safety

In the event of the boiler overheating the safety devices will
cause a safety shutdown. If this happens, call your Installation/
Servicing company.

Frost Protection

The appliance has a built in frost protection programme as long
as the electricity and gas are left switched on.

This device operates the burner and system pump when the
temperature inside the boiler falls to 3

Any other exposed areas of the system should be protected by
a separate frost thermostat.

0

C.

Condensate Drain Blockage

As a safety feature the boiler will stop working if the condensate
drain becomes blocked. During freezing conditions this may be
due to the forming of ice in the condense drain external to the
house. Release an ice blockage by the use of warm cloths on
the pipe. The boiler should then restart. Contact your installation/
servicing company if the fault persists.

Maintenance and Servicing - User Instructions

Maintenance and Servicing

To ensure the continued efficient and safe operation of the
appliance 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,
refer to guarantee registration on the inside front cover of this
literature.

If this appliance is installed in a rented property in the UK 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.

Servicing/maintenance should be carried out by a competent
person in accordance with the rules in force in the countries of
destination.

To obtain service, please call your installer or Glow-worm’s own
service organisation using the telephone number on the inside
front cover of this literature.

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
benchmark Logbook. You can check your installer is CORGI
registered by calling CORGI direct on: 01256 372300.

Spare Parts

Remember, when replacing a part on this appliance, use only
spare parts that you can be assured conform to the safety and
performance specification that we require. Do not use
reconditioned or copy parts that have not been clearly authorised
by Glow-worm.

If a part is required contact Glow-worm’s own service organisation
using the telephone number on the inside front cover of this
booklet.

Please quote the name of the appliance, this infomation will be
on the name badge on the front of the appliance.

If in doubt seek advice from the local gas company or Glow­worm’s own service organisation using the telephone number
on the inside front cover of this booklet.

7 0020008155A

Operating the Boiler - User Instructions

CONTROLS
FASCIA

CONTROL LIGHT

MAINS RESET
SWITCH

CENTRAL HEATING
WATER TEMPERATURE
CONTROL

DIGITAL
DISPLAY

OPERATION OF THE BOILER

1. Check that all isolating valves on the boiler are open and that water flows from the hot water tap.

2. If you are in any doubt about the boiler being filled with water contact your installer or Glow-worm's own service

organisation using the telephone number on the inside front cover of this booklet. Do not operate the boiler

without water.

3. Check that the electrical supply to the boiler is ON and set any remote controls as required.

4. With the Central Heating Water Temperature Control in its "OFF" (0) position, turn the Mains Reset Switch to the
ON (1) position, the running lamp will initially illuminate (green) then go off, the system pressure will be
displayed and should read on the digital display, at least 0.7bar (recommended 1.0bar), if less you MUST contact
your installation / servicing company.

9239

Diagram 1

USER CONTROLS

CENTRAL HEATING CONTROL

1. Turn the central heating water temperature control "ON", the lighting sequence will begin, the running lamp will
illuminate (green) to indicate the boiler has lit, the system temperature will now be displayed instead of system
pressure.

The temperature of the central heating water can be adjusted by turning the central heating water temperature
control to desired setting between 1 'Min' and

Set the control to

If the boiler fails to light, reset the controls, see paragraph below, TO RESET

If a fault occurs the running lamp will flash red and a fault code will appear on the digital display.

TO RESET

2. Turn the Mains Reset Switch to 0, wait for 5 seconds, turn Mains Reset Switch to 1, the boiler is reset.

If the fault persists contact your installer/service provider using the telephone number on the inside font cover of
this booklet.

TO TURN THE BOILER OFF

3. Turn the Mains Reset Switch to the OFF (0) position.

Turn the gas supply OFF at the gas service cock if the boiler is to be out of use for some time.

'0' to switch off heating.

'Max'. Maximum setting is appoximately 82°C.

0020008155A

8

1 Technical Information

87

THIS DIMENSION CAN BE
INCREASED TO 600mm MAX.

77

176

334

FLUE

GAS

14

FLUE
CENTRE LINE

C

L

76

C

L

BOILER

715

SAFETY
DISCHARGE
DRAIN

177

22

48

18

12860

Standard Flue

1.1 IMPORTANT NOTICE

The boiler is supplied in one pack, the flue and fixing jig are
supplied seperately.

This boiler is for use only on G20 natural gas, but the 30sxi may
be converted for use on G31 gas (Propane L.P.G.).

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

Refer to Manual Handling Operations, 1992 Regulations.

The installation of this boiler must be carried out by a competent
person in accordance with the rules in force in the countries of
destination.

Manufacturer’s instructions must not be taken as overriding
statutory requirements.

1.2 Statutory Requirements

In GB the installation of the boiler must be carried out by a
competent person as described in the following regulations:

The manufacturer’s instructions supplied.

The Gas Safety (Installation and Use) Regulations.

The appropriate Buildings Regulations either The Building
Regulations, The Building Regulations (Scotland),The Building
Regulations (Northern Ireland).

The Water Fittings Regulations or Water byelaws in Scotland.

The Health and Safety at Work Act, Control of Substances
Hazardous to Health (COSHH).

The Current I.E.E. Wiring Regulations.

156

450

134

Diagram 1.1

Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.

In IE, the installation must be carried out by a competent person
and installed in accordance with the current edition of I.S.813
"Domestic Gas Installations", the current Building Regulations
and reference should be made to the current ETCI rules for
Electrical Installation.

In GB the following Codes of Practice apply:

BS4814, BS6798, BS5440 Part 1 and 2, BS5546 Part 1,
BS5449, BS6891, BS6700, BS7074 Part 1 and 2, BS7593,
BS7671.

In IE: I.S.813, BS5546, BS 5449, BS 7074, BS 7593.

Manufacturer’s instructions must not be taken as overriding
statutory requirements.

NOTE: For further information, see the current issue of the
Building Regulations, approved document L1 ( in the UK) and
the references:

1) GIL 59, 2000: Central heating system specification (CheSS)
and

2) GPG 302, 2001: Controls for domestic central heating
system and hot water. BRECSU.

Certification

This boiler certificated to the current issue of EN 483 for
performance and safety.

It is important that no alteration is made to the boiler, without
permission, in writing, from Glow-worm.

Any alteration that is not approved by Glow-worm, could
invalidate the warranty and could also infringe the current issue
of the Statutory Requirements.

9 0020008155A

1 Technical Information

1.3 Gas Supply

The gas installation must be in accordance with the relevant
standards.

In GB this is BS6891.

In IE this is the current edition of I.S.813 "Domestic Gas
Installations".

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 for soundness using the
pressure drop method and suitable leak detection fluid, purge
in accordance with the above standard.

1.4 Technical Data

All dimensions are given in millimetres (except as noted).

Refer to diagrams 1.1, 1.3 and Tables 1 and 2.

The data label is positioned on the inner door, refer to
diagram 1.2.

The Seasonal Efficiency Domestic Boilers UK (SEDBUK) is:
18 and 30 sxi: Class ‘A’.

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 has been certified by B.S.I..

12341

12531

1.5 Condensation Drain

A plastic drain pipe must be fitted to allow discharge of
condensate to a drain.

Condensate should, if possible, be discharged into the internal
household draining system. If this is not practical, discharge
can be made externally into the household drainage system or
a purpose designed soak away, see section 8.2 for more
details.

1.6 Vertical Plumbing Kit

Where the heating flow and return pipes come from above the
boiler a vertical plumbing kit is available,

Central Heating Kit Pt. No. 2000460477.

Contact Glow-worm for further details.

Do not route any pipes behind the boiler, unless a vertical
plumbing kit is used or the pipes are "chased" into the wall.

Diagram 1.2

0020008155A

10

1 Technical Information

Total Weight 18sxi 41kg (90lb)

● Gas connection Rc1/2 (1/2in BSPT)

● Water connection 22mm copper

Safety valve Preset 3bar (43.5lbf/in

Safety valve discharge 15mm copper

TABLE 1

30sxi 44.5kg (98lb)

2

)

HEAT EXCHANGER

FAN

BURNER

OVERHEAT
CUT-OFF

EXPANSION

VESSEL

FLOW
THERMISTOR

RETURN
THERMISTOR

10155

■ Expansion vessel capacity 8 litres (1.76 gallons)
Charge pressure 0.5bar (7.3lbf/in

System min. pressure 0.7bar (10.1lbf/in2)

■ Maximum system 130 litres (28.6 gallons)
content using fitted at 750C average system
expansion vessel temperature

Electrical supply 230V~50Hz

Electrical rating 180W fused 3A

IP classification X4D

Internal Fuse rating

On PCB 630mAT

2

)

● Ball valves are fitted in water and gas connections.

■ For larger systems use an additional

expansion vessel.

GAS
CONTROL
VALVE

AUTOMATIC
AIR VENT

PUMP

C.H.
FLOW

SAFETY
VALVE

DISCHARGE

BYPASS

C.H. INLET
FILTER

GAS

SCHEMATIC LAYOUT OF BOILER

C.H.
RETURN

Diagram 1.3

DRAIN
TA P

TABLE 2

18sxi

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

Case Off 9.1 +0.2 -0.5

Case On 9.3 +0.3 -0.5

2

MIN MAX

m3/h

0.53 2.00

ft3/h

18.7 71

30sxi

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

11 0020008155A

Case Off 9.1 +0.2 -0.5

2

Case On 9.3 +0.3 -0.5

MIN MAX

m3/h

0.53 3.0

ft3/h

18.7 107

2 Boiler Location and Ventilation

2.1 Location

This boiler is not suitable for outdoor installation.

This boiler may be installed in any room, although particular
attention is drawn to the installation of a boiler in a room
containing a bath or shower where reference must be made to
the relevant requirements.

This boiler is suitable for installation in bathroom zones 2 and 3.

In GB this is the current I.E.E. WIRING REGULATIONS and
BUILDING REGULATIONS.

In IE reference should be made to the current edition of I.S.813
"Domestic Gas Installations" and the current ETCI rules.

The boiler must be mounted on a flat wall, which is sufficiently
robust to take its total weight, see Table 1.

12344

5

5

600

†

2.2 Clearances

The boiler should be positioned so that at least the minimum
operational and servicing clearances are provided, see diagram

2.1.

Additional clearances may be beneficial around the boiler for
installation and servicing.

For flue installations where external access is not practicable,
consideration should be given for the space required to insert
the flue internally, which may necessitate clearance larger than
those specified in diagram 2.1.

2.4 Timber Frame Buildings

If the boiler is to be installed in a timber 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 Glow-worm.

2.5 Room Ventilation

The boiler is room sealed, so when it is installed in a room or
space, a permanent air vent is not required.

2.6 Cupboard or Compartment Ventilation

Due to the high efficiency and hence low casing temperature of
this boiler, cupboard or compartment ventilation is not necessary.

Leave existing air vents.

150

5

20 20

200

† A removable compartment door can be
placed at least 5mm in front of the appliance.

0020008155A

MINIMUM CLEARANCE FROM
PERMANENT SURFACES

12

Diagram 2.1

3 Flue Location and Ventilation

3.1 Flue Options

This boiler is suitable for concentric Horizontal and Vertical
flues, elevated horizontal and vertical twin, all are fitted onto the
top of the boiler.

The Glow-worm Flue Options Guide, available on request or
through the web site, describes in detail the necessary
accessories.

These instructions describe the use of the standard and
telescopic horizontal flues.

The instructions for all other flues will be contained in those
packs.

75 min. to 540 max.

WALL THICKNESS

87min

112

3.2 Flue Length

The maximum permissable horizontal flue length is 10 metres
plus the flue terminal, this can be achieved by use of the
accessories, however should additional 90
be used then the length MUST be reduced by 1metre.

When extension pipes are used the flue system must be
designed to have a continuous fall to the boiler of at least 2.5
44mm/metre to allow condensate to run back into the boiler and
out via the drain.

The flue can be installed from inside the building, when access
to the outside wall face is not practicable.

The diagrams 3.1 to 3.4 describe the lengths achievable without
the use of extensions or elbows.

208 min. to 413 max.

12839

87min

WALL THICKNESS

o

or 2 x 45o elbows

112

o

12837

176

OUTSIDE
WALL FACE

NOTE. If necessary, it is permitted to increase
this dimension to 600mm max.

BOILER
MOUNTING WALL

TOP REAR FLUE - STANDARD

NOTE. If necessary, it is permitted to
increase this dimension to 600mm max.

87min

Max flue length 717mm

20mm
min.
clearance

A

Diagram 3.1

211239

C

L

FLUE

12840

176

OUTSIDE
WALL FACE

NOTE. If necessary, it is permitted to increase
this dimension to 600mm max.

BOILER
MOUNTING WALL

TOP REAR FLUE - TELESCOPIC

NOTE. If necessary, it is permitted to
increase this dimension to 600mm max.

87min

Max flue length 589mm

20mm
min.
clearance

A

Diagram 3.3

211239

C

L

FLUE

12838

OUTSIDE
WALL FACE

INTERNAL
SURFACE

A

Max. distance from outside

wall face to min clearance.
LH - 458mm

Min. distance from outside
wall face to min clearance.
LH/RH - 75mm

RH - 486mm

TOP SIDE FLUE - STANDARD

OUTSIDE
WALL FACE

Max. distance from outside
wall face to min clearance.
LH - 330mm
RH - 358mm

Diagram 3.2 Diagram 3.4

TOP SIDE FLUE - TELESCOPIC

INTERNAL
SURFACE

A

Min. distance from outside

wall face to min clearance.
LH - 125mm
RH - 153mm

13 0020008155A

3 Flue Location and Ventilation

MINIMUM SITING DIMENSIONS FOR
FANNED FLUE TERMINALS POSITION MM

HORIZONTAL FLUES

A DIRECTLY BELOW AN OPENING, AIR BRICK,

OPENING WINDOWS 300

B ABOVE AN OPENING, AIR BRICK,

OPENING WINDOWS 300

C HORIZONTALLY TO AN OPENING,

AIR BRICK, OPENING WINDOWS 300

D BELOW GUTTER, DRAIN/SOIL PIPE 25

E BELOW EAVES 25

F BELOW A BALCONY OR CAR PORT 25

G FROM VERTICAL DRAIN PIPES AND

SOIL PIPES 25

H FROM INTERNAL/EXTERNAL CORNERS 25

H TO A BOUNDARY ALONGSIDE THE

*

TERMINAL 300

I ABOVE ADJACENT GROUND OR

BALCONY LEVEL 300

J FROM SURFACE OR A BOUNDARY

*

FACING THE TERMINAL 600

K FACING TERMINALS 1200

L FROM OPENING (DOOR/WINDOW)

IN CAR PORT INTO DWELLING 1200

M VERTICAL FROM A TERMINAL 1500

N HORIZONTALLY FROM A TERMINAL 300

3.4 Terminal Position

The minimum acceptable siting dimensions for the terminal
from obstructions, other terminals and ventilation openings are
shown in diagram 3.5. For Ireland the minimum distances for
flue terminal positioning must be those detailed in I.S.813
"Domestic Gas Installations".

The terminal must be exposed to the external air, allowing free
passage of air across it at all times.

Being a condensing boiler some pluming may occur from the
flue outlet. This should be taken into consideration when
selecting the position for the terminal.

H

* and J* See diagram 3.5 . These dimensions comply with

the building regulations, but they may need to be increased to
avoid wall staining and nuisance from pluming depending on
site conditions.

Increased siting flexibility can be achieved by using the Glow­worm Plume Management Kit, A2044000 (black) or A2044100
(white).

NOTE: If necessary it is permitted to increase the terminal
protrusion through the outside wall to greater than the minimum
dimension of 87mm but no more than 600mm, see diagram 1.1.

Carports or similar extensions of a roof only, or a roof and one
wall, require special consideration with respect to any openings,
doors, vents or windows under the roof. Care is required to
protect the roof if made of plastic sheeting. If the carport
comprises of a roof and two or more walls, seek advice from the
local gas supply company before installing the boiler.

H

* and J* See diagram 3.5 . These dimensions comply with

the building regulations, but they may need to be increased to
avoid wall staining and nuisance from pluming depending on
site conditions.

3.5 Terminal Guard

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

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

The guard should be similar to that shown in diagram 3.6.

A suitable guard is manufactured by:

Tower Flue Components

Morley Rd.

Tonbridge

Kent

TN9 1RA

Size: 280 x 280 x 270mm.

TERMINAL GUARD

VERTICAL FLUES

P FROM ANOTHER TERMINAL 600

Q ABOVE ROOF LEVEL 300

R FROM ADJACENT OPENING WINDOW 1000

S FROM ADJACENT WALL TO FLUE 300

Diagram 3.5

0020008155A

Diagram 3.6

14

4 Heating System

4.1 General

The boiler is for use only with sealed central heating systems.

The safety valve is an integral part of the boiler and it cannot be
adjusted.

The digital read-out on the controls fascia indicates the system
pressure when there is no demand.

The circulation pump is integral with the boiler.

4.2 Expansion Vessel

The boiler has an integral expansion vessel with a capacity of
8 litres (1.76 gallons), with a change pressure of 0.5bar.

NOTE: The expansion vessel volume depends on the total
water system volume and the initial system design pressure. To
check if an additional expansion vessel is required, an accurate
calculation of vessel size is given in the current issue of BS5449
and BS7074 Part 1, for IE refer to the current edition of I.S.813
"Domestic Gas Installations".

4.3 Flow Rate

The flow rate through the boiler must not be allowed to fall below
that given in Table 3.

The system can be fitted with a lockable balancing valve if
necessary in the main flow or return pipes shown as valve “A”
in diagram 4.1.

4.4 Bypass

The boiler is fitted with an adjustable automatic bypass. Ensure
that under no circumstances does the flow rate drop below the
figure specified, refer to table 3 and section 11.6.

The installation of the boiler must comply with the requirements
of the current issue of BS6798, in Ireland, refer also to the
current edition of I.S.813 "Domestic Gas Installations".

In GB it is necessary to comply with the Water Supply (Water
Fittings) Regulations 1999 (for Scotland, the Water Byelaws
2000, Scotland).

To comply with the Water regulations your attention is drawn to:
The Water Regulations guide published by the Water Regulations
Advisory Service (WRAS) gives full details of the requirements.

In IE the requirements given in the current edition of I.S.813
"Domestic Gas Installations" and the current Building Regulations
must be followed.

4.5 Filling the Sealed System

Provision for filling the system at low level must be made, see
diagram 4.2. There must be no permanent connection to the
mains water supply, even through a non-return valve.

NOTE: It is important that fittings used for connection to potable
water comply with the water undertakings requirements.

Table 3. Flow Rate

MODEL MINIMUM FLOW RATE

18sxi 774 litres/hr.

30sxi 1289 litres/hr.

This is equal to 20oC differential at maximum heat input.

BOILER

ADDITIONAL
EXPANSION
VESSEL
(if required)

* BYPASS

RETURN

(if required)

HEATING
CIRCUIT

FLOW CONTROL
VALVE

'A'

DRAIN
POINT

* Refer to section 11.6

Diagram 4.1

10157

15 0020008155A

4 Heating System

4.6 Water Treatment

In the case of an existing installation, it is ESSENTIAL that prior
to installing the new boiler the system is thoroughly flushed. For
optimum performance after installation of a new system, the
boiler and its associated central heating system should also be
flushed. Flushing should be carried out in accordance with
BS7593: 1992 using a cleanser such as Sentinel X300 or X400,
or Fernox Superfloc.

For long-term corrosion protection, after flushing, an inhibitor
suitable for stainless steel exchangers should be used, refer to
the current issue of BS 5449 and BS 7593 on the use of
inhibitors in central heating systems. Examples are Sentinel
X100 and Fernox.

IMPORTANT: It is ESSENTIAL that the cleanser is fully removed
from the system after flushing and before adding inhibitor. Take
care to ensure that all low points in the system are fully drained.

For all systems follow the manufacture's instructions, but where
new radiators are fitted do not leave the cleanser in the system
for longer than 24 hours.

4.7 Draining Tap

A draining tap must be provided at the lowest points of the
system, which will allow the entire system to be drained.

A drain tap for the appliance is provided as an integral part of the
hydroblock, see diagram 12.11.

HEATING
CIRCUIT

Method 1

BOILER

BOILER

RETURNFLOW

CONTROL

VALVE

DRAIN
POINT

CONTROL

VALVE

DOUBLE

CHECK

VALVE

HOSE

UNION

HOSE

UNION

SUPPLY

PIPE

TEMPORARY
CONNECTION

11593

5 Domestic Hot Water System

5.1 General

General - All domestic hot water circuits, connections, fittings

must be in accordance with the relevant standards and water
supply regulations.

For GB: Guidance G17 to G24 and recommendation R17 to
R24 of the Water Regulations Guide.

For IE: The current edition of I.S.813 "Domestic Gas Installations".

The domestic water hot service must be in accordance with the
current issue of BS5546, refer also to the current issue of
BS6700.

TYPE CA BACKFLOW
PREVENTION DEVICE

RETURNFLOW

CONTROL

VALVE

HEATING
CIRCUIT

DRAIN
POINT

Method 2

CONTROL

VALVE

AIR GAP

TUNDISH

SUPPLY

PIPE

Diagram 4.2

5.2 Domestic Hot Water Cylinder

SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE
AND SHOULD NOT BE USED.

The domestic hot water cylinder must be of the double feed
indirect coil type. It must be suitable for working at a gauge
pressure of 0.35bar above the safety valve setting.

0020008155A

16

6 Installation Preparation

6.1 Appliance Pack

IMPORTANT: With regards to the Health and Safety Manual

Handling requirements, two persons shall be required to lift the
appliance, refer to manual handling on page 5.

Please check the contents of packs as shown in diagram 6.1.

NOTE: The fixing pack is located in the base polystyrene
packing under the boiler base.

Remove the polystyrene end packing pieces then carefully lay
the boiler on its back, remove the two front casing panel
securing screws and lift off the panel from two retaining lugs.

Remove the transit packaging behind the front panel and
discard.

Carefully place front panel and screws to one side.

12346

Diagram 6.1

17 0020008155A

6 Installation Preparation

6.2 Wall Template

Remove the wall template from the wall mounting pack and
place in the desired position on a flat wall, giving due consideration
to boiler clearances, see section 2.2, and the flue you are fitting.

6.3 Flue Hole Cutting

The standard horizontal flues are designed with an internal
fall of 44mm/metre towards the boiler for disposal of condensate.
If the standard flue length alone is being used then the flue hole
of diameter 105mm can be cut in the position marked on the wall
template.

For standard side flues the horizontal flue centre line on the
wall template should be extended to the side wall, and the
vertical centre of the flue hole marked at 176mm from the back
wall.

For installations with external access, a 105mm diameter core
drill can be used.

For installations with internal access only, a 125mm diameter
core should be used.

When using extension pipes with the horizontal rear flue, a core
drill size of 125mm should be used to allow the extension pieces
to slope at 44mm/metre (2.5

For extended side flues the flue hole centre should be
determined by extending the dashed inclined line on the template
to the side wall. This dashed line is drawn at 44mm/metre (2.5o)
rise from the boiler. Where this line reaches the side wall, a
horizontal line should be marked. The vertical centre line of the
flue should then be marked at 176mm from the back wall, see
diagram 6.2.

To allow for the flue passing through the wall at this angle a
125mm hole should be drilled irrespective of internal or external
installation.

If necessary remove the wall template whilst drilling the flue
hole.

o

) towards the boiler.

12075

2.5°

16

°

2.5
130

130

WALL
TEMPLATE

EXTENDED SIDE FLUE

HANGING
BRACKET

127

WALL
TEMPLATE

176

0

90

Ø 125

Diagram 6.2

WALL
PLUG

12050

6.4 Fixing Jig and Hanging Bracket Fixing

Reposition the wall template over the flue hole and mark the
position of the fixing holes for the jig and the hanging bracket,
see diagram 6.3.

Drill the four fixing holes, 2 for the hanging bracket and 1 each
for the top hole of the fixing jig wall brackets and insert suitable
wall plugs.

If gas and/or water pipes are to be connected through the rear
wall, the holes must be drilled as marked on the wall template
prior to securing the fixing jig.

Secure the fixing jig wall brackets to the wall using suitable
screws.

NOTE: Due to the varied site conditions we do not supply
fixings and advise that the installer should supply those which
are suitable.

Locate the jig plate between the wall brackets and secure with
the No. 8 self tapping fixing screws supplied in the fittings pack.

SCREW

WALL
PLUG

SCREW
(2 OFF)

FIXING JIG
PLATE

SCREW

FIXING
JIG WALL
BRACKETS
(2 OFF)
(Handed as shown)

Diagram 6.3

0020008155A

18

7 Gas/Water & Appliance Connection

7.1 System Connection

The system can now be connected without the boiler being
mounted. All water and gas connections are on the fixing jig with
the exception of the condense drain and safety discharge, the
positions of these are shown on the wall template.

The gas supply pipe must be chased into the wall if routed up
the back of the boiler.

A Vertical Piping Kit can be used to route the central heating or
DHW pipes, see section 1.6.

Make connections to fixing jig, gas, water and heating cocks
with the tube assemblies supplied in fixing pack as shown in
diagram 7.1.

7.2 Gas Connection

The gas supply can be connected from below or through the
wall at the rear of the boiler, the position is shown on the wall
template.

Refer also to section 1.2.

Fit the sealing washer into the securing nut and make good the
final connection to the gas service cock on the wall mounting jig,
see diagram 7.1.

Do not subject the gas service cock to heat.

Make sure the on/off lever is accessible.

The whole of the gas installation, including the meter, should be
inspected, tested for soundness and purged in accordance with
the current issue of BS6891 and in IE the current edition of
I.S.813 "Domestic Gas Installations".

7.3 Water Connections

Flush out the heating system before connecting to the boiler,
refer to section 4.6.

Make the connections to the heating system by fitting the
sealing washers into the securing nuts and make good the final
connection to the isolating valves on the fixing jig, see diagram

7.1.

Do not subject the isolation valves to heat.

Make sure the drain point is accessible, refer diagram 12.11.

7.4 Appliance Connection

IMPORTANT: With regards to the Manual Handling Operations,

1992 Regulations, the following lift operation exceeds the
recommended weight for a one man lift, refer to manual handling
on page 5.

The appliance will contain a small amount of water, place a
water container beneath the boiler connections before removing
the protective caps.

Position gasket/sealing washers supplied in the fittings pack, as
shown in diagram 7.1.

Lifting the boiler into position, lean the top of the boiler slightly
to the wall and position just above the hanging bracket. Lower
the boiler slowly and engage onto the hanging bracket.

Pivot the boiler to engage the fixing jig connections, ensuring
that the previously positioned washers /gaskets are not disturbed,
see diagram 7.1.

Make good the final connections.

A

12350

C

A

12348

Diagram 7.1

19 0020008155A

8 Safety Discharge Valve and Condensate Connections

8.1 Safety Discharge Valve

The pipe from the safety discharge valve must not discharge
above an entrance, window or any type of public access area.

A short discharge tube is supplied loose in the wall mounting
pack. This must be extended, using not less than 15mm o.d.
pipe, to discharge, in a visible position, outside the building,
facing downwards, preferably over a drain, see diagram 8.1.

The pipe must have a continuous fall and be routed to a position
so that any discharge of water, possibly boiling, or steam,
cannot create any danger to persons, damage to property or
external electrical components and wiring.

To ease future servicing it is advisable to use a compression
type fitting to extend the discharge pipe.

8.2 Condensate Drain Connection

The condensate drain connection is behind the pump at the rear
of the boiler, see diagram 8.2. 21.5mm plastic overflow pipe
should be used to fit into the drain connection on the condensate
siphon and discharge condensate to a drain. The drain pipe
should have a fall of at least 2.5

Condensate should, if possible be discharged into the household
internal drainage system. If this is not practicable, discharge
can be allowed into the external household drains or a purpose
designed soak-away.

It is recommended that any external condensate drain pipe is
insulated or of a 32mm diameter, to prevent freezing in adverse
weather conditions.

The condensate is discharged periodically in ‘slugs’ by siphonic
action.

It is not necessary to provide air breaks or extra traps in the
discharge pipe as there is already a trap inside the boiler. Fitting
an extra trap may cause the boiler siphon to work incorrectly.

Refer to BS5546 or BS6798 for advice on the disposal of boiler
condensate.

A range of condensate fittings are available. These cost effective
easy to install condensate fittings, when used, are designed to
help installers with the easy removal of condensate.

The fittings are available from Hepworth Plumbing Products
and normal distribution channels.

o

away from the boiler.

SAFETY
DISCHARGE
VALVE

UNION NUT
Tighten half turn
past finger tight

SAFETY
DISCHARGE
VALVE PIPE

CONDENSATE
DRAIN

11694

Diagram 8.1

11504

SPIGOT

CONDENSATE FITTINGS

Description Nom Dia. mm.

Overflow to Waste Adaptor (A021). 21.5

For connection to 32mm.
or 40mm Push - Fit or
Solvent Weld pipe.

Overflow to Rainwater 21.5
Adaptor (A022).

For connection to round
and square section downpipe.

Overflow to Soil 32 or 21.5
Adaptor (S117).

For connection to 110mm
soil pipe.

Overflow to Soil 40 or 21.5
Adaptor (S118).

For connection to 110mm
soil pipe.

Conensate Soakaway (S951). 21.5

0020008155A

CAP

Diagram 8.2

20

8 Safety Discharge Valve and Condensate Connections

Typical Gravity Draining Condensate Installations

INTERNAL SOIL
AND VENT STACK

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

Internal Soil and Vent Pipe

EXTERNAL LENGTH
OF PIPE 3M MAX.

OPEN END OF PIPE
DIRECT INTO GULLEY
BELOW GROUND BUT
ABOVE WATER LEVEL

*

MIN. DIA. 21MM

BOILER

BOILER

*NOTE: FOR EXTENDED
PIPE RUNS 32MM DIA.
PIPE SHOULD BE USED.

EXTERNAL SOIL
AND VENT STACK

EXTERNAL
MAX. 3M

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

BOILER

External Soil and Vent Pipe or Rainwater Pipe

SINK
(CONSTITUTES
AIR BREAK)

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

BOILER

12333

Internal Termination into Combined Sink WasteExternal Termination to a Gulley or Hopper

21MM TERMINATION FROM APPLIANCE
*NOTE: FOR EXTENDED PIPE RUNS 32MM DIA.
PIPE SHOULD BE USED.

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

BOILER

OPEN END OF PIPE DIRECT INTO
GULLEY BELOW GROUND LEVEL
BUT ABOVE WATER LEVEL.

SINK

Internal Termination Downstream of
Sink Waste

CEMENT MORTAR SEALING

100MM PLASTIC TUBE

BOTTOM OF TUBE SEALED

HOLE DEPTH
400MM

2 ROWS OF 3 x 12MM
HOLES AT 25MM CENTRES
50MM FROM BOTTOM OF
TUBE. HOLES TO FACE AWAY
FROM HOUSE.

External Termination into Soakaway

NOTE: PIPEWORK SHOULD ALWAYS FALL AWAY FROM BOILER BY AT LEAST 2.5
44mm FOR EVERY 1M.

o

2.5 FALL

25MM

300MM

0

Diagram 8.3

21 0020008155A

9 Flue Preparation Telescopic and Standard Flue

9.1 Flue Components

The components supplied in the Standard and Telescopic kit
are shown in diagram 9.1.

Top Outlet Horizontal Concentric Flue Packs:
A2043600 Horizontal telescopic flue pack.
A2043400 Standard horizontal flue pack.

SEALING
TAPE (telescopic only)

SCREW x 2

Additional flue accessories are available to suit your site
conditions, see diagram 9.2.

The Glow-worm Flue Options Guide, available on request or
through the web site, describes in detail the necessary
accessories.

FLUE

SECURING
COLLAR

SEALING
COLLAR

ELBOW

SCREW x 2

SCREW x 4

GASKET
(fitted)

12841

SEALING
COLLAR

0.5m

EXTENSION

2000460481

SCREW x 1

TELESCOPIC
TERMINAL ASSEMBLY

45o Bend

2000460485

(2off)

STANDARD
TERMINAL ASSEMBLY

o

90

Bend

2000460484

Diagram 9.1

12842

0020008155A

1m

EXTENSION

2000460482

2m

EXTENSION

2000460483

VERTICAL

FLUE

ADAPTOR

A2024600

Diagram 9.2

22

9 Flue Preparation Telescopic and Standard Flue

9.2 Flue Length

Top Rear flue - Telescopic - with the flue elbow temporarily

fitted, measure the distance from the outside wall to the butt
joint, see diagram 9.4. If the measurement 'Y' exceeds 525mm,
then the appropriate length of extension pipe is required, if the
dimension is less than 320mm DO NOT cut the flue, it can
project to a maximum of 600mm, if this is not desirable then a
Standard flue MUST be used and cut to length.

Top Rear flue - Standard - with the flue elbow temporarily
fitted, measure the distance from the outside wall to the butt
joint, see diagram 9.3. If the measurement 'Y' exceeds 652mm,
then the appropriate length of extension pipe is required. The
minimum dimension is 187mm to suit a 75mm min wall thickness.

Top Side flue - Telescopic - with the flue elbow temporarily
fitted, measure the distance from the outside wall to the butt
joint, see diagram 9.6. If the measurement 'Y' exceeds 525mm,
then the appropriate length of extension pipe is required, if the
dimension is less than 320mm DO NOT cut the flue, it can
project to a maximum of 600mm, if this is not desirable then a
Standard flue MUST be used and cut to length.

Y

WALL THICKNESS

112

Top Side flue - Standard - with the flue elbow temporarily fitted,
measure the distance from the outside wall to the butt joint, see
diagram 9.5. If the measurement 'Y' exceeds 652mm, then the
appropriate length of extension pipe is required. The minimum
dimension for Lhd is 270 and Rhd 242 to suit a minimum wall
thickness of 75mm.

Y

OUTER
RUBBER
COLLAR

FLUE
DUCT

AIR
DUCT

COLLAR

12658

12843

DRILL AND
SCREW

OUTSIDE
WALL FACE

BOILER
MOUNTING WALL

TOP REAR FLUE - STANDARD

Y

WALL THICKNESS

COLLAR

112

DRILL AND
SCREW

Diagram 9.3

DRILL AND
SCREW

12850

OUTSIDE
WALL FACE

INNER
PLASTIC
COLLAR

TOP SIDE FLUE - STANDARD

Y

OUTER
RUBBER
COLLAR

FLUE
DUCT

AIR
DUCT

C

L

FLUE

Diagram 9.5

COLLAR

DRILL AND
SCREW

12851

OUTSIDE
WALL FACE

BOILER
MOUNTING WALL

DRILL AND
SCREW

TOP REAR FLUE - TELESCOPIC

COLLAR

Diagram 9.4

OUTSIDE
WALL FACE

INNER
PLASTIC
COLLAR

TOP SIDE FLUE - TELESCOPIC

C

L

FLUE

Diagram 9.6

23 0020008155A

9 Flue Preparation Telescopic and Standard Flue

9.2 (cont'd) Flue and Air Ducts

Telescopic:

The Telescopic Flue system MUST NOT be cut.

Adjust the flue to your required length "Y", mark the securing
hole position in the air duct. Drill a 3mm diameter hole at this
position, take care not to pierce the inner flue duct. Secure with
screw provided and tape the joint, see diagram 9.7.

Standard:

Separate the flue duct from the terminal by twisting to release
the terminal catch, then pull out of the retaining seal, refer to
diagram 9.8.

The duct cutting lengths are shown in diagram 9.8.

The air duct should be cut at the opposite end to the terminal
fixing.

The terminal plastic duct MUST be cut at the opposite end to the
catch.

The plastic flue duct extensions MUST be cut at the opposite
end to seal.

The cut ducts must be de-burred and all filings and debris
removed.

NOTE: If you require to lubricate the seals to ease installation,
please do not use a mineral oil based grease, we would
recommend the use of water.

AIR DUCT - TELESCOPIC

TOP TELESCOPIC
AIR DUCT SECURING

12852

Diagram 9.7

L

12847

9.3 Flue Assembly

The flue assembly is a push fit design with securing collars.

Having adjusted the telescopic or cut the air and flue ducts as
described in section 9.2

Assemble the flue elbow to the air duct, ensuring the correct
alignment of the terminal. Fit the collar into position, mark
through two of the pre drilled holes in the collar. Remove collar
and drill two 3mm diameter holes in the elbow, take care not to
pierce the inner flue duct.

Insert the terminal flue duct, remembering to engage the catch
within the terminal, check for alignment.

Fit the rubber sealing collar behind the locating lugs on the flue
terminal, see diagram 9.1.

Push the flue assembly into the wall, externally or internally,
initially until the end of the assembly protrudes a short way from
the inside face of the wall. This will enable the internal trim ring(if
required) to be positioned and allow the flue duct to be drawn
back into the flue elbow after the boiler has been mounted.

9.4 Flue Attachment To Boiler

Secure the flue elbow in position on top of the boiler with four
torque headed screws supplied.

Draw the flue assembly from wall and engage the flue duct into
the elbow and butt fit the air duct, then fit the collar and secure
with screws provided, see diagram 9.9.

NOTE: If the air and flue ducts have been correctly cut to the
instructions given in section 9.2, the rubber sealing collar
should fit flush with the outside wall, check this.

Slide the internal trim ring back against the wall, securing in
place with a small amount of sealant if required.

AIR DUCT

L

13mm

TERMINAL
CATCH

FLUE DUCT

L + 11mm

DUCT CUTTING LENGTHS

12846

Diagram 9.8

0020008155A

Diagram 9.9

24

10 Electrical Connections

WARNING: This appliance must be wired in accordance with

these instructions. Any fault arising from incorrect wiring cannot
be put right under the terms of the Glow-worm guarantee.

All system components must be of an approved type.

Electrical components have been tested to meet the equivalent
requirements of the BEAB.

Connection of the whole electrical system and any heating
system controls to the electrical supply must be through a
common isolator.

Isolation should preferably be by a double pole switched fused
spur box having a minimum contact separation of 3mm on each
pole. The fused spur box should be readily accessible and
preferably adjacent to the boiler. It should be identified as to its
use.

A fused three pin plug and shuttered socket outlet may be used
instead of a fused spur box provided that:

a) They are not used in a room containing a fixed bath or
shower.

b) Both the plug and socket comply with the current issue of
BS1363.

The mains electrical supply must be maintained at all times in
order to provide domestic hot water.

Do not interrupt the mains supply with a time switch or
programmer.

WARNING: UNDER NO CIRCUMSTANCES MUST ANY
MAINS VOLTAGE BE APPLIED TO ANY OF THE TERMINALS
ON THE VOLTAGE FREE HEATING CONTROLS
CONNECTION PLUG.

RETAINING
LATCHES

CONTROLS FASCIA

EXTERNAL CONTROLS
CABLE (MAINS VOLTAGE)

11408

11505

Diagram 10.1

10.1 Mains Cable

IMPORTANT: If a replacement supply cable is required it must

be purchased. Part No. S1008600.

10.2 External controls (Mains Voltage)

Gain access to the 230V interface by unclipping the controls
fascia and hinging forward, see diagram 10.1.

Remove the red link from the mains voltage heating controls
connection plug and connect as shown in diagrams 10.2 & 10.3,
then route the external control cable as shown on diagram 10.2.

Close the fascia panel and open the rear cover of control panel,
see diagram 10.4.

Secure the external control cable in the strain relief, see
diagram 10.4.

Thread the external control cable through rear of the control
panel where the other cables exit, see diagram 10.4.

Close rear cover of control panel.

External control should be fitted in accordance with the rules in
force.

Refer to wiring diagram in Section 13.

PLUG

Diagram 10.2

25 0020008155A

10 Electrical Connections

10.4 Electrical Connections - Testing

Carry out preliminary electrical system checks as below:

1. Test insulation resistance to earth of mains cables.

2. Test the earth continuity and short circuit of cables.

3. Test the polarity of the mains.

9808

11627

CONTROL
PANEL REAR
COVER

STRAIN
RELIEF

CABLE
EXIT

SECURING
SCREW (3)

12406

MAINS
CABLE

EXTERNAL
CONTROL
CABLE

Diagram 10.3

Diagram 10.4

0020008155A

26

11 Commissioning

Please ensure the "Benchmark" logbook is completed and left
with the user and the magnetic lighting instruction label is
placed on the surface of the boiler casing.

LPG CONVERSION - 30sxi only

NOTE: Steps 11.1 to 11.3 will need to be completed before the

appliance can be converted.

The 30sxi can be converted to run on LPG-Propane (G31).

This conversion should only be carried out by a competent

person.

During the conversion to Propane use of a suitable flue gas
analyser is necessary.

As an option a chargeable boiler only commissioning service
can be provided by Glow-worm Service by calling telephone No.
01773 828100.

Tools required to make the conversion are a 2mm Allen key and
an electricians screwdriver.

Ensure that the appliance supply pressure = 37mb.

(1) Access the gas valve.

(2) Refer to diagram 11.3 and turn the gas valve throttle fully

clockwise.

1

(3) Turn the throttle back anti-clockwise by 5

(4) Ensure that the gas analyser is set to the correct fuel

setting - Propane.

(5) Attach combustion analyser to the combustion test point.

See diagram 12.1.

(6) Unclip the controls fascia to reveal the service potentiometer

on the rear of the user interface. See diagram 12.7.

(7) Turn on the mains electrical supply and turn on the gas

service cock. Switch the boiler on.

(8) Ensure external controls are calling for heat. The boiler

should fire automatically.

(9) Using an electrical screwdriver, rotate the service

potentiometer to the mid point or 3 o’clock position. See
diagram 12.7. The fan speed should now reduce to minimum
and ‘12’ should be shown flashing on the digital display.
Check the CO
and using a 2mm allen key carefully adjust the offset screw
until a CO
the offset screw clockwise increases the CO2 reading.

(10) After setting combustion, rotate the service

potentiometer fully anti-clockwise so that the display
indicates the water temperature. Check that the CO
combustion remains between 9.8% and 10.8% CO2. Further
adjustment should not be necessary, however if required,
carefully adjust the gas valve throttle (see diagram 11.3)
until this is achieved.

(11) Remove analyser probe from the test point and replace the

cap. Refit the control panel.

(12) Fit the LPG conversion label supplied in the documentation

pack to the inner front panel alongside the data
label. Refit the inner door and outer door.

value. If necessary refer to diagram 11.3

2

reading of 10.5% ± 0.2% is achieved. Turning

2

/2 turns.

2

INNER
CASING

CASING

PANEL

PANEL

SECURING

SECURING
SCREWS

SCREW (2)

Diagram 11.1

AUTOMATIC

11507

CAP

AIR VENT

PUMP

Diagram 11.2

11.1 Preliminaries

A competent person in accordance with the current issue of
BS6798 should carry out commissioning.

NOTE: Remove the inner casing panel, see diagram 11.1.

Make sure that the system has been thoroughly flushed out with
cold water without the pump in place.

Refit the pump, fill the system with water, making sure that all
the air is properly vented from the system and pump, see
diagram 11.2.

Before operating the boiler check that all external controls are
calling for heat.

12353

27 0020008155A

11 Commissioning

11.2 System Commissioning

Open the two central heating isolating valves, slots in line with
the length of the valve, see diagram 7.1

To enable the system pressure to be viewed, turn the heating
temperature knob to the OFF position .

Turn the mains electricity supply on to the appliance and ensure
that the mains switch on the appliance fascia is set to the on
position.

The system pressure should be viewed on the digital display on
the front of the appliance, see diagram 1 of the Users Instructions.

Pressurise the system until the pressure on the display reads at
least 1.0bar.

Make sure that the automatic air vent works correctly and that
the black cap is loosely fitted to allow air to escape, see diagram

11.2

Check the heating system and boiler connections for water
soundness.

11.3 Preparation for Lighting

Isolate the boiler from the mains electrical supply.

Test for gas soundness and purge air from the gas supply. Turn
on the gas isolation valve, slot in line with the length of the valve,
see diagram 7.1.

11.4 Initial Lighting

The lighting procedure of the boiler is fully automated.

Ensure that the central heating water temperature control knob
is turned OFF.

Turn on the mains electrical supply and the mains reset knob to
(I) on the controls fascia.

The digital display will show system pressure.

Turn the central heating water temperature control knob to (I)
MINIMUM.

The digital display will now show water temperature.

The fan should start and after a few seconds the ignition will
commence

If the burner fails to light the fan will stop. Initially this may be due
to air in the gas supply line. The boiler will automatically have
three attempts at ignition.

If necessary turn the reset switch to the off position (O), then
back to the on position (I) and the boiler will restart.

After the boiler has lit, allow to warm at minimum temperature
setting to purge any air from the system.

NOTE: If the appliance is operated above MINIMUM on initial
lighting, there is a possibility that the overheat thermostat will
trip and "F5" will be displayed on controls fascia, this is due to
air not having been completely purged. See diagram 14.15 for
reset switch.

Once the system has been purged of air, turn the central heating
water temperature control knob to the desired temperature.

The appliance will then continue to fire until the user controls are
satisfied.

NOTE: That after first power up the firing sequence changes.
After one minute stabilisation time the boiler will ramp slowly to
full rate rather than going immediately to full rate. This is an
adaptive feature to cope with small system requirements.

OFFSET
ADJUSTMENT

12402

GAS
VALVE

THROTTLE

ELECTRICAL
PLUG

PRESSURE TEST
POINT

Diagram 11.3

11.5 Testing - Gas

Case Off Case On

Burner CO2 (G20) 9.1+0.2-0.5 9.3+0.3-0.5
Burner CO2 Propane (G31) 10.5+0.3-0.7 10.7+0.3-0.8
Should any doubt exist about the gas rate, check it using the
gas meter test dial and stop watch at least 10 minutes after the
burner has lit, making sure that all other gas burning appliances
and pilot lights are off.

3

The approximate gas rate: 18sxi : 2.0m

30sxi : 3.0m

NOTE: (LPG (G31) should be adjusted as described on the

previous page. (It should be checked that the supply pressure
is 37mb for LPG appliances).

The gas valve is factory set and should need no adjustment. It
should be checked that the supply pressure is 20mb when the
boiler is firing at full rate. This can be achieved by checking the
inlet pressure at the pressure test point on the gas valve shown
in diagram 11.3.

Disconnect pressure gauge.

NOTE: That the burner pressure cannot be measured at the
gas valve as it is altered by the suction of the fan and modulated
according to demand.

Replace inner casing panel and front casing panel, see diagram

11.1.

/h (71 ft3/h)

3

/h (107 ft3/h)

0020008155A

28

11 Commissioning

11.6 Testing - Heating System

Check that all remote controls are calling for heat. The boiler will
fire automatically. Fully open all radiator valves and flow control
valve ‘A’ if fitted, see diagram 4.1.

Balance the radiators as required and if fitted adjust valve ‘A’ to
give the required system differential. Turn off all radiators that
can be shut off by the user and check to see if less than the
maximum differential allowed of 20
flow and return.

This boiler has a built in bypass, see diagram 11.4. and 14.17.

The boiler is supplied with the bypass open half a turn. It should
not be necessary to adjust the bypass, but if required turn the
adjustment screw clockwise to close the valve, see diagram

11.4.

Allow the system to reach maximum temperature then switch off
the boiler by isolating from the electrical supply.

Drain the entire system rapidly whilst hot, using the drain tap at
the lowest part of the system. Fill and vent the system as
described previously in section 11.2.

Lock or remove the handle from control valve ‘A’ to prevent
unauthorised adjustment.

o

C can be achieved across

AUTOMATIC
BYPASS
VALVE

BYPASS
TUBE

9531

Diagram 11.4

11.7 Completion

Adjust the boiler temperature control and any system controls
to their required settings. In addition it is necessary to complete
the "Benchmark" logbook.

11 Commissioning - Instructions to the User

11.8 User Controls and Options

The mains / reset switch is used to restart the boiler after a fault
condition has occurred, i.e. ignition failure.

The central heating water temperature control knob allows the
user to set the desired temperature.

NOTE: If there is no demand the digital display shows the water
pressure.

Temperature Display

The digital display normally shows the operating temperature
of the unit when there is a central heating demand.

11.9 Pump Exercise Program

After a power cut or every 24 hours in frost setting/summer
mode the pump will run for one minute to prevent it from sticking.
This will also occur during normal operating if there is no
demand for more than 24 hours.

11.10 Frost Protection

The boiler has a built in frost protection programme as long as
the electricity and gas are left switched on.

This device operates the burner and system pump when the
temperature inside the boiler falls to 3

When the temperature inside the appliance reaches 10°C the
burner will shut down and after a short period the pump will stop.

This device primarily protects the boiler. Any other exposed
areas of the system should be protected by a separate frost

thermostat.

0

C.

For IE, it is necessary to complete a "Declaration of Conformity"
to indicate compliance to I.S.813. An example of this is given in
the current edition of I.S.813.

Testing Flue Gases: If any doubt exists that the flue products
are not exhausting correctly, investigate by use of a gas
analyser (FGA).

11.11 Instruct the User

Instruct and demonstrate the lighting procedure and advise the
user on the safe and efficient operation of the boiler.

Instruct on and demonstrate the operation of any heating
system controls.

Advise the user on the use and maintenance of any scale
reducer and pass on any relevant instructional documents.

Advise that to ensure the continued 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.

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 in the UK.

The user shall not interfere with or adjust sealed components.

It is the Law that any servicing is carried out by a competent
person.

Advise the user that, like all condensing boilers this appliance
will produce a plume of condensation from the flue terminal in
cool weather. This is due to the high efficiency and hence low
flue gas temperature of the boiler.

Advise the user of the precautions necessary to prevent damage
to the system, boiler and the building, in the event of the heating
system being out of use during frost or freezing conditions.

Advise the user that the permanent mains electrical supply
SHOULD NOT be switched off, as the built in frost protection
and pump saver program would not be operable.

Reminder, leave these instructions and the ‘Benchmark’ logbook
with the user.

29 0020008155A

12 Servicing

Important Notes

To ensure the continued 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 particular installation and usage, but in general once a year
should be enough.

It is the Law that any servicing is carried out by a competent
person.

When replacing a part on this appliance, use only spare parts
that you can be assured conform to the safety and performance
specification that we require. Do not use reconditioned or copy
parts that have not been clearly authorised by Glow-worm.

FLUE ELBOW

12853

12.1 General

Refer to Table 2 Section 1 Technical Information. Measurement
of the products of combustion can be achieved by connection
of a probe to the combustion analyser test point, see diagram

12.1.

IMPORTANT NOTE: Products of combustion will be discharged
when the cap is removed. It is important to replace the cap
immediately.

Before commencing with a service or replacement of parts the
boiler should be isolated from the electrical supply and the gas
supply should be turned off at the gas valve, see diagram 7.1.

All routine servicing requirements can be achieved by the
removal of the front panel and inner panel only. To remove
simply undo the two screws on the underside of the front panel
and lift off, see diagram 11.1. Undo the two screws on the front
of inner panel and lift off, see diagram 11.1.

Unless stated otherwise any part removed during servicing
should be replaced in the reverse order to removal.

Servicing should always include the removal of any debris from
the condensate pipe and siphon.

After completing any servicing of gas carrying components,
ALWAYS test for gas soundness and carry out a functional test
of the controls.

Testing Flue Gases: If any doubt exists that the flue products
are not exhausting correctly, investigate by use of a gas
analyser (FGA).

COMBUSTION
ANALYSER
TEST POINT

FLUE DUCT
EXTENSION

SPARK
ELECTRODE

SPARK GAP

3.5 to 4.5

Diagram 12.1

11410

12.2 Spark Electrode

Disconnect the electrode lead and two securing screws.
Withdraw the spark electrode carefully from the combustion
chamber, see diagram 12.2 and 12.5.

Inspect the tips for damage.

Clean away any debris and check the spark gap is

3.5mm to 4.5 mm.

Check the electrode gasket for signs of leakage and replace if
necessary.

SECURING
SCREW (2 OFF)

EARTH
LEAD

GASKET

Diagram 12.2

0020008155A

30

12 Servicing

12.3 Burner

NOTE: IF THE BURNER HAS TO BE REMOVED IT WILL

REQUIRE A NEW GASKET WHEN REFITTED.

Drop down the control panel into the service position, see
diagram 10.4.

Disconnect the gas supply at the gas service cock.

Remove the two gas pipe retaining clips, one located below gas
valve and the other one located on the underside of the boiler
chassis, see diagram 12.4.

Pull sealing grommet down gas pipe, see diagram 12.4.

Push the gas pipe upwards further into gas valve connection
and then rotate anti-clockwise (looking down) until the gas pipe
end is over the large hole in boiler chassis, see diagram 12.4.

Withdraw the gas pipe from gas valve connection and remove.

NOTE: When replacing ensure that the sealing grommet,
situated below the gas valve is correctly re-seated.

Disconnect the gas control valve plug at the gas control valve.

Disconnect the electrical leads from the fan.

Remove the five combustion chamber front retaining nuts, see
diagram 12.5.

Gently remove the fan, gas control valve and burner assembly
from the combustion chamber, see diagram 12.3.

Clean the burner with a soft brush taking great care not to
damage the front insulation. DO NOT use wire or sharp
instruments to clean the holes of the burner.

Inspect the burner for any signs of damage.

Inspect the sealing rings and replace if necessary.

Removal of the burner is not necessary during a normal service.

12.4 Combustion Chamber and Heat
Exchanger

Refer to diagram 12.3.

Remove loose debris from combustion chamber using a soft
brush and vacuum cleaner. Carefully flush by spraying water
any remaining debris through the condensate trap (Ensure the
water is kept away from electrical components).

GAS PIPE
RETAINING
CLIP

GAS SUPPLY AT
GAS SERVICE
COCK

HEAT
EXCHANGER

GAS
VALVE

GAS PIPE
RETAINING CLIP

SEALING GROMMET

GAS PIPE

Diagram 12.4

NUT
(5 OFF)

SPADE
CONNECTOR

12402

11480

11531

12343

SEALING
RING

FAN

COMBUSTION
CHAMBER

BURNER

GAS
VALVE

Diagram 12.3

ELECTRODE
LEAD

31 0020008155A

Diagram 12.5

12 Servicing

12.5 Condensate Drain

The condense drain does not normally need removing during
servicing.

To flush the condense drain carefully pour water into the heat
exchanger and check that water flows freely to drain.

If the condense drain is blocked refer to section 14.27 for
removal.

12.6 Combustion Check

Once the appliance has been re-assembled (apart from the
front and inner casing panels) connect a CO
analyser to the test point on the flue elbow, see diagram 12.1.

IMPORTANT NOTE: Products of combustion will be discharged
when the cap is removed. It is important to replace the cap
immediately.

Turn on the gas service cock, see diagram 7.1.

With the power off and the appliance cold, unclip the controls
fascia and hinge it down to reveal the potentiometers on the rear
of the User interface, see diagram 12.7. Take care not to allow
the fascia to drop down and damage the wiring.

Turn on the electrical supply.

Ensure external controls are calling for heat. The boiler should
fire automatically.

Allow the boiler to fire for a minimum of 60 seconds and then,
using an electrical screwdriver, rotate the service potentiometer
fully clockwise. This will allow the digital display to indicate the
‘flashing’ fan speed on the appliance fascia.

In the fully clockwise position the display should be indicating
the maximum fan speed of the appliance, 57±1 for 30sxi and
41±1 for 18sxi.

Check the CO

18sxi 30sxi 9.1+0.2-0.5 Case Off

30sxi LPG 10.5+0.3-0.7 Case Off

Note that with the inner case front panel fitted the
combustion readings will increase slightly to:

18sxi 30sxi 9.1+0.3-0.5 Case On

30sxi LPG 10.7+0.3-0.7 Case On

If adjustment proves necessary then proceed as follows.

For LPG appliances refer to the begining of commissioning

LPG CONVERSION - 30sxi only.

Any adjustment to the gas valve should only be carried out by
a competent person.

Refer to diagram 12.6.

Adjust the maximum rate CO

9.1+0.2-0.5 in small incrimental adjustments, then wait for the
analyser to reflect the change before continuing to 9.1+0.2-0.5
(anti-clockwise to increase).

Rotate the service potentiometer fully anti-clockwise. Hold it in
this position for about 5 seconds before rotating the service
potentiometer clockwise to the mid-point or 3 o’clock position.
The fan should reduce to 1200 ±100 rpm which will flash ‘12’ on
the digital display.

Check the CO

If adjustment proves necessary then proceed as follows.

Adjustment of the CO2 at minimum rate is very coarse so
carefully adjust the CO

9.1+0.2-0.5, see diagram 12.6.

Rotate the service potentiometer fully clockwise and recheck
the maximum rate combustion, which should be

9.1+0.2-0.5 ± 0.2%.

value, which should be:

2

by rotating the throttle to

2

value, which should be 9.1+0.2-0.5.

2

with the offset adjustment to

2

combustion

2

After checking combustion rotate the service potentiometer
fully anti-clockwise so that the display indicates the water
temperature.

Replace the cap on the test point and refit the control cover rear
panel.

OFFSET
ADJUSTMENT

THROTTLE

Diagram 12.6

RETAINING LATCHES

CONTROLS

USER INTERFACE

FASCIA

MIN.
SERVICE
POTENTIOMETER

MAX.

POTENTIOMETERS

Diagram 12.7

12402

11505

11417

0020008155A

32

12 Servicing

12.7 Central Heating Return Filter

Turn off the electrical supply to the boiler.

Refer to section12.8 and drain the heating circuit of the boiler.

Remove the filter retaining clip and clean filter or renew if
necessary, see diagram 12.10.

Refit the filter, ensuring the correct orientation. The flat and hole
in the filter positioned as shown in diagram 12.10. Secure with
retaining clip.

Open the heating flow and return isolating valves and refill, vent
and pressurise the heating circuit. See section 11.2.

Check for leaks.

12.8 Draining of Boiler Heating Circuit

Drain down the Heating Circuit only, by closing the heating flow
and return isolating valves on the wall mounting jig, see diagram

7.1.

Attach a length of hose to the drain point and open the drain
valve, see diagram 12.11.

After servicing or replacing parts, close the drain valve and
remove the hose. Open the heating flow and return isolating
valves and refill, vent and pressurise the heating circuit. See
section 11.2.

Check for leaks.

RETAINING
CLIP

HOUSING

FIXING JIG

CENTRAL
HEATING
RETURN
FILTER

GAS SERVICE
COCK

FLAT
AND
HOLE

Diagram 12.10

DRAIN POINT

9184

11533

12.9 Inner Casing Panel Seal Check

Check the condition of the seal, replace as required.

To replace remove the old seal, thoroughly clean the casing
sufaces. Fit the new seal, it is supplied to the correct length, see
diagram 12.12.

FRONT
CASING
PANEL

DRAIN VALVE

MOUNTING JIG

Diagram 12.11

10063

INNER
CASING
PANEL

SEAL

Diagram 12.12

33 0020008155A

13 Fault Finding

NOTE:

Before trying to operate the boiler make sure that :

• All gas supply cocks are open and that the gas supply has
been purged of air.

• There is a permanent mains supply to the boiler.

• There is a heating demand from the external controls.

WARNING:

Always isolate the boiler from the electrical supply before
carrying out any electrical replacement work.

Always check for gas soundness after any service work.

Electrical Testing

Should there be any doubt about the voltage supply to any of the
components, it is possible to carry out a simple electrical test.

IMPORTANT: On completion of the Service/Fault Finding tasks
which have required the breaking and remaking of the electrical
connections the earth continuity, polarity, short circuit and
resistance to earth checks must be repeated using a suitable
multimeter.

To carry out the electrical test, gain access, as follows:

Hinge down the control box and remove Torx screws and
unhook the rear panel, refer diagram 13.1.

Refer to the Wiring diagram 13.2 and fault finding charts
diagrams 13.3 and 13.4.

RETAINING
SLOTS

RETAINING
CORD

TORX
SCREWS (3)

REAR PANEL

9808

CONTROL BOX

Diagram 13.1

0020008155A

34

13 Fault Finding

12454

Diagram 13.2

35 0020008155A

13 Fault Finding

12189

Does ’F’ flash?

YES

YES

REFER TO
DIAGRAM 13.4.

0020008155A

Diagram 13.3

36

13 Fault Finding

12355

Diagram 13.4

37 0020008155A

14 Replacement of Parts

14.1 Important Notes

When replacing a part on this appliance, use only spare parts
that you can be assured conform to the safety and performance
specification that we require. Do not use reconditioned or copy
parts that have not been clearly authorised by Glow-worm.

Replacement of parts must be carried out by a competent
person.

Before replacing any parts the boiler should be isolated from the
mains electric supply and the gas should be turned off at the
service cock on the boiler, see diagram 7.1.

Unless stated otherwise parts are replaced in the reverse order
to removal.

After replacing any parts always test for gas soundness and if
necessary carry out functional test of the controls.

For replacement of parts the front casing and the inner casing
panel of the boiler will need to be removed. To remove undo the
two screws on the underside of the front casing and lift off. Undo
the two screws on the front of the inner front panel and lift off.

The side panels can be hinged sideways to aid replacement of
parts.

Undo and remove the three screws securing each side panel to
the boiler, two at the front and one at the top.

SECURING
SCREWS (2)

ELECTRICAL
CONNECTIONS

11492

IGNITER
UNIT

SPADE
CONNECTOR

IGNITION LEAD

Diagram 14.1

14.2 Spark Electrode

For access, refer to section 14.1.

Remove the spark plug lead, earth lead and two securing
screws. Withdraw the spark electrode carefully from the
combustion chamber, see diagram 12.2.

14.3 Igniter Unit

For access, refer to section 14.1.

Remove ignition lead and electrical connections, then remove
igniter unit by removing two securing screws, see diagram 14.1.

14.4 Ignition Lead

For access, refer to section 14.1.

Refer to diagram 12.5.

Pull the spark plug style connector off the spark electrode and
the spade connector connected to the igniter unit, see diagram

14.1.

0020008155A

38

14 Replacement of Parts

14.5 Gas Valve

For access, refer to section 14.1.

Remove the electrical plug from the gas valve, see diagram

14.2.

Refer to section 12.3 for removal of the fan, gas valve and
burner assembly.

Before removing the gas valve note its position on the fan.

Remove the three securing screws, which fix the gas valve,
plastic swirl plate to the venturi on the fan.

Remove the gas valve.

Remove the flexible gas supply pipe from the gas valve.

When refitting the gas valve take care as it can be fitted more
than one way.

After assembly test for gas soundness and purge in accordance
with the current issue of BS6891 or in IE, the current edition of
I.S.813 "Domestic Gas Installations".

14.6 Fan

For access, refer to section 14.1.

Refer to section 12.3 for removal of the fan gas valve and burner
assembly.

Remove the gas valve as described in the relevant parts of
section 14.5.

Remove the venturi plate secured with four screws and remove
the two screws securing the fan to the gas manifold, see
diagram 14.3.

Check the gasket and replace if necessary.

NOTE: The 30sxi fan is secured through an extension piece
with two securing screws, check and replace any seals or
gaskets if necessary.

11486

VENTURI
PLATE

SECURING
SCREW (3)

Diagram 14.3

11485

GAS
MANIFOLD

SECURING
SCREW (2)

14.7 Burner

NOTE: THE BURNER WILL REQUIRE A NEW GASKET

WHEN REFITTED.

For access, refer to section 14.1.

Refer to section 12.3 for removal of the fan, gas valve and
burner assembly.

Remove the four screws that secure the burner, see diagram

14.5.

GAS
VALVE

ELECTRICAL
PLUG

12402

FAN

BURNER

Diagram 14.4

11487

INSULATION

PRESSURE
TEST POINT

Diagram 14.2

SECURING
SCREW (4)

39 0020008155A

Diagram 14.5

14 Replacement of Parts

14.8 Front Insulation

For access, refer to section 14.1.

Refer to section 12.3 for removal of the fan, gas valve and
burner assembly.

Remove burner as described in section 14.7.

Remove spark electrode, see section 14.2.

NOTE: THE BURNER WILL REQUIRE A NEW GASKET
WHEN REFITTED.

14.9 Rear Insulation

For access, refer to section 14.1.

Refer to section 12.3 for removal of the fan, gas valve and
burner assembly.

Remove securing screw and washer in the centre of the
insulation and withdraw insulation, see diagram 14.6.

SECURING SCREW

WASHER

14.10 Viewing Window

For access, refer to section 14.1.

Refer to diagram 14.7.

Remove circlip.

Remove steel washer.

Remove glass.

Remove fibre washer.

Replace in reverse order.

SECURING

11412

BOLT

UPPER SUPPORT
BRACKET

11488

CIRCLIP

STEEL
WASHER

HEAT
EXCHANGER

FIBRE
WASHER

REAR
INSULATION

Diagram 14.6

GLASS

Diagram 14.7

11413

EXPANSION
VESSEL

11489

COUPLING

Diagram 14.8

0020008155A

40

14 Replacement of Parts

14.11 Expansion Vessel

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Undo the coupling at the base of the vessel, see diagram 14.8.

While holding the vessel remove the securing bolt on the top
panel of the boiler and upper support bracket on top of the
expansion vessel.

Lift the vessel up, draw bottom out to the left, lower and remove.

Fit the replacement unit.

Refill, vent and pressurise the boiler.

Check for leaks.

14.12 Heat Exchanger

For access, refer to section 14.1.

Refer to section 12.3 for removal of the fan, gas valve and
burner assembly.

Drain the boiler heating circuit, see section 12.8.

Remove the clip securing the clear condense pipe to heat
exchanger.

Pull to remove the condense pipe out of the bottom of the heat
exchanger.

Undo the two nuts of the flow and return pipes from the heat
exchanger.

Move the pipes away from the heat exchanger.

Loosen the three heat exchanger securing screws and clamps
(two at the top and one at the bottom) to remove the heat
exchanger, see diagram 14.9.

CAUTION: There will be water in the heat exchanger.

Remove condense pipe connector from bottom of heat
exchanger.

Carefully ease heat exchanger out.

11490

FLOW AND
RETURN PIPE
NUTS

FLUE HOOD

SECURING SCREWS
AND CLAMPS

Diagram 14.9

11602

14.13 Flue Hood

For access, refer to section 14.1.

Refer to diagram 14.10.

Remove heat exchanger as per section 14.12.

Remove the two securing screws and pull the flue hood down
and away from the flue hood bracket and flue elbow, see
diagram 14.10.

14.14 Pump (head only)

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.11.

Remove the four cap head screws.

Carefully remove the pump head together with cable, do not
strain cable.

Support the pump head, unscrew cable cover at the side of
pump head and remove.

Disconnect wiring from pump head.

Reconnect wiring to new pump head and fit cover.

Fit the new pump head with ‘O’ ring.

Refill, vent and pressurise the boiler.

Check for leaks.

SECURING
SCREWS

Diagram 14.10

41 0020008155A

14 Replacement of Parts

14.15 Safety Discharge Valve

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.12.

Undo the safety discharge valve union and remove from the
pipework.

Remove the securing clip and withdraw the safety discharge
valve.

Refill, vent and pressurise the boiler.

Check for leaks.

14.16 Heating Flow Thermistor

For access, refer to section 14.1.

Refer to diagram 14.13.

Remove the electrical connections from the thermistor.

Remove the retaining clip from the flow pipe.

Remove the thermistor from the retaining clip.

Note that the polarity of the wiring to thermistors is unimportant.

14.17 Heating Return Thermistor

For access, refer to section 14.1.

Refer to diagram 14.15.

Remove the electrical connections from the thermistor.

Remove the retaining clip from the return pipe.

Remove the thermistor from the retaining clip.

Note that the polarity of the wiring to thermistor is unimportant.

14.18 Overheat Thermostat

For access, refer to section 14.1.

Refer to diagram 14.13.

Remove the electrical connections from the overheat stat.

Remove the retaining clip from the return pipe.

Remove the overheat stat from the retaining clip.

Ensure that the replacement thermostat is correctly located on
the flat on the return pipe and carefully push the thermistor clip
into place.

SAFETY
DISCHARGE
VALVE

FLOW
PIPE

OVERHEAT
THERMOSTAT

RETURN
PIPE

11694

Diagram 14.12

11503

CAP HEAD
SCREW (4)

0020008155A

PUMP HEAD

OUTLET
CONNECTOR

CABLE
COVER

Diagram 14.11

11507

42

RESET
SWITCH

FLOW
THERMISTOR

RETURN
THERMISTOR

Diagram 14.13

14 Replacement of Parts

14.19 Automatic Air Vent

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.14.

Unscrew the automatic air vent.

Fit the new automatic air vent and ‘O’ ring ensuring the vent cap
is left loose.

Refill, vent and pressurise the boiler.

Check for leaks.

14.20 Low Water Pressure Sensor

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.15.

Disconnect the electrical lead by pushing up retaining tab and
withdraw lead plug.

Remove the retaining clip to remove the low water pressure
sensor.

Fit the new low water pressure sensor. Refill vent and pressurise
the boiler.

Check for leaks.

14.21 Bypass Tube

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.15.

Remove the retaining clips to remove the bypass tube.

Replace the bypass tube, refill, vent and pressurise the boiler.

Check for leaks.

14.22 Automatic Bypass Valve

For access, refer to section 14.1.

Refer to section 12.8 and drain the boiler heating circuit.

Refer to diagram 14.15.

Remove the retaining clip to remove the bypass valve.

Replace the reduced pressure zone valve, refill, vent and
pressurise the boiler.

Check for leaks.

14.23 Central Heating Filter

Refer to section 12.7.

AUTOMATIC
AIR VENT

11507

FLOW PIPE
CONNECTOR

AUTOMATIC
BYPASS
VALVE

Diagram 14.14

ELECTRICAL
LEAD AND
PLUG

LOW WATER
PRESSURE
SENSOR

BYPASS
TUBE

Diagram 14.15

11605

43 0020008155A

14 Replacement of Parts

14.24 Heating Circuit Drain Point

Refer to section 12.8 to drain the boiler heating circuit.

Refer to diagram 14.16.

Remove the retaining clip to remove the drain point.

Replace the draining point, refill, vent and pressurise the boiler.

Check for leaks.

14.25 Inner Casing Panel Seal

For access, refer to section 14.1.

Refer to diagram 14.17.

Remove the inner casing panel.

To replace remove the old seal, thoroughly clean the casing
surfaces. Fit the new seal, it is supplied to the correct length.

Refit the inner casing panel.

NOTE: Ensure the seal is fitted correctly giving an airtight joint.

RETAINING
CLIP

DRAIN POINT

11533

14.26 Condense Drain

Refer to diagram 14.18.

Remove the clips securing the flexible tubes to the siphon
adapter by twisting the clips slightly to disengage the clip jaws
from each other.

Remove black flexible tubes from siphon adapter.

Lift off the siphon adapter.

Remove the drain connection downstream of the condense
trap.

Remove the two condense trap securing screws. Lift up and
carefully remove the condense trap taking care not to spill any
water which may be left in the unit. As the unit is lifted remove
the flexible pipe on the outlet.

Remove the cap at the base of the condense trap.

Remove any solids found.

Remove the float to clean it.

Flush water through the trap to remove any remaining solids.

Check for any debris in the outlet pipe of the condensate drain
and clean as necessary.

Reassemble and refit the condense trap.

When refitting the cap ensure that a watertight seal is achieved,
but do not use excessive force.

Remove the siphon adaptor from the flexible tubes, using a
suitable container, flush the heat exchanger until the water
appears clear in the container.

FRONT
CASING
PANEL

SIPHON
ADAPTER

FLOAT

Diagram 14.16

10063

INNER
CASING
PANEL

SEAL

Diagram 14.17

9948

0020008155A

44

CAP

SEAL

CONDENSE
TRAP

SCREW

Diagram 14.18

14 Replacement of Parts

14.27 Hydroblock Assembly Left-Hand

Refer to section 12.8 to drain the boiler heating circuit.

Refer to diagram 14.15.

Undo the connector on the bottom of the flow pipe from the
hydroblock.

Undo the nut connecting flow pipe to heat exchanger.

Lift the flow pipe up out of the way.

Remove the bypass tube, refer to section 14.20.

Undo the safety discharge valve union and remove the pipework.

Remove the securing clip and withdraw the safety discharge
valve, refer to section 14.15.

Remove securing clip 1 below hydroblock, see diagram 14.19.

Undo three securing screws on the underside of the left-hand
hydroblock.

Remove screw in back plate.

Lift out the left hand hydroblock.

Remove any remaining components for refitting into the
replacement left hand hydroblock.

Refill, vent and pressurise the boiler.

Check for any leaks.

14.28 Hydroblock Assembly Right-Hand

For access, refer to section 14.1.

Refer to section 12.8 to drain the boiler heating circuit.

Refer to diagram 14.15.

Undo the connector on the bottom of the return pipe from the
hydroblock.

Undo the nut connecting return pipe to heat exchanger.

Lift the return pipe up out of the way.

Undo the coupling at the base of the expansion vessel, see
diagram 14.8.

Remove the clip holding the expansion vessel coupling into the
top of the right hand hydroblock.

Move the coupling out of the way.

Remove pump head, refer to section 14.14.

NOTE: It is not necessary to disconnect the electrical lead but
put pump head in a convenient place where it will not strain the
lead.

Remove the bypass tube, refer to section 14.21.

Remove the electrical connection to the low water pressure
sensor, refer to section 14.20.

Remove the water connection clip 2 below the hydroblock, see
diagram 14.19.

Remove the central heating filter, refer to section 12.7.

Remove the retaining clip to remove the drain point, refer to
section 14.24.

Undo two securing screws on underside of the right hand
hydroblock.

Remove screw in back plate.

Lift out the right hand hydroblock.

Remove the remaining components for refitting into the
replacement right hand hydroblock.

Refill, vent and pressurise the boiler.

Check for leaks.

11480

SECURING
CLIP 1

CENTRAL
HEATING
FLOW

SECURING
CLIP 2

CENTRAL
HEATING
RETURN

Diagram 14.19

45 0020008155A

14 Replacement of Parts

14.29 Access to Switches and User Interface

For access, refer to section 14.1.

Release the front of the fascia by carefully prising up the two
retaining latches, see diagram 14.20.

Do not allow the front of the controls fascia to swing down and
be loosely held by the electrical connections to the mainsreset
switch, user interface and programmer. Either remove the
connections or support the fascia.

14.30 Mains Reset Switch

Refer to section 14.29 for access and diagram 14.21.

Remove the switch retaining screw.

Remove switch from housing.

Remove electrical leads.

14.31 Mains Reset Knob

Refer to section 14.29 for access.

Remove actuator by springing back retaining clips, see diagram

14.21.

Spring back knob retaining clips and push knob out from the
back.

14.32 User Interface

Refer to section 14.29 for access and diagram 14.23.

Remove electrical plug.

Remove the two securing screws.

Withdraw the board.

When replacing the board refer to instructions supplied with
replacement PCB on setting it up.

CONTROLS
FASCIA

KNOB
RETAINING
CLIPS

RETAINING
LATCHES

11505

Diagram 14.20

MAINS RESET
SWITCH

14.33 Main PCB

For access, refer to section 14.1.

Hinge down the control box.

Remove three TORX screws and unhook the rear panel.

Remove the electrical connections to the PCB.

Prise back the two PCB retaining clips and withdraw the PCB.

When refitting the rear panel ensure the leads are not trapped.

14.34 Control Box

For access, refer to section 14.33.

Remove relevant plugs and connectors, refer to wiring diagram

13.2.

Withdraw grommets and leads so they are hanging loose.

Unthread the retaining strap and remove the control box by
drawing it outwards away from its retaining slots, see diagram

14.22.

MAINS RESET
KNOB

Diagram 14.21

0020008155A

46

14 Replacement of Parts

RETAINING
SLOTS

RETAINING
STRAP

MAIN PCB

REAR
PANEL

CONTROL
BOX

PCB RETAINING
CLIPS

TORX
SCREWS (3)

FUSE

Diagram 14.22

12411

230V CONTROLS
INTERFACE BOARD

USER
INTERFACE

11419

Diagram 14.24

SECURING SCREWS

USER INTERFACE

14.35 Fuse - Main PCB - Control Box

For access, refer to section 14.33.

The fuse (rated 630mAT) is located at bottom right hand side of
the PCB, see diagrams 13.2 or 14.22.

14.36 230V Controls Interface

For access, refer to section 14.29.

Disconnect the electrical connection from the 230V controls
board and the electrical connection from the Main PCB, see
diagram 14.24.

Remove the 230V controls interface retaining screw.

Remove the 230V controls interface board.

Diagram 14.23

47 0020008155A

15 Spare Parts

When ordering spare parts, contact Glow-worm’s own service organisation using the telephone number on the front cover of this
booklet.

Please quote the name of the appliance and serial number, to be found on the data label, see diagram 1.2.

If ordering from British Gas also quote the G.C. number of the part.

Key No. Part No. Description GC Part No.

1 801724 Overheat Thermostat E83996

2 801911 Pressure Sensor E83997

3 801637 Spark Electrode E83999

4 2000801904 Safety Discharge Valve E84000

5 2000801898 Automatic Air Vent E84001

6 2000801897 Central Heating Filter E84002

7 801722 Heating flow thermistor /Heating return thermistor E84003

8 801649 Gas valve E84004

9 2000802779 Mains Reset Switch H20701

10 801655 Igniter Unit E84015

11 2000801909 By-pass E84016

12 2000801923 230V Controls Interface E84018

13 2000802731 Main PCB

14 2000801380 Pump (head only) E77408

15 801645 Fan

16 2000802661 User Interface - 18sxi E84024

16 2000802642 User Interface - 30sxi

17 801632 Burner - 18sxi E84021

17 801702 Burner - 30sxi E84249

10 3

11

16

12

1

2

12503

4

8

5

7

9

6

14

17

13

15

Diagram 15.1

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

0020008155A

48