Glow-worm 12hxi, 15hxi, 24hxi, 30hxi, 18hxi Instructions For Use And Installation

0020008153A.02.05

Instructions for Use

Installation and Servicing

To be left with the user

12hxi 15hxi

G.C. No. 41-047-73

G.C. No. 41-047-74

18hxi 24hxi

G.C. No. 41-047-63

G.C. No. 41-047-69

30hxi 38hxi

G.C. No. 41-047-64

High Efficiency

Condensing Boilers

G.C. No. 41-047-71

12041

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

0020008153A

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 13
Flue Location and Ventilation 3 14
Water System 4 16
Installation Preparation 5 20
Boiler Fixing 6 21
Gas, Water and Condensate Conns. 7 22
Flue Preparation Telescopic and Standard Flue 8 24
Electrical Connections 9 27
Commissioning 10 28

Servicing 11 31
Fault Finding 12 35
Replacement of Parts 13 39
Spare Parts 14 44

3

0020008153A

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 30hxi
may be converted for use on G31 gas (Propane L.P.G.).

Gas Safety (Installation and Use) Regulations

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

Testing and Certification

The boiler is tested and certificated for safety and
performance. It is, therefore, important that no alteration is
made to the boiler unless approved, in writing,
by 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 harmonisation of the Laws of the
Member States relating to 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

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

These can cause irritation to skin, eyes and the respiratory tract.

If you have a history of skin complaint you may be susceptible
to irritation. High dust levels are usual only if the material is
broken.

Normal handling should not cause discomfort, but follow normal
good hygiene and wash your hands before eating, drinking or
going to the lavatory.

If you do suffer irritation to the eyes or severe irritation to the skin
seek medical attention.

Electrical Supply

The boiler must be earthed.

All system components shall be of an approved type and all
wiring to current I.E.E. wiring 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 and must be fused 3 Amp maximum.

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 connection can be made through an unswitched
shuttered socket and 3A fused 3-pin plug both to the current
issue of BS 1363 may be used, provided they are not used in a
room containing a bath or shower.

The colours of three core flexible cable are, blue - neutral, brown

- live, green and yellow - earth.

0020008153A

4

General Information

General Note

This boiler is designed to provide central heating from a fully
pumped open-vented or sealed water system with a fully
indirect cylinder.

Once the controls are set the boiler operates automatically.

Please read these instructions and follow them carefully for the
correct installation 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 7.3, 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.

NOTE: If you have a sealed water system contact your
installation/servicing company as draining, refilling and
pressurising MUST be carried out by a competent person.

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

0020008153A

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.

0020008153A

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 30C.

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

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

For 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.

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 booklet.

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

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

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 replacement parts are 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

0020008153A

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.

0020008153A

8

1 Technical Information

1.1 IMPORTANT NOTICE

The boiler is supplied in one carton, which includes a fittings and
documentation pack.

This boiler is for use only on G20 natural gas, but the 30hxi 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.

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

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

1.2 Statutory Requirements

The appliance is suitable only for installation in GB and IE and
should be installed in accordance with the rules in force.

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.

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

0020008153A

600

MAX.

87

MIN.

1 Technical Information

334

176

48

76

12856

113.5

53

INSIDE WALL
FIXING FACE

CONDENSATE
DRAIN

48

73

TABLE 1

12 hxi = 30kg

TOTAL WEIGHT

GAS CONNECTION Rc1/2 (1/2in BSPT)

WATER CONNECTION 22mm. copper

15 hxi = 30kg
18 hxi = 30kg
24 hxi = 33kg
30 hxi = 33kg
38 hxi = 33kg

33

GAS

600

CONDENSATE
DRAIN

133

30

13

54

375

Diagram 1.1

1.3 Gas Supply

The gas installation shall 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)
(Propane G31, 37mbar) 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.

ELECTRICITY SUPPLY 230V~50Hz fused 3A

ELECTRICAL RATING 60W

INTERNAL FUSE RATE Main PCB 630mAT

0020008153A

10

1 Technical Information

12 hxi

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

15 hxi

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

Case Off 9.1 +0.2 -0.5

2

Case On 9.3 +0.3 -0.5

18 hxi

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

Case Off 9.1 +0.2 -0.5

2

Case On 9.3 +0.3 -0.5

24 hxi

TABLE 2

MIN MAX

m3/h

ft3/h

m3/h

ft3/h

m3/h

ft3/h

0.53 1.29

18.7 45.6

MIN MAX

0.53 1.61

18.7 57.0

MIN MAX

0.53 2.00

18.7 70.6

TABLE 2 (cont'd)

30 hxi

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

ft3/h

0.56 3.02

19.8 107

38 hxi

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

1.4 Technical Data

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

See diagram 1.1 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:
All hxi boilers: 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.

Case Off 8.8 +0.2 -0.5

2

Case On 9.0 +0.3 -0.5

MIN MAX

m3/h

ft3/h

0.67 4.06

23.8 143

BURNER

%CO

APPROXIMATE

GAS RATE

(after 10 mins.

from cold)

Case Off 9.1 +0.2 -0.5

2

Case On 9.3 +0.3 -0.5

m3/h

ft3/h

MIN MAX

0.56 2.58

19.8 91.1

1.5 Condensate 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 7.3 for more
details.

11

0020008153A

1 Technical Information

12334

12335

12336

12327

11975

12330

Diagram 1.2

0020008153A

12

2 Boiler Location and Ventilation

2.1 Boiler 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. Section 1.

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.

12344

5

5

600

†

150

5

2.3 Timber Frame Buildings

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

2.4 Room Ventilation

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

2.5 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.

20

200

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

MINIMUM CLEARANCE FROM
PERMANENT SURFACES

Diagram 2.1

20

13

0020008153A

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 90o or 2 x 45o elbows
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

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

136239

C

L

FLUE

12855

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

136239

C

L

FLUE

12854

OUTSIDE
WALL FACE

INTERNAL
SURFACE

A

Max. distance from outside

wall face to min clearance.
LH - 458mm
RH - 561mm

TOP SIDE FLUE - STANDARD

0020008153A

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

Diagram 3.2 Diagram 3.4

OUTSIDE
WALL FACE

Max. distance from outside
wall face to min clearance.
LH - 330mm
RH - 433mm

INTERNAL
SURFACE

TOP SIDE FLUE - TELESCOPIC

14

A

Min. distance from outside

wall face to min clearance.
LH - 125mm
RH - 228mm

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

3.3 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.

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

H
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.

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

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

3.4 Terminal Guard

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

If a terminal guard is required, it must be positioned to provide
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 2.6.

A suitable guard is manufactured by: -

Tower Flue Components

Morley Rd.

Tonbridge

Kent

TN9 1RA.

Size: 280mm x 280mm x 270mm.

TERMINAL GUARD

12325

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

15

Diagram 3.6

0020008153A

4 Water System

12342

0020008153A

Diagram 4.1

16

4 Water System

4.1 Draining Tap

A draining tap must be provided at the lowest point of the
system, which will allow the entire system and hot water system
to be drained.

Draining taps shall be to the current issue of BS 2879.

4.2 Safety Valve

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

4.3 Pump

The pump should be fitted on the flow pipe from the boiler and
have isolating valves each side.

A variable duty pump should be set to give a temperature
difference of no greater than 20
with the thermostat set at “MAX”, which is about 800C, to give
a flow rate as shown in table 3.

See chart for pressure loss of the boiler, diagram 4.1.

High resistance microbore systems may require a higher duty
pump.

0

C between the flow and return,

4.4 Flow Rate

If it is necessary to alter the flow rate, the system can be fitted
with a lockable balancing valve in the main flow or return pipes
shown as valve “A” in diagram 4.3. The flow rate through the
boiler must not be allowed to fall below that given in Table 3.

Table 3. Flow Rate

MODEL MINIMUM FLOW RATE

12 hxi 520 litres/hr

15 hxi 646 litres/hr

18 hxi 773.8 litres/hr

24 hxi 500 litres/hr

30 hxi 1220 litres/hr

38 hxi 1633 litres/hr

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

450mm
MIN.
HEIGHT

1000mm
MIN.

Open (vented) system.
Recommended
relationship between
pump, cold feed and vent.

22mm (MIN.) VENT
FEED AND
EXPANSION CISTERN

15mm (MIN) COLD FEED

15mm (MIN.) BY-PASS
WITH LOCKSHIELD
VALVE IF REQUIRED

FLOW

RETURN

CYLINDER

9235

BOILER

PUMP

150mm MAX.

HEATING

Diagram 4.2

17

0020008153A

4 Water System

(Make-up
alternatives)

3 LITRES (0.66 gals)
MAKE-UP BOTTLE
(if required)

NON-RETURN
VALVE

HEATING

CIRCUIT

AUTO
AIR
VENT

FLOW

RETURN

FLOW
CONTROL
VALVE 'A'

FLOW
CONTROL
VALVE 'A'

DRAIN
COCK

BOILER

BY-PASS
VALVE 'B'
IF REQUIRED

SAFETY
VALVE

AIR
RELEASE
POINT

FILLING POINT

CIRCULATING
PUMP

PRESSURE
GAUGE

EXPANSION
VESSEL

9236

4.5 Bypass

A bypass is not required on the central heating system unless
the system controls could allow the boiler and pump to operate
when there is no flow.

Where a bypass has to be fitted, the bypass must be placed at
least 1.5 metres away from the boiler.

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.

Diagram 4.3

4.7 Open (Vented) Water System

The boiler must be supplied from an unrestricted water supply
taken from a feed and expansion cistern situated at a maximum
height of 27 metres (90ft) above the boiler.

The cold feed must be 15mm minimum size.

The vent must rise continuously and be unrestricted.

It is important that the relative positions of the pump, cold feed
and open vent are as shown in diagram 4.2.

4.8 Combined Feed and Vent

For combined feed and vent, a 22mm pipe must be fitted in
accordance with BS 5449.

4.9 Domestic Hot Water Cylinder

SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE

The domestic hot water cylinder must be of the double feed fully
indirect coil type.

0020008153A

18

TEMPORARY
CONNECTION

HOSE
UNION

HOSE

UNION

SUPPLY

PIPE

CONTROL
VALVE

CONTROL

VALVE

DOUBLE
CHECK
VALVE

HEATING
CIRCUIT

DRAIN
POINT

SUPPLY

PIPE

AIR GAP

TUNDISH

CONTROL

VALVE

CONTROL

VALVE

TYPE CA BACKFLOW

PREVENTION DEVICE

BOILER

RETURNFLOW

BOILER

RETURNFLOW

HEATING
CIRCUIT

DRAIN
POINT

Method 1

Method 2

4 Water System

4.10 Domestic Hot Water System - unvented

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".

Where a storage system will not have a vent to atmosphere the
installation must comply with the building regulations and local
Water Company bylaws, see also the current issue of BS5546
and BS6700.

If fitting to an existing system the local authority should be
informed.

4.11 Sealed water Systems

The installation must comply with the appropriate requirements
of the current issue of BS4814, BS5449, BS6759, BS6798 and
BS7074 Part 1 and 2.

See diagram 4.3 for a suggested layout.

4.12 Safety Valve

A safety valve must be fitted to a sealed system.

It shall be preset, non-adjustable with a lift pressure of 3 bar,
incorporating seating of a resilient material, a test device and a
connection for drain.

The drain from the safety valve must be routed outside the
building, must not discharge above an entrance or window or
any type of public access area, be clear of any electrical fittings
and positioned so that any discharge can be seen.

4.13 Expansion Vessel

A diaphragm type expansion vessel, conforming to the current
issue of BS4814 (see also BS7074 Part 1 and 2) must be
connected at a point close to the inlet side of the circulating
pump, see the diagrammatic layout, diagram 4.3 unless laid
down differently by the manufacturer.

The expansion vessel volume depends on the total water
system volume and the initial system design pressure. For any
system an accurate calculation of vessel size is given in the
current issue of BS5449 and BS7074 Part 1.

Example: For an initial design pressure of 0.7 bar, the minimum
total vessel volume required is 0.063 x Total System Volume.

NOTE: A higher initial design pressure requires a larger volume
expansion vessel.

Guidance on vessel sizing is also 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".

The charge pressure must not be less than the static head of the
system, that is, the height of the highest point of the system
above the expansion vessel.

4.16 Water Makeup

Provision should be made for replacing water loss from the
system using a make up bottle mounted in a position higher than
the top point of the system, connected through a non-return
valve to the return side of either the heating circuit or the hot
water cylinder.

Alternatively, provision for make up can be made using a filling
loop.

4.17 Filling a Sealed Water System

Provision for filling the system at low level must be made, see
diagram 4.4. There must be no permanent connection to the
mains water supply, even through a non-return valve.

11680

4.14 Pressure Gauge

A pressure gauge with a set pointer and covering at least 0 to
4 bar (0 to 60 lb/in
a position where it can be seen when filling the system.

4.15 Domestic Hot Water Cylinder

SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE

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

2

) shall be fitted permanently to the system in

19

Diagram 4.4

0020008153A

5 Installation Preparation

5.1 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.

NOTE: The fittings 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,
see diagram 5.1.

Remove the transit packaging behind the front panel and
discard.

Carefully place front panel and screws to one side.

5.2 Wall Template

Remove the wall template from the documentation 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.

5.3 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 drill 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 (2.5
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 5.2.

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.

0

) towards the boiler.

RETAINING
LUG

SECURING

(2 OFF)

SCREW (2 OFF)

9171



FRONT CASING
PANEL

Diagram 5.1

WALL

(44mm/metre)

176

12046

TEMPLATE

0

90

Ø 125

0

)

EXTENDED SIDE FLUE

Diagram 5.2

0020008153A

20

6 Boiler Fixing

6.1 Hanging Bracket Fixing

If previously removed, reposition the wall template over the flue
hole and mark the position of the fixing holes for the hanging
bracket, see diagram 6.1.

Mark and drill the fixing holes and secure the hanging bracket,
which is supplied in the polystyrene pack.

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

6.2 Boiler Fixing

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
section on page 5.

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.

Make good the final connections.

WALL
TEMPLATE

WALL PLUG
(4 OFF)

SCREW No12 x 50mm
(4 OFF)

12047

HANGING
BRACKET

Diagram 6.1

21

0020008153A

7 Gas, Water and Condensate Connections

GAS SERVICE
COCK SHOWN IN
OPEN POSITION

GAS SERVICE
COCK LINER

GAS
SERVICE
COCK

GAS
SUPPLY
PIPE IN

7.1 Gas Connection

Before connection check the supply of local gas.

The gas supply can be connected from below, see diagram 7.1.
or through the wall at the rear of the boiler.

Refer also to section 1.2 and 1.3.

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".

UNION CONNECTOR

SPIGOT

CAP

PLASTIC
OVERFLOW
PIPE

CONDENSATE DRAIN
CONNECTION

9245

Diagram 7.1

9244

22mm compression is the
recommended fixing
for servicing.
(not supplied)

7.2 Water Connections

Provision is made for the water connections to be made from
above the boiler, see diagram 7.2. The position is shown on the
wall template.

Flush out the domestic hot water and the heating systems
before connecting to the boiler.

7.3 Condensate Drain Connection

The condensate drain connection is at the rear of the boiler, see
diagram 7.1. Using 21.5mm plastic overflow pipe connected to
the spigot on the condense trap (push fit). The drain pipe should
have a fall of a least 2.50 away from the boiler. 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, refer to diagram 7.3.

It is recommended that any external condensate drain pipe is
insulated and also preferably of 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 75mm high trap inside the
boiler. Fitting an extra trap may cause the boiler siphon to work
incorrectly.

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

FLOW

RETURN

Diagram 7.2

0020008153A

22

7 Gas, Water and Condensate Connections

INTERNAL SOIL
AND VENT STACK

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

Internal Soil and Vent Pipe

EXTERNAL LENGTH
OF PIPE 3M MAX.

*

MIN. DIA. 21MM

BOILER

BOILER

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)

BOILER

12333

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

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

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

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

BOILER

SINK

Internal Termination Downstream of
Sink Waste

MIN. DIA. 21MM
NO RESTRICTION
ON LENGTH

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.

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

o

2.5 FALL

25MM

300MM

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

Diagram 7.3

23

0020008153A

0

8 Flue Preparation Telescopic and Standard Flue

8.1 Flue Components

The components supplied in the Standard and Telescopic kit
are shown in diagram 8.1.

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 8.2.

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 8.1

12842

0020008153A

1m

EXTENSION

2000460482

2m

EXTENSION

2000460483

VERTICAL

FLUE
ADAPTOR
A2024600

Diagram 8.2

24

8 Flue Preparation Telescopic and Standard Flue

8.2 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 8.4. 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 8.3. If the measurement 'Y' exceeds 652mm,
then the appropriate length of extension pipe is required. The
minimum dimension is187mm 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 8.6. 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 8.5. If the measurement 'Y' exceeds 652mm, then the
appropriate length of extension pipe is required. The minimum
dimension for Lhd is 270 and Rhd is167 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 8.3

DRILL AND
SCREW

12850

OUTSIDE
WALL FACE

INNER
PLASTIC
COLLAR

TOP SIDE FLUE - STANDARD

Y

OUTER
RUBBER
COLLAR

OUTSIDE
WALL FACE

FLUE
DUCT

INNER
PLASTIC
COLLAR

AIR
DUCT

C

L

FLUE

Diagram 8.5

COLLAR

DRILL AND
SCREW

C

L

FLUE

12851

OUTSIDE
WALL FACE

BOILER
MOUNTING WALL

DRILL AND
SCREW

TOP REAR FLUE - TELESCOPIC

COLLAR

Diagram 8.4

TOP SIDE FLUE - TELESCOPIC

25

0020008153A

Diagram 8.6

8 Flue Preparation Telescopic and Standard Flue

8.2 (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 8.7.

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 8.8.

The duct cutting lengths are shown in diagram 8.8.

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 8.7

L

12847

8.3 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 8.2

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 8.1.

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.

8.4 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 8.9.

NOTE: If the air and flue ducts have been correctly cut to the
instructions given in section 8.2, 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 8.8

0020008153A

Diagram 8.9

26

9 Electrical Connections

Warning. This boiler must be earthed.

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.

9.2 Electrical connections - testing

Carry out preliminary electrical system checks as below:

1. Test insulation resistance to earth of mains cable.

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

3. Test the polarity of the mains.

RETAINING
SCREWS (2)

11831

9.1 External controls (Mains Voltage)

Important: If a replacement supply cable is required it must be

purchased. Part No. S1008600.

Ensure that a seperate external controls cable and pump supply
cable are fed to the boiler.

Refer to wiring diagram in section 12.

All hxi boilers are fitted with a connection box located at the base
of the boiler into which all connections are made.

To gain access to the connection box remove the two retaining
screws indicated in Diagram 9.1 and carefully lower and pull
forward the box to reveal the terminal strip inside.

Remove the test cable from the terminal strip and discard.

Connect both the mains supply and switched live from the
external controls (room thermostat and, if applicable, frost
thermostat) into the marked terminals as shown in diagrams 9.2
and 9.3.

If a room thermostat is not fitted, then the connecting link must
be fitted between terminals 1 and 2, see diagram 12.2.

Connect the pump supply into the marked pump terminals as
shown in diagram 9.2.

Observe all terminal markings and colour codes as shown in
diagram 12.2.

NOTE: The boiler incorporates a pump overun thermostat. Only
feed the pump from the marked terminals in the connection box
on the boiler, not from a separate supply.

Ensure that all flexible cords are routed through the strain relief
cable glands on the inlet of the connection box.

Refit the connection box to the underside of the boiler using the
two retaining screws.

CONNECTION
BOX

CABLE CONNECTIONS

TERMINAL
1
2
3

4
5
6
7
8

MAINS
SUPPLY
CABLE

controls to connections

this will make the boiler

MAINS INLET CONNECTIONS
MAINS (L) 230V ~ 6A RATED CABLE (0.75mm
SWITCHED LIVE (L) 230V ~
FROST STAT (L) 230V ~
MAINS NEUTRAL (N) 230V ~ 6A RATED CABLE (0.75mm
MAINS EARTH (GND 0V) 6A RATED CABLE (0.75mm
PUMP EARTH (GND 0V) 6A RATED (0.75mm
PUMP NEUTRAL (N) 230V ~ 6A RATED (0.75mm
PUMP LIVE (L) 230V ~ 6A RATED (0.75mm

MAINS INLET

TO BOILER

MAINS LIVE

1

MAINS LIVE

2

If there are no external

2 or 3 then a "link"

between connections

1 and 2 must be fitted,

run continuously.

ROOM STAT

34

ROOM STAT

FROST STAT

NEUTRAL

5

FROST STAT

6

NEUTRAL

TERMINAL
CONNECTIONS
1 TO 8.
REFER TO TABLE

Diagram 9.1

2

)

2

)

2

)

PUMP
SUPPLY
CABLE

PUMP

PUMP LIVE

NEUTRAL

8

7

PUMP LIVE

NEUTRAL

PUMP

Diagram 9.2

11833

2

)

2

)

2

)

27

0020008153A

9 Electrical Connections

9.3 Pump Connection

Ensure that a seperate pump supply cable is fed to the boiler,
see diagram 9.2.

Remove connection box, see diagram 9.1.

Route the pump supply cable through the strain relief cable
gland, connect to the connection box as shown in diagram 9.2.
Refer to diagram 12.1 for wiring colour code.

Refit the connection box to the underside of the boiler using the
two retaining screws.

11627

10 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 - 30hxi only

NOTE: Steps 10.1 to 10.3 will need to be completed before the

appliance can be converted.

The 30hxi 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 = 37mbar.

NOTE: Remove the inner casing panel, see diagram 10.1.

(1) To access the gas valve. If necessary remove chassis

front for extra access. See diagram 11.3

(2) Refer to diagram 10.3 and turn the gas valve throttle fully

clockwise.

(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 11.6.

1

/2 turns.

Diagram 9.3

(6) Unclip the controls fascia to reveal the service

potentiometer on the rear of the user interface.
See diagram 11.7.

(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 11.7. The fan speed should now reduce
to minimum and ‘12’ should be shown flashing on the
digital display. Check the CO
refer to diagram 10.3 and using a 2mm allen key
carefully adjust the offset screw until a CO2 reading
of 10.5% ± 0.2% is achieved. Turning 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.
If it does not, carefully adjust the gas valve throttle
(see diagram 10.3) 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

2

2

0020008153A

28

10 Commissioning

10.1 Preliminaries - All Systems

Remove inner casing panel, see diagram 10.1.

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

Make sure that the system has been thoroughly flushed out with
cold water.

Refill the system with water, making sure that all the air is
properly vented from the system and pump, diagram 10.2
shows vent point.

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

10.2 Sealed Systems

Fill the system until the pressure gauge registers the
recommended pressure. Clear any air locks and check for
leaks.

Release the cold water to the initial design pressure.

10.3 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 service cock, slot in line with the length of the valve,
see diagram 7.1.

10.4 Initial Lighting

The lighting procedure of the boiler is fully automated.

Check that all external controls are calling for heat. If an integral
programer is fitted check that it is correctly programmed and if
necessary overridden to provide heat.

Ensure that the water temperature control knob is turned OFF.

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

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

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 mains 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 stat will trip, this
is due to air in the system having not been purged. See diagram

10.2 for overheat thermostat/reset switch.

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

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

NOTE: After first power up the firing sequence for central
heating 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.

INNER
CASING

CASING

PANEL

PANEL

SECURING
SCREWS

FLOW
THERMISTOR

RETURN
THERMISTOR

SECURING
SCREWS (2
OFF)

OVERHEAT
THERMOSTAT /
RESET SWITCH

RETURN
PIPE

OFFSET
ADJUSTMENT

THROTTLE

12354

Diagram 10.1

11404

FLOW
PIPE

VENT POINT

Diagram 10.2

12412

GAS
VALVE

ELECTRICAL
PLUG

29

PRESSURE TEST
POINT

Diagram 10.3

0020008153A

10 Commissioning

10.5 Testing - Gas (Natural Gas only)

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.

The approximate gas rates: 12hxi : 1.29m

15hxi : 1.61m

18hxi : 2.0m

24hxi : 2.57m

30hxi : 3.02m

38hxi : 4.06m

The gas valve is factory set for natural gas (G20) and should
need no adjustment. (LPG (G31) should be adjusted as described
on page 27, LPG CONVERSION). 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 10.3.

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 casing panel, see diagram

10.1.

3

/h (45.6ft3/h)

3

/h (57ft3/h)

3

/h (70.6ft3/h)

3

/h (90.8ft3/h)

3

/h (107ft3/h)

3

/h (143ft3/h)

10.6 Testing - Heating System

Check that all remote controls are calling for heat. The boiler will
fire automatically. Fully open all radiator valves, flow control
valve ‘A’ and bypass valve ‘B’ if fitted, see diagram 4.3.

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

0

C can be achieved across

flow and return.

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 10.2

Lock or remove the handles from controls valve ‘A’ and bypass
valve ‘B’ to prevent unauthorised adjustment.

10.11 Completion

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

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).

10 Commissioning - Instructions to the User

10.7 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 water temperature control knob allows the user to set the
desired temperature.

Temperature Display

The digtal display normally shows the operating temperature
of the unit.

10.8 Pump Exercise Program

After a power cut or every 24 hour 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

10.9 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 30C.

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.

10.10 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.

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.

0020008153A

30

11 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 British Gas.

11.1 General

Measurement of the products of combustion can be achieved
by connection of a probe to the combustion analyser test point
on the flue elbow, see diagram 11.6. Refer to section 11.6 and
table 4. in Section 10. Commissioning.

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

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

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 service cock, see diagram

11.1.

All routine servicing requirements can be achieved by the
removal of the front panel, inner panel and chassis front only.
Remove the two screws on the underside of the front panel and
lift off. Undo the two screws on the front of inner panel and lift
off, see diagram 10.1 and 11.3.

For access inside the appliance a Torx T20 drive is required or
alternatively a flat blade screwdriver can be used.

To remove chassis front, refer to section 11.3.

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.

SEALING
GROMMET

UNION NUT

GAS SERVICE
COCK

GAS
SUPPLY PIPE IN

11410

SPARK GAP

3.5 to 4.5mm

SPARK
ELECTRODE

SECURING
SCREW
2 OFF

EARTH
LEAD

GAS PIPE BRACKET
SECURING SCREW

CONDENSE
TRAP

Diagram 11.1

HEAT
EXCHANGER

Diagram 11.2

9248

GASKET

11.2 Spark Electrode

Disconnect the ignition lead and earth lead from the ignitor unit
and two securing screws at the spark electrode. Withdraw the
spark electrode carefully from the combustion chamber, see
diagram 11.2.

Inspect the tips for damage.

Clean away any debris and check the spark gap is 3.5mm to

4.5mm.

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

31

0020008153A

11 Servicing

11.3 Burner

Refer to diagrams, 11.2,11.3,11.4 and 11.5.

Isolate the gas supply at the gas service cock.

Disconnect the gas supply at the gas service cock.

NOTE: DO NOT DISCONNECT AT THE GAS VALVE.

Remove the two gas pipe bracket securing screws from
underside of inner case, see diagram 11.1.

Drop down the control panel into the service position.

Remove the four screws from the chassis front, see diagram

11.3.

Remove the chassis front by pulling it out at the top from its
retaining slots.

NOTE: When replacing chassis front panel ensure the bottom
fits behind lip.

Disconnect the gas valve plug at the gas valve, see diagram

11.4.

Disconnect the electrical leads from the fan.

Remove the five combustion chamber front securing nuts, see
diagram 11.5.

Gently remove the fan, gas valve and burner assembly from the
combustion chamber complete with the gas pipe bracket and
seal.

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.

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

NOTE: IF THE BURNER HAS TO BE REMOVED IT WILL
REQUIRE A NEW GASKET WHEN REFITTED.

When replacing the assembly ensure the sealing grommet is
correctly fitted.

CHASSIS
FRONT

SECURING
SCREW
(4 OFF)

CONTROL PANEL
SERVICE POSITION

Diagram 11.3

9247

ELECTRODE
CONNECTOR

IGNITION
LEAD

FAN

ELECTRICAL
LEAD

GAS PIPE
BRACKET

12453

HEAT EXCHANGER

EARTH SPADE
CONNECTOR

COMBUSTION
CHAMBER FRONT
SECURING NUTS
(5 OFF)

IGNITER UNIT

GAS VALVE

CHASSIS FRONT
RETAINING SLOTS

GAS VALVE
ELECTRICAL PLUG

0020008153A

Diagram 11.4

32

11 Servicing

11.4. Combustion Chamber and Heat
Exchanger.

Refer to diagram 13.3.

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).

11.5 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 13.16 for
removal.

11.6 Combustion Check

Once the appliance has been reassembled (apart from the front
and inner casing panels) connect a CO2 combustion analyser to
the test point on the flue elbow, see diagram 11.6.

Turn on the gas service cock, see diagram 11.1.

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 11.7. 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, see diagram 11.7. 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, (27±1 for 12hxi, 32 ±1
for 15hxi, 41±1 for 18hxi, 47±1 for 24hxi and 57±1 for 30hxi and
38hxi). Check the CO

Note that with the inner casing panel fitted the combustion
readings will increase slightly to 9.3% +0.3 -0.5.

If adjustment proves necessary then proceed as follows.

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

Refer to diagram 10.3.

Adjust the maximum rate CO
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 CO2 value which should be 9.1% + 0.2 - 0.5.

For Propane the CO

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

Natural gas should read 9.3% + 0.3 - 0.5

Propane gas should read 10.7% + 0.3 - 0.8

value, which should be 9.1% +0.2 -0.5.

2

with the throttle to 9.1%. (Rotate

2

value should be 10.5% + 0.3 - 0.7.

2

Refer to diagram 11.6

For adjustment of Propane appliance refer to section 10 (LPG
conversion).

If adjustment proves necessary then proceed as follows.

Adjustment of the CO
carefully adjust the CO2 with the offset adjustment to 9.1%, see
diagram 10.3.

Rotate the ‘service’ potentiometer fully clockwise, see diagram

11.7, and recheck the maximum rate combustion, which should
be 9.1% + 0.2 -0.5.

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

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

at minimum rate is very coarse so

2

COMBUSTION
CHAMBER

SECURING

BURNER

NUTS (5
OFF)

GAS PIPE
BRACKET
& SEAL

FAN

GAS VALVE

Diagram 11.5

11475

33

0020008153A

11 Servicing

FLUE ELBOW

COMBUSTION
ANALYSER
TEST POINT

FLUE DUCT
EXTENSION

RETAINING
LATCHES

Diagram 11.6

12853

11407

FRONT
CASING
PANEL

INNER
CASING
PANEL

SEAL

9949

Diagram 11.8

CONTROLS
FASCIA

11.7 Inner Casing Panel Seal Check.

Refer to diagram 11.8.

Check the condition of the seal, replace as required.

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

USER
INTERFACE

11417

SERVICE
POTENTIOMETER

MAX.

POTENTIOMETERS

0020008153A

MIN.

Diagram 11.7

34

12 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 12.1.

Refer to the Wiring diagram 12.2 and fault finding charts
diagrams 12.3 and 12.4.

RETAINING
STRAP

RETAINING
SLOT

9247

CONTROL PANEL

Diagram 12.1

35

0020008153A

12 Fault Finding

12452

0020008153A

Diagram 12.2

36

12 Fault Finding

12191

37

Diagram 12.3

0020008153A

12 Fault Finding

12188

0020008153A

Diagram 12.4

38

13 Replacement of Parts

13.1 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 must be isolated from the
mains electric supply and the gas must be turned off at the
service cock on the boiler, see diagram 11.2.

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 casing panel the inner casing
panel and chassis front panel of the boiler will need to be
removed, see diagrams 10.1 and 11.3 to remove undo the two
screws on the underside of the front casing. Undo the two
screws on the front of the inner front panel and lift off. Remove
the four screws from the chassis front and remove it by pulling
it out at the top from its retaining slots.

NOTE: When replacing chassis front panel ensure the bottom
fits behind the lip.

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.

13.3 Igniter Unit

For access, refer to section 13.1.

Remove ignition lead and electrical connections, see diagram

11.4.

Remove igniter unit by removing two securing screws.

13.4 Ignition Lead

For access, refer to section 13.1.

Refer to diagram 11.4.

Pull the spark plug style connector off the spark electrode and
the spade connector connected to the igniter unit.

13.2 Spark Electrode

For access, refer to section 13.1.

Remove the spark plug lead, earth lead and two securing
screws. Withdraw the spark electrode carefully from the
combustion chamber, see diagram 11.1.

MAIN PCB

12411

RETAINING
CLIPS

39

FUSE

Diagram 13.1

0020008153A

13 Replacement of Parts

13.5 Gas Valve

For access, refer to section 13.1.

Remove the electrical plug from the gas valve, see diagram

10.3.

Refer to section 11.3 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 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".

13.6 Fan

For access, refer to section 13.1.

Remove electrical plug.

Refer to section 11.3 for removal of the fan, gas valve and
burner assembly.

Remove the gas valve as described in the relevant parts of
section 13.5.

Remove the venturi plate secured with three screws and
remove the two screws securing the fan to the gas manifold, see
diagram 13.2.

Check the gasket and replace if necessary.

NOTE: The 30hxi and 38hxi fan is secured through an extension
piece with two securing screws, check and replace any seals or
gaskets if necessary.

13.7 Burner

For access, refer to section 13.1.

Refer to section 11.3 for removal of the fan, gas valve and
burner assembly.

Remove the four screws that secure the burner.

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

13.8 Front Insulation

For access, refer to section 13.1.

Refer to section 11.3 for removal of the fan, gas valve and
burner assembly.

Remove burner as per section 13.7.

Remove spark electrode, see section 13.2.

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

GAS
MANIFOLD

SECURING
SCREW
(2)

FAN

VENTURI
PLATE

18hxi Illustrated

SECURING
SCREW

HEAT
EXCHANGER

FIBRE
WASHER

SECURING
SCREW (3)

Diagram 13.2

WASHER

REAR
INSULATION

Diagram 13.3

GLASS

11485

11412

11413

13.9 Rear Insulation

For access, refer to section 13.1.

Refer to section 11.3 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 13.3.

0020008153A

CIRCLIP

STEEL
WASHER

Diagram 13.4

40

13 Replacement of Parts

13.10 Viewing Window

For access, refer to section 13.1.

Refer to diagram 13.4.

Remove circlip.

Remove steel washer.

Remove glass.

Remove fibre washer.

Replace in reverse order.

13.11 Heat Exchanger

Refer to Manual Handling section on page 5.

For access, refer to section 13.1.

Refer to section 11.3 for removal of the fan, gas valve and
burner assembly.

Drain the boiler.

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

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

Undo the two nuts of the flow and return pipes from the heat
exchanger, see diagram 13.5.

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 13.5.

CAUTION: There will be water in the heat exchanger.

Remove clear condense pipe connector from bottom of heat
exchanger.

FLOW AND

11411

RETURN
PIPE NUTS

SECURING
SCREWS
AND
CLAMPS
(3 OFF)

Diagram 13.5

FLUE HOOD

11602

FLUE HOOD
BRACKET

13.12 Flue Hood

For access, refer to section 13.1.

Remove heat exchanger as per section 13.11.

Remove the two securing screws and pull the flue hood down
and away from the flue hood bracket and flue elbow, see
diagram 13.6.

13.13 Heating Flow Thermistor

For access, refer to section 13.1.

Refer to diagram 13.7.

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.

13.14 Heating Return Thermistor

For access, refer to section 13.1.

Refer to diagram 13.7.

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 thermistor is unimportant.

HEATING FLOW
THERMISTOR

HEATING RETURN
THERMISTOR

SECURING
SCREWS

Diagram 13.6

OVERHEAT
THERMOSTAT

FLOW
PIPE

RETURN
PIPE

Diagram 13.7

11404

41

0020008153A

13 Replacement of Parts

13.15 Overheat Thermostat

For access, refer to section 13.1.

Refer to diagram 13.7.

Remove the electrical connections from the overheat thermostat.

Remove the retaining clip from the flow pipe.

Remove the overheat stat from the retaining clip.

NOTE: When fitting new thermostat, please ensure that it is
located correctly onto the flat area of the pipe and the retaining
clip is secure.

13.16 Condensate Drain

Refer to diagram 13.8.

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.

13.17 Inner Casing Sealing Panel

Refer to section 11.7.

13.18 Access to Switches, User Interface and
230v controls Interface

For access, refer to section 13.1.

Release the front of the controls fascia by carefully prising up
the two retaining latches, see diagram 11.7.

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

CAP

MAINS RESET
SWITCH

11416

HOUSING

KNOB
RETAINING
CLIPS

SIPHON
ADAPTER

FLOAT

SEAL

MAINS RESET
KNOB

SECURING SCREWS

9948

CONDENSE
TRAP

SCREW

Diagram 13.8

ELECTRICAL
CONNECTIONS

MAINS RESET
SWITCH

Diagram 13.9

11417

13.19 Mains Reset Switch

Refer to section 13.18 for access.

Remove the switch retaining screw.

Remove switch from housing, see diagram 13.9.

Remove electrical leads.

0020008153A

42

USER INTERFACE

Diagram 13.10

13 Replacement of Parts

13.20 Mains Reset Knob

Refer to section 13.18 for access.

Remove actuator by springing back retaining clips.

Spring back knob retaining clips and push knob out from the
back, see diagram 13.9.

13.21 User Interface

Refer to section 13.18 for access and diagram 13.10.

Remove electrical plug.

Remove the three securing screws.

Withdraw the board.

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

9247

RETAINING
STRAP

13.22 Main PCB

For access, refer to section 13.1

Hinge down the control box, see diagram 13.11.

Remove 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,
see diagram 13.1.

13.23 Control Box

For access refer to section 13.22.

Remove relevant plugs and connectors, refer to wiring diagram

12.1.

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

13.11.

13.24 Fuse - Main PCB - Control Box

For access, refer to section 13.22.

The fuse is located at bottom right hand side of the PCB, see
diagram 12.2 or 13.1.

RETAINING
SLOT

CONTROL PANEL

USER INTERFACE BOARD

Diagram 13.11

11419

230V
CONTROLS
INTERFACE
BOARD

Diagram 13.12

13.25 230V Controls Interface

For access, refer to section 13.18.

Disconnect the electrical connection from the 230V controls
interface board and the electrical connection from the main
PCB, see diagram 13.12.

Remove the 230V controls interface retaining screw.

Remove the 230V controls interface board.

43

0020008153A

14 Spare Parts

When ordering spare parts, 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 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 No

1 801645 Fan assembly

2 801637 Spark electrode E83999

3 801655 Igniter unit E84015

4 801649 Gas valve E84004

4 2000802452 Gas valve (38hxi only) H20596

5 801722 Heating flow & return thermistor (2)

6 801724 Overheat stat E83996

7 4000124180 Main P.C.B. E84019

8 801809 Mains Reset Switch

9 2000802640 User interface - 18 hxi *****

9 2000802641 User interface - 30 hxi *****

9 2000802658 User interface - 12 hxi *****

9 2000802659 User interface - 15 hxi H17-407

9 2000802660 User interface - 24 hxi H17-409

9 2000802801 User interface - 38hxi H17-411

10 801632 Burner - 12 hxi / 15 hxi / 18 hxi E84021

10 2000801702 Burner - 24 hxi / 30 hxi E84249

10 2000801702 Burner - 38 hxi E84249

11 2000801923 230V Controls Interface E84018

E84024

E84003

E84794

6

12451

10

5

23

8

4

1

7

9

11

Diagram 14.1

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

0020008153A

44