Glow-worm Flexicom cx User Manual

Installation
and Servicing

Condensing Boilers/
Flexicom cx
24cx
30cx G.C.No. 47-047-34
35cx G.C.No. 47-047-35

G.C.No. 47-047-33

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 and 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 competent

person approved at the time by the Health and Safety Executive 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 benet 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.

Customer Service:

01773 828100

Technical Helpline:

01773 828300

General and Sales enquiries:

Tel. [phone]

Fax: [phone]

To register your Glow-worm appliance call:

0800 0732142

Benchmark places responsibilities on both manufacturers and installers. The purpose is to ensure that customers are provided
with the correct equipment for their needs, that it is installed, commissioned and serviced in accordance with the manufacturer’s
instructions by competent persons and that it meets the requirements of the appropriate Building Regulations. The Benchmark
Checklist can be used to demonstrate compliance with Building Regulations and should be provided to the customer for future
reference.
Installers are required to carry out installation, commissioning and servicing work in accordance with the Benchmark Code of
Practice which is available from the Heating and Hotwater Industry Council who manage and promote the Scheme.
Visit www.centralheating.co.uk for more information.

TABLE OF CONTENTS

These instructions consist of, Installation, Servicing, Fault Finding, Replacement of Parts

and Spares. 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

Warnings 4
Important Information 4

INTRODUCTION

INSTALLATION

Statutory Requirements 5
Boiler Design 6
Safety Devices 6
Servicing, Maintenance and Spare Parts 6

Boiler Specication 1 7

Boiler Dimensions and
Hydraulic Schematic 2 8
Boiler Location, Clearances
and Ventilation 3 9
Evacuation of Combustion Gas 4 10
Water Systems 5 14
Installation Preparation 6 18
Gas/Water Connections 7 20
Boiler Fixing 8 21
Safety Discharge Valve and
Condensate Connections 9 22
Electrical Connection 10 24
Commissioning 11 25

MAINTENANCE

APPENDIX

Servicing 12 29
Fault Finding 13 34
Replacement of Parts 14 40
Spare Parts 15 48
Manual Handling 16 49

Benchmark Logbook 50
Commissioning Flow Chart 53

- 3 -

INTRODUCTION

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.

Metal Parts

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

with particular regard to edges.

Sealed Components

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

Important Information

Gas Category

This boiler is for use only on G20 natural gas.

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 approved
at the time by the Health and Safety Executive in accordance
with the current issue of these regulations.

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.

Manual Handling

With regards to the “Manual Handling Operations, 1992
Regulations”, the appliance exceeds the recommended weight
for a one man lift, refer to section 16 for more information.
The handling of the boiler may involve lifting, pushing and
pulling, the use of a sack truck may be required.
The following handling techniques and precautions should be
considered:

- Grip the boiler at its base

- Be physically capable

- Use safety clothing where appropriate, e.g. gloves, safety
footwear.
Ensure safe lifting techniques are used

- Keep back straight.

- Avoid twisting at the waist.

- Avoid upper body/top heavy bending.

- Always grip using the palm of the hand.

- Use designated hand holds.

- Keep load as close to body as possible.

- Always use assistance if required.

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 7671.
In IE, this is the current edition of ETCI rules.
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 identied 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, provided they are not used in a room
containing a bath or shower.
Wiring to the boiler must be PVC 85°C insulated cable, not less
than 0.75mm2 (24/0.20mm).

Testing and Certication

This boiler is tested and certicated for safety and performance.

It is, therefore, important that no alteration is made to the boiler,
without permission, in writing, by Glow-worm.
Any alteration not approved by Glow-worm, could invalidate the

certication, boiler warranty and may also infringe the current

issue of the statutory requirements.

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INTRODUCTION

CE Mark

This boiler meets the requirements of Statutory Instrument,

No. 3083 The Boiler (Efciency) Regulations, and therefore is

deemed to meet the requirements of Directive 92/42/EEC on

the efciency requirements for new hot water boilers red with

liquid or gaseous fuels.

Type test for purposes of Regulation 5 certied by: Notied

body 0087.

Product/production certied by: Notied body 0086.

The CE mark on this appliance shows compliance with:

1. Directive 2009/142/EC 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.

IMPORTANT

Where no British Standards exists, materials and equipment

should be t for their purpose and of suitable quality and

workmanship.
The installation of this boiler must be carried out by a
competent person approved at the time by the Health and
Safety Executive in accordance the rules in force in the
countries of destination.
Manufacturer’s instructions must not be taken as overriding
statutory requirements.

Statutory Requirements

In GB, the installation of the boiler must comply with the

requirements of the current issue of BS6798 and be carried out
by a competent person, approved at the time by the Health
and Safety Executive, 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 Supply (water ttings) Regulations 1999 and water

byelaws 2000, Scotland.
The Health and Safety at Work Act, Control of Substances
Hazardous to Health (COSHH).
The Current I.E.E. Wiring Regulations.

Where no specic 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 approved at the time by the Health and Safety

Executive 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.
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.

IE: I.S.813, BS5546, BS 5449, BS 7074, BS 7593.
NOTE: For further information, see the current issue of the

Building Regulations, approved document L1 ( in the UK) and
the following current issues of:

1) Central heating system specication (CheSS)

and

2) Controls for domestic central heating system and hot water.
BRECSU.

Gas Supply

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

In GB, this is BS6891.
In IE, this is the current edition of I.S.813 “Domestic Gas

Installations”.
The supply from the governed meter must be of adequate size
to provide a steady inlet working pressure of 20mbar (8in wg) at
the boiler.
On completion, test the gas installation for tightness using the

pressure drop method and suitable leak detection uid, purge in

accordance with the above standard.

Domestic Hot Water

All domestic hot water circuits, connections, ttings must be

in accordance with the relevant standards and water supply
regulations.
GB: Guidance G17 to G24 and recommendation R17 to R24 of
the Water Regulations Guide.

IE: The current edition of I.S.813 “Domestic Gas Installations”.

Heating System

In GB, it is necessary to comply with the Water Supply (Water

Fittings) Regulations 1999 (for Scotland, the Water Byelaws
2000, Scotland).
To comply with the Water regulations your attention is drawn
to: The Water Regulations guide published by the Water
Regulations Advisory Service (WRAS) gives full details of the
requirements.
In IE, the requirements given in the current edition of I.S.813
“Domestic Gas Installations” and the current Building
Regulations must be followed.

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- 5 -

INTRODUCTION

Boiler Design

Boiler Design

These boilers are designed for use as part of a sealed water
central heating system with fully pumped circulation. The
pump, expansion vessel and associated safety devices are all

tted within the boiler. The hot water PRE HEAT temperature

facility will improve the boilers hot water delivery response.
The daily pump and 3 way valve exercise programme combined
with the built-in frost protection will help to maintain and protect
the boiler.

Range Rating

The boilers are fully modulating for central heating, it is
therefore not necessary to range rate the boiler. However, if
desired, it is possible to range rate the max. CH output in 1kW
increments, refer to section 11.

Safety Devices

Electrical Supply Failure

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 press the reset button. If
the boiler does not resume normal operation after this call your
Installation/Servicing company or Glow-worm service.

Overheating Safety

The boiler software is designed to recognise the potential for
an overheat lockout and will shutdown before this happens. To
restart the boiler, press the reset button on the controls fascia.
If the boiler fails to resume normal operation and all external
controls are calling for heat, then call your Installation/Servicing
company or Glow-worm service.

Safety Discharge Valve

A safety discharge valve and discharge pipe are tted to the

boiler. This valve must not be interferred with, should there be
any discharge from the pipe, isolate the boiler electrical supply
and call your installer or Glow-worm’s own service organisation
using the telephone number on the inside front cover of this
booklet.

Condensate Drain

A plastic drain pipe must be tted to allow discharge of

condensate to a drain. Condensate should, if possible, be
discharged into the internal household draining system. If
this is not practical, discharge can be made externally into the
household drainage system or a purpose designed soak away,
see section 8 for more details.

Pluming from ue terminal

Like all condensing boilers this appliance will produce a plume

of condensation from the ue terminal in cool weather. This is
due to the high efciency and hence low ue gas temperature of

the boiler. This is normal and not an indication of a fault.

Frost protection

The appliance has a built in frost protection device that protects
the boiler from freezing. With the gas and electric supplies
ON and irrespective of any room thermostat setting, the frost
protection device will operate the pump when the temperature
of the boiler water falls below 8°C.
A timer is used so that the temperature can be checked
periodically. After 10 minutes the pump will be stopped if the
temperature is higher than 10°C or has already reached 35°C.
The burner will activate if the boiler temperature does not reach
10°C after 30 minutes or at any time if the temperature drops to
5°C.
The burner will switch off when the temperature reaches 35°C.

Condensate Drain Blockage

As a safety feature the boiler will stop working if the condensate
drain becomes blocked. During freezing conditions an ice
blockage in the condense drain, external to the house would
also activate the safety feature. Use warm cloths on the pipe to
release an ice blockage.
Once the blockage is removed the boiler should then restart.

Servicing, Maintenance and Spare Parts

Servicing and Maintenance

To ensure the continued efcient and safe operation of the

boiler it is recommended that it is checked and serviced as
necessary at regular intervals. The frequency of servicing will
depend upon the particular installation conditions and usage.
If this applaince is installed in a rented property there is a duty
of care imposed on the owner of the property by the current
issue of the Gas Safety (Installation and Use) Regulations,
Section 35.
Servicing/maintenance should be carried out by a competent
person approved at the time by the Health and Safety
Executive in accordance with the rules in force in the countries
of destination.
To obtain service, please call your installer or Glow-worm’s own
service organisation using the telephone number on the inside
front cover of this literature.
After servicing, complete the relevant Service Interval Record

- 6 -

section of the Benchmark Checklist located on the inside back
pages of these instructions.

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 specication that we require. Do not

use reconditioned or copy parts that have not been clearly
authorised by Glow-worm.
If a part is required contact Glow-worm’s own service
organisation using the telephone number on the inside front
cover of this booklet.
Please quote the name of the appliance, this infomation will be
on the name badge on the front of the appliance.
If in doubt seek advice from the local gas company or Glow­worm’s own service organisation using the telephone number
on the inside front cover of this booklet.

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BOILER SPECIFICATION 24cx 30cx 35cx

Lift weight 36kg (79Ib) 36kg (79Ib) 36kg (79lb)

Total weight (installed) 41kg (90Ib) 41kg (90Ib) 41kg (90lb)

Gas connection Ø O.D. 15mm. copper 15mm. copper 15mm. copper

Heating and return connection Ø O.D. 22mm. copper 22mm. copper 22mm. copper

Domestic hot water connection Ø O.D. 15mm. copper 15mm. copper 15mm. copper

Condensate connection Ø I.D. 21.5mm. plastic 21.5mm. plastic 21.5mm. plastic

Safety valve discharge connection ØO.D. 15mm. copper 15mm. copper 15mm. copper

Heating circuit safety valve (preset) 3 bar (43.5Ibf/in

2

) 3 bar (43.5Ibf/in2) 3 bar (43.5Ibf/in2)

Heating system minimum pressure 0.7bar (10.1Ibf/in

2

) 0.7bar (10.1Ibf/in2) 0.7bar (10.1Ibf/in2)

Maximum domestic hot water circuit 10bar (145Ibf/in

2

) 10bar (145Ibf/in2) 10bar (145Ibf/in2)

1.0bar (14.5lbf/in

2

) 1.0bar (14.5lbf/in2) 1.0bar (14.5lbf/in2)

0.2bar (2.9Ibf/in

2

) 0.2bar (2.9Ibf/in2) 0.2bar (2.9Ibf/in2)

Specific water rate at 35° rise 9.85L/min. 12.3L/min. 14.4L/min

Min. flow rate around C.H. at 20° rise 776L/hr. 1032L/hr. 1204L/hr

Maximum domestic hot water temperature 63° 63° 63°

Expansion vessel capacity 8 litres (1.76 gallons) 8 litres (1.76 gallons) 8 litres (1.76 gallons)

Expansion vessel charge pressure 0.5bar (7.3Ibf/in

2

) 0.5bar (7.3Ibf/in2) 0.5bar (7.3Ibf/in2)

Electrical supply 230V~50Hz fused 3A 230V~50Hz fused 3A 230V~50Hz fused 3A

Electrical rating 180W fused 3A 180W fused 3A 180W fused 3A

EN437 IP clasification IPX4D IPX4D IPX4D

Internal fuse rating on main PCB 2A 2A 2A

Gas supply (governed meter only) and Cat G20 natural gas G20 natural gas G20 natural gas

Gas Category I

2H

I

2H

I

2H

Inlet gas working pressure 20mbar 20mbar 20mbar

Burner % CO

2

case on 9.3 nominal 9.3 nominal 9.3 nominal

Burner % CO

2

case off 9.3 nominal 9.3 nominal 9.3 nominal

1.93 m

3

/h 2.59 m3/h 3.26 m3/h

68.1 ft

3

/h 91.5 ft3/h 115 ft3/h

0.99 m

3

/h 0.99 m3/h 0.99 m3/h

35.1 ft

3

/h 35.1 ft3/h 35.1 ft3/h

Flue type C

13, C33, C43 C13, C33, C43 C13, C33, C43

NOx Class 5 Class 5 Class 5

Heat output condensing mode 18.8kW 24.9kW 31.0kW

Heat input Nett Q = kW DHW max. 25.5 min. 9.4 DHW max. 30.8 min. 9.4 DHW max. 35.8 min. 9.4

CH max. 18.3 min. 9.4 CH max. 24.5 min. 9.4 CH max. 30.8 min. 9.4

Heat output P = kW DHW max. 25.1 min. 9.3 DHW max. 30.0 min. 9.3 DHW max. 35.0 min. 9.3

CH max. 18.0 min. 9.3 CH max. 24.0 min. 9.3 CH max. 30.0 min. 9.3

SEDBUK rating % 2005 90.3 90.0 90.2

SEDBUK rating % 2009 88.4 88.3

89.1

Approximate max. gas rate
after 10 mins. from cold

Approximate min. gas rate
after 10 mins. from cold

Minimum working pressure to obtain
domestic hot water

Minimum working pressure to obtain
maximum domestic flow

PLEASE REFER TO THE COMMISSIONING SECTION

Approximate gas rate
at part load.

1 Boiler Specication

TECHNICAL DATA

14732

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- 7 -

INSTALLATION

13893

2 Boiler Dimensions and Hydraulic
Schematic

All dimensions are given in millimetres (except as noted).
The general arrangment of the boiler is shown in diagram 2.1
and the hydraulic and gas schematic, diagram 2.2.
The data label is positioned on the front of the inner casing
panel.

13089

- 8 -

Diagram 2.2Diagram 2.1

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INSTALLATION

3 Boiler Location, Clearances and
Ventilation

3.1 Location

This boiler is not suitable for outdoor installation.
This boiler may be installed in any room, although particular
attention is drawn to the installation of a boiler in a room
containing a bath or shower where reference must be made to
the relevant requirements.
This boiler is suitable for installation in bathroom zones 2 and 3.
In GB this is the current I.E.E. WIRING REGULATIONS and
BUILDING REGULATIONS.
In IE reference should be made to the current edition of I.S.813
“Domestic Gas Installations” and the current ETCI rules.

3.2 Clearances

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

3.1.

Additional clearances may be benecial around the boiler for

installation and servicing.

For ue installations where external access is not practicable,

consideration should be given for the space required to insert

the ue internally, which may necessitate clearance larger than
those specied in diagram 3.1.

13127

3.3 Timber Frame Buildings

If the boiler is to be installed in a timber frame building it should

be tted in accordance with the Institute of Gas Engineers

document IGE/UP/7/1998. If in doubt seek advice from local
gas undertaking or Glow-worm.

3.4 Combustible Material

The boiler and ue are suitable for installation onto and through

combustible materials provided that:-

1) Minimum 5mm clearance is maintained around the

circumference of the ue (air intake).

2) The combustible surface and xings are suitable for

supporting the load.

3) The minimum clearances from the boiler case are
maintained.

3.5 Room Ventilation

The boiler is room sealed so a permanent air vent is not
required.

3.6 Cupboard or Compartment Ventilation

Due to the high efciency and low casing temperature of this

boiler, cupboard or compartment ventilation is not necessary.

• Existing ventilation should be investigated for its purpose
before removing.

Diagram 3.1

3.7 Airing Cupboard Installation

If the boiler is to be installed in an airing cupboard it is not
required to separate the boiler with a non-combustible partition.
However, installation and servicing clearances must be
maintained, and the boiler kept clear of any clothing. Details of
essential features of cupboard/compartment design including
airing cupboard installations are given in BS 6891. In IE the
current edition of IS 813.

3.8 Roof Restricting Installation

It is not necessary to ensure sufcient clearance between

the boiler and combustible materials or components. This is
because the temperature of the boiler will always be less than

o

C due to its nominal heat output.

85

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INSTALLATION

4 Evacuation of Combustion Gas

4.1 Regulation

Only ue accessories supplied by Glow-worm
must be used.

Different ue outlet congurations can be carried out.

• Consult your supplier for more information about the other
possibilities and associated accessories.

44 mm/m

• Standard ue terminal kits have an in-built fall back to the
boiler to drain the condensate. These can be tted level

between the appliance and the termination position. All other

extended ues must have a fall of at least 44mm/m

If the ue terminal is positioned near a light
source insects may enter the ue system.
Where safe and practical to do so advise the
homeowner to check the ue outlet and clear
visible insects from the terminal end.

H* and J* See diagram 4.2. These dimensions comply with
the building regulations, but they may need to be increased to
avoid wall staining and nuisance from pluming depending on
site conditions.

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 4.1.
A suitable guard is manufactured by: ­Tower Flue Components
Morley Rd.
Tonbridge
Kent TN9 1RA.
Size: 280mm x 165mm. Part No: CGDK3

15583

The maximum length of the ue outlet is dened according to its

type (for example C13).

• Whatever the kind of ue system chosen, observe the
minimum distances indicated in the chart below to position

the ue terminals.

• To install the ue, refer to the separate ue instruction
supplied with your appliance.

• Explain these requirements to the user of the appliance.

If necessary, you must install terminal

a

In GB the minimum acceptable siting dimensions for the
terminal from obstructions, other terminals and ventilation
openings are shown in diagram overleaf.

In IE the minimum distances for ue 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.

protection.

Caution! The connection between the ue
elbow and the ue outlet must be sealed.

Diagram 4.1

Being a condensing boiler some pluming may occur from

the ue outlet. This should be taken into consideration when

selecting the position for the terminal.

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.

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INSTALLATION

J

J

U

E

F

A 300mm adjacent to a boundary.

B The dimension below eaves, balconies and car ports

can be reduced to 25mm, as long as the flue terminal
is extended to clear any overhang. External flue
joints must be sealed with a suitable silicon sealant.

C 1500mm between a vertical ue terminal and a

window or dormer window.

D 1200mm between terminals facing each other.

E Vertical ue clearance, 300mm adjacent to a

boundary line.

F 600mm distance to a boundary line, unless it will

cause a nuisance. BS 5440:Part 1 recommends
that care is taken when siting terminal in relation to
boundary lines.

G 300mm minimum clearance from a skylight to a

vertical ue or to another vertical ue.

H Vertical ue clearance, 500mm to non-combustible

building material, and 1500mm clearance to
combustible building material.

J 300mm above, below and either side of an opening

door, air vent or opening window.

K 600mm diagonally to an opening door, air vent or

opening window.

L 300mm to an internal or external corner.

M 2000mm below a Velux window, 600mm above or to

either side of the Velux window.

N 400mm from a pitched roof or 500mm in regions with

heavy snowfall.

P 25mm from vertical drain pipes and soil pipes.

A

G

J

J

H

K

J

Q

G

B

S

D,T

M

V

C

N

R

L

L

P

L

S

S

Q 200mm below eaves and 75mm below gutters, pipe

and drains.

R The dimension below eaves, balconies and car ports

can be reduced to 25mm, as long as the ue terminal
is extended to clear any overhang. External ue

joints must be sealed with suitable silicon sealant.

S 300mm above adjacent ground, balcony or storm

porch.

T 600mm distance to a surface facing a terminal,

unless it will cause a nuisance. BS 5440: Part 1
recommends that care is taken when siting terminals
in relation to surfaces facing a terminal.

U 300mm clearance alongside another terminal.

V 300mm above roof level.

ll measurements are the minimum clearances required.

A

Terminals must be positioned so to avoid combustion products
entering the building.

Support the ue at approximately one metre intervals and at a change
of direction, use suitable brackets and xings.

Installations in car ports are not recommended.

A ue outlet should be protected with a guard if persons could come

into contact with it or if it could be damaged.

The ue cannot be lower than 1 metre from the top of a light well due to

the build up of combustion products.

Dimensions from a ue terminal to a fanned air inlet to be determined

by the ventilation equipment manufacturer.

S

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- 11 -

INSTALLATION

4.2 Flue conguration description

4.2.1 Horizontal concentric ue Ø 60/100 mm

or Ø 80/125 mm (C13 type installation)

Ø 60/100 mm

L

1

63

4.2.2 Telescopic direct rear ue Ø 60/100 mm

Ø 60/100 mm

L

Type Max length

Ø 60/100 512 mm

4.2.3 Vertical concentric ue Ø 60/100 mm
or Ø 80/125 mm (C33 type installation)

Key

1 Gasket (tted)

1

Key

1 Gasket (tted)

Ø 60/100 8 m
Ø 80/125 20 m

Ø 80/125 mm

L

Type Max length

L

Type Max length (L)

Ø 60/100 8 m
Ø 80/125 20 m

Each time an additional 90° bend is necessary (or 2 at 45°), the
length (L) must be reduced by 1 m.

Each time an additional 90° bend is necessary (or 2 at 45°), the
length (L) must be reduced by 1 m.

- 12 -

0020107232_03 - 12/14 - Glow-worm

4.2.4 Multiple boiler chimney ue

L

B

A

1

2

3

4

5

Ø 60/100 mm (C43 type installation)

The ue connecting from the appliance to
the ue system must be supplied from the
manufacturer of the boiler.

C43 ue systems must not be a 'pressurised
system' but act under natural draught principles

C43 type ue systems must have their
own condensate drain tted and not allow
condensate to mix into other appliances

INSTALLATION

Multiple Boiler Chimney Flue Length

The ue length must be calculated and installed according to
the relevant standards EN 13384-1 and 2 (C43 ue systems

only) with reference to the table below and the manufacturers
instructions supplied.

The appliance maximum ue length must be included when
calculating the overall design of the ue system.

NOTE: The horizontal ue terminal must be removed.

Flexicom

24cx

Exhaust mass rate (g/s)

At Min Thermal
Load (40C°/30°C)

At Max Thermal
Load (80C°/60°C)

Exhaust temperature (ºC)

At Min Thermal
Load (40C°/30°C)

At Max Thermal
Load (80C°/60°C)

11.67 14.10 16.39

Key
1 Pressure balancing system
2 Air-inlet pipe
3 Collector pipe
4 Boiler
5 Inspection hatch
A Final storey

B Ground oor

Type Max length (L)

Ø 60/100 8 m

Each time an additional 90° bend is necessary (or 2 at 45°), the
length (L) must be reduced by 1 m.

30cx

Flexicom

Flexicom

35cx

4.30 4.30 4.30

33.2 33.2 36.0

73.3 87.4 86.0

0020107232_03 - 12/14 - Glow-worm

- 13 -

INSTALLATION

5 Water Systems - General

5.1 General

This boiler is designed for use as part of a sealed water central
heating system with fully pumped circulation. The pump,

expansion vessel and associated safety devices are all tted

within the boiler.

5.2 Draining Points

Draining taps must be provided at all low points of the system,
which will allow the entire system to be drained.
Draining taps shall be to the current issue of BS2879.
Drain points for the appliance are provided at the positions
shown in diagram 5.1.

13925

Diagram 5.1

13102

- 14 -

Diagram 5.2

0020107232_03 - 12/14 - Glow-worm

INSTALLATION

5.3 Water treatment

5.3.1 General

The Glow-worm Flexicom range of boilers have an
Aluminium alloy heat exchanger. Water treatment products
used in the system should be suitable for use with
Aluminium.

Existing system- It is ESSENTIAL that prior to installing

the new boiler the system is thoroughly ushed.

New system- For optimum performance after installation, the
boiler and its associated central heating system should also be

ushed.

For long-term corrosion protection, after ushing, an inhibitor

should be used, refer to the current issue of BS 5449 and BS
7593 on the use of inhibitors in central heating systems.

Debris left in the system can damage the boiler,
reduce efciency and also lead to system
corrosion and generation of ammable gas.
Failure to comply with the guidelines for the
use of water treatment with the appliance will
invalidate the appliance warranty.

The pH value of the system water must be
between 6.5 and 8.5 or the appliance guarantee
will be invalidated.

5.3.3 Inhibiting the system

Add a suitable inhibitor or combined inhibitor/anti-freeze, if the
system is exposed to freezing conditions, to the heating system
in accordance with the DWTA code of practice and inhibitor
manufacturer’s guidelines.

Examples of suitable inhibitors are:

Sentinel X100

Fernox protector F1

Articially softened water must not be used to
ll the central heating system.

Sealing agents - The addition of sealing agents
to the system water is not permitted as this can
cause problems with deposits left in the heat
exchanger.

Ensure that the pH of the treated system water is

i

i

conrmed as between 6.5 and 8.5 and free of any
residual deposits from the ushing process.

Ensure the Benchmark Logbook is completed with
information on water treatment products before
handing over to the user.

Before ushing the system

• Ensure that the system and pipe work is in good working
order.

• Where possible keep the existing boiler/circulating pump in

place when ushing the system.

5.3.2 Flushing the system

• Fill the system with cold water and check for leaks.

• Open all drain cocks and drain the system.

• Close drain cocks and add a suitable ushing agent (cleaner)
compatible with Aluminium at the correct strength for the
system conditions in accordance with the manufacturer’s
instructions.

Examples of suitable ushing agents/cleansers are:

Sentinel X300, X400

Fernox F3

• Circulate the ushing agent before the boiler is red up.

• Run the boiler/system at normal operating temperature as

directed by the manufacturer of the ushing agent.

• It is essential to drain and thoroughly ush the whole system
to remove the ushing agent and debris.

• It may be necessary to use a power ushing machine to aid
the cleansing procedure in some circumstances.

• Close the drain cocks and rell with fresh water and a
suitable inhibitor

• Vent any air from the boiler and system.

0020107232_03 - 12/14 - Glow-worm

- 15 -

INSTALLATION

5 Water systems - Domestic Hot Water

5.4 General

All domestic hot water circuits, connections, ttings 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 Scotland, the Water

Byelaws 2000, Scotland).

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

5.5 Water Pressure

The minimum working pressure to obtain the maximum

domestic ow is:-

24cx 1.0bar
30cx 1.0bar
35cx 1.0bar
The maximum working pressure of the domestic hot water
circuit is 10 bar. If the cold water supply pressure exceeds this,

then a pressure-reducing valve must be tted in the supply to

the boiler.

5.6 ‘Hard’ Water Areas

The temperatures within the heat exchanger are limited by the
boiler control system to minimise scale formation within the hot
water pipework. However, in areas where the water is ‘hard’ (i.e.
more than 200mg/litre), it is recommended that the hot water

setting is reduced and that a scale reducer is tted, refer to the

manufacturer’s instructions or consult the local water company
for additional advice.

5 Water Systems - Sealed Central Heating
system

5.8 Flow Rate

If it is necessary to alter the ow rate, the system can be tted
with a lockable balancing valve in the main ow or return pipes
shown as valve “A” in diagram 5.3. The ow rate through the

boiler must not be allowed to fall below that given in section 1 -

Specication Table.

5.9 Bypass

The boiler is tted with an automatic bypass.

Diagram 5.2 shows the pump head remaining for the heating
system depending on the bypass setting and the speed setting
of the pump, see section 11 Commisioning.

Ensure that under no circumstances does the ow rate drop
below the gure specied, refer to section 1 - Specication

Table and section 11.9.

5.10 Safety Valve

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

not discharge above an entrance, window or any type of public
access area.

15725

5.7 Domestic Water Flow Rate

The water ow rate is restricted to a maximum 9.4 l/min for

24cx, 11.7 l/min for 30cx and 13.0l/min for 35cx by a restrictor

factory tted within the boiler.

- 16 -

Diagram 5.3

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INSTALLATION

5.11 Filling the Sealed System

The boiler is supplied with a lling device, see diagram 5.1.
This lling device is designed to enable the lling and

pressurisation of the system in the event of loss of pressure.
NOTE: The water pressure at the boiler must be at least

1.2bar to enable lling the boiler to a minimum pressure. If not

pressurisation must be carried out by an alternative lling loop.
Suitable external lling systems are shown diagramatically,

see diagram 5.4. The system should be pressurised to 1bar,
indicated on the digital display with no heating demand.

5.12 Expansion Vessel

The boiler has an integral expansion vessel with a capacity of 8
litres (1.76 gallons), with a charge pressure of 0.5bar.
NOTE: The expansion vessel volume depends on the total
water system volume and the initial system design pressure.
In GB, Guidance on vessel sizing is also given in the current
issue of BS5449 and BS7074 Part 1.
In IE, current edition of I.S.813 “Domestic Gas Installations”.

12253

0020107232_03 - 12/14 - Glow-worm

Diagram 5.4

- 17 -

INSTALLATION

H

H - Boiler Securing Screw

15708

- 18 -

Diagram 6.1

0020107232_03 - 12/14 - Glow-worm

INSTALLATION

6 Installation Preparation

6.1 Appliance Pack

Please check the contents of packs as shown in diagram 6.1.
The packs are located in the top polystyrene packing.
Remove the carton sleeve and top pack then lift the boiler and
its polystyrene base support out of the lower pack.

6.2 Site Requirements

The boiler mounting wall should be suitable for the weight of the

appliance and be true and at.

NOTE: Due to the varied site conditions we do not supply

xings and advise that the installer should supply those which

are suitable.

6.3 Wall Template

Take the wall template from the document pack located within
the top polystyrene packing and place in the desired position
on the wall, giving due consideration to the required boiler

clearances, see section 3, and the ue you are tting.
Mark the position of the ue centre, if tting a side ue, extend
the ue centre line into the corner then 149mm along the

adjacent wall, see diagram 6.2.

For extended side ues, the ue hole centre should be

determined by extending the dashed inclined line on the
template to the side wall, then 149mm along the adjacent wall,
see diagram 6.2. This dashed line is drawn at 44mm/metre
(2.5°) rise from the boiler.

To allow for the ue passing through the wall at this angle a

125mm hole should be drilled irrespective of internal or external
installation.

Remove the wall template whilst drilling the ue hole.

13894

Diagram 6.2

14810

HANGING
BRACKET
FIXINGS

6.4 Flue Hole Cutting

External access ue installation can use a 105mm diameter

core drill.

Internal access only ue installation will need a 125mm

diameter core drill.

NOTE: The ue is designed with an internal fall of 44mm/metre

(2.5°), therefore the hole can be drilled horizontally.

If ue extension pipes are to be used then a core drill size of

125mm is required. This will allow the extension pieces to
slope at 44mm/metre (2.5°) towards the boiler.

6.5 Wall Hanging Bracket Assembly

The Wall Hanging Bracket is supplied in the main boiler
packaging at the rear of the boiler.

Reposition the wall template over the ue hole and mark the
position of the xing holes for the hanging bracket, see diagram

6.3.

NOTE: Due to the varied site conditions we do not supply

xings and advise that the installer should supply those which

are suitable.

Drill xing holes and insert suitable wall plugs.

Direct Rear Flue only - If external access is not available the

ue to be used should be assembled as described in sections

10.11 to 10.13 and inserted through the hole in the wall before

tting the wall hanging bracket.
Fit the xing jig support plate to the bottom of the wall hanging

bracket, push down to locate.

Mark, drill and plug at xing points and secure the jig support

plate, see diagram 6.3.

JIG SUPPORT
PLATE FIXINGS

Diagram 6.3

Direct Rear Flue only - The ue can now be pulled back

through the hanging bracket and secured as shown in diagram

6.3.

0020107232_03 - 12/14 - Glow-worm

- 19 -

INSTALLATION

7 Gas/Water Connections

7.1 System connection

NOTE: The appliance may contain a small amount of water,

place a water container beneath the boiler connections

NOTE: The Gas and Water systems can be connected

and lled prior to installation of boiler, refer to section 12

Commissioning. Make sure the drain points are accessible,
refer diagram 5.4.

All water and gas connections are on the xing jig with the

exception of the condense drain and safety discharge, the
positions of these are shown on the wall template.
An Upward Piping Frame, part no. A2041500 should be used
if the supplies come from above the boiler otherwise the pipes
will have to be chased into the wall.

Assemble the pipes to the jig as shown in diagram 7.1.

Fit ‘O’ ring seal to the Double Check Valve assembly.

13129

Fit the Central Heating Isolation Valve handles and secure with
screws provided.

Fit the assembled Jig Plate to the Support Plate as shown in
diagram 7.2.

Assemble the Gas service isolation valve and position onto the
plastic plug.

Plumb system pipe work to the copper tails. Do not subject
isolation valves to heat.

Fit Double Check Valve into Isolation Valve and secure with the
wire retaining clip.

Prior to lling the water system ensure that the blanking plugs

and isolation valves are secured.

Flush out the domestic hot water and the heating systems.

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

12957

- 20 -

Diagram 7.1

Diagram 7.2

0020107232_03 - 12/14 - Glow-worm

INSTALLATION

8 Boiler Fixing

8.1 Boiler Hanging

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 section 16
Manual Handling.

IMPORTANT: Direct Rear Flue only - The direct rear ue must
be tted before hanging the boiler, refer to sections 10.11 to

10.13, and the rear outlet cover plate should be removed.

The appliance and jig (pre-lled) may contain a small amount of

water, place a water container beneath the boiler connections.
Make sure the isolation valves are closed before disconnecting
the blanking plugs and discarding the jig plate.
Position the sealing washers supplied in the Loose Items pack,
as shown in diagram 6.1.

Lifting the boiler into position, lean the top of the boiler slightly
to the wall and position just above the hanging bracket. Lower
the boiler slowly, push back and engage onto the hanging
bracket making sure the boiler is located over the retaining
bosses, secure with screw provided, see diagram 8.1.
Remove the protective caps.

Engage the xing jig connections, ensuring that the previously

positioned washers have not been disturbed.

There are ats on the body of the valves for locating a spanner

to aid tightening to copper tails using the tightening sequence
shown in diagram 8.2.

Make good the nal connections.

14811

SECURING
SCREW

Diagram 8.1

A - Central Heating Isolation Valve
B - Domestic Hot Water
C - Gas Service Isolation Valve
D - Domestic Cold Water
E - Washers (not shown)
F - Condensate Connection
G - Double check inlet valve
H - Safety Discharge Valve

13926

Numbers 1 - 5
show the sequence to be used
when tightening to copper tails.

Diagram 8.2

0020107232_03 - 12/14 - Glow-worm

- 21 -

INSTALLATION

9 Condensate Connections

9.1 Safety Discharge Valve

Take the safety discharge pipe, supplied in the pipe pack and

the union nut and seal, supplied in the loose items pack and t

as shown in diagram 9.1.
This must be extended, using not less than 15mm o.d. pipe,
to discharge, in a visible position, outside the building, facing
downwards, preferably over a drain.
To ease future servicing it is advisable to use a compression

type tting to extend the safety discharge valve tube.

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

9.2 Condensate Trap and Siphonic Drain

Connection

A exible condensate outlet pipe is tted and should be used

to couple the condensate trap and siphonic drain to a 22mm

to 25mm O.D. non corrosive plastic pipe (overow pipe), see

diagram 8.2.

IMPORTANT: Please remove the bung from the exible pipe
before tting to a drain outlet pipe.

12667

NOTE: the pipe should have a fall of a least 2.5o 44mm/metre
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 9.2.
It is recommended that any external condensate drain pipe is
protected 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.

Diagram 9.1

- 22 -

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INSTALLATION

15826

0020107232_03 - 12/14 - Glow-worm

Diagram 9.2

- 23 -

INSTALLATION

10 Electrical Connection

WARNING: This appliance 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.

● Do not interrupt the mains supply with a time switch or

programmer.

● 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 identied as

to its use.

● A fused three pin plug and shuttered socket outlet may be

used instead of a fused spur box provided that it is not used in a

room containing a xed bath or shower.

● The boiler is suitable for installation in bathroom zones 2 and

3.

10.1 Electrical Wiring

Remove the electrical cartridge from the ttings pack.

Remove the securing screw to open the cartridge.
NOTE: There are two screws supplied loose in the electrical
cartridge, these will be required to secure the cartridge into the
electrical interface housing.

13921

Slacken the screws of the cable strain relief in the electrical
cartridge, see diagram 10.1.

Route the mains supply and system cables through the strain
relief and connect to the relevant plug, refer to the appropriate
sections 10.2 or 10.3.

Initially, if system controls are not tted, leave the “Red Link” in

place, this will create a continuous demand.

10.2 System Controls 24V

WARNING: UNDER NO CIRCUMSTANCES MUST ANY
MAINS VOLTAGE BE APPLIED TO ANY OF THE TERMINALS
ON THE 24V CONNECTION PLUG.

Connect the mains supply and system heating controls e.g.
room thermostat as diagram 10.2.

External controls should be tted in accordance with the rules

in force.

10.3 Mains Voltage System Controls

WARNING: UNDER NO CIRCUMSTANCES MUST ANY
MAINS VOLTAGE BE APPLIED TO ANY OF THE TERMINALS
ON THE 24V CONNECTION PLUG.

Diagram 10.1

13368

Connect mains supply and system controls as diagram 10.3.

External controls should be tted in accordance with the rules

in force.

- 24 -

Diagram 10.2

0020107232_03 - 12/14 - Glow-worm

INSTALLATION

13369

13922

Diagram 10.3

10.4 Electrical Cartridge Securing

With the gas service isolation valve closed and with no demand

from any external controls, t the electrical cartridge into the

interface housing, see diagram 10.4.
Secure with the two cartridge retaining screws provided in the
cartridge body.

11 Commissioning

IMPORTANT: If the appliance is to be left out of operation after

initial commissioning, ensure all system cleansing and inhibition
has been carried out fully and that power is left on to the

appliance. This is to ensure that there is no risk of ammable

gas collecting in the system due to corrosion.
At the time of commissioning, complete all relevant sections of
the Benchmark Checklist located in the inside back pages of
this document.

11.1 Pre-lling the Heating Circuit

Do Not operate the boiler without water.
The commissioning should be carried out by a competent
person approved at the time by the Health and Safety

Executive and in accordance with the current issue of BS6798.

Make sure that the system has been thoroughly ushed out with

cold water and that all cleanser if used has been removed.
With the gas service isolation valve closed, with no demand
from any external controls and the power supply to the boiler
switched off.
Test for gas tightness and purge air from the gas supply.

Diagram 10.4

10.5 Electrical Connections - Testing

Carry out preliminary electrical system checks as below:

1. Test insulation resistance to earth of mains cables.

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

3. Test the polarity of the mains.

NOTE: If you require to test the appliance refer to section 13.

Refer to diagram 11.1

1. Ensure that the exible hose is connected to the double

check valve by tightening the knurled nut marked ‘E’.

2. Ensure that the water isolation valves are securely
tightened onto the jig blanking plugs.

3. Open the Central Heating Flow and Return isolation valves
marked ‘A’ using a screwdriver or a 4mm allen key - slot
in line with the axis of the isolation valves (shown closed in
diagram).

4. Ensure ALL cold water taps are shut off then open the
Domestic Cold Water isolation valve marked ‘B’ using a
screwdriver or a 3mm allen key - slot in line with the axis of
the isolation valve (shown closed in diagram).
NOTE: A manometer kit accessory, part no. 0020016995 is

available to monitor system pressure during lling, this should

be attached to the drain point connection marked ‘C’ and the
drain point opened to enable a reading of the system pressure
to be taken. If the manometer kit is not used caution should be
taken not to overpressurise the system.

5. Open the two lling taps marked ‘D’ by rotating them
through 90° to ll the heating system to a pressure of

1.0bar. Close the two lling taps.

6. Vent all air from the system - repeat step 5 as neccessary
until the system is full and all the air has been removed.

0020107232_03 - 12/14 - Glow-worm

- 25 -

INSTALLATION

7. Close the Domestic Cold Water isolation valve marked

‘B’ using a screwdriver or a 3mm allen key (shown closed
in diagram).

8. Close the Central Heating Flow and Return isolation

valves marked ‘A’ using a screwdriver or a 4mm allen key
(shown closed in diagram). If the manometer kit was used,
close drain point marked ‘C’ and remove the manometer.

9. To comply with the water regulations the exible hose

must be disconnected from the double check valve - undo

the knurled nut marked ‘E’ and pull the exible hose from

the double check valve.

11.2 Filling the System and Boiler

1. Ensure that the exible hose is connected to the double

check valve by tightening the knurled nut marked ‘E’.

2. Open the Central Heating Flow and Return isolation valves

marked ‘B’ using a screwdriver or a 4mm allen key - slot
in line with the axis of the isolation valve (shown closed in
diagram).

3. Open the Domestic Cold Water cock marked ‘B’ using a

screwdriver or a 3mm allen key - slot in line with the axis
of the isolation valve (shown closed in diagram).

4. Switch on the appliance, refer to diagram 11.2.

Set the Central Heating temperature and the Domestic Hot
Water temperature to OFF by pressing the MODE button
on the User Interface until it shows the appropriate symbol

or

and then pressing the - (minus) SELECTOR
button.
The display will now permanently show system pressure.

5. Open the two lling taps marked ‘D’ by rotating them

through 90O to ll the heating system to a pressure of

1.0bar. Close the two lling taps marked ‘D’.

6. Vent all air from the system - repeat step 5 as neccessary
until the system is full and all the air has been removed.

7. After lling is complete set the Central Heating

temperature and the Domestic Hot Water temperature
to the desired level using the MODE and + (plus)
SELECTOR buttons as described above.

8. To comply with the water regulations the exible hose

must be disconnected from the double check valve - undo

the knurled nut marked ‘E’ and pull the exible hose from

the double check valve.

11.3 Filling Domestic Water Circuit

Fully open any valves in the domestic water supply to the boiler.
Open the domestic water isolation valve, slot in line with the
length of the valve (shown closed in diagram).

Open all hot water taps in turn and close them when water

ows. Check for water soundness of the complete domestic

water system.

The water ow rate is restricted by a restrictor factory tted to

the boiler.

11.4 Re-pressurising System

1. Ensure that the exible hose is connected to the double

check valve by tightening the knurled nut marked ‘E’.

2. Open the two lling taps marked ‘D’ by rotating them

through 90

1.0bar. Close the two lling taps marked ‘D’.

3. Vent all air from the system - repeat step 2 as neccessary
until the system is full and all the air has been removed.

4. To comply with the water regulations the exible hose must

be disconnected from the double check valve - undo the

knurled nut marked ‘E’ and pull the exible hose from the

double check valve.

O

to ll the heating system to a pressure of

11.5 Gas Supply

The gas valve is factory set for natural gas (G20) and should
need no adjustment. Turn on the gas supply at the isolation
valve, see diagram 11.1. Check the supply pressure at the
pressure test point is 20mbar.

Commissioning should only be carried out by a competent
person approved at the time by the Health and Safety
Executive.

11.6 Initial Lighting

NOTE: Ensure that initial lighting of the appliance takes
place with the front casing door removed and the control
box lowered. Initially run the appliance pump to ensure all
air has been vented from the system (observe the
operation of the auto air vent, if possible).
The combustion for this appliance has been checked,
adjusted and preset at the factory for operation on natural

gas (G20) as dened on the appliance data label.
Do not adjust the Gas/Air ratio valve.

As an option, a chargeable boiler performance and function
service can be provided by Glow-worm Service by calling
telephone No. 01773 828100.
It is a requirement to measure and record the CO value and
CO/CO2 ratio. Guidance on measuring the values can be
documented in the Benchmark log book at the very back of this
manual.

- 26 -

13895

Diagram 11.1

0020107232_03 - 12/14 - Glow-worm

MODE

INSTALLATION

14507

MODE

DO NOT operate the boiler without water.
Check that all external controls are calling for heat.
Set the Central Heating temperature and the Domestic Hot
Water temperature to ON by pressing the MODE button
on the User Interface until it shows the appropriate symbol

or
The lighting procedure of the boiler is fully automated.
The digital display, refer to diagram 12.2, will show water
temperature in central heating demand.

● The appliance will enter a self checking routine then the

fan should start and the ignition will commence.
The boiler, if necessary, will automatically repeat the
ignition sequence a further 4 times.

● If the burner fails to ignite “F1” will be displayed, initially,

this may be due to air in the gas supply line.

● Once the system has been purged of air. Set the hot water

to the desired temperature by using the MODE and +
(plus) SELECTOR buttons.
Open a hot water tap, the diverter valve motor will move to
hot water supply and the display will read domestic hot water
temperature.
Check that hot water is available at all taps, then close.

● Set the Central heating water temperature to the desired

temperature by using the MODE and + (plus) SELECTOR
buttons.
The appliance will then continue to operate in central heating

until the user controls are satised or there is another demand

made for hot water.

and then pressing the - (minus) SELECTOR button.

11.7 Check the Gas Inlet Pressure & Gas
Rate

The supply from the governed meter must be of adequate size
to provide a steady inlet working pressure of 20mbar (8in wg) at
the boiler.On completion, test the gas installation for tightness
using the pressure drop method and suitable leak detection

uid, purge as necessary.

NOTE: Due to the modulating operation of the boiler and the
need to check the gas inlet pressure and measure the gas rate
at maximum rate, it will be necessary to force it to maximum.

Diagram 11.2

After a period of 10 minutes, with the boiler operating in C.H.
mode, turn on several hot water taps, this will operate the boiler
at maximum rate.

Operational Gas Inlet Pressure

With ALL other gas appliances operating, check the operational
supply pressure at the gas service isolation valve test point, see
diagram 11.1.
The nominal supply pressure for Natural Gas (G20) is 20mbar.
Turn the taps and appliances off, then disconnect the pressure
gauge.
Additionally the safe nominal maximum heat input of the
appliance can be achieved at an inlet pressure down to 15mbar.

NOTE:

The BURNER PRESSURE cannot be measured and is

not used to measure the gas rate.

Gas Rate

Make sure that ALL other gas burning appliances and pilot
lights are off.
Check the gas rate using the gas meter test dial and stop
watch, at least 10 minutes after the burner has lit.
The approximate maximum gas rates are:
24cx : 1.9m3/h (68ft/3/h)
30cx : 2.6m3/h (92ft/3/h)
35cx : 3.3m3/h (115ft/3/h)

kW m3/hr ft3/hr kW m3/hr ft3/hr

20 2.1 74.2
30 3.2 113 19 2.0 70.6
29 3.1 109.5 18 1.9 67.1
28 3.0 106 17 1.8 63.6
27 2.9 102.4 16 1.7 60.0
26 2.8 98.9 15 1.6 56.5
25 2.6 91.8 14 1.5 53.0
24 2.5 88.3 13 1.4 49.5
23 2.4 84.8 12 1.3 45.9
22 2.3 81.2 11 1.2 42.4
21 2.2 77.7 10 1.1 38.9

0020107232_03 - 12/14 - Glow-worm

- 27 -

INSTALLATION

11.8 Central Heating Range Rating

The boilers are fully modulating for central heating, therefore
it is not necessary to range rate them, however, if desired, you
can adjust the CH output in 1kW increments between:
24cx : 10 - 18kW
30cx : 10 - 24kW
35cx : 10 - 30kW
as follows:
a) Press and hold the ‘MODE’ and “+” button for 5

seconds. The display will change to ashing ‘0’.

b) Use the ‘+’ or ‘-’ button to scroll to 96.

c) Press ‘MODE’ and hold 5 seconds to conrm.
d) The display now shows a ashing ‘d. 0’.

e) The part load setting is displayed in kW.
Press ‘MODE’ the max rate will be indicated, to
change the value to the desired setting, use the ‘+’
or ‘-’ button.

f) Press ‘MODE’ for 5 sec to conrm the new setting

has been saved.
g) Press and hold ‘MODE’ and “+” to exit.

Please refer to the above table to check the gas rates.

11.9 Heating System

Ensure that the external controls and programmer are calling for
heat.

Fully open all radiator valves, ow control valve, if tted, see

diagram 5.3.
Press the “MODE” button to change to the CH.

Balance the radiators as required and if tted adjust valve 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

ow and return.

NOTE: Should the system require that the appliance has to be
adjusted, the front casing will need to be removed as described
in the servicing section 12 and the control box lowered into its
service position.
The appliance pump has two speeds and can be adjusted to
suit the requirements of the system.
The appliance has an inbuilt automatic adjustable bypass valve,
see diagram 11.3. The pressure can be adjusted between
approx 1.5 and 3.5mH

2.5mH

2O. The pressure changes by approx 0.1mH2O for each

full turn of the bypass screw. Turning clockwise increases the
pressure and turning anti-clockwise decreases the pressure.
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 taps
at all the low points of the system. Fill and vent the system as
described previously in section 11.2.

Lock or remove the handle from control valve, if tted.

Adjust the boiler temperature controls and any system controls
to their required settings.

2O but is factory pre-set to approx

o

C can be achieved across

11.10 Completion

Ensure that the magnetic lighting instruction label is placed on
the surface of the boiler casing.
GB: In addition it is necessary to complete the “Benchmark”
logbook.
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.

13072

Diagram 11.3

11.11 Instruct the User

● Demonstrate, then instruct the User about the lighting

procedure and heating system controls operation.

● Advise that to ensure the continued efcient and safe

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

● Draw attention, if applicable, to the current issue of the Gas

Safety (Installation and Use) Regulations, Section 35, which
imposes a duty of care on all persons who let out any property
containing a gas appliance in the UK.

● The user shall not interfere with or adjust sealed components.

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

person approved at the time by the Health and Safety
Executive.

● Advise the user that, like all condensing boilers this appliance
will produce a plume of condensation from the ue terminal in
cool weather. This is due to the high efciency and hence low
ue 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 will not operate.

● Advise the User 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.
NOTE: Sealed System: Contact your installation/servicing

company as draining, relling and pressurising MUST be

carried out by a competent person approved at the time by the
Health and Safety Executive.

● Leave these instructions and the ‘Benchmark’ Installation,

Commissioning and Service Record with the user.

- 28 -

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MAINTENANCE

IMPORTANT NOTES:

1. To ensure the continued efcient 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.

2. It is the Law that any servicing is carried out by a competent person approved at the time by the Health and Safety
Executive.

3. 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 isolation valve.

4. When replacing a part on this appliance, use only spare parts that you can be assured conform to the safety and

performance specication that we require. Do not use reconditioned or copy parts that have not been clearly authorised

by Glow-worm.

5. If any electrical connections have been disconnected and after their connection, checks to the earth continuity, polarity,
short circuit and resistance to earth must be repeated using a suitable multimeter, as described in section 13.

6. After servicing, complete the relevant Service Interval Record section of the Benchmark Checklist located in the inside
back pages of this document.

12 Servicing

General Inspection

Prior to, during servicing and after any maintenance or changed
parts, the following must be checked.

● The integrity of the ue system and ue seals.

● The integrity of the appliance combustion circuit and

relevant seals.

● Electrical, gas and water connections.

● System pressure.

● the combustion performance, refer to the following procedure.

● The operational gas inlet pressure and gas rates, refer to the

commissioning section paragraph 11.7.
Correct any fault before continuing.

COMPETENCY TO CARRY OUT THE CHECK OF
COMBUSTION PERFORMANCE

NOTE: BS 6798: 2009 Specication for installation and

maintenance of gas-red boilers of rated input not exceeding

70kW net advises that:

● The person carrying out a combustion measurement must
be assessed as competent in the use of a ue gas analyser

and the interpretation of the results.

● The ue gas analyser used should be one meeting the

requirements of BS7927 or BS-EN50379-3 and be calibrated in
accordance with the analyser manufacturers’ requirements.

● Competence can be demonstrated by satisfactory completion

of the CPA1 ACS assessment, which covers the use of
electronic portable combustion gas analysers in accordance
with BS 7967, parts 1 to 4.

● Ensure that the gas analyser is set to the correct fuel

setting.

● Select the “

function by pressing the “Mode” button repeatedly, refer to

commissioning section.The boiler should re automatically.
NOTE: Safe combustion can only be veried by measuring CO/

CO2 ratio. This must not exceed the value shown in the table
below.

MODEL CHECK SETTING CO/CO2

24cx 8.8 to 9.8 9.2 +0.3

30cx 8.8 to 9.8 9.1 +0.3

35cx 8.8 to 9.8 8.8 +0.3

”, constant central heating with DHW

G20 BURNER % CO2

ratio

0.004

- 0.3

0.004

- 0.3

0.004

- 0.3

COMBUSTION CHECK AND SETTING THE AIR/

GAS RATIO VALVE

● Remove the front casing panel, see diagram 12.2 and hinge

down the control box. Taking care not to touch any internal
components, proceed as follows:

● Connect the CO2 combustion analyser to the relevant test

point, see diagram 12.1.

15445

Diagram 13.1

1. Maximum Rate Check and Adjustment

NOTE: To verify the maximum gas rate CO2 setting the

appliance must be checked at the maximum rate rst. Press the

“reset” button on the controls fascia, release and
immediately press and hold in the “+” button. After
approximately 5 seconds “Hi” will be displayed. Pressing
the mode button when “Hi” is selected will force the boiler

to maximum rate, the display will ash between “Hi” and the

“default display” this will indicate the boiler has been forced to
maximum. Wait until the CO2 value is stable and check that

the value is within the range specied in table in the “check”

column.
If the combustion reading is not within the acceptable values

AND the integrity of the complete ue system and combustion
circuit seals have been veried and the inlet gas pressure
(and gas rate) have been veried, then, it will necessary to

adjust the combustion rate of the appliance.
NOTE: Adjustment is made by turning the gas valve throttle

an ⅛ of a turn, waiting 1 minute to allow the appliance to

stabilise before checking or making further adjustments.

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- 29 -

MAINTENANCE

FRONT
PANEL

SECURING
SCREWS

● Rotate the “throttle”(anti-clockwise to increase), to the

required CO2, refer to diagram 12.4 and the “SETTING” column
in the table.

● Exit the forced rate function, press the “mode” and “+”

buttons simultaneously, this will reset the boiler to the default
display. Now proceed to check the minimum rate adjustment.

2. Minimum Rate Check and Adjustment

● Now check the minimum gas rate CO2 setting: Press

and release the “reset” button on the controls fascia, then
immediately press and hold in either of the “+” buttons. After
approximately 5 seconds “Hi” will be displayed. Pressing the
“+” or “-” buttons will toggle between “Hi” and “Lo”. Press the
mode button when “Lo” is selected, this will force the boiler to

minimum rate and the display will ash “Lo”, indicating the boiler

is operating at minimum.

● Wait until the CO2 value is stable and check that the value is
within the range specied in table in the “check” column.

If adjustment is necessary, proceed as follows:
NOTE: Adjustment of the CO2 at minimum rate is very

coarse and should not be adjusted more than an ⅛ of

a turn at a time. Wait 1 minute to allow the appliance to
stabilise before checking or making further adjustments.

● Gradually rotate the “offset adjustment” (anti-clockwise to

decrease) to the required CO2, refer to diagram 12.4 and the
“SETTING” column in the table.

● Exit the minimum rate function, press the “mode” and “+”

buttons simultaneously, this will reset the boiler to the default
display.

All routine servicing requirements can be achieved by the
removal of the front panel, see diagram 12.2. Position the
control box into the service position, see diagram 12.3.
Before commencing with a service or replacement of parts.
The boiler should be isolated from the electrical and gas
supplies.

13093

3. Re-Check CO2 and check the CO/CO2
combustion ratio.

● Re-check the maximum and minimum CO2 values to ensure

that they are within the “setting” limits in the table then check
the CO/CO2 combustion ratio does not exceed the value in the
CO/CO2 column of the table. If the CO/CO2 ratio exceeds the
value in the table, a complete servicing of the appliance will be
necessary, refer to section 12.1.
If the CO2 and the CO/CO2 ratio falls within the tolerances
quoted, exit the function press the “mode” and “+” buttons
simultaneously, this will reset the boiler to the default display.
Remove the analyser probe and replace the cap on the
sampling point, replace the controls fascia, inner and front
casing panels.
IMPORTANT: Remember to replace the sample point cap on
completion of the test.

GAS RATE CHECK

Check the gas rates as described in the commissioning
section.

COMPLETION

If it is not possible to achieve the required results for either
the combustion or gas rates, it will be necessary to complete
a full service of the appliance and then repeat the combustion
check procedure. If after servicing and adjustment of the
appliance the combustion values are still unacceptable and
after further remedial work has been carried out, the appliance
must be disconnected until the CO/CO2 ratio is acceptable.
Advice can be sought from the Glow-worm Technical Helpline.

Diagram 12.2

13554

Diagram 12.3

12776

12.1 Servicing

NOTE: If the Combustion CO2, CO/CO2 ratio & Gas rate

checks did not require adjustment then it will not be necessary
to complete a full service.

- 30 -

Diagram 12.4

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MAINTENANCE

12.2 Spark Electrode

NOTE: If the functional checks did not indicate poor
combustion then it is not necessary to service this
component.

Ease the securing clips away from the sump to release the

retaining catch then push the ue hood up to disengage from

the sump, see diagram 12.5.

To remove, swivel ue hood 90

diagram 12.5.
Check seal for wear or damage and replace if necessary.

IMPORTANT: Do not allow xings, nuts, screws, etc. to fall
into the open ue hood sump, use a temporary cover whilst

removing any parts.
Disconnect the spark electrode plug and earth lead. Remove
the two securing screws and withdraw the spark electrode
carefully from the combustion chamber, see diagram 12.6.
Inspect the tips for damage.
Clean away any debris and check the spark gap is 4mm.
Check the electrode gasket for signs of damage and replace if
necessary.

o

and pull down and out, see

12.3 Burner

NOTE: If the functional checks did not indicate poor
combustion then it is not necessary to service this
component.

Disconnect the gas supply at the gas valve and electrical
connections, see diagram 12.7.

The Silencer (front) is a push t, so there is no need for tools to
remove or t, see diagram 12.8.

Release the igniter unit support bracket, see diagram 12.9.
Remove the fan retaining bracket.
To ease removal of the securing nut from the fan retaining

bracket, a at bladed screwdriver can be used in the position

shown and gently levered down as indicated, see diagram

12.10.
Remove the fan and gas valve assembly.

The silencer (rear) is a push t so no tools are required for its
removal or tting, see diagram 12.9.

Check the spark electrode gap is 4mm. Clean and adjust as
necessary, see diagram 12.6.
It should not be necessary to remove the spark electrode from
the burner during servicing.

Remove the anged nuts and studs that secure the burner, note

that two studs at the rear also hold the fan clamping bracket,
see diagram 12.12.
Clean the burner with a soft brush taking great care not to
damage the surface of the burner. DO NOT use wire or sharp
instruments to clean the mesh of the burner.
NOTE: The burner gasket should be inspected but will not need
replacing unless there are signs of wear or damage.

Follow the tightening sequence when re-tting the burner, see

diagram 12.12.

15585

15586

Diagram 12.5

14408

12.4 Heat Exchanger

NOTE: If the functional checks did not indicate poor
combustion then it is not necessary to service this
component.

Remove loose debris from inside the heat exchanger using a
soft brush and vacuum cleaner.

Carefully ush by spraying water into the heat exchanger, any

remaining debris should pass through the condensate trap
(Ensure the water is kept away from electrical components).

0020107232_03 - 12/14 - Glow-worm

Diagram 12.6

- 31 -

MAINTENANCE

SECURING

SECURING

UNIT

CONNECTION

ELECTRICAL
CONNECTIONS

SCREW (3)

ELECTRICAL
CONNECTION
(removed)

GAS
VALVE

TUBING
NUT

GAS
PIPE

Diagram 12.7

14079

13128

IGNITER

EARTH

14409

NUT

SUPPORT

BRACKET
IGNITION
LEAD

SPADE
CONNECTOR

Diagram 12.9

14081

Diagram 12.8

Diagram 12.10

14288

Diagram 12.11

- 32 -

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

A

SECURING
NUTS (6)

BURNER

FAN CLAMPING
BRACKET

12.5 Condense Trap and Siphonic Drain

The condense trap and siphonic drain does not normally need

servicing unless material deposits exceed beyond the service ll

level, see diagram 12.13.
To clean the condense trap remove the sump and rinse with
water.

12.6 Casing panel seal check

NOTE: If the functional checks did not indicate poor
combustion then it is not necessary to service this
component.

Check the condition of the seal and replace if worn or damaged.
To replace remove the old seal and thoroughly clean the casing
surfaces. Fit the new seals, these are supplied to the correct
lengths and are in four pieces, for use on the sides, top and
bottom.

12.7 Service Completion

Re-check the combustion as described at the beginning of this
section.
On completion of the service the “Benchmark” Service Record
should be completed.

14410

14397

13929

CONDENSE TRAP

ND SIPHONIC DRAIN

Diagram 12.12

SECURING
SCREW

SUMP

SERVICE
FILL LEVEL

0020107232_03 - 12/14 - Glow-worm

Diagram 12.13

- 33 -

MAINTENANCE

13 Fault Finding

13.1 Preliminary fault nding

The following checks should be performed before proceeding

onto specic diagnostics:

• Check the external electrical supply to the boiler is on and
a supply of 230V is present at the ‘L’ and ‘N’ terminals at
the installer interface.
For access remove and open the electrical cartridge, see
diagrams 10.4. and 10.1.
Test at the ‘L’ and ‘N’ terminals on the installer interface,
refer to diagrams 10.1 and 13.4.

• Check the electrical installation and appliance, carry
out tests for earth continuity, polarity, short circuit and
resistance to earth, using a suitable multimeter.
An aid to test
Remove the front casing panel, see diagram 13.1 and
hinge down the control box.
Unclip the rear cover to gain access to the main PCB.
Carry out the tests at connector plug X17, see diagram

13.2. Check chassis earth at a bare metal point on the
boiler.

• Check that there is a gas supply to the boiler and the gas
service isolation valve is turned on, see diagram 8.2.

• Check pressure at the gas service isolation valve, refer to
section 11.7.

• Check that the heating system pressure indicates at least

1mb, if not, ll and vent the system as described in section

11.2.

• Check that all external controls are on.

• Check the functional ow diagram, 13.5.

13093

Diagram 13.1

13845

13.2 Fault Codes

Fault codes take priority over all other display functions in the
event of a fault occuring, refer to diagram 13.6.
If multiple faults occur the codes will be displayed for approx. 2
seconds, alternatively.

13.3 Fault Memory

The Fault memory stores details of the ten
most recent faults.

To access this menu, refer to diagram 13.3:
a) Press and hold ‘MODE’ and ‘-’ buttons for 5 seconds.

b) The display will stop ashing and alternate between the fault

memory number and the fault code.
c) Press ‘+’ button to scroll through the fault memory (Position
1 is most recent), see fault codes.
To exit this menu, press the ‘MODE’ button.

13.4 Diagnostic Menu

The Diagnostic Menu provides the ability to view and change
certain parameters. See diagram 13.7 for available parameters.

13.5 Status Codes

The status codes provide information about the current
operating condition of the boiler and can be accessed through
the diagnostic display, refer to diagram 13.8.

Diagram 13.2

14028

- 34 -

Diagram 13.3

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

14516

0020107232_03 - 12/14 - Glow-worm

MODE

Diagram 13.4

- 35 -

MAINTENANCE

CENTRAL HEATING

13012

DHW

13015

- 36 -

Diagram 13.5

0020107232_03 - 12/14 - Glow-worm

FAULT CODES

MAINTENANCE

14027

0020107232_03 - 12/14 - Glow-worm

Diagram 13.6

- 37 -

MAINTENANCE

State list - To access the state lists the ‘-’ button must be pressed for longer than 5 seconds until it begins to ash ‘S’ and

then a number to indicate the state. The state numbers are given below.

STATE LISTS

Central heating mode Description

S.00 no heating required
S.01 fan pre-run
S.02 pump pre-run
S.03 ignition
S.04 burner on
S.05 pump / fan overrun
S.06 fan overrun
S.07 pump overrun
S.08 Anti cycling period

NORMAL OPERATING
STATE FOR CH MODE

Domestic hot water mode

S.10 domestic hot water demand
S.11 fan pre-run
S.13 ignition
S.14 burner on
S.15 pump / fan overrun
S.16 fan overrun
S.17 pump overrun

NORMAL OPERATING
STATE FOR DHW MODE

Preheat mode

S.20 domestic hot water cycling mode active
S.21 fan pre-run
S.22 Pump pre run
S.23 ignition
S.24 burner on
S.25 pump / fan overrun
S.26 fan overrun
S.27 pump overrun
S.28 Anticycling period

NORMAL OPERATING
STATE FOR PRE-HEAT MODE

13011

Special cases of status messages

S.30 No Heating demand from external controls 230V Check wiring in external controller.

Check wiring at Installer Interface.

S.31 summer mode Check CH setpoint / Check external controls
S.32 Antifreeze active – fan speed variation too high Check fan connection.
– waiting during blocking function
S.34 frost protection active (Priority 4) Te mperature below 8
connection if this is not true.
S.36 No Heating demand from external controls 24V Check wiring in external controller.

Check wiring at Installer Interface.

S.42 Accesory Module is blocking burner operation Check accessory module.
S.53 waiting time: temperature difference flow

- return sensor too high (Check thermistor fit)

S.54 waiting time: no water in system, temperature
(gradient error) rise flow / return sensor too high

S.76 Waiting period – pressure sensor Check system pressure - default display.
S.96 Return-Sensor check is running, demand Check return thermistor connection to pipe.
(DHW or heating) is blocked Check harness connection to thermistor.
S.97 Water pressure sensor check is running, Check connection to pressure sensor.
demand (DHW or heating) is blocked Check pump has not seized.
S.98 Flow / Return - sensor check is running, demand
(DHW or heating) is blocked.

Check flow & return thermistor connections to pipes.
Check harness connection to thermistor.
Check harness wires are not trapped between any
internal components.

Check flow & return thermistor connections to pipes.
Check harness connection to thermistor.
Check harness wires are not trapped between any
internal components.

Check flow & return thermistor connections to pipes.
Check harness connection to thermistor.
Check harness wires are not trapped between any
internal components.

O

C - check thermistor

- 38 -

Diagram 13.7

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

To enter the diagnostics menu follow the procedure below:­Press and hold the ‘MODE’ and ‘+’ buttons for approx 5 seconds until the screen changes. Use the ‘+’ or ‘-’ button to select the
number 96, this is the password. Hold the ‘MODE’ for approx 5 seconds when 96 is selected, when the screen changes release

the button. The screen will ash between ‘L1’ and a number. ‘L1’ indicates you have level 1 access, the number indicates

the diagnostic number below. Use the ‘+’ and ‘-’ to cycle through the selections below. To select a diagnostic number press
the ‘MODE’ button when the correct number is selected. The display will show the parameter value of the diagnostic number
selected. To return to the diagnostic number selector simply press the ‘MODE’ button. To change the parameter use the + or

- buttons. Once the value has been changed it must be saved by holding the ‘MODE’ button for approximately 5 seconds. This
will return to the diagnostic number selector.

DIAGNOSTIC CODES - LEVEL 1 Installer Access

14512

Indicates read and write function - all other diagnostics are read only

0020107232_03 - 12/14 - Glow-worm

Diagram 13.8

- 39 -

MAINTENANCE

14 Replacement of Parts

14.1 General

Replacement parts that have associated components that need
replacing on removal, i.e. ‘O’ ring, seals, gasket, etc., will be

supplied and should be tted.

Replacement of parts must be carried out by a competent
person approved at the time by the Health and Safety

Executive.
Before replacing any parts of the boiler it should be isolated
from the mains electric supply and the gas should be turned
off at the gas service isolation valve on the boiler, see diagram

14.1.
Unless stated otherwise parts are replaced in the reverse order
to removal.
After replacing any parts always test for gas tightness and if
necessary carry out functional test of the controls.

Boiler Access

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

If the appliance site situation has sufcient side clearances

the side panels can be hinged sideways and removed to aid
replacement of parts.
To hinge a side panel undo and remove the four screws
securing each side panel to the boiler, two below and two at the
top.

Draining of Boiler Heating Circuit

Drain down the Heating Circuit of the boiler only, by closing the

heating ow and return isolating valves on the wall mounting

jig. Attach a length of hose to the drain point and open the drain
valve, see diagram 14.1.
After replacing parts, close the drain valve and remove the

hose. Open the heating ow and return isolating valves and
rell, vent and pressurise the heating circuit, refer to section 11.

Check for leaks.

13931

Diagram 14 .1

15584

Draining of Boiler Hot Water Circuit

Drain the Domestic Hot Water circuit by closing the cold-water
isolation valve on the wall mounting jig, see diagram 14.1.
Open one or more hot water taps to drain the hot water circuit.
After replacing parts open the cold-water isolation valve and
slowly open a hot water tap to remove air. Close the hot water
tap and check for any leaks.

14.2 Igniter Unit

For access, refer to section 14.1.
Remove ignition lead and electrical connections then remove
igniter unit by removing two securing screws, see diagram 12.9.

14.3 Ignition Lead

For access, refer to section 15.1.
Pull the spark plug style connector off the spark electrode and
the spade connector connected to the igniter unit, see diagram

12.6.

Diagram 14.2

- 40 -

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

14.4 Gas Valve

Remove the three securing screws, holding the gas valve to the
fan, see diagram 12.7.
Remove the gas valve.

After re-tting check the combustion CO2 and adjust if

necessary, refer to section 12, Combustion Check.
After assembly test for gas tightness and purge in accordance
with the current issue of BS6891or in IE, the current edition of
I.S.813 “Domestic Gas Installations”.

14.5 Flue Hood

For access, refer to section 14.1.

Pull the ue hood securing clips away from the ue hood sump
and push ue hood up slightly towards ue hood top, see

diagram 12.5.

To remove swivel ue hood 90° and pull down and out towards

front of boiler.

14.6 Fan

For access, refer to section 13.1.
Remove the gas valve as described in the relevant parts of
section 14.8.
Remove the securing nut holding the fan retaining bracket, lift
front of bracket away from stud and pull forward to release the
fan, see diagram 12.10, check and replace any seals or gaskets
if necessary.

14.10 Spark Electrode

For access, refer to section 14.1.
Remove the spark plug lead and earth lead.
Remove the two securing nuts, see diagram 12.6.
Withdraw the spark electrode by slowly pulling up and leaning it
forward towards the centre of the heat exchanger to ensure that
the electrode does not foul on the hole in the burner casing.
Check spark gap.

14.11 Burner

For access, refer to section 14.1.

Remove igniter unit, ue hood, fan and gas valve assembly and

spark electrode lead, refer to relevant sections.

Remove the anged nuts and studs that secure the burner, note

that two studs at the rear also hold the fan clamping bracket,
see diagram 12.12.
NOTE: The burner gasket should be inspected but will not need
replacing unless there are signs of wear or damage.

IMPORTANT: Do not allow xings, nuts, screws, etc. to fall
into the open ue hood sump, use a temporary cover whilst

removing any parts.

14.7 Expansion Vessel

For access, refer to section 14.1.
Drain the boiler heating circuit, refer to section 14.1.
Undo the coupling at the base of the vessel, see diagram 14.2.
The expansion vessel can now be removed by sliding it forward
clear of its support guides.

When re-tting a new gasket will be required between the

expansion vessel and coupling.

Rell, vent and pressurise the boiler.

Check for leaks.

14.8 Fan/Gas valve assembly

For access, refer to section 14.1.
Undo the tubing nut to remove the gas valve from the gas pipe
and any electrical connections, see diagram 12.7.
Remove the securing nut holding the fan retaining bracket,
press down on burner to ease removal of securing nut. Slide out
the fan retaining bracket.
Lift front of bracket away from stud and pull forward to release
the fan, see diagram 12.10.
Lift fan/gas valve assembly up and forward away from locating
studs.
Remove fan gasket and replace if necessary.
To replace the fan and retaining bracket correctly, insert into
slots on fan clamping bracket, see diagram 12.12 and locate
onto lugs on the burner.

13027

14.9 Silencer assembly (rear)

For access, refer to section 14.1.
Remove the fan/gas valve assembly, see relevant sections.
Pull Silencer rear away from fan/gas valve assembly.

The rear silencer is a push t so no tools or xings are required
for its removal or tting, see diagram 14.11.

0020107232_03 - 12/14 - Glow-worm

Diagram 14.3

- 41 -

MAINTENANCE

14.12 Silencer Assembly (front)

For access, refer to section 14.1.
Pull forwards to remove.

The silencer is a push t so no tools or xings are required for
its removal or tting, see diagram 12.8.

14.13 Condensate Trap

For access, refer to section 14.1.
Remove the drain outlet pipe from the base of the trap. Remove
the condensate drain securing screw and carefully pull the trap
forward, see diagram 12.13.
On the condensate trap there is a key symbol that should be
in line with the locked padlock symbol on the condense drain.
To remove the trap turn in the direction indicated, see diagram

12.13, toward the unlock symbol and carefully pull down clear of
the condense drain.
Remove any solids found in the condense trap.
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 ret the condense trap.

14.14 Heating Flow Thermistor

For access refer to section 14.1.

Remove the silencer front, fan/gas valve assembly and ue

hood for access. See relevant sections.
Refer to diagram 14.3.
Remove the electrical connections from the thermistor.

Remove the retaining clip from the ow pipe.

Remove the thermistor from the retaining clip.
Note that the polarity of the wiring to thermistors is unimportant.

14.18 Domestic Hot Water Thermistor

For access, refer to section 14.1.
Refer to diagram 14.5.
Remove the electrical connections from the thermistor.
Remove the retaining clip from the DHW pipe.
Remove the thermistor from the retaining clip.
Note that the polarity of the wiring to thermistor is unimportant.

14.19 Plate-to-Plate Heat Exchanger

For access, refer to section 14.1.
Drain the boiler heating circuit, refer to section 14.1.
Refer to section 14.3 and drain the boiler hot water circuit.
Refer to diagram 14.6.
Remove the gas supply pipe from the gas service isolation
valve and the gas valve, refer to relevant parts of section 14.4.
Remove the condensate trap as described in section 14.13.
Remove the four screws securing the plate-to-plate heat
exchanger to the hydroblock, see diagram 14.6.
Remove the plate-to-plate heat exchanger.
When replacing the plate-to-plate heat exchanger ensure that

the four rubber sealing washers are tted into the hydroblock.
NOTE: The plate-to-plate heat exchanger only ts one way

round.

Rell, vent and pressurise the boiler.

Open the cold-water isolation valve and slowly open a hot water
tap to remove air.
Close the hot water tap and check for any leaks.
Open the heating circuit isolation valves, re-pressurise the
system as necessary, refer to diagram 14.1.

14.15 Heating Return Thermistor

For access, refer to section 14.1.
Refer to diagram 14.4.
Remove the electrical connections from the thermistor.
Remove the retaining clip from the return pipe.
Remove the thermistor from the retaining clip.
Note that the polarity of the wiring to thermistor is unimportant.
Note that the polarity of the wiring to thermistor is unimportant.

13063

13060

- 42 -

Diagram 14.4

Diagram 14.5

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

14.20 Pump (head only)

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler heating circuit.
Refer to diagram 14.7.
Remove the four cap head screws.
Carefully remove the pump head together with cable. Do not
strain cable.
Support the pump head, unscrew cable cover at the side of
pump head and remove.
Disconnect wiring from pump head.

Reconnect wiring to new pump head and t cover.

Fit the new pump head with ‘O’ ring.

Rell, vent and pressurise the boiler and check for leaks.

14.21 Safety Discharge Valve

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler heating circuit.
Refer to diagram 14.8.
Undo the safety discharge valve union and remove from the
pipework.
Remove the retaining clip and withdraw the safety discharge
valve.
Fit new ‘O’ ring.

Rell, vent and pressurise the boiler and check for leaks.

14.22 Automatic Air Vent

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler heating circuit.
Refer to diagram 14.9.
Remove the retaining clip to release the automatic air vent.
Fit the new automatic air vent and ‘O’ ring ensuring the vent
cap is left loose.

Rell, vent and pressurise the boiler and check for leaks.

15587

Diagram 14.7

12667

Diagram 14.6

14031

Diagram 14.8

12669

Diagram 14.9

0020107232_03 - 12/14 - Glow-worm

- 43 -

MAINTENANCE

14.23 Flow Sensor

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler hot water circuit.
Refer to diagram 14.10.
Undo the brass securing nut on the domestic cold water return
pipe.

Remove the securing clip between the hydroblock and the ow

sensor.

Remove the electrical connection to the ow sensor.
Remove the securing clip holding the brass elbow to the ow

sensor.

Partially withdraw the ow sensor to allow removal of the

electrical connection before full removal of the sensor.

Remove ow sensor.

Fit new ‘O’ rings.

After replacing the ow sensor, open the cold-water isolation

valve and slowly open a hot water tap to remove air.
Close the hot water tap and check for any leaks.

14.24 Three Way Valve

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler heating circuit and
the boiler hot water circuit.
Refer to diagram 14.11.
Undo the nut retaining the heating return isolation valve to the

xing jig. Be careful not to lose the sealing washer.
Undo the securing nut on the underside of the xing jig and pull

the pipe away from the three-way valve assembly.
Fully remove the three securing screws and pull the three­way valve assembly towards the left to disengage from the
hydroblock. (Ensure that the original o-ring has not been
retained in the hydroblock.)
Fit the new three-way valve assembly.

Reassemble, rell, vent and pressurise the boiler and check for

leaks.

13064

Diagram 14.10

12668

- 44 -

Diagram 14.11

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

14.25 Heat Exchanger

For access, refer to section 14.1.
Refer to section 14.1 and drain the boiler heating circuit and the
boiler hot water circuit.

Remove the silencer front

Pull forwards to remove.

The silencer is a push t so no tools or xings are required for
its removal or tting, see diagram 12.8.

Remove the ue hood front

Ease the securing clips away from the sump to release the

retaining catch then push the ue hood up to disengage from

the sump, see diagram 12.5.

To remove, swivel ue hood 90° and pull down and out, see

diagram 12.5.

Remove the igniter unit with support bracket

Disconnect the electrical connections and ignition lead.
Release the igniter unit support bracket.
Remove the igniter unit assembly, see diagram 12.9.

Remove the gas valve/fan

Disconnect the tubing nut at the gas valve, see diagram 12.7.
Remove the fan retaining bracket, see diagram 12.10.
To ease removal of the securing nut from the fan retaining

bracket, a at bladed screwdriver can be used in the position

shown and gently levered down as indicated.
Remove the spark electrode plug and earth connection.
Remove the fan and gas valve electrical connections.
Remove the fan and gas valve assembly.

Remove the condensate trap

Remove the drain outlet pipe from the base of the trap, see
diagram 14.1. Remove the condensate drain securing screw
and carefully pull the trap forward, see diagram 12.13.

Remove the heat exchanger

Remove the retaining clip, see diagram 14.12, which secures

the ow pipe brass elbow into the hydroblock. Remove the
retaining clip, which secures the ow pipe into the anged

elbow in the top right hand corner of the heat exchanger, see
diagram 14.14.
Remove the left hand side panel to aid removal of the copper

ow pipe. Note that the minimum clearance from the side panel
is 5mm. Remove the ow pipe.
Undo the union nut connecting the ow pipe to the pump.
Remove the retaining clip from the anged elbow at the right

hand bottom of the heat exchanger, see diagram 14.13.
Remove screws securing the heat exchanger, one on top and
one underneath the heat exchanger, see diagram 14.14.
Lift up heat exchanger slightly to disengage it from its hanging
bracket.
Remove the heat exchanger by pulling forward and tilting
backwards to ease removal complete with sump, return pipe

and anged elbows. Remove the return pipe then discard the
heat exchanger complete with sump and anged elbows.

RETAINING
CLIP

FLANGED
ELBOW

15589

FLOW
PIPE

Diagram 14.12

15558

RETAINING
CLIP

FLOW
PIPE

UNION
NUT

Diagram 14.13

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- 45 -

MAINTENANCE

RETAINING
CLIP

14414

14399

Diagram 14.14

Remove the burner

Remove the anged nuts and studs that secure the burner, note

that two studs at the rear also hold the fan clamping bracket,
see diagram 14.15.
Taking great care not to damage the surface of the burner.
NOTE: Replace the burner gasket and follow the tightening

sequence when re-tting the burner, see diagram 14.15.
NOTE: Fit all replacement gaskets and seals when re-tting

parts.

Filling the boiler heating circuit/domestic hot water system
and re-pressurising

After replacing parts open the cold-water isolation valve and
slowly open a hot water tap to remove air. Close the hot water
tap and check for any leaks.
After replacing parts, close the drain valve and remove the

hose. Open the heating ow and return isolating valves and
rell, vent and pressurise the heating circuit, refer to Section 11,

Commissioning.

- 46 -

Diagram 14.15

0020107232_03 - 12/14 - Glow-worm

MAINTENANCE

14.26 Access to User interface and Main
PCB

For access, refer to section 14.1.
Hinge down the control box and unclip the rear cover to gain
access.
Remove electrical connections from main PCB noting their
positions for replacement.
Unclip main PCB and remove, see diagram 14.16.
Unclip user interface and remove.
For replacement, see diagram 14.17 and ensure that the user

interface connection cable is retted.
NOTE: When re-tting any of the control boards make sure you

support the control box to avoid straining hinges as you push
down and clip back into place.

14.27 Control Box

For access, refer to section 14.1.
Hinge down the control box and unclip the rear cover to gain
access.
Remove relevant electrical connections from main PCB and
grommets from the control box.
IMPORTANT: Support the control box whilst undoing the
hinges.
Remove the hinge securing screws accessed from beneath the
boiler and remove the control box, see diagram 15.18.

14.29 Installer Interface Electrical Cartridge

Remove the Installer Interface securing screw accessed from
beneath the boiler.
Carefully pull down the electrical cartridge, disconnect the
cables.

13001

14.28 Fuse - Main PCB - Control Box

For access, refer to section 14.26.
The fuse is located at the top left hand corner of the main PCB,
see diagram 14.16.

13003

Diagram 14.17

13004

0020107232_03 - 12/14 - Glow-worm

Diagram 14.16

Diagram 14.18

- 47 -

MAINTENANCE

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

Key No. Part No. Description GC No

1 0020020734 Fan H42723
2 0020020763 Igniter unit H42773

3 0020020781 Heating ow & return thermistor (2) H42792

4 0020014160 DHW thermistor H36325
5 0020020735 Gas valve 24cx / 30cx H42724
5 0020059600 Gas valve 35cx H69002
6 0020020731 Electrode H42720
7 0020020728 Burner 24cx / 30cx H42718
7 0020059602 Burner 35cx H69008
8 0020023826 User interface H42784
9 0020014402 Plate to plate heat exchanger 24cx H43160
9 0020014402 Plate to plate heat exchanger 30cx H43160
9 0020014403 Plate to plate heat exchanger 35cx H69009
10 0020014171 Pump H42760
11 0020014174 Flow sensor H43155
12 0020023825 Main PCB H42783
13 0020079644 Water pressure sensor H80-150

14507

- 48 -

Diagram 15.1

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MAINTENANCE

16 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 co-ordinated movements during lift. Always use
assistance if required.

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

ground oor.

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 co-ordinated 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.

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

rst or higher oor, 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 co-ordinated 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,

ooring 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 ooring, 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. Cut the carton straps, lift carton up and slide over

polystyrene end packs. Remove top polystyrene pack with ttings.

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 rm

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 oor 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 rm 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 rm 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 oor 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 posi-

tion. Obtain rm 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 rm 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 rm grip

supporting base of boiler. Ensure safe lifting techniques are used – keep

back straight – bend using legs - when lifting load from oor 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 rm grip on front and sides of appliance, lift upwards, ensure sta­ble balance achieved and lift upwards to drop into place onto bracket. If 2

persons positioning onto bracket obtain rm 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 rec-

ommend obtain rm grip supporting base of boiler. Ensure safe lifting

techniques are used - keep back straight – bend using legs - when lifting

load from oor 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 ooring, lighting and other

factors, and appropriate measures taken.

0020107232_03 - 12/14 - Glow-worm

- 49 -

THE AIR GAS RATIO VALVE IS FACTORY

SET AND MUST NOT BE ADJUSTED
DURING COMMISSIONING UNLESS THIS
ACTION IS RECOMMENDED FOLLOWING

CONTACT WITH THE MANUFACTURER.

If any such adjustment is recommended and

further checking of the boiler is required the

installer/service engineer must be competent

to carry out this work and to use the flue gas

If the boiler requires conversion to operate with

a different gas family (e.g. conversion from

natural gas to LPG) separate guidance will be

provided by the boiler manufacturer

NOTE

analyser accordingly.

The boiler manufacturer’s installation instructions should have been followed, gas type verified and gas

As part of the installation process, especially where a flue has been fitted by persons other than the

boiler installer, visually check the integrity of the whole flue system to confirm that all components are

correctly assembled, fixed and supported. Check that manufacturer’s max. flue lengths have not been

exceeded and all guidance has been followed (e.g. Gas Safe Technical Bulletin TB008).

Prior to its use, the flue gas analyser should have been maintained and calibrated as specified by the

The flue gas analyser should be of the correct type, as specified by BS 7967

manufacturer. The installer must have the relevant competence for use of the analyser.

Check and zero the analyser IN FRESH AIR as per analyser manufacturer’s instructions.

PRIOR TO CO AND COMBUSTION RATIO CHECK

supply pressure/rate checked as required prior to commissioning.

In accordance with boiler instructions, set boiler to operate at max. rate

(full load condition). Allow sufficient time for combustion to stabilise.

NOTE - Do not insert analyser probe during this period to avoid

CARRY OUT FLUE INTEGRITY CHECK USING ANALYSER

Insert analyser probe into air inlet test point and allow readings to stabilise.

NOTE - where no air inlet test point is provided then a flue integrity check

with the analyser is not possible. The installer should verify that flue

integrity has been visually checked in accordance with the yellow “Prior to

CO and combustion ratio check” box above before proceeding to the

“Check CO and combustion ratio at maximum rate” stage below.

SET BOILER TO MAXIMUM RATE

possible “flooding” of sensor.

Analyser readings indicate that combustion products
and inlet air must be mixing. Further investigation of

Check that flue and flue terminal are not obstructed.

VERIFY FLUE INTEGRITY

the flue is therefore required.

Check that flue components are assembled, fixed

and supported as per boiler/flue manufacturer’s

instructions.

Is

≥ 20.6%

O

2

and

CO

< 0.2%

2

YES

NO

TURN OFF APPLIANCE AND CALL

MANUFACTURER’S TECHNICAL HELPLINE

COMMISSIONED UNTIL PROBLEMS ARE

Check all seals around the appliance burner,

internal flue seals, door and case seals.

FOR ADVICE.

THE APPLIANCE MUST NOT BE

IDENTIFIED AND RESOLVED.

Rectify where necessary.

Is

CO

less than

335ppm

and

ratio less

CO/CO

2

than 0.004

YES

NO

NO

≥ 20.6%

O

2

CO

Is

and
< 0.2%

2

YES

CHECK CO AND COMBUSTION RATIO AT MAX. RATE

With boiler still set at maximum rate, insert analyser probe into flue gas

sampling point. Allow readings to stabilise before recording.

NOTE - If no flue gas sampling point is present and the correct procedure is

not specified in the manual, consult boiler manufacturer for guidance.

Is

NO

CO less than

350ppm and

ratio

CO/CO

2

less than 0.004

YES

In accordance with boiler instructions, set boiler to operate at minimum rate (to

minimum load condition). Allow sufficient time for combustion to stabilise.

NOTE - If manufacturer’s instructions do not specify how to set boiler to minimum

SET BOILER TO MINIMUM RATE

rate contact Technical Helpline for advice.

TURN OFF APPLIANCE AND CALL

MANUFACTURER’S TECHNICAL HELPLINE

COMMISSIONED UNTIL PROBLEMS ARE

COMMISSIONING CANNOT BE FULLY

COMPLETED, THE APPLIANCE MUST BE

DISCONNECTED FROM THE GAS SUPPLY IN

NOTE: Check and record CO and combustion ratio

at both max. and min. rate before contacting the

FOR ADVICE.

THE APPLIANCE MUST NOT BE

IDENTIFIED AND RESOLVED. IF

ACCORDANCE WITH THE GSIUR.

manufacturer.

NO

CHECK CO AND COMBUSTION RATIO AT MINIMUM RATE

With boiler still set at minimum rate, insert analyser probe into flue gas sampling

NOTE - If no flue gas sampling point is present and the correct procedure is not

point. Allow readings to stabilise before recording.

specified in the manual, consult boiler manufacturer for guidance.

Is

CO less than

350ppm and

ratio

CO/CO

2

less than 0.004

YES

BOILER IS OPERATING SATISFACTORILY

Ensure test points are capped, boiler case is correctly replaced and

all other commissioning procedures are completed.

Complete Benchmark Checklist, recording CO and combustion ratio

no further actions required.

readings as required.

0020107232

GLOW-WORM

Nottingham Road,
Belper, Derbyshire.
DE56 1JT

Subject to engineering changes0020107232_03 - 12/14

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

www.glow-worm.co.uk