Glowworm 12hx User manual

1
INSTALLATION AND SERVICING
18hx
High Efficiency
Condensing
Boilers
Glow-worm, Nottingham Road, Belper, Derbyshire. DE56 1JT
www.glow-worm.co.uk
2000225262-04 02.06
G.C. No. 41-315-42
12786
Flexicom
15hx
G.C. No. 41-315-29
12hx
G.C. No. 41-315-28
24hx
G.C. No. 41-315-61

2
Thank you for installing a new Glow-worm appliance in your home.
Glow-worm appliances are manufactured to the very highest standard so we are pleased to offer our
customers a Comprehensive Guarantee.
This product is guaranteed for 24 months from the date of installation or 30 months from the date of
manufacture, whichever is the shorter, for parts. In addition this product is guaranteed for 12 months
from the date of installation or 18 months from the date of manufacture, whichever is the shorter, for
labour.
The second year of the parts guarantee, from the beginning of the 13th month onwards after instal-
lation or manufacture, is conditional upon the boiler having been serviced by a CORGI registered
gas installer,
in accordance with the manufacturer’s recommendations. We strongly recommend regular servicing
of your gas appliance, but where the condition is not met, any chargeable spare parts or components
issued within the applicable guarantee period still benefit from a 12 month warranty from the date of
issue by the manufacturer.
We recommend you complete and return as soon as possible your guarantee registration card.
If your guarantee registration card is missing you can obtain a copy or record your registration by
telephoning the Glow-worm Customer Service number 01773 828100.
Guarantee Registration
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

3
CONTENTS DESCRIPTION SECTION PAGE
Warnings 4
Important Information 4
General Information 5
Appliance Safety Devices 6
Maintenance and Servicing 6
Technical Information 1 7
Boiler Location and Ventilation 2 9
Flue Options & Terminal Clearances 3 10
Water System 4 12
Installation Preparation 5 15
Boiler Fixing 6 16
Gas/Water & Appliance Connection 7 17
Condensate Connection 8 18
Flue Preparation and Installation 9 20
Electrical Connection 10 33
Commissioning 11 35
Servicing 12 36
Fault Finding 13 40
Replacement of Parts 14 46
Spare Parts 15 52
Manual Handling 16 53
INTRODUCTION
INSTALLATION
INSTRUCTIONS
The instructions consist of two parts, Installation and Servicing Instructions. The instruc-
tions 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.

4
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 in accord-
ance with the current issue of the above regulations.
Testing and Certification
This boiler is tested and certificated for safety and perform-
ance. 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 certification, boiler warranty and may also infringe the cur-
rent issue of the statutory requirements.
CE Mark
This boiler meets the requirements of Statutory Instrument,
No. 3083 The Boiler (Efficiency) Regulations, and therefore is
deemed to meet the requirements of Directive 92/42/EEC on
the efficiency requirements for new hot water boilers fired with
liquid or gaseous fuels.
Type test for purposes of Regulation 5 certified by: Notified
body 0087.
Product/production certified by: Notified body 0086.
The CE mark on this appliance shows compliance with:
1. Directive 90/396/EEC on the approximation of the laws
of the Member States relating to appliances burning gaseous
fuels.
2. Directive 73/23/EEC on the harmonisation of the Laws of
the Member States relating to electrical equipment designed
for use within certain voltage limits.
3. Directive 89/336/EEC on the approximation of the Laws of
the Member States relating to electromagnetic compatibility.
Control of Substances Hazardous to Health
Under Section 6 of The Health and Safety at Work Act 1974,
we are required to provide information on substances hazard-
ous to health.
The adhesives and sealants used in this appliance are cured
and give no known hazard in this state.
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 I.S.813 “Domestic Gas Instal-
lations”.
The boiler must be connected to a permanent 230V ac, 50Hz
supply.
Connection of the whole electrical system of the boiler,
including any heating controls, to the electrical supply must
be through one common isolator and must be fused 3 Amp
maximum.
Isolation should be by a double pole switched fused spur box,
with a minimum gap of 3mm for both poles. The fused spur
box should be readily accessible and preferably adjacent to
the appliance. It should be identified as to its use.
Alternatively connection can be made through an unswitched
shuttered socket and 3A fused 3-pin plug both to the current
issue of BS 1363, provided they are not used in a room con-
taining a bath or shower.
Wiring to the boiler must be PVC 85OC insulated cable, not
less than 0.75mm2 (24/0.20mm).
IMPORTANT NOTE
ALL electrical connections to the boiler
must be permanently fixed to a wall or a
sturdy support feature in a tidy manner.
WARNINGS
Gas Leak or Fault
Turn off the gas emergency control valve immediately. Eliminate all sources of ignition, i.e.smoking, blowlamps, hot
air guns etc. Do not operate electrical lights or switches either on or off. Open all doors and windows,ventilate the
area.
Sheet Metal Parts
This boiler contains metal parts (components) and care should be taken when handling and cleaning, with particular
regard to edges.
Sealed Components
Under no circumstances must the User interfere with or adjust sealed parts.
Important Information

5
General Information
General Note
Once the controls are set the boiler operates automatically.
Please read these instructions and follow them carefully for
the correct installation and economical use of your boiler.
Water Treatment
In the case of an existing system, it is ESSENTIAL that prior
to installing the new boiler the system is thoroughly flushed.
For optimum performance after installation of a new system,
the boiler and its associated central heating system should
also be flushed. Flushing should be carried out in accordance
with BS7593: 1992 using a cleanser such as Sentinel X300
or X400, Fernox Restorer or Salamander corrosion guard
cleaner.
For long-term corrosion protection, after flushing, a suitable
inhibitor should be used, refer to the current issue of BS
5449 and BS 7593 on the use of inhibitors in central heating
systems. Examples are Sentinel X100, Fernox Protector or
Salamander corrosion guard inhibitor.
Compartment or Cupboard Installations
If the boiler is fitted into a compartment or cupboard it does
not require ventilation openings.
Do not use the compartment or cupboard for storage.
Clearances
If fixtures are positioned close to the boiler, space must be
left as shown in diagram 2.1.
Condensate Drain
The condensate drain, see diagram 8.2, must not be modified
or blocked.
Pluming from flue terminal
Like all condensing boilers this appliance will produce a plume
of condensation from the flue terminal in cool weather. This is
due to the high efficiency and hence low flue gas temperature
of the boiler. It is normal and not a fault indication.
Electrical Supply
If the mains electricity and gas are to be turned off for any
long periods during severe weather, it is recommended that
the whole system, including the boiler, should be drained to
avoid the risk of freezing. Make sure that, if fitted, the immer-
sion heater in the cylinder is switched off.
NOTE: If you have a sealed water system contact your instal-
lation/servicing company as draining, refilling and pressurising
MUST be carried out by a competent person.
Manual Handling
IMPORTANT: With regards to the “Manual Handling
Operations, 1992 Regulations”, the appliance is deemed to be
a one person lift.

6
Electrical Supply Failure
The boiler will not work without an electrical supply.
Normal operation of the boiler should resume when the electri-
cal supply is restored.
Reset any external controls, to resume normal operation of the
central heating.
If the boiler does not resume normal operation press reset but-
ton on fascia.
Overheating safety
In the event of the boiler overheating the safety devices will
cause a safety shutdown. If this happens, press the reset but-
ton before calling your Installation/Servicing company.
Appliance Safety Devices
Frost protection
The appliance has a built in frost protection device that pro-
tects 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 8OC.
A timer is used so that the temperature can be checked periodi-
cally. After 10 minutes the pump will be stopped if the tempera-
ture is higher than 10OC or has already reached 35OC.
The burner will activate if the boiler temperature does not reach
10OC after 30 minutes or at any time if the temperature drops
to 5OC.
The burner will switch off when the temperature reaches
35OC.
Condensate Drain Blockage
As a safety feature the boiler will stop working if the condensate
drain becomes blocked. During freezing conditions this may be
due to the forming of ice in the condense drain external to the
house. Release an ice blockage by the use of warm cloths on
the pipe. The boiler should then restart. Contact your installa-
tion/servicing company if the fault persists.
Maintenance and Servicing
Maintenance and Servicing
To ensure the continued efficient and safe operation of the ap-
pliance 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 appliance is installed in a rented property there is a duty
of care imposed on the owner of the property by the current is-
sue of the Gas Safety (Installation and Use) Regulations, Sec-
tion 35.
Servicing/maintenance should be carried out by a competent
person in accordance with the rules in force in the countries
of destination.
To obtain service, please call your installer or Glow-worm’s
own service organisation using the telephone number on the
inside front cover of this literature.
Please be advised that the ‘Benchmark’ logbook, located at
centre of the literature, should be completed by the installation
engineer on completion of commissioning and servicing.
Spare Parts
Remember, when replacing a part on this appliance, use only
spare parts that you can be assured conform to the safety and
performance specification that we require. Do not use recon-
ditioned or copy parts that have not been clearly authorised by
Glow-worm.
If a part is required contact Glow-worm’s own service organisa-
tion 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 Glow-
worm’s own service organisation using the telephone number
on the inside front cover of this booklet.

7
1 Technical Information
1.1 IMPORTANT
The boiler is supplied in one carton, which includes the appli-
ance fixings and fittings, see diagram 5.1.
The flue is supplied separately.
This boiler is for use only on G20 natural gas.
Where no British Standards exists, materials and equipment
should be fit for their purpose and of suitable quality and work-
manship.
The installation of this boiler must be carried out by a compe-
tent person in accordance the rules in force in the countries
of destination.
Manufacturer’s instructions must not be taken as overriding
statutory requirements.
1.2 Statutory Requirements
In GB the installation of the boiler must be carried out by a
competent person as described in the following regulations:
The manufacturer’s instructions supplied.
The Gas Safety (Installation and Use) Regulations.
The appropriate Buildings Regulations either The Building
Regulations, The Building Regulations (Scotland),The Building
Regulations (Northern Ireland).
The Water Fittings Regulations or Water byelaws in Scotland.
The Health and Safety at Work Act, Control of Substances
Hazardous to Health (COSHH).
The Current I.E.E. Wiring Regulations.
Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
In IE, the installation must be carried out by a competent
person and installed in accordance with the current edition of
I.S.813 “Domestic Gas Installations”, the current Building Regu-
lations and reference should be made to the current ETCI rules
for Electrical Installation.
In GB the following Codes of Practice apply:
BS4814, BS6798, BS5440 Part 1 and 2, BS5546 Part 1,
BS5449, BS6891, BS6700, BS7074 Part 1 and 2, BS7593,
BS7671.
In IE: I.S.813, BS5546, BS 5449, BS 7074, BS 7593.
Manufacturer’s instructions must not be taken as overriding
statutory requirements.
NOTE: For further information, see the current issue of the
Building Regulations, approved document L1 ( in the UK) and
the references:
1) Central heating system specification (CheSS)
and
2) Controls for domestic central heating system and hot water.
BRECSU.
12788
Diagram 1.1
87
600
375
GAS
280
C
L
FLUE
246.5
Condense
Drain Point
52
BOILER
C
L
25

8
BOILER SPECIFICATION 12hx to 24hx
Lift weight 25kg (55Ib)
Total weight (installed) 28kg (62Ib)
Gas connection Ø O.D. 15mm. copper
Heating Flow & Retrn connection Ø O.D. 22mm. copper
Condensate connection Ø I.D. 21.5mm. plastic
Electrical supply 230V~50Hz
Electrical rating 60W fused 3A
IP clasification X4D
Internal fuse rating on main PCB 2A
Gas supply (governed metre only) I2H G20 natural gas
Inlet gas working pressure 20mbar
Burner % CO2 case on 9.3 nominal
Burner % CO2 case off 9.3 nominal
12hx 15hx 18hx 24hx
m3/h 1.28 1.60 1.93 2.58
ft3/h 45 56.5 68.1 90.9
m3/h 0.99 0.99 0.99 0.99
ft3/h 35.1 35.1 35.1 35.1
Approximate max. gas rate
after 10 mins. from cold
Heat input NETT Q = kW max. 12.1 15.1 18.2 24.4
min. 9.4 9.4 9.4 9.4
Heat output P = kW max. 12 15 18 24
min. 9.3 9.3 9.3 9.3
Approximate min. gas rate
after 10 mins. from cold
Flue type (all models) C13, C33, C53
NOx (all models) Class 5
1 Technical Information
13214
1.3 Technical Data
All dimensions are given in millimetres (except as noted).
See diagrams 1.1 and 1.2.
The data label is positioned on the base of the boiler.
1.4 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 Instal-
lations”.
The supply from the governed meter must be of adequate size
to provide a steady inlet working pressure of 20mbar (8in wg)
at the boiler.
On completion, test the gas installation for soundness using the
pressure drop method and suitable leak detection fluid, purge
in accordance with the above standard.
1.5 Condensate Drain
A plastic drain pipe must be fitted to allow discharge of conden-
sate 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.
Diagram 1.2

9
2 Boiler Location and Ventilation
2.1 Location
This boiler is not suitable for outdoor installation.
This boiler may be installed in any room, although particular
attention is drawn to the installation of a boiler in a room
containing a bath or shower where reference must be made to
the relevant requirements.
This boiler is suitable for installation in bathroom zones 2 and
3.
In GB this is the current I.E.E. WIRING REGULATIONS and
BUILDING REGULATIONS.
In IE reference should be made to the current edition of I.S.813
“Domestic Gas Installations” and the current ETCI rules.
2.2 Clearances
The boiler should be positioned so that at least the minimum
operational and servicing clearances are provided, see diagram
2.1.
Increased clearances would be beneficial for the installation.
Where external access is not practicable, for flue installations
consideration should be given for the space required to insert
the flue internally, which may necessitate the clearance to be
greater than those specified in diagram 2.1.
2.3 Timber Frame Buildings
If the boiler is to be installed in a timber frame building it should
be fitted in accordance with the Institute of Gas Engineers
document IGE/UP/7/1998. If in doubt seek advice from the
local gas undertaking or Glow-worm.
2.4 Room Ventilation
The boiler is room sealed so a permanent air vent is not
required.
2.5 Cupboard or Compartment Ventilation
Due to the high efficiency and hence low casing temperature
of this boiler, cupboard or compartment ventilation is not
necessary.
Leave existing air vents.
12792
Diagram 2.1
600
55
5
55
150
+
+ A removable compartment door can be placed
a minimum of 5mm in front of the appliance.
150
This can be reduced to 20mm for a direct rear flue

10
3 Flue Options and Terminal Clearances
Top horizontal telescopic flue Ø60/100
Part No. A2043600
Top horizontal standard flue Ø60/100
Part No. A2043400
Rear telescopic flue Ø60/100
Part No. A2043500
Vertical Flue
Vertical Flue Adapter, concentric flue Ø60/100
Part. No. A2024600
Vertical flue terminal kit, concentric flue Ø60/100
Part. No. 2000460480
Twin Flue
Twin Flue Adapter, concentric flue Ø80
Part No. A2011000
Flue Accessories
Black Horizontal Terminal Kit, for use with
A2043500; A2043600; A2043400
Black Horizontal Terminal Kit,
concentric flue Ø60/100 - Part No. A2043700
Plume Management Kit, for use with
A2043500; A2043600; A2043400
Plume Management Kit, basic set, white,
concentric flue Ø60/100 - Part No. A2044100
1m extension, white - Part No. A2044300
87o elbow, white - Part No. A2044700
45o bend (2), white - Part No. A2044500
Plume Management Kit, basic set, black,
concentric flue Ø60/100 - Part No. A2044000
1m extension, black - Part No. A2044200
87o elbow, black - Part No. A2044600
45o bend (2), black - Part No. A2044400
Concentric Flue Ø60/100 accessories:
2 metre extension kit, concentric flue
Ø60/100 - Part No. 2000460483
1 metre extension kit, concentric flue
Ø60/100 - Part No. 2000460482
0.5 metre extension kit, concentric flue
Ø60/100 - Part No. 2000460481
Adjustable flue pipe 0-50mm kit,
concentric flue Ø60/100 - Part No. 2000460487
90o flue elbow pack,
concentric flue Ø60/100 - Part No. 2000460484
45o flue bend pack,
concentric flue Ø60/100 - Part No. 2000460485
Flue support clips (3),
concentric flue Ø60/100- Part No. A2043900
Additional accessories are available.
See Glow-worm “Flexicom Range Guide” for
configurations available.
Diagram 3.1

11
HORIZONTAL FLUES
A DIRECTLY BELOW AN OPENING, AIR BRICK,
OPENING WINDOWS 300
B ABOVE AN OPENING, AIR BRICK,
OPENING WINDOWS 300
C HORIZONTALLY TO AN OPENING,
AIR BRICK, OPENING WINDOWS 300
D BELOW GUTTER, DRAIN/SOIL PIPE 25
E BELOW EAVES 25
F BELOW A BALCONY OR CAR PORT 25
G FROM VERTICAL DRAIN PIPES AND
SOIL PIPES 25
H FROM INTERNAL/EXTERNAL CORNERS 25
H* TO A BOUNDARY ALONGSIDE THE
TERMINAL 300
I ABOVE ADJACENT GROUND OR
BALCONY LEVEL 300
J* FROM SURFACE OR A BOUNDARY
FACING THE TERMINAL 600
K FACING TERMINALS 1200
L FROM OPENING (DOOR/WINDOW)
IN CAR PORT INTO DWELLING 1200
M VERTICAL FROM A TERMINAL 1500
N HORIZONTALLY FROM A TERMINAL 300
VERTICAL FLUES
P FROM ANOTHER TERMINAL 600
Q ABOVE ROOF LEVEL 300
R FROM ADJACENT OPENING WINDOW 1000
S FROM ADJACENT WALL TO FLUE 300
Diagram 3.2
3.1 Flue Options
There are various flue options to choose from as illustrated in
diagram 3.1. The flue lengths and installation are described in
section 9.
3.2 Flue Terminal Position
The minimum acceptable siting dimensions for the terminal
from obstructions, other terminals and ventilation openings are
shown in diagram 3.2. For Ireland the minimum distances for
flue terminal positioning must be those detailed in I.S.813 “Do-
mestic Gas Installations”.
The terminal must be exposed to the external air, allowing free
passage of air across it at all times.
Being a condensing boiler some pluming may occur from the
flue outlet. This should be taken into consideration when se-
lecting the position for the terminal.
NOTE: If necessary it is permitted to increase the terminal pro-
trusion through the outside wall to greater than the minimum di-
mension of 87mm but no more than 600mm, see diagram 1.1.
Carports or similar extensions of a roof only, or a roof and one
wall, require special consideration with respect to any open-
ings, doors, vents or windows under the roof. Care is required
to protect the roof if made of plastic sheeting. If the carport
comprises of a roof and two or more walls, seek advice from
the local gas supply company before installing the boiler.
H* and J* See diagram 3.2 . 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.
Plume Management Kit: Part No.A2044100 (white) or
A2044000 (black) can be used to overcome many site issues.
3.3 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 3.3.
A suitable guard is manufactured by: -
Tower Flue Components
Morley Rd.
Tonbridge
Kent
TN9 1RA.
Size: 280mm x 280mm x 270mm.
3 Flue Options and Terminal Clearances
Diagram 3.3

12
0510 15 20 25 30
Flow Rate (litres/min)
24kW
Pressure Loss (metres)
15kW
4 Water System
4.1 Safety Valve
A safety valve need not be fitted to an open-vented system.
4.2 Pump
The pump should be fitted on the flow pipe from the boiler and
have isolating valves each side.
A variable duty pump should be set to give a temperature dif-
ference of no greater than 200C between the flow and return,
with the thermostat set at “MAX”, which is about 800C, to give
a flow rate as shown in table 3.
See chart for pressure loss of the boiler, diagram 4.1.
High resistance microbore systems may require a higher duty
pump.
4.3 Flow Rate
If it is necessary to alter the flow rate, the system can be fit-
ted with a lockable balancing valve in the main flow or return
pipes shown in diagram 4.3. The flow rate through the boiler
must not be allowed to fall below that given in diagram 4.1.
4.4 Bypass
A bypass is not required on the central heating system unless
the system controls could allow the boiler and pump to oper-
ate when there is no flow.
Where a bypass has to be fitted, the bypass must be placed
at least 1.5 metres away from the boiler.
4.5 Water Treatment
In the case of an existing system, it is ESSENTIAL that prior
to installing the new boiler the system is thoroughly flushed.
For optimum performance after installation of a new system,
the boiler and its associated central heating system should
also be flushed. Flushing should be carried out in accordance
with BS7593: 1992 using a cleanser such as Sentinel X300
or X400, Fernox Restorer or Salamander corrosion guard
cleaner.
For long-term corrosion protection, after flushing, a suitable
inhibitor should be used, refer to the current issue of BS
5449 and BS 7593 on the use of inhibitors in central heating
systems. Examples are Sentinel X100 Fernox Protector or
Salamander corrosion guard inhibitor.
4.6 Open (Vented) Water System
The boiler must be supplied from an unrestricted water supply
taken from a feed and expansion cistern situated at a maxi-
mum height of 27 metres (90ft) above the boiler.
The cold feed must be 15mm minimum size.
The vent must rise continuously and be unrestricted.
It is important that the relative positions of the pump, cold feed
and open vent are as shown in diagram 4.2.
4.7 Combined Feed and Vent
For combined feed and vent, a 22mm pipe must be fitted in
accordance with BS 5449.
4.8 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE
The domestic hot water cylinder must be of the double feed
fully indirect coil type.
Diagram 4.1
13215

13
Open (vented) system.
Recommended
relationship between
pump, cold feed and vent.
22mm (MIN.) VENT
FEED AND
EXPANSION CISTERN
15mm (MIN.)
AUTOMATIC
BY-PASS
15mm (MIN.) COLD FEED
CYLINDER
RETURN
FLOW
HEATING
PUMP
BOILER 150mm MAX.
1000mm
MIN.
450mm
MIN.
HEIGHT
4.9 Draining Points
Draining taps must be provided at the lowest points of the
system, which will allow the entire system to be drained.
A Draining point for the appliance is provided at the position
shown in diagram 4.2.
4.10 Domestic Hot Water System -
unvented
General - All domestic hot water circuits, connections, fittings
must be in accordance with the relevant standards and water
supply regulations.
For GB: Guidance G17 to G24 and recommendation R17 to
R24 of the Water Regulations Guide.
For IE: The current edition of I.S.813 “Domestic Gas Installa-
tions”.
Where a storage system will not have a vent to atmosphere
the installation must comply with the building regulations and
local Water Company bylaws, see also the current issue of
BS5546 and BS6700.
If fitting to an existing system the local authority should be
informed.
4.11 Sealed Water Systems
The installation must comply with the appropriate require-
ments of the current issue of BS4814, BS5449, BS6759,
BS6798 and BS7074 Part 1 and 2.
See diagram 4.3 for a suggested layout.
Diagram 4.3
13147
Diagram 4.2
12793
4 Water System
DRAIN POINT

14
4 Water System
4.12 Safety Valve
A safety valve must be fitted to a sealed system.
It shall be preset, non-adjustable with a lift pressure of 3 bar,
incorporating seating of a resilient material, a test device and
a connection for drain.
The drain from the safety valve must be routed outside the
building, must not discharge above an entrance or window or
any type of public access area, be clear of any electrical fit-
tings and positioned so that any discharge can be seen.
4.13 Expansion Vessel
A diaphragm type expansion vessel, conforming to the current
issue of BS4814 (see also BS7074 Part 1 and 2) must be
connected at a point close to the inlet side of the circulating
pump, see the diagrammatic layout, diagram 4.3 unless laid
down differently by the manufacturer.
The expansion vessel volume depends on the total water
system volume and the initial system design pressure. For
any system an accurate calculation of vessel size is given in
the current issue of BS5449 and BS7074 Part 1.
Example: For an initial design pressure of 0.7 bar, the mini-
mum total vessel volume required is 0.063 x Total System
Volume.
NOTE: A higher initial design pressure requires a larger vol-
ume expansion vessel.
Guidance on vessel sizing is also given in the current issue of
BS5449 and BS7074 Part 1, for IE refer to the current edition
of I.S.813 “Domestic Gas Installations”.
The charge pressure must not be less than the static head
of the system, that is, the height of the highest point of the
system above the expansion vessel.
4.14 Pressure Gauge
A pressure gauge with a set pointer and covering at least 0 to
4 bar (0 to 60 lb/in2) shall be fitted permanently to the system
in a position where it can be seen when filling the system.
4.15 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE
The domestic hot water cylinder must be of the double feed
fully indirect coil type. It must be suitable for working at a
gauge pressure of 0.35 bar above the safety valve setting.
4.16 Water Makeup
Provision should be made for replacing water loss from the
system using a make up bottle mounted in a position higher
than the top point of the system, connected through a non-re-
turn valve to the return side of either the heating circuit or the
hot water cylinder.
Alternatively, provision for make up can be made using a
filling loop.
4.17 Filling a Sealed Water System
Provision for filling the system at low level must be made, see
diagram 4.4. There must be no permanent connection to the
mains water supply, even through a non-return valve.
TEMPORARY
CONNECTION
HOSE
UNION
HOSE
UNION
SUPPLY
PIPE
CONTROL
VALVE
CONTROL
VALVE
DOUBLE
CHECK
VALVE
HEATING
CIRCUIT
DRAIN
POINT
SUPPLY
PIPE
AIR GAP
TUNDISH
CONTROL
VALVE
CONTROL
VALVE
TYPE CA BACKFLOW
PREVENTION DEVICE
BOILER
RETURNFLOW
BOILER
RETURNFLOW
HEATING
CIRCUIT
DRAIN
POINT
Method 1
Method 2
Diagram 4.4
11680

15
HANGING
BRACKET
GAS COCK
GAS PIPE
5.1 Appliance Fixings and Fittings
IMPORTANT: With regards to the Health and Safety Manual
Handling requirements, the following lift operation is deemed
to be a one person lift, refer to section 16 Manual Handling.
The fixings, fittings and documentation pack are contained
in the top polystyrene packing and should be as shown in
diagram 5.1.
5 Installation Preparation
Diagram 5.1
12794
Documentation Pack (not illustrated)
Wall Template, User Instructions,
Installation and Servicing Instructions.
5.2 Wall Template
Take the wall template from the documentation pack located
within the top polystyrene packing and place in the desired
position on a flat wall, giving due consideration to boiler clear-
ances, see section 2, and the flue you are fitting.
5.3 Flue Hole Cutting
External access flue installation can use a 105mm diameter
core drill.
Internal access only flue installation will need a 125mm diam-
eter core drill.
If flue 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.
Top horizontal flue - (standard and
telescopic)
The standard horizontal flue is designed with an internal fall of
44mm/metre (2.5°) towards the boiler for disposal of con-
densate therefore the hole can be drilled horizontally. If the
standard flue length alone is being used then the flue hole of
diameter 105mm can be cut in the position marked on the wall
template.
For standard side flues the horizontal flue centre line on the
wall template should be extended to the side wall, and the
vertical centre of the flue hole marked at 176mm from the
back wall.
For extended side flues, the flue hole centre should be
determined by extending the dashed inclined line on the
template to the side wall. This dashed line is drawn at 44mm/
metre (2.5°) rise from the boiler. Where this line reaches the
side wall, a horizontal line should be marked. The vertical
centre line of the flue should then be marked at 176mm from
the back wall.
To allow for the flue 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 flue hole.
5.4 Flue Hole Cutting (rear flue - telescopic)
The rear flue is designed with an internal fall of 44mm/metre
towards the boiler for disposal of condensate therefore the
hole can be drilled horizontally. For installations with external
access, a 105mm diameter core drill can be used.

16
Diagram 6.1
12965
6 Boiler Fixing
6.1 Hanging Bracket
Reposition the wall template over the flue hole and mark
the position of the fixing holes for the hanging bracket, see
diagram 6.1.
NOTE: Due to the varied site conditions we do not supply
fixings and advise that the installer should supply those which
are suitable.
Drill fixing holes and insert suitable wall plugs.
Rear Flue only - If external access is not available the flue
to be used should be assembled as described in section 9
and inserted through the hole in the wall before fitting the wall
hanging bracket.
6.2 Boiler Fixing
IMPORTANT: With regards to the Manual Handling
Operations, 1992 regulations, the following lift operation is
deemed to be a one person lift, refer to section 16 Manual
Handling.
NOTE: If fitting a rear flue this must be fitted before hanging
the boiler, refer to section 9.15.
Lift the boiler and position onto the mounting lugs.
Push the boiler firmly towards the wall to locate over the
retaining bosses at the top centre of the fixing plate, see
diagram 6.2.
Diagram 6.2
12959

17
GAS SERVICE
COCK GAS SUPPLY
PIPE IN
PRESSURE
TEST POINT
7 Gas / Water & Appliance Connection
Diagram 7.1
7.1 Gas Connection
Before connection check the supply of local gas.
The gas supply can be connected from below, see diagram
7.1. or through the wall at the rear of the boiler.
Refer also to section 1.2 and 1.3.
The whole of the gas installation, including the meter, should
be inspected, tested for soundness and purged in accordance
with the current issue of BS6891 and in IE the current edition
of I.S.813 “Domestic Gas Installations”.
7.2 Water Connections
Provision is made for the water connections to be made from
above the boiler, see diagram 7.1. The position is shown on
the wall template.
Flush out the domestic hot water and the heating systems
before connecting to the boiler.
RETURN FLOW
22mm compression
is the recommended
fixing for servicing
(not supplied)
Gas Connection Water Connections
12799
12796

18
8 Condensate Connections
8.1 Condensate Drain Connection
For condensate drain connection, see diagram 8.1. To
discharge condensate to a drain, the drain pipe should have a
fall of a least 44mm/metre (2.5°) 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 8.2.
It is recommended that any external condensate drain pipe is
insulated and also preferably of 32mm diameter, to prevent
freezing in adverse weather conditions.
The condensate is discharged periodically in ‘slugs’ by
siphonic action.
It is not necessary to provide air breaks or extra traps in the
discharge pipe as there is already a 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.
CONDENSATE DRAIN
CONNECTION
13009
Diagram 8.1

19
INTERNAL SOIL
AND VENT STACK
BOILER
MIN. DIA. 21mm
NO RESTRICTION
ON LENGTH
EXTERNAL SOIL
AND VENT STACK
MIN. DIA. 21mm
NO RESTRICTION
ON LENGTH
BOILER
BOILER
MIN. DIA. 21mm
EXTERNAL LENGTH
OF PIPE 3M MAX.
OPEN END OF PIPE
DIRECT INTO GULLEY
BELOW GROUND BUT
ABOVE WATER LEVEL
MIN. DIA. 21mm
NO RESTRICTION
ON LENGTH
BOILER
SINK
(CONSTITUTES
AIR BREAK)
BOILER
MIN. DIA. 21mm
NO RESTRICTION
ON LENGTH
SINK
OPEN END OF PIPE DIRECT INTO
GULLEY BELOW GROUND LEVEL
BUT ABOVE WATER LEVEL.
Ø22mm MIN.
TERMINATION FROM APPLIANCE.
EXTERNAL LENGTH OF PIPE
3M MAX.
25mm MIN.
SEAL
BOTTOM OF
TUBE SEALED
Ø100mm
PLASTIC TUBE
300mm
MIN.
GROUND
(either/or)
500mm MIN.
HOLE DEPTH
400mm MIN.
LIMESTONE CHIPPINGS
2 ROWS OF 3 x 12mm HOLES AT
25mm CENTRES 50mm FROM
BOTTOM OF TUBE. HOLES TO
FACE AWAY FROM HOUSE.
External Soil and Vent Pipe or Rainwater Pipe
Internal Soil and Vent Pipe
External Termination into Soakaway
Internal Termination Downstream of
Sink Waste
Internal Termination into Combined Sink Waste
External Termination to a Gulley or Hopper
*
NOTE: PIPEWORK SHOULD ALWAYS FALL AWAY FROM BOILER BY AT LEAST 2.5
44mm FOR EVERY 1M.
o
EXTERNAL
MAX. 3M
*NOTE: FOR EXTENDED
PIPE RUNS 32mm DIA.
PIPE SHOULD BE USED.
8 Condensate Connections
12333
Diagram 8.2

20
9 Flue Preparation and Installation
9.1 Top Horizontal Rear flue - Telescopic
Part No. A2043600. Refer to diagram 9.1 for
kit contents.
9.2 Flue Length
If a wall thickness of 232 min. to 437 max. is available the
Top horizontal rear flue - telescopic can be used without
extensions.
If the wall thickness is greater than 437 then using extensions
a maximum horizontal flue length of 8 metres plus the Top
horizontal rear flue - telescopic can be achieved. However, for
every 90o or 45o elbows used the flue length MUST be reduced
by 1 metre.
When extension pipes are used the flue system must be
designed to have a continuous fall to the boiler of at least
44mm/metre (2.5°) to allow condensate to run back into the
boiler and out via the drain.
9.3 Preparation
Remove the top flue outlet cover secured with four screws,
see diagram 9.2.
Temporarily fit the flue elbow, measure the distance from the
outside wall to flue elbow. If the measurement ‘Y’ exceeds
525mm, see diagram 9.3 then the appropriate length of
extension pipe is required. If the dimension is less than
320mm DO NOT cut the flue, it can project beyond the
outside wall face, see diagrams 9.4. If this is not desirable
then a Top horizontal rear flue - standard MUST be used and
cut to length.
9.4 Flue Fitting
Set the flue to the required length ‘Y’, ensure the air duct
seams line up.
Remove the flue elbow.
Mark the securing hole position in the air duct. Drill a 3mm
diameter hole at this position, take care not to pierce the
inner flue duct. Secure with screw provided and tape the joint,
see diagram 9.5.
Fit the sealing collar onto the locating ring on the flue terminal,
see diagram 9.6.
Push the flue assembly into the wall, externally or internally,
until the end of the assembly protrudes a short way from the
inside face of the wall. This will enable the internal trim ring (if
required) to be positioned and allow the flue assembly to be
drawn back up to the flue elbow.
Secure the flue elbow in position on top of the boiler with four
torque headed screws supplied.
Draw the flue assembly from wall and engage the flue duct
into the elbow and butt fit between the air duct and flue elbow.
Ensure the correct alignment of the flue.
Fit the securing collar in position, mark through two of the pre
drilled holes in the securing collar. Remove securing collar
and drill two 3mm diameter holes one in the elbow and one in
the air duct, take care not to pierce the inner flue duct. Fit the
securing collar and secure with screws provided, see diagram
9.7.
Slide the internal trim ring back against the wall, securing in
place with a small amount of sealant if required.
12925
Diagram 9.1
Diagram 9.2
12978
Diagram 9.3
12806