Glowworm 12hxi User guide

1
Installation and Servicing
High Efficiency
Condensing Boilers
Ultracom
15hxi
G.C. No. 41-019-02
12hxi
G.C. No. 41-019-01
18hxi
G.C. No. 41-019-03
30hxi
G.C. No. 41-019-05
24hxi
G.C. No. 41-019-04
38hxi
G.C. No. 41-019-06
13204
www.glow-worm.co.uk

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 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 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
Statutory Requirements 5
Boiler Design 6
Safety Devices 6
Servicing, Maintenance and Spare Parts 6
Boiler Specification 1 7
Boiler Dimensions &
Hydraulic Schematic 2 8
Boiler Location, Clearances and
Ventilation 3 9
Flue Options and Terminal Clearances 4 10
Water Systems 5 12
Installation Preparation 6 16
Boiler Fixing 7 17
Gas/Water & Condensate Connection 8 18
Flue Length Preparation and Installation 9 20
Electrical Connection 10 35
Commissioning 11 37
Servicing 12 40
Fault Finding 13 44
Replacement of Parts 14 52
Spare Parts 15 57
Manual Handling 16 58
Declaration of Conformity - 59
INTRODUCTION
INSTALLATION
MAINTENANCE
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.

4
Gas Category
This boiler is for use only on G20 natural gas, but may be
converted for use on G31 gas (Propane L.P.G.).
Gas Safety (Installation and Use) Regulations
In your own interests and that of safety, it is the Law that
ALL gas appliances are installed by a competent person in
accordance with the current issue of 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.
Insulation Pads
These can cause irritation to skin, eyes and the respiratory
tract.
If you have a history of skin complaint you may be
susceptible to irritation. High dust levels are usual only if the
material is broken.
Normal handling should not cause discomfort, but follow
normal good hygiene and wash your hands before eating,
drinking or going to the lavatory.
If you do suffer irritation to the eyes or severe irritation to the
skin seek medical attention.
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.
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 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
containing a bath or shower.
Wiring to the boiler must be PVC 85OC insulated cable, not
less than 0.75mm2 (24/0.20mm).
Testing and Certification
This boiler is tested and certificated for safety and
performance. It is, therefore, important that no alteration is
made to the boiler, without permission, in writing, by Glow-
worm.
Any alteration not approved by Glow-worm, could invalidate
the certification, boiler warranty and may also infringe the
current issue of the statutory requirements.
CE Mark
This boiler meets the requirements of Statutory Instrument,
No. 3083 The Boiler (Efficiency) Regulations, and therefore
is deemed to meet the requirements of Directive 92/42/EEC
on the efficiency requirements for new hot water boilers fired
with liquid or gaseous fuels.
Type test for purposes of Regulation 5 certified by: Notified
body 0087.
Product/production certified by: Notified body 0086.
The CE mark on this appliance shows compliance with:
1. Directive 90/396/EEC on the approximation of the laws
of the Member States relating to appliances burning gaseous
fuels.
2. Directive 73/23/EEC on the harmonisation of the Laws of
the Member States relating to electrical equipment designed
for use within certain voltage limits.
3. Directive 89/336/EEC on the approximation of the Laws of
the Member States relating to electromagnetic compatibility.
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

5
IMPORTANT
Where no British Standards exists, materials and equipment
should be fit for their purpose and of suitable quality and
workmanship.
The installation of this boiler must be carried out by a
competent person in accordance the rules in force in the
countries of destination.
Manufacturer’s instructions must not be taken as overriding
statutory requirements.
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 as described in the following
regulations:
The manufacturer’s instructions supplied.
The Gas Safety (Installation and Use) Regulations.
The appropriate Buildings Regulations either The Building
Regulations, The Building Regulations (Scotland),The
Building Regulations (Northern Ireland).
The Water Fittings Regulations or Water byelaws in Scotland.
The Health and Safety at Work Act, Control of Substances
Hazardous to Health (COSHH).
The Current I.E.E. Wiring Regulations.
Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
In IE, the installation must be carried out by a competent
person and installed in accordance with the current edition
of I.S.813 “Domestic Gas Installations”, the current Building
Regulations and reference should be made to the current
ETCI rules for Electrical Installation.
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 specification (CheSS)
and
2) Controls for domestic central heating system and hot
water. BRECSU.
Statutory Requirements
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 fluid,
purge in accordance with the above standard.
Domestic Hot Water
All domestic hot water circuits, connections, fittings 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.

6
Boiler Design
Boiler Design
These boilers are designed to provide central heating from
a fully pumped open vented or sealed water system and
domestic hot water using a fully indirect cylinder.
Once the controls are set the boiler operates automatically.
Condensate Drain
A plastic drain pipe must be fitted to allow discharge of
condensate to a drain.
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 Devices
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 8OC.
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 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.
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 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.
This is normal and not an indication of a fault.
Servicing, Maintenance and Spare Parts
Servicing and Maintenance
To ensure the continued efficient and safe operation of the
boiler it is recommended that it is checked and serviced as
necessary at regular intervals. The frequency of servicing will
depend upon the particular installation conditions and usage.
If this appliance is installed in a rented property there is a duty
of care imposed on the owner of the property by the current
issue of the Gas Safety (Installation and Use) Regulations,
Section 35.
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.
“Benchmark” scheme
Glow-worm support the Benchmark initiative. It is very
important that the Installation, Commissioning and Service
Record is completed by the installation engineer and handed
over to the user.
Spare Parts
Remember, when replacing a part on this appliance, use
only spare parts that you can be assured conform to the
safety and performance specification that we require. Do not
use reconditioned or copy parts that have not been clearly
authorised by Glow-worm.
If a part is required contact Glow-worm’s own service
organisation using the telephone number on the inside front
cover of this booklet.
Please quote the name of the appliance, this infomation will be
on the name badge on the front of the appliance.
If in doubt seek advice from the local gas company or Glow-
worm’s own service organisation using the telephone number
on the inside front cover of this booklet.

7
1 Boiler Specification
13497
BOILER SPECIFICATION 12hxi 15hxi 18hxi
Lift weight 25kg (55Ib) 25kg (55Ib) 25kg (55lb)
Total weight (installed) 30kg (66Ib) 30kg (66Ib) 30kg (66lb)
Gas connection Rc1/2 (1/2in BSPT) Rc1/2 (1/2in BSPT) Rc1/2 (1/2in BSPT)
Heating flow and return connection Ø O.D. 22mm. copper 22mm. copper 22mm. copper
Condensate connection Ø I.D. 21.5mm. plastic 21.5mm. plastic 21.5mm. plastic
Water circuit 3 bar (43/5Ibf/in2) 3 bar (43/5Ibf/in2) 3 bar (43/5Ibf/in2)
Electrical supply 230V~50Hz fused 3A 230V~50Hz fused 3A 230V~50Hz fused 3A
Electrical rating 60W fused 3A 60W fused 3A 60W fused 3A
EN60529 IP clasification IPX4D IPX4D IPX4D
Internal fuse rating on main PCB 2A 2A 2A
Gas supply (governed meter only) / category G20 natural gas / II2H3P G20 natural gas / II2H3P G20 natural gas / II2H3P
Inlet gas working pressure 20mbar 20mbar 20mbar
Burner % CO2 case on 9.3 nominal 9.3 nominal 9.3 nominal
Burner % CO2 case off 9.1 nominal 9.1 nominal 9.1 nominal
1.29 m3/h 1.61 m3/h 2.00 m3/h
45.6 ft3/h 57 ft3/h 70.6 ft3/h
0.53 m3/h 0.53 m3/h 0.53 m3/h
18.7 ft3/h 18.7 ft3/h 18.7 ft3/h
Flue type C13, C33, C53 C13, C33, C53 C13, C33, C53
NOx Class 5 Class 5 Class 5
Heat output condensing mode 12.9kW 16.2kW 20.02kW
Heat input Nett Q = kW max. 12.20 min. 5 max. 15.26 min. 5.0 max. 18.9 min. 5
Heat output P = kW max. 12 min. 4.95 max. 15 min. 4.95 max. 18.57 min. 4.95
SEDBUK rating Band A 90.5% Band A 90.5% Band A 90.4%
Approximate max. gas rate
after 10 mins. from cold
Approximate min. gas rate
after 10 mins. from cold
BOILER SPECIFICATION 24hxi 30hxi 38hxi
Lift weight 28kg (62Ib) 28kg (62Ib) 28kg (62lb)
Total weight (installed) 33kg (73Ib) 33kg (73Ib) 33kg (73lb)
Gas connection Rc1/2 (1/2in BSPT) Rc1/2 (1/2in BSPT) Rc1/2 (1/2in BSPT)
Heating flow and return connection Ø O.D. 22mm. copper 22mm. copper 22mm. copper
Condensate connection Ø I.D. 21.5mm. plastic 21.5mm. plastic 21.5mm. plastic
Water circuit 3 bar (43/5Ibf/in2) 3 bar (43/5Ibf/in2) 3 bar (43/5Ibf/in2)
Electrical supply 230V~50Hz fused 3A 230V~50Hz fused 3A 230V~50Hz fused 3A
Electrical rating 60W fused 3A 60W fused 3A 60W fused 3A
EN60529 IP clasification IPX4D IPX4D IPX4D
Internal fuse rating on main PCB 2A 2A 2A
Gas supply (governed meter only) / category G20 natural gas / II2H3P G20 natural gas / II2H3P G20 natural gas / II2H3P
Inlet gas working pressure 20mbar 20mbar 20mbar
Burner % CO2 case on 9.3 nominal 9.3 nominal 9.0 nominal
Burner % CO2 case off 9.1 nominal 9.1 nominal 8.8 nominal
2.58 m3/h 3.02 m3/h 4.06 m3/h
91.1 ft3/h 107 ft3/h 143 ft3/h
0.56 m3/h 0.56 m3/h 0.67 m3/h
19.8 ft3/h 19.8 ft3/h 23.8 ft3/h
Flue type C13, C33, C53 C13, C33, C53 C13, C33, C53
NOx Class 5 Class 5 Class 5
Heat output condensing mode 25kW 30.6kW 41kW
Heat input Nett Q = kW max. 24.4 min. 5.3 max. 28.6 min. 5.3 max. 38.35 min. 6.7
Heat output P = kW max. 24 min. 5.25 max. 28.2 min. 5.25 max. 38 min. 6.3
SEDBUK rating Band A 90.5% Band A 90.6% Band A 90.8%
Approximate max. gas rate
after 10 mins. from cold
Approximate min. gas rate
after 10 mins. from cold

8
2 Boiler Dimensions & Hydraulic Schematic
Diagram 2.1
13751
Diagram 2.2
CONDENSATE
CONNECTION
13205
2.1 Boiler Dimensions & 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.

9
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 beneficial around the boiler for
installation and servicing.
For flue installations where external access is not practicable,
consideration should be given for the space required to insert
the flue internally, which may necessitate clearance larger
than those specified in diagram 3.1.
3.3 Timber Frame Buildings
If the boiler is to be installed in a timber frame building it
should be fitted in accordance with the Institute of Gas
Engineers document IGE/UP/7/1998. If in doubt seek advice
from local gas undertaking or Glow-worm.
3.4 Combustible Material
The boiler and flue are suitable for installation onto and
through combustible materials provided that:-
1) Minimum 5mm clearance is maintained around the
circumference of the flue (air intake).
2) The combustible surface and fixings 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 efficiency and hence low casing temperature
of this boiler, cupboard or compartment ventilation is not
necessary.
Leave existing air vents.
Diagram 3.1
150
200
*5
600
CLEARANCES
5
5mm clearance
to combustible
material
5
5
13204

10
4 Flue Options and Terminal Clearances
Diagram 4.1
Top horizontal telescopic flue (Ø60/100)
Part No. A2043600 - Section 9, page 20
Top horizontal standard flue (Ø60/100)
Part No. A2043400 - Section 9, page 24
Twin Flue
Twin Flue Adapter, concentric flue (Ø80)
Part No. A2011000 - Section 9, page 31
Plume Management Kit
basic set, white, concentric flue
(Ø60/100) - Part No. A2044100 for
use with Part No. A2043400 and
Part No. A2043600 - Section 9, page
34
Vertical Flue
Vertical Flue Adapter, concentric flue (Ø60/100)
Part. No. A2024600 - Section 9, page 28
Vertical flue terminal kit, concentric flue (Ø60/100)
Part. No. 2000460480 - Section 9, page 28

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 4.2
4.1 Flue Options
There are various flue options to choose from as illustrated in
diagram 4.1. The flue lengths and installation are described in
section 9.
4.2 Flue Terminal Position
In GB the minimum acceptable siting dimensions for the
terminal from obstructions, other terminals and ventilation
openings are shown in diagram 4.2. In IE the minimum
distances for flue terminal positioning must be those detailed
in I.S.813 “Domestic Gas Installations”.
The terminal must be exposed to the external air, allowing
free passage of air across it at all times.
Being a condensing boiler some pluming may occur from
the flue outlet. This should be taken into consideration when
selecting the position for the terminal.
Carports or similar extensions of a roof only, or a roof and
one wall, require special consideration with respect to any
openings, doors, vents or windows under the roof. Care is
required to protect the roof if made of plastic sheeting. If
the carport comprises of a roof and two or more walls, seek
advice from the local gas supply company before installing
the boiler.
H* and J* See diagram 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.
4.3 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 4.3.
A suitable guard is manufactured by: -
Tower Flue Components
Morley Rd.
Tonbridge
Kent TN9 1RA.
Size: 280mm x 280mm x 270mm.
4 Flue Options and Terminal Clearances
Diagram 4.3
12325

12
5 Water Systems
0 1000800600400
0
1
0.5
1.5
2
2.5
200
12342
Diagram 5.1

13
5 Water Systems - General
5.1 General
This boiler is designed to provide central heating from a fully
pumped open vented or sealed water system and domestic
hot water using a fully indirect cylinder.
An options board accessory is available to link the internal
programmer with a Honeywell S or Y plan system.
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.
5.3 Pump
The pump should be fitted on the flow pipe from the boiler
and have isolating valves each side.
A variable duty pump should be set to give a temperature
difference of no greater than 200C between the flow and
return, with the thermostat set at “MAX”, which is about
800C, to give a flow rate as given in the table.
See chart for pressure loss of the boiler, diagram 5.1.
High resistance microbore systems may require a higher duty
pump.
5.4 Flow Rate
If it is necessary to alter the flow rate, the system can be
fitted with a lockable balancing valve in the main flow or
return pipes shown as valve “A” in diagram 5.3. The flow
rate through the boiler must not be allowed to fall below that
given in diagram 5.1.
5.5 Bypass
A system bypass will be required fitted at least 1.5 metres
away from the boiler, refer to the current issue of the central
heating system specifications (CHeSS).
5.6 Water Treatment
Existing system- It is ESSENTIAL that prior to installing the
new boiler the system is thoroughly flushed.
New system- For optimum performance after installation,
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.
IMPORTANT: Ensure all cleanser is removed from the whole
system before adding an inhibitor.
For long-term corrosion protection, after flushing, an inhibitor
suitable for stainless steel exchangers should be used, refer
to the current issue of BS 5449 and BS 7593 on the use of
inhibitors in central heating systems. Examples are Sentinel
X100 Fernox Protector or Salamander corrosion guard
inhibitor.

14
5 Water Systems - Open Vented
Diagram 5.3
12999
5.7 Open (Vented) Water System
The boiler must be supplied from an unrestricted water
supply taken from a feed and expansion cistern situated at a
maximum height of 27 metres (90ft) above the boiler.
The cold feed must be 15mm minimum size.
The vent must rise continuously and be unrestricted.
It is important that the relative positions of the pump, cold
feed and open vent are as shown in diagram 5.2.
5.8 Combined Feed and Vent
For combined feed and vent, a 22mm pipe must be fitted in
accordance with BS 5449.
5.9 Safety Valve
A safety valve need not be fitted to an open-vented system.
5.10 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.
5.11 DHW. System - unvented
General - All domestic hot water circuits, connections,
fittings must be in accordance with the relevant standards
and water supply regulations.
For GB: Guidance G17 to G24 and recommendation R17 to
R24 of the Water Regulations Guide.
For IE: The current edition of I.S.813 “Domestic Gas
Installations”.
Where a storage system will not have a vent to atmosphere
the installation must comply with the building regulations and
local Water Company bylaws, see also the current issue of
BS5546 and BS6700.
If fitting to an existing system the local authority should be
informed.
Diagram 5.2
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
13147

15
5.12 Sealed water Systems
The installation must comply with the appropriate
requirements of the current issue of BS4814, BS5449,
BS6759, BS6798 and BS7074 Part 1 and 2.
See diagram 5.3 for a suggested layout.
5.13 Safety Valve
A safety valve must be fitted to a sealed system. It shall
be preset, non-adjustable with a lift pressure of 3 bar,
incorporating seating of a resilient material, a test device and
a connection for drain.
The drain from the safety valve must be routed outside the
building, must not discharge above an entrance or window
or any type of public access area, be clear of any electrical
fittings and positioned so that any discharge can be seen.
5.14 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 5.3
unless laid down differently by the manufacturer.
The expansion vessel volume depends on the total water
system volume and the initial system design pressure. For
any system an accurate calculation of vessel size is given in
the current issue of BS5449 and BS7074 Part 1.
Example: For an initial design pressure of 0.7 bar, the
minimum total vessel volume required is 0.063 x Total System
Volume.
NOTE: A higher initial design pressure requires a larger
volume expansion vessel.
In GB, guidance on vessel sizing is also given in the current
issue of BS5449 and BS7074 Part 1.
In 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.
5.15 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.
5.16 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.
5.17 Water Makeup
Provision should be made for replacing water loss from the
system using a make up bottle mounted in a position higher
than the top point of the system, connected through a non-
return valve to the return side of either the heating circuit or
the hot water cylinder. Alternatively, provision for make up
can be made using a filling loop.
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 5.4
11680
5 Water Systems - Sealed
5.18 Filling a Sealed Water System
Provision for filling the system at low level must be made, see
diagram 5.4. There must be no permanent connection to the
mains water supply, even through a non-return valve.
We do not recommend filling using artificially softened water.

16
6.1 Appliance Pack
The top polystyrene pack contains all the items illustrated in
diagram 6.1.
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 flat.
NOTE: Due to the varied site conditions we do not supply
fixings and advise that the installer should supply those
which are suitable.
6.3 Wall Template
Take the wall template from the document pack and place in
the desired position on the wall, giving due consideration to
the required boiler clearances and the flue you are fitting.
Mark the position of the flue centre, if fitting a side flue,
extend the flue centre line into the corner then 176mm along
the adjacent wall, see diagram 6.2.
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.
6.4 Flue Hole Cutting
External access flue installation can use a 105mm diameter
core drill.
Internal access only flue installation will need a 125mm
diameter core drill.
NOTE: The flue is designed with an internal fall of 44mm/
metre (2.5°), therefore the hole can be drilled horizontally.
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.
6 Installation Preparation
13501
Documentation Pack
(not illustrated)
Electrical
Cartridge
Wall Template, User Instructions,
Installation and Servicing Instructions
and Guarantee Pack.
Hanging
Bracket
Gas Valve
Cover Plate
Diagram 6.2
Diagram 6.1
13569

17
7 Boiler Fixing
Diagram 7.1
Diagram 7.2
HANGING
BRACKET
13506
WALL
PLUG
SCREW
NO 12 x 50mm
WALL
TEMPLATE
Preferred
fixing points
HANGING
BRACKET
13503
7.1 Hanging Bracket Fixing
If previously removed, reposition the wall template over the
flue hole and mark the position of the fixing holes for the
hanging bracket, see diagram 7.1.
Mark and drill the fixing holes and secure the hanging bracket
which is supplied in the polystyrene base pack.
NOTE: Due to the varied site conditions we do not supply
fixings and advise that the installer should supply those
which are suitable.
7.2 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 17 Manual Handling.
Lifting the boiler into position, lean the top of the boiler
slightly to the wall and position just above the hanging
bracket. Lower the boiler slowly and engage onto the
hanging bracket, see diagram 7.2.
Remove the polystyrene base support.

18
8 Gas / Water & Condensate Connection
8.1 Gas Connection
Before connection check the supply of local gas.
Refer to diagram 8.1, the gas supply can be connected from
below or through the wall at the rear of the boiler.
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”.
8.2 Water Connections
Provision is made for the water connections to be made from
above the boiler, see diagram 8.2.
Flush out the heating systems before connecting to the
boiler, refer to section 5.6.
8.3 Condensate Trap and Siphonic Drain
Connection
The condensate drain, see diagram 8.1, is suitable for use
with standard “Push fit” overflow pipe and couplings. DO
NOT use adhesive when connecting to the spigot. The drain
pipe should be non corrosive plastic.
IMPORTANT: Please remove spigot bung before fitting
condensate drain connection.
The condensate drain pipe should have a fall of at least
2.5o 44mm/metre away from the boiler and 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 8.3.
It is recommended that any external condensate drain pipe
is insulated and also preferably of 32mm diameter, to prevent
freezing in adverse weather conditions.
The condensate is discharged periodically in ‘slugs’ by
siphonic action.
It is not necessary to provide air breaks or extra traps in the
discharge pipe as there is already a 75mm high trap inside
the boiler. Fitting an extra trap may cause the boiler siphon to
work incorrectly.
Refer to BS5546 or BS6798 for advice on disposal of boiler.
condensate.
13504
Diagram 8.2
13505
FLOW
RETURN
22mm compression is the
recommended fixing
for servicing.
(not supplied)
GAS SERVICE
ISOLATION VALVE
LINER
GAS SERVICE
ISOLATION VALVE
(shown open)
GAS SUPPLY
PIPE IN
COUPLING
SPIGOT
CONDENSATE
DRAIN PIPE
UNION
CONNECTOR
PRESSURE
TEST POINT
Diagram 8.1

19
8 Gas / Water & Condensate Connection
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.
Diagram 8.3
13000

20
380 min. to 590 max.
WALL THICKNESS
BOILER
MOUNTING WALL
OUTSIDE
WALL FACE
203 min. to 413 max.
87min 65
112
176
NOTE. If necessary, it is permitted to increase
this dimension to 600mm max.
FLUE LENGTH
9.1 Flue Length
The maximum permissable horizontal flue length is 10 metres
plus the flue terminal assembly, this can be achieved by use
of the accessories, see diagram 9.3.
However should an additional 90o or 2 x 45o elbows be used
then the length MUST be reduced by 1metre.
The diagram 9.1 shows the length achievable by using the kit
A2043600.
12838
9 Telescopic Flue - Length, Preparation and Installation
L
FLUE
C
Min flue length 380mm
Max flue length 590mm
134
240
5mm
min.
clearance
A
A
Max. distance from outside
wall face to min clearance.
LH - 345mm
RH - 451mm
Min. distance from outside
wall face to min clearance.
LH - 135mm
RH - 241mm
OUTSIDE
WALL FACE
87min
NOTE. If necessary, it is permitted to
increase this dimension to 600mm max.
INTERNAL
SURFACE
When extension pipes are used the flue system must be
designed to have a continuous fall to the boiler of at least
2.5o 44mm/metre to allow condensate to run back into the
boiler and out via the condensate drain.
The flue can be installed from inside the building, when
access to the outside wall face is not practicable.
Horizontal Telescopic Flue - Rear
13558
Diagram 9.1
Horizontal Telescopic Flue - Side