Baxi Duo-tec Combi 24 HE A Release note

Please leave these instructions with the user
Baxi Platinum Combi HE Range
Gas Fired Wall Mounted Condensing
Combination Boiler
Installation & Servicing Instructions

2
Natural Gas
Baxi Platinum Combi 24 HE
G.C.No47 075 20
Baxi Platinum Combi 28 HE
G.C.No47 075 21
Baxi Platinum Combi 33 HE
G.C.No47 075 22
Building Regulations and the Benchmark Commissioning
Checklist
Building Regulations (England & Wales) require notification of
the installation of a heating appliance to the relevant Local
Authority Building Control Department. From 1 April 2005 this
can be achieved via a Competent Persons Self Certification
Scheme as an option to notifying the Local Authority directly.
Similar arrangements will follow for Scotland and will apply in
Northern Ireland from 1 January 2006.
CORGI operate a Self Certification Scheme for gas heating
appliances.
These arrangements represent a change from the situation
whereby compliance with Building Regulations was accepted as
being demonstrated by completion of the Benchmark Logbook
(which was then left on site with the customer).
With the introduction of Self Certification Schemes, the
Benchmark Logbook is being withdrawn. However, a similar
document in the form of a commissioning checklist and service
interval record is incorporated at the back of these instructions.
Baxi is a member of the Benchmark initiative and fully supports
the aims of the programme. Its aim is to improve the standards
of installation and commissioning of central heating systems in
the UK and to encourage the regular servicing of all central
heating systems to ensure safety and efficiency.
Building Regulations require that installations should comply
with manufacturer's instructions. It is therefore important that
the commissioning checklist is completed by the installer. The
relevant section of Building Regulations only relates to
dwellings. Therefore the checklist only applies if the appliance is
being installed in a dwelling or some related structure.
The flowchart opposite gives guidance for installers on the
process necessary to ensure compliance with Building
Regulations.
Baxi is a BS-EN ISO 9001
Accredited Company
The boiler meets the requirements of Statutory Instrument “ The
Boiler (Efficiency) Regulations 1993 No3083” and is deemed to
meet the requirements of Directive 92/42/EEC on the energy
efficiency requirements for new hot water boilers fired with liquid
or gaseous fuels:-
Type test for purpose of Regulation 5 certified by:
Notified Body 0085.
Product/Production certified by:
Notified Body 0085.
For GB/IE only.

3
Installer Notification Guidelines
Choose Building
Regulations Notification
Route
Contact your relevant Local
Authority Building Control
(LABC) who will arrange
an inspection or contact
a government approved
inspector
LABC will record the data
and will issue a
certificate of compliance
CORGI will record the data and
will send a certificate of
compliance to the property
You must ensure that the
notification number issued by
CORGI is writen onto the
Benchmark Checklist
Scheme Members only
Call CORGI on: 0870 88 88 777
or log onto:
www.corgi-notify.com
within 10 days
If you notify via CORGI Scheme,
CORGI will then notify the
relevant Local Authority
Building Control Scheme
on member's behalf
Complete the
Benchmark Checklist
Install and Commission this
appliance to manufacturer's
instructions
Competent Person's
Self Certification Scheme Building Control

4
Legislation
Codes of Practice - refer to the most recent version
IMPORTANT - Installation, Commissioning, Service & Repair
This appliance must be installed in accordance with the manufacturer’s instructions and
the regulations in force. Read the instructions fully before installing or using the
appliance.
In GB, this must be carried out by a competent person as stated in the Gas Safety
(Installation & Use) Regulations.
Definition of competence: A person who works for a CORGI registered company and
holding current certificates in the relevant ACS modules, is deemed competent.
In IE, this must be carried out by a competent person as stated in I.S. 813 “Domestic
Gas Installations”.
Lifting - This product should be lifted and handled by two people. Stooping should be
avoided and protective equipment worn where necessary. Carrying & lifting equipment
should be used as required, e.g. when installing in a loft space.
The addition of anything that may interfere with the normal operation of the appliance
without express written permission from the manufacturer or his agent could invalidate
the appliance warranty. In GB this could also infringe the Gas Safety (Installation and
Use) Regulations.
Warning - Check the information on the data plate is compatible with local supply
conditions.
All CORGI registered installers carry a CORGI identification card and have a
registration number. You can check your installer is registered by telephoning 0870
4012300 or writing to:-
1 Elmwood,
Chineham Business Park,
Crockford Lane,
Basingstoke. RG24 8WG
or check online at www.corgi-gas-safety.com
Baxi declare that no substances harmful to health are
contained in the appliance or used during appliance
manufacture.
The appliance is suitable only for installation in GB and IE and
should be installed in accordance with the rules in force, and
only used in a suitably ventilated location.
In GB, the installation must be carried out by a CORGI
Registered Installer. It must be carried out in accordance with
the relevant requirements of the:
• Gas Safety (Installation & Use) Regulations.
• The appropriate Building Regulations either The Building
Regulations, The Building Regulations (Scotland), Building
Regulations (Northern Ireland).
• The Water Fittings Regulations or Water Byelaws in
Scotland.
• 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.
All systems must be thoroughly flushed and treated with
inhibitor (see section 6.2).
In GB the following Codes of Practice apply:
Standard Scope
BS 6891 Gas Installation.
BS 5546 Installation of hot water supplies for domestic
purposes.
BS 5449 Forced circulation hot water systems.
BS 6798 Installation of gas fired hot water boilers.
BS 5440 Part 1 Flues.
BS 5440 Part 2 Ventilation.
BS 7074 Expansion vessels and ancillary equipment for
sealed water systems.
BS 7593 Treatment of water in domestic hot water
central heating systems.
In IE the following Codes of Practice apply:
Standard Scope
I.S. 813 Domestic Gas Installations.
The following standards give valuable additional information;
BS 5546 Installation of hot water supplies for domestic
purposes.
BS 5449 Forced circulation hot water systems.
BS 7074 Expansion vessels and ancillary equipment for
sealed water systems.
BS 7593 Treatment of water in domestic hot water
central heating systems.

5
CONTENTS
1.0 Introduction 6
2.0 General Layout 7
3.0 Appliance Operation 8
4.0 Technical Data 9
5.0 Dimensions and Fixings 12
6.0 System Details 13
7.0 Site Requirements 16
8.0 Installation 22
9.0 Commissioning 28
10.0 Completion 31
11.0 Servicing 32
12.0 Changing Components 34
13.0 Combustion Check 43
14.0 Electrical 44
15.0 Short Parts List 45
16.0 Fault Finding 46
17.0 Notes 52
Benchmark Checklist 54
Section Page

6
1.0 Introduction
1.1 Description
1. The Baxi Platinum Combi HE is a fully automatic gas fired
wall mounted condensing combination boiler. It is room sealed
and fan assisted, and will serve central heating and mains fed
domestic hot water.
2. The boiler is set to give a maximum output of :-
24 models - 24 kW DHW
25.9 kW CH (Condensing)
28 models - 28 kW DHW
25.9 kW CH (Condensing)
33 models - 33 kW DHW
30.3 kW CH (Condensing)
3. It is designed for use on Natural Gas (G20).
4. The boiler is suitable for use only on fully pumped sealed
heating systems. Priority is given to domestic hot water.
5. The boiler is supplied with a filling loop and integral timer.
6. The boiler data badge gives details of the model, serial
number and Gas Council number and is situated on the inner
door panel. It is visible when the case front panel is removed
(Fig. 1).
7. The boiler model name and serial number are also shown
on the information label on the iner face of the right hand
case panel. This is for user reference.
8. The boiler is intended to be installed in residential /
commercial / light industrial E.M.C. environments on a
governed meter supply only.
9. The boiler must be installed with one of the purpose
designed flues such as the standard horizontal flue kit, part no.
5111073.
10. All systems must be thoroughly flushed and treated with
inhibitor (see section 6.2).
1.2 Optional Extras
Various flue extensions, bends, vertical flue kits, control
accessories etc. are available as optional extras. These are
detailed in a separate publication.
NOTE: All illustrations show the Platinum Combi 24 HE
unless otherwise stated.
Fig. 1
Control Box
Case Front Panel
Data Badge
Information
Label

7
2.0 General Layout
2.1 Layout
1. Expansion Vessel
2. Automatic Air Vent
3. DHW Plate Heat Exchanger
4. Circulation Pump
5. Drain Off Point
6. Pressure Relief Valve
7. Integral Timer Position
8. Central Heating System Pressure Gauge
9. PCB
10. Control Box
11. 3-Way Valve Assembly
12. Condensate Trap
13. Flame Sensing Electrode
14. Spark Electrode
15. Primary Heat Exchanger
16. Fan Assembly
17. On/Off/Reset Selector Switch
18. Central Heating Temperature Control
19. Hot Water Temperature Control
20. Venturi
21. Air/Gas Collector
22. Combustion Box Cover & Burner
23. Igniter
24. Burner On Light
25. Central Heating Mode Light
26. Domestic Hot Water Mode Light
27. Display
1
17 18 19 87
2
1
0
4
3
bar
1
2
3
4
5
PM
7
8
9
10
11
12
1
2
3
4
5
AM
7
8
9
10
11
12
GRASSLIN
0
22
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
20
21
23
24
25 26
27

8
3.0 Appliance Operation
3.1 Central Heating Mode (Fig. 2)
1. With a demand for heating, the pump circulates water
through the primary circuit.
2. Once main burner ignites the fan speed controls the gas
rate to maintain the heating temperature measured by the
temperature sensor.
3. When the flow temperature exceeds the setting
temperature, a 3 minute delay occurs before the burner
relights automatically (anti-cycling). The pump continues to
run during this period.
4. When the demand is satisfied the burner is extinguished
and the pump continues to run for a period of 3 minutes
(Pump Overrun).
3.2 Domestic Hot Water Mode (Fig. 3)
1. Priority is given to the domestic hot water supply. A
demand at a tap or shower will override any central heating
requirement.
2. The flow of water will operate the Hall Effect Sensor
which requests the 3 way valve to change position. This will
allow the pump to circulate the primary water through the
DHW plate heat exchanger.
3. The burner will light automatically and the temperature of
the domestic hot water is controlled by the temperature
sensor.
4. When the domestic hot water demand ceases the burner
will extinguish and the diverter valve will remain in the
domestic hot water mode, unless there is a demand for
central heating.
IMPORTANT: When the selector switch is in the ‘0’
(Off) position the electrical supply to the boiler is isolated.
The boiler will not operate and the integral timer will
require resetting once the selector switch is set to either
Position (i) or Position (ii).
3.3 Frost Protection Mode
1. The frost protection mode is integral to the appliance and
functions only with the selector switch (see Section 2.1) in
the domestic hot water and central heating position. If the
system temperature falls below 5° C then the boiler will fire
on its minimum setting until a flow temperature of 30° C is
reached. Further protection can be incorporated by using a
system frost thermostat.
3.4 Pump Protection
1. With the selector switch (see Section 2.1) in either the
central heating or central heating and domestic hot water
position, the pump will automatically operate for 1 minute in
every 24 hours to prevent sticking.
1
2
4
5 6
7
8
9
10
11
1213141516
17
18
19
21
22
24
25
26
3
1 Primary Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Plate Heat Exchanger
9 Flow Sensor with Filter & Regulator
10 Pressure Relief Valve
11 Boiler Drain Point
12 Heating Return
13 Cold Water Inlet On/Off Valve and Filter
14 Gas Inlet
15 Domestic Hot Water Outlet
16 Heating Flow
17 Pressure Gauge
18 Water Pressure Sensor
19 Automatic By-Pass
20 Fan
21 Diverter Valve Assembly
22 Diverter Valve Motor
23 Domestic Hot Water Flow Temperature Sensor
24 Safety Thermostat
25 Central Heating Temperature Sensor
26 Expansion Vessel
Key
Central Heating Circuit
Domestic Hot Water Circuit
Fig. 3
1
2
4
5 6
7
8
9
10
11
1213141516
17
18
19
21
22
24
25
26
3
Fig. 2
23
23
20
20

9
4.0 Technical Data
4.1 Platinum Combi 24 HE
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue
Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Weights kg
Packaged Boiler Carton 56.5
Installation Lift Weight 45
Central Heating Primary Circuit
Pressures
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommended Operating Range 1-2
DHW Circuit bar
Pressures
Max Operating 8
Min Operating 0.15
Flow Rates l/min
DHW Flow Rate
@ 30o C Rise 11.43
DHW Flow Rate
@ 35o C Rise 9.8
Min Working
DHW Flow Rate 2
Pump
Available Head See graph below
Expansion Vessel - (For Central Heating
only. Integral with appliance)
bar
Min Pre-charge Pressure 0.5
litre
Max Capacity of
CH System 125
Primary Water Content
of Boiler (unpressurised) 2.5
Connections copper tails
Gas Supply - 22mm
Central Heating Flow - 22mm
Central Heating Return - 22mm
Cold Water Mains Inlet - 15mm
DHW Flow - 15mm
Pressure Relief Discharge - 15mm
Temperatures
C.H. Flow Temp (adjustable)
25°C to 80°C max (± 5°C)
D.H.W. Flow Temp (adjustable)
35°C to 60°C max (± 5°C)
dependent upon flow rate
NOxClass 5
0
200 400 600 800 1000 1200
0.5
1
1.5
2
2.5
3
3.5
4
Metre (wg)
Flow Rate (l/h)
Pump - Available Head
0
5
5.5
4.5
Clearances
Above Casing 200 mm Min
Below Casing 200 mm Min
Front 450 mm Min (For Servicing)
Front 5 mm Min (In Operation)
L.H. Side 5 mm Min
R.H. Side 5 mm Min (In Operation)
Heat Input CH (Net)
Max Min
kW 24.7 7
Heat Output CH (Non-Condensing)
Max Min
kW 24 6.8
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 155W
Electrical Protection IPX0D
Internal Fuse Rating
F2L
Appliance Category CAT I 2H
Inlet Pressure (Natural Gas - G20)
mbar 20
Injector (Natural Gas - G20)
7.5mm
Appliance Type C13 C33
Heat Output CH (Condensing)
Max Min
kW 25.9 7.4
Heat Input DHW (Net)
Max
kW 24.7
Heat Output DHW
Max
kW 24
Max Gas Rate (Natural Gas - G20)
(After 10 mins)
m3/h 2.61
This value is used in the UK Government’s Standard Assessment Procedure
(SAP) for energy rating of dwellings. The test data from which it has been
calculated have been certified by 0085.
SEDBUK Declaration For Platinum 24 HE
The seasonal efficiency (SEDBUK) is 90.1%
Band A
Condensate Drain
To accept 21.5mm (3/4in) plastic waste pipe
Heat Input CH (Gross)
Max Min
kW 27.4 7.8
Heat Input DHW (Gross)
Max
kW 27.4
External Fuse Rating 3A

10
4.0 Technical Data
4.2 Platinum Combi 28 HE
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue
Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Weights kg
Packaged Boiler Carton 56.5
Installation Lift Weight 45
Central Heating Primary Circuit
Pressures
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommended Operating Range 1-2
DHW Circuit bar
Pressures
Max Operating 8
Min Operating 0.15
Flow Rates l/min
DHW Flow Rate
@ 30o C Rise 13.3
DHW Flow Rate
@ 35o C Rise 11.5
Min Working
DHW Flow Rate 2
Pump
Available Head See graph below
Expansion Vessel - (For Central Heating
only. Integral with appliance)
bar
Min Pre-charge Pressure 0.5
litre
Max Capacity of
CH System 125
Primary Water Content
of Boiler (unpressurised) 2.5
Connections copper tails
Gas Supply - 22mm
Central Heating Flow - 22mm
Central Heating Return - 22mm
Cold Water Mains Inlet - 15mm
DHW Flow - 15mm
Pressure Relief Discharge - 15mm
Temperatures
C.H. Flow Temp (adjustable)
25°C to 80°C max (± 5°C)
D.H.W. Flow Temp (adjustable)
35°C to 60°C max (± 5°C)
dependent upon flow rate
NOxClass 5
0
200 400 600 800 1000 1200
0.5
1
1.5
2
2.5
3
3.5
4
Metre (wg)
Flow Rate (l/h)
Pump - Available Head
0
5
5.5
4.5
Clearances
Above Casing 200 mm Min
Below Casing 200 mm Min
Front 450 mm Min (For Servicing)
Front 5 mm Min (In Operation)
L.H. Side 5 mm Min
R.H. Side 5 mm Min (In Operation)
Heat Input CH (Net)
Max Min
kW 24.7 9
Heat Output CH (Non-Condensing)
Max Min
kW 24 8.7
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 155W
Electrical Protection IPX0D
Internal Fuse Rating
F2L
Appliance Category CAT I 2H
Inlet Pressure (Natural Gas - G20)
mbar 20
Injector (Natural Gas - G20)
7.5mm
Appliance Type C13 C33
Heat Output CH (Condensing)
Max Min
kW 25.9 9.5
Heat Input DHW (Net)
Max
kW 28.9
Heat Output DHW
Max
kW 28
Max Gas Rate (Natural Gas - G20)
(After 10 mins)
m3/h 3.1
This value is used in the UK Government’s Standard Assessment Procedure
(SAP) for energy rating of dwellings. The test data from which it has been
calculated have been certified by 0085.
SEDBUK Declaration For Platinum 24 HE
The seasonal efficiency (SEDBUK) is 90.1%
Band A
Condensate Drain
To accept 21.5mm (3/4in) plastic waste pipe
Heat Input CH (Gross)
Max Min
kW 27.4 10
Heat Input DHW (Gross)
Max
kW 32.1
External Fuse Rating 3A

11
4.0 Technical Data
4.3 Platinum Combi 33 HE
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue
Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Weights kg
Packaged Boiler Carton 57.5
Installation Lift Weight 46
Central Heating Primary Circuit
Pressures
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommended Operating Range 1-2
DHW Circuit bar
Pressures
Max Operating 8
Min Operating 0.15
Flow Rates l/min
DHW Flow Rate
@ 30o C Rise 15.7
DHW Flow Rate
@ 35o C Rise 13.5
Min Working
DHW Flow Rate 2
Pump
Available Head See graph below
Expansion Vessel - (For Central Heating
only. Integral with appliance)
bar
Min Pre-charge Pressure 0.5
litre
Max Capacity of
CH System 155
Primary Water Content
of Boiler (unpressurised) 2.8
Connections copper tails
Gas Supply - 22mm
Central Heating Flow - 22mm
Central Heating Return - 22mm
Cold Water Mains Inlet - 15mm
DHW Flow - 15mm
Pressure Relief Discharge - 15mm
Temperatures
C.H. Flow Temp (adjustable)
25°C to 80°C max (± 5°C)
D.H.W. Flow Temp (adjustable)
35°C to 60°C max (± 5°C)
dependent upon flow rate
NOxClass 5
0
200 400 600 800 1000 1200
0.5
1
1.5
2
2.5
3
3.5
4
Metre (wg)
Flow Rate (l/h)
Pump - Available Head
0
5
5.5
4.5
Clearances
Above Casing 200 mm Min
Below Casing 200 mm Min
Front 450 mm Min (For Servicing)
Front 5 mm Min (In Operation)
L.H. Side 5 mm Min
R.H. Side 5 mm Min (In Operation)
Heat Input CH (Net)
Max Min
kW 28.9 9.7
Heat Output CH (Non-Condensing)
Max Min
kW 28 9.4
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 160W
Electrical Protection IPX0D
Internal Fuse Rating
F2L
Appliance Category CAT I 2H
Inlet Pressure (Natural Gas - G20)
mbar 20
Injector (Natural Gas - G20)
12mm
Appliance Type C13 C33
Heat Output CH (Condensing)
Max Min
kW 30.3 10.2
Heat Input DHW (Net)
Max
kW 34
Heat Output DHW
Max
kW 33
Max Gas Rate (Natural Gas - G20)
(After 10 mins)
m3/h 3.6
This value is used in the UK Government’s Standard Assessment Procedure
(SAP) for energy rating of dwellings. The test data from which it has been
calculated have been certified by 0085.
SEDBUK Declaration For Platinum 24 HE
The seasonal efficiency (SEDBUK) is 90.1%
Band A
Condensate Drain
To accept 21.5mm (3/4in) plastic waste pipe
Heat Input CH (Gross)
Max Min
kW 32.1 10.8
Heat Input DHW (Gross)
Max
kW 37.7
External Fuse Rating 3A

12
5.0 Dimensions and Fixings
Dimensions
A780mm
B345mm
C450mm
D116mm Ø Min.
E185mm
F145mm
G131mm
H 180mm
Domestic Hot
Water Outlet
(15mm)
Cold Water
Inlet
(15mm)
Heating
Return
(22mm)
Heating
Flow
(22mm)
Pressure Relief
Valve
(15mm)
Gas
Inlet
(22mm)
65 mm 65 mm 65 mm 65 mm 65 mm
32.5 mm
Condensate
Drain
Tap Rail
360° Orientation
Tube Ø 100mm
DC
B
A
E
G
F
3o
H

13
6.0 System Details
6.1 Information
1. The Baxi Platinum Combi HE Condensing Combination Boiler
is a ‘Water Byelaws Scheme - Approved Product’.
To comply with the Water Byelaws your attention is drawn to
the following installation requirements and notes (IRN).
a) IRN 001 - See text of entry for installation
requirements and notes.
b) IRN 302 - Byelaw 14.
2. Reference to the WRc publications, ‘Water fittings and
materials directory’ and ‘Water supply byelaws guide’ give full
details of byelaws and the IRNs.
6.2 Central Heating Circuit
1. The appliance is suitable for fully pumped SEALED SYSTEMS
ONLY.
Treatment of Water Circulating Systems
• All recirculatory water systems will be subject to
corrosion unless an appropriate water treatment is
applied. This means that the efficiency of the system will
deteriorate as corrosion sludge accumulates within the system,
risking damage to pump and valves, boiler noise and circulation
problems.
• When upgrading existing systems that exhibit evidence of
sludging, it is advisable to clean the system prior to treatment in
order to remove any sludge and reduce the likelihood of these
deposits damaging new components.
• When fitting new systems flux will be evident within the system,
which can lead to damage of system components.
• All systems must be thoroughly drained and flushed out. The
recommended flushing and cleansing agents are Betz-Dearborn
Sentinel X300 or X400 and Fernox Superfloc Universal Cleanser
which should be used following the flushing agent manufacturer’s
instructions.
• System additives - corrosion inhibitors and flushing
agents/descalers should comply to BS7593 requirements. The
only system additives recommended are Betz-Dearborn Sentinel
X100 and Fernox-Copal which should be used following the
inhibitor manufacturer’s instructions.
Failure to flush and add inhibitor to the system will
invalidate the appliance warranty.
• It is important to check the inhibitor concentration after
installation, system modification and at every service in
accordance with the manufacturer’s instructions. (Test kits are
available from inhibitor stockists.)
• For information or advice regarding any of the above contact
Technical Enquiries.
6.3 Bypass
1. The boiler is fitted with an automatic integral bypass.
6.4 System Control
1. A 24 hour electro - mechanical timer is supplied fitted to
the boiler.
2. Further external controls (e.g. room thermostat) should be
fitted to optimise the economical operation of the boiler.

14
6.0 System Details
6.5 System Filling and Pressurising
1. A filling point connection on the central heating return
pipework must be provided to facilitate initial filling and
pressurising and also any subsequent water loss
replacement/refilling.
2. There are connection points on the mains cold water inlet
and central heating return isolating taps (Fig. 5) to which the
filling loop kit supplied can be assembled. If the boiler is to be
installed in a location (e.g. loft space) the filling point must be
accessible. The kit supplied can still be used for this, or if
necessary a more suitable propriety kit.
3. The filling method adopted must be in accordance with all
relevant water supply regulations and use approved
equipment.
4. Your attention is drawn to:
for GB: Guidance G24.2 and recommendation R24.2 of the
Water Regulations Guide.
for IE: the current edition of I.S. 813 “Domestic Gas
Installations”.
5. The sealed primary circuits may be filled or replenished by
means of a temporary connection between the circuit and a
supply pipe, provided a ‘Listed’ double check valve or some
other no less effective backflow prevention device is
permanently connected at the inlet to the circuit and the
temporary connection is removed after use.
6.6 Expansion Vessel (Central Heating only)
1. The appliance expansion vessel is pre-charged to 0.5 bar.
Therefore, the minimum cold fill pressure is 0.5 bar. The
vessel is suitable for correct operation for system capacities up
to 125 litres. For greater system capacities an additional
expansion vessel must be fitted. For GB refer to BS 7074 Pt 1.
For IE, the current edition of I.S. 813 “Domestic Gas
Installations”.
6.7 Pressure Relief Valve (Fig. 6)
1. The pressure relief valve is set at 3 bar, therefore all
pipework, fittings, etc. should be suitable for pressures in
excess of 3 bar and temperature in excess of 100°C.
2. The pressure relief discharge pipe should be not less than
15mm dia, run continuously downward, and discharge outside
the building, preferably over a drain. It should be routed in
such a manner that no hazard occurs to occupants or causes
damage to wiring or electrical components. The end of the
pipe should terminate facing down and towards the wall.
3. The discharge must not be above a window, entrance or
other public access. Consideration must be given to the
possibility that boiling water/steam could discharge from the
pipe.
Fig. 4
Fig. 6
Fig. 5
Stop
Valve
Double
Check
Valve
DHW
Mains
Inlet
CH
Return
Temporary
Hose
Pressure Relief Valve
Discharge Pipe
Filling Loop
Stop
Valve

15
6.0 System Details
6.8 Domestic Hot Water Circuit (Fig. 7)
1. All DHW circuits, connections, fittings, etc. should be fully
in accordance with relevant standards and water supply
regulations.
2. Your attention is drawn to:
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”.
3. A single check valve must be fitted as shown in Fig. 7 to
prevent backflow to the supply pipe and to ensure the
efficient operation of the expansion vessel which is required
to accommodate the thermal expansion of the water.
4. When the domestic water system includes any device
which prevents water expanding back towards the supply
(check valve, loose jumpered stopcock, water meter, water
treatment device) then an expansion vessel must be fitted
(eg. Zilmet 160ml, R1/215bar).
5. If the hot water expansion is not provided for, then high
pressures can develop which may result in damage to fittings
and devices on the system.
6. The boiler’s maximum working mains pressure is 8 bar,
therefore all pipework, connections, fittings, etc. should be
suitable for pressures in excess of 8 bar. A pressure reducing
valve must be fitted for pressures in excess of 8 bar. The
manufacturer of any outlet fittings, such as a shower valve,
may require a lower maximum pressure. The pressure
reduction must take account of all fittings connected to the
DHW system.
6.9 Showers
1. If a shower control is supplied from the appliance it
should be of the thermostatic or pressure balanced type.
Thermostatic type shower valves provide the best comfort
and guard against water at too high a temperature. Existing
controls may not be suitable - refer to the shower valve
manufacturer.
6.10 Hard Water Areas
1. If the area of the installation is recognised as a HARD
WATER AREA then a suitable device should be fitted to
treat the mains water supply to the boiler. Contact your
Water Distribution Company for advice on suitable devices.
Boiler
Other Tap
Outlets
Expansion
Vessel
To Hot
Taps
Check
Valve
Pressure Reducer
Valve
Stop Tap
Fig. 7

16
7.0 Site Requirements
7.1 Location
1. The boiler may be fitted to any suitable wall with the flue
passing through an outside wall or roof and discharging to
atmosphere in a position permitting satisfactory removal of
combustion products and providing an adequate air supply.
The boiler should be fitted within the building unless
otherwise protected by a suitable enclosure i.e. garage or
outhouse. (The boiler may be fitted inside a cupboard-see
Section 7.3).
2. If the boiler is sited in an unheated enclosure then it is
recommended to leave the ON/OFF Selector Switch in the
domestic hot water and central heating position to give frost
protection.
3. If the boiler is fitted in a room containing a bath or shower
reference must be made to the relevant requirements.
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.
4. If the boiler is to be fitted into a building of timber frame
construction then reference must be made to the current
edition of Institute of Gas Engineers Publication IGE/UP/7
(Gas Installations in Timber Framed Housing).
7.2 Clearances (Figs. 8 & 9)
1. A flat vertical area is required for the installation of the
boiler.
2. These dimensions include the necessary clearances around
the boiler for case removal, spanner access and air
movement. Additional clearances may be required for the
passage of pipes around local obstructions such as joists
running parallel to the front face of the boiler.
2
1
0
4
3
bar
1
2
3
4
5
PM
7
8
9
10
11
12
1
2
3
4
5
AM
7
8
9
10
11
12
GRASSLIN
0
200mm Min
780mm
450mm
200mm Min
5mm Min
5mm Min
450mm Min
For Servicing
Purposes
Fig. 8
Fig. 9
In Operation
5mm Min
3°

17
7.0 Site Requirement
7.3 Ventilation of Compartments
1. Where the appliance is installed in a cupboard or
compartment, no air vents are required.
2. BS 5440: Part 2 refers to room sealed appliances
installed in compartments. The appliance will run sufficiently
cool without ventilation.
7.4 Gas Supply
1. The gas installation should be in accordance with the
relevant standards. In GB this is BS 6891. In IE this is the
current edition of I.S. 813 “Domestic Gas Installations”.
2. The connection to the appliance is a 22mm copper tail
located at the rear of the gas service cock (Fig. 10).
3. Ensure that the pipework from the meter to the
appliance is of adequate size. Do not use pipes of a smaller
diameter than the boiler gas connection (22mm).
7.5 Electrical Supply
1. External wiring must be correctly earthed, polarised and
in accordance with relevant regulations/rules. In GB this is
the current I.E.E. Wiring Regulations. In IE reference should
be made to the current edition of ETCI rules.
2. The mains supply is 230V ~ 50Hzfused at 3A.
NOTE: The method of connection to the electricity
supply must facilitate complete electrical isolation of the
appliance.
Connection may be via a fused double-pole isolator
with a contact separation of at least 3mm in all poles
and servicing the boiler and system controls only.
Fig. 10
Gas Service Cock

18
7.0 Site Requirements
7.6 Condensate Drain
FAILURE TO INSTALL THE CONDENSATE DISCHARGE
PIPEWORK CORRECTLY WILL AFFECT THE RELIABLE
OPERATION OF THE BOILER
The condensate discharge pipe MUST NOT RISE at any point
along its length. There MUST be a fall of AT LEAST 2.5°
(50mm per metre) along the entire run.
1. The condensate outlet will accept 21.5mm (3/4in) plastic
overflow pipe which should generally discharge internally into
the household drainage system. If this is not possible, discharge
into an outside drain is acceptable.
2. Ensure the discharge of condensate complies with any
national or local regulations in force.
BS 6798:2000 & Part H1 of the Building Regulations give
further guidance.
3. The discharge pipe should be run in a proprietary drain pipe
material e.g. PVC, PVC-U, ABS, PVC-C or PP.
4. Metal pipework is NOT suitable for use in condensate
discharge systems.
5. The pipe should be a minimum of 21.5mm diameter and
must be supported using suitably spaced clips to prevent
sagging.
6. Any pipe fitted externally must not exceed 3 metres.
7. Any condensate discharge pipework external to the
building (or in an unheated part of it e.g. garage) must be
insulated to protect against frost. It is also recommended
that the pipe diameter is increased to 32mm.
8. If the boiler is fitted in an unheated location the entire
condensate discharge pipe should be treated as an external
run.
9. In all cases discharge pipe must be installed to aid disposal
of the condensate. To reduce the risk of condensate being
trapped, as few bends and fittings as possible should be used.
10. When discharging condensate into a soil stack or waste
pipe the effects of existing plumbing must be considered. If soil
pipes or waste pipes are subjected to internal pressure
fluctuations when WC's are flushed or sinks emptied then
back-pressure may force water out of the boiler trap and
cause appliance lockout.
Examples are shown of the following methods of termination:-
i) to an internal soil & vent pipe
ii) via an internal discharge branch (e.g. sink waste)
iii) to a drain or gully
iv) to a purpose made soakaway
Boiler
2.5° Minimum fall
Termination to an internal soil and
vent pipe
450mm min
Boiler
2.5° Minimum fall
External termination via internal discharge
branch
e.g sink waste - downstream
Sink
Pipe must terminate
above water level but
below surrounding
surface
Boiler Pipe must terminate above
water level but below
surrounding surface
2.5° Minimum fall
Termination to a drain or gully
Boiler
500mm min
2.5° Minimum fall
Termination to a purpose made soak-
away
Holes in the soak-away must
face away from the building
50mm per metre of pipe run
50mm per metre of pipe run
50mm per metre of pipe run
50mm per metre of pipe run

19
7.0 Site Requirements
7.7 Flue
NOTE: Due to the nature of the boiler a plume of water
vapour will be discharged from the flue. This should be
taken into account when siting the flue terminal.
1. The following guidelines indicate the general requirements
for siting balanced flue terminals. For GB recommendations
are given in BS 5440 Pt 1. For IE recommendations are given
in the current edition of I.S. 813 “Domestic Gas
Installations”.
2. If the terminal discharges onto a pathway or passageway,
check that combustion products will not cause a nuisance
and that the terminal will not obstruct the passageway.
3. If a terminal is less than 2 metres above a balcony, above
ground or above a flat roof to which people have access,
then a suitable terminal guard must be provided.
Terminal Position with Minimum Distance (Fig. 11) (mm)
A* Directly below an openable window, air vent or any other
ventilation opening. 300
B Below gutter, drain/soil pipe. 25
C Below eaves. 25
D Below a balcony/car port roof. 25
E From vertical drain pipes and soil pipes. 25
F From internal or external corners. 25
G Above adjacent ground or balcony level. 300
H From a surface facing a terminal. 600
I Facing a terminals. 1200
J From opening (door/window) in carport into dwelling. 1200
K Vertically from a terminal on the same wall. 1500
L Horizontally from a terminal on the same wall. 300
M* Above an opening, air brick, opening window etc. 300
N* Horizontally to an opening, air brick, opening window etc. 300
L
G
G
E
J
D
K
G
AAD
F
H,I
B,C
F
Likely flue positions requiring 
a flue terminal guard
M
N
Fig. 11
300 min
Terminal
Assembly
Top View Rear Flue
Property Boundary Line
* In addition, the terminal should be no nearer than 150mm to an opening
in the building fabric formed for the purpose of accommodating a built-in
element such as a window frame. See BS 5440 Pt. 1.
Fig. 12

20
7.0 Site Requirements
7.8 Flue Dimensions
The standard horizontal flue kit allows for flue lengths between
100mm and 685mm from elbow to terminal (Fig. 13).
The maximum permissible equivalent flue length is:
10 metres
7.9 Flue Trim
1. The rubber flue trim supplied may be fitted to either the
outside wall or on the inner wall of installation.
7.10 Terminal Guard (Fig. 14)
1. When codes of practice dictate the use of terminal guards,
they can be obtained from most Plumbers’ and Builders’
Merchants.
2. There must be a clearance of at least 50mm between any
part of the terminal and the guard.
3. When ordering a terminal guard, quote the appliance name
and model number.
4. The flue terminal guard should be positioned centrally over
the terminal and fixed as illustrated.
Fig. 13
Fig. 14
100mm 685mm