Potterton Promax FSB 30 HE User guide

© Baxi Heating UK Limited 2005
Installation & Service Instructions
Benchmark Commissioning Checklist
Promax FSB 30 HE
Floor Standing Fanned Flue
Condensing Boiler
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 0087.
Product/Production certified by:
Notified Body 0086.
For GB/IE only.
Only a flue approved for the Promax FSB 30 HE can be used.
These instructions include the Benchmark Commissioning Checklist and should be left with the User for safe keeping.

2© Baxi Heating UK Limited 2005
Natural Gas
Potterton Promax FSB 30 HE
G.C. No 41 595 39
© Baxi Heating UK Limited 2005 All rights reserved. No part of this publication
may be reproduced or transmitted in any form or by any means, or stored in any
retrieval system of any nature (including in any database), in each case whether
electronic, mechanical, recording or otherwise, without the prior written
permission of the copyright owner, except for permitted fair dealing under
Copyrights, Designs and Patents Act 1988.
Applications for the copyright owner’s permission to reproduce or make other
use of any part of this publication should be made, giving details of the proposed
use, to the following address:
The Company Secretary, Baxi Heating UK Limited, Pentagon House,
Sir Frank Whittle Road, Derby, DE21 4XA.
Full acknowledgement of author and source must be given.
WARNING: Any person who does any unauthorised act in relation to a
copyright work may be liable to criminal prosecution and civil claims for damages.
Baxi Heating UK Limited is a
BS-EN ISO 9001 Accredited Company
This product has an energy rating (A) on a scale of A to G.
For more information see www.boilers.org.uk. This is a certification mark.
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.
This company 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.
The code of practice for the installation,
commissioning & servicing of central
heating systems.
“Potterton” supports

Installer Notification Guidelines
3
© Baxi Heating UK Limited 2005
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 written 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
Complete the
Benchmark Checklist
Install and Commission this
appliance to manufacturer's
instructions

Legislation
4© Baxi Heating UK Limited 2005
Potterton declare that no substances harmful to
health are contained in the boiler or used during
boiler manufacture.
The boiler is suitable only for installation in GB and IE, and
must only be used in a suitably ventilated location.
The installation 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.
Codes of Practice
Most recent version should be used
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 BS 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.
In IE, the installation must be carried out 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).
Failure to flush and add inhibitor to the system will
invalidate the boiler warranty.
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.
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
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. For recommended
hand holds see section 8.3. 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.

5
© Baxi Heating UK Limited 2005
1.0 Introduction 6
2.0 General Layout 7
3.0 Boiler Operation 8
4.0 Technical Data 9
5.0 Dimensions and Fixings 10
6.0 System Details 11
7.0 Site Requirements 15
8.0 Installation 22
9.0 Electrical 27
10.0 Commissioning the Boiler 29
11.0 Completion 30
12.0 Servicing the Boiler 31
13.0 Changing Components 33
14.0 Short Parts List 40
15.0 Fault Finding 41
Benchmark Checklist 50
Section Page
Contents

1.1 Description
1. The Potterton Promax FSB 30 HE is a gas fired room
sealed fan assisted condensing central heating boiler.
2. The maximum output of the boiler is 30.18 kW. The
boiler automatically adjusts the output down to 9.2 kW
according to system load.
3. The boiler is designed for use on Natural Gas (G20)
only.
4. The boiler is suitable for fully pumped open vented and
sealed systems, providing heating and hot water.
5. A label giving details of the model, serial number and
Gas Council number is situated on the rear of the drop
down facia panel (Fig. 1).
6. The boiler data badge is positioned on the air box door
(Fig. 2).
7. The boiler is intended to be installed in residential /
commercial / light industrial E.M.C. environments on a
governed meter supply only.
8. The boiler must be installed with one of the purpose
designed flues such as the standard horizontal flue kit, part
no 236921.
1.2 Important Information
Man-made mineral fibre
• Some component parts of this boiler (insulation pads,
gaskets and rope seals) are manufactured from man-made
mineral fibre.
• Prolonged or excessive exposure to this material may
result in some irritation to the eyes, skin or respiratory
tract.
• It is advisable to wear gloves when handling these items.
• Irritant dust will only be released from the items if they
are broken up or subjected to severe abrasion. In these
instances a suitable dust mask and goggles should be
worn.
• Always thoroughly wash hands after installation,
servicing or changing components.
• When disposing of any items manufactured from man-
made mineral fibre care must be exercised.
• If any irritation of the eyes or severe irritation of the skin
is experienced seek medical attention.
1.0 Introduction
6© Baxi Heating UK Limited 2005
Fig. 1
Data Badge
Air Box Door
Position of Label
Fig. 2
Optional Integral Timer
Facia Securing Screws
Case Securing Screws

2.0 General Layout
7
© Baxi Heating UK Limited 2005
2.1 Layout (Figs. 3, 4, 5 & 6)
1. Condensate Pump
2. Flue Elbow (supplied in std. flue kit)
3. Heat Exchanger
4. Burner
5. Air Box
6. Fan Protection Thermostat - Black
7. Fan Assembly
8. Condensate Trap
9. PCB Housing Assembly
10. Gas Tap
11. Gas / Air Ratio Valve
12. Flow Pipe Connection
13. Return Pipe Connection
14. Flow Temperature Safety Thermostat - Black
15. Flow Temperature Thermistor - Red
16. Flow Switch (dry fire protection)
17. Position of Optional Integral Timer Wiring
18. Pipe Access Panel
19. Manual Air Vent
2
3
4
5
6
7
9
8
10
11
15 14
12
13
16
Fig. 4
Fig. 3
Fig. 5
2.2 110Ø Concentric Flues & Optional Extras
KIT PART No
Standard Flue Kit 850mm (inc. elbow) 236921
Extended Flue Kit - 1.75M ( inc. elbow) 5111457
Flue Plume Deflector Kit 248167
Terminal Guard (suitable for use with above) 248484
FLUE EXTENSION KITS (110/70)
Flue Extension 250mm 241692
Flue Extension 500mm 241694
Flue Extension 1000mm (Use two kits for 2M etc.) 241695
Flue Bend x 2 - 45° (Reduce overall length of flue
by 0.5m when fitting this bend) 241689
Flue Bend - 93° (Reduce overall length of flue
by 1m when fitting each bend) 241687
VERTICAL FLUE
Vertical Flue Terminal 242802
Vertical Flue Adaptor 5106888
See Section 7.12 for more flue option details
Integral Twin Channel Timer 5117455
Fig. 6
1
17
18
19

3.1 Boiler Operation
1. Switched Live On: When switched live is supplied to
the boiler and the flow temperature is less than the set
point the sequence below commences.
2. Flow Switch: After 10 seconds if the flow switch has
made then fan pre-purge occurs. After 10 seconds if
the flow switch has not made then anti-cycle occurs.
3. Fan Pre-Purge: The flow switch is made and the fan
is on while the spark generator and gas valve are off.
After 5 seconds ignition occurs.
4. Ignition: The flow switch is made, fan, spark
generator and gas valve are on. If a flame is detected
then burner on occurs. If a flame is not detected within
5 seconds and less than 5 ignition attempts have been
made then fan purge occurs. If a flame is not detected
within 5 seconds and 5 ignition attempts have been
made then ignition lockout occurs.
5. Burner On: The flow switch is made, fan and gas
valve are on while the spark generator is off. Flow
temperature is controlled by varying the fan speed (and
thereby the gas rate) to achieve optimum operation. If
the flow temperature is greater than the set point or
the TRVs all shut down then fan post purge occurs.
6. Fan Post Purge: The fan is on while the spark
generator and gas valve are off. After 5 seconds if the
TRVs are shut down then anti-cycle occurs.
7. Anti-cycle: The fan, spark generator and gas valve
are off.
8. Ignition Lockout: The fan, spark generator and gas
valve are off. The boiler can only be reset by manually
using the reset button.
9. Condensate Pump: Condensate accumulates in a
reservoir within the pump assembly. The pump may
run at any time, independent of boiler operation, to
discharge the condensate to drain.
3.0 Boiler Operation
8© Baxi Heating UK Limited 2005
Mains On.
Flow
temperature less
than set point ?
YES
5 second
Fan Pre-Purge.
Flame Detected ?
Burner On.
Ignition
Lockout.
5 second
Ignition Period.
All TRVs
shut down ?
Ignition done and
5 attempts made ?
Ignition done
and less than 5
attempts made ?
System Pump
Running and Flow
switch made ?
NO
YES
YES
YES
All TRVs
shut or Flow temperature
greater than set point ?
5 second
Fan Post Purge.
3 minute
Anti-cycle.
YES
YES
YES
Condensate Pump will
operate as necessary (3.1.9)

Appliance Category CAT I 2H
4.0 Technical Data
9
© Baxi Heating UK Limited 2005
Horizontal
Flue Terminal Diameter - 110mm
Dimensions Projection - 150mm
Outercase Dimensions
Casing Height - 850mm
Casing Width - 390mm
Casing Depth - 520mm
Weights kg
Packaged Boiler Carton - 49.5
Packaged Flue Kit - 3.6
Installation Lift Weight - 37.5
Installed Weight (dry) - 44.5
Connections
Gas Supply - 15mm
Central Heating Flow - 28mm
Central Heating Return - 28mm
Condensate Drain (Pump) - 10mm o.d.
Recommended System
Temperature Drop
Condensing 20°C
Heat Input (Q)(Gross) Max Min
kW 33.76 10.3
Heat Output (P)
(Non Condensing 70° C Mean Water Temp)
Max Min
kW 30.18 9.2
Electrical Supply 230V~ 50Hz
The boiler must be connected to an earthed
supply. A permanent and switched live are
required. The boiler has a 4 wire connection.
Power Consumption 80W
External Fuse Rating 3A
Internal Fuse Rating (BS 4265)
Fuse 3.15 AT (PCB)
Max Gas Rate (2H - G20 - 20mbar)
(After 10 Mins)
kW Input 33.76
m3/hr 3.4
Inlet Pressure at Gas Valve (Natural Gas)
Min 18.1 mbar
Max 22.5 mbar
(see Section 10.1)
Injector (Natural Gas)
Diameter 6.5mm
Minimum Clearances
(For unventilated compartments see Section 7.2)
Both Sides - 5mm
Above Casing - 15mm
Above Casing
Under fixed worktop -
(It is recommended that any
worktop is removable) - 25mm
Front (For Servicing) - 500mm
Front (In Operation) - 5mm
010203040
20
40
60
80
100
120
140
160
180
200
220
Water Flow Rate (litres/min)
Pressure Drop (mbar)
8
17
25
33
42
50
58
66
75
83
91
Pressure Drop (in wg)
Boiler Hydraulic Resistance Chart
Appliance Type C13 C33
NOxClass 5
Heat Output (P)
(Condensing 40° C Mean Water Temp)
Max Min
kW 32.61 10.0
Water Content
litres 2.6
Static Head
max 30 metres
min 1 metre
Low Head 0.2m min
System Detail
Fully pumped open vented & sealed systems.
No bypass required.
Controls
boiler thermostat, safety thermostat,
flow switch, electronic flame sensing,
temperature protection thermostat &
condensate blockage and level sensors
The efficiency is 90.9%
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 has been certified by 0087.
SEDBUK Declaration
Electrical Protection IPXX
CO/CO2 Ratio 0.001
Boiler Flow Temperature (adjustable)
55° C to 78° C (± 5° C)
Condensate Pump
Head 3 metres
Flow Rate 1.8 l/min
Connection 10mm o.d. (pipe supplied)

5.0 Dimensions and Fixings
10 © Baxi Heating UK Limited 2005
DIMENSIONS
A850mm
B520mm
C390mm
D125mm Ø Min.
E175mm
F150mm
SIDE FLUE (left and right)
For every 1m of horizontal flue
length, the clearance above the top
of the flue elbow should be 55mm
to incorporate the 3° (1 in 20) fall in
the flue from the terminal to the
elbow. It is especially important to
consider this when fitting the boiler
under a work top !
The 3° (1 in 20) fall provided by the
elbow is to allow condensate to run
back to the boiler, for discharge
through the condensate disposal
system.
Flue length (Y)
up to 1m
1m - 2m
2m - 3m
3m - 4m
Clearance (X)
55mm
110mm
165mm
220mm
Tube Ø 110mm
DC
B
A
E
Y
3°
(1 in 20)
X
3°
(1 in 20)
Fig. 7
Fig. 8
F

6.0 System Details
11
© Baxi Heating UK Limited 2005
6.1 Water Circulating Systems
1. The boiler is suitable for use with open vent fully
pumped systems and sealed systems .
The following conditions should be observed on all
systems:
• The static head must not exceed 30m of water.
• The boiler must not be used with a direct cylinder.
• Drain cocks should be fitted to all system low points.
• All gas and water pipes and electrical wiring must be
installed in a way which would not restrict the servicing
of the boiler.
• Position isolating valves as close to circulating pump as
possible.
6.2 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. Using, for example Betz-Dearborn Sentinel X300
or X400 or Fernox Superfloc Universal Cleanser. They
should be used following the flushing agent
manufacturer’s instructions.
• System additives - corrosion inhibitors and flushing
agents/descalers should be suitable for aluminium and
comply to BS7593 requirements, e.g. 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 boiler 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 Tel. [phone]

6.0 System Details
12 © Baxi Heating UK Limited 2005
6.3 Pipework
1. The sizes of flow and return pipes from the boiler
should be determined by normal methods, according to
the requirements of the system.
2. The connection tails for the boiler are 28mm diameter.
The 28mm section of the tails can be cut back to 22mm if
required.
3. The flow & return tails are push - fit ‘O’ ring
and clip connections within the boiler case.
4. A 20 °C drop in temperature across the system is
recommended for condensing boilers. Existing radiators
may be oversized and so allow this, but where radiator
sizing is marginal it may be advisable to retain a system
temperature drop of 11°C.
5. In systems using non-metallic pipework it is necessary
to use copper pipe for the boiler Flow and Return. The
copper must extend at least 1 metre from the boiler and
include any branches (Fig. 9).
6. This boiler does not require a bypass.
6.4 Low Head Installation
1. Using a close couple arrangement the minimum head is
as shown in the diagrams (Figs. 10 & 11) subject to the
following conditions:
a) The pump being adjusted to give a 20°C drop across
the boiler.
b) The pump must be fitted on the flow.
c) The pump must be fitted in accordance with the
pump manufacturer's instructions.
d) The open vent pipe must be taken up from a tee in a
horizontal section of the flow pipe.
2. For heads below 400mm then an alternative utilising a
combined vent and feed pipe may be connected (Fig. 12).
This must be a minimum of 22mm diameter. It is
recommended that an air separator is fitted when using a
combined feed and vent pipe.
6.5 Air Vents
For correct operation of the flow switch the boiler
and system MUST be completely vented.
1. A manual air vent is fitted on the flow pipe, to enable
complete venting of the boiler. The pipe access panel
must be removed to do this.
2. Additional vents should be fitted at suitable points on
the system as required.
Boiler
Boiler
Boiler
Typical Low Head Installation
If Conditions Require,
This System Possible
Alternative Low Head Installation
500mm
45°
22mm
Open Vent
1000mm
Min
150mm
Max
15mm
Cold
Feed
400mm
Min Head
Return
Pump
Flow
Boiler
500mm
45°
22mm
Open Vent
400mm
Min Head
1000mm
Min
Boiler Air
Vent
15mm
Cold
Feed
150mm
Max
Return
Pump
Flow
Return
Pump
Flow
200mm
Min
Air
Separator
22mm
Feed & Vent
Pipe
Fig. 10
Fig. 11
Fig. 12
Boiler
Flow
Return
Copper
0.5m
Copper
1m
Copper
0.5m
Fig. 9
Boiler Air
Vent
Boiler Air
Vent
Boiler Air
Vent

6.0 System Details
13
© Baxi Heating UK Limited 2005
6.6 System Controls & Wiring
This boiler requires a permanent live for
operation of the condensate pump and frost
protection.
1. To comply with Part L1 of the Building Regulations the
heating system into which the boiler is installed should
include the following:
a) zone controls
b) timing controls
c) boiler control interlocks
2. Such a system needs to be fully pumped and must
provide independent temperature and time control to
both the heating and hot water circuits and have a boiler
and system pump interlock.
3. The boiler should be controlled so that it operates on
demand only. Where it is proposed to effect control by
thermostatic radiator valves a room thermostat should
also be provided to switch off the boiler when there is
no demand for heating.
Y Plan
Diverter
Valve
Cylinder
Stat
Room
Stat
Boiler Connection
(4 Core Wire)
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
HW off
LNE
S/L NE
b
g/y w
o
gr
1
C2
P/L
System Control
Wiring Centre
g/y
S Plan
Valve
Cylinder
Stat
Room
Stat
Boiler Connection
(4 Core Wire)
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
LNE
S/L NE
Motor
S Plan
Valve
Motor
o
o
gr
b
g/y
b
gr
br
br
P/L
System Control
Wiring Centre
Y Plan, Room Thermostat System, CH Interlocked By Room Thermostat,
DHW Interlocked By Cylinder Thermostat
At least the Radiator(s) near the Room Thermostat not TRV’d
Pump run from Switched Live
S Plan, Room Thermostat System, CH Interlocked By Room Thermostat,
DHW Interlocked By Cylinder Thermostat
At least the Radiator(s) near the Room Thermostat not TRV’d
Pump run from Switched Live
Key to colours
b - Blue
br - Brown
w - White
o - Orange
gr - Grey
g/y - Green/Yellow

6.0 System Details
14 © Baxi Heating UK Limited 2005
6.7 Sealed Systems (Fig. 13)
1. SAFETY VALVE - A safety valve complying with the
requirements of BS 6750 Part 1 must be fitted close to
the boiler on the flow pipe by means of a horizontal or
vertically upward connection with no intervening valve
or restrictions and should be positioned to facilitate
testing. The valve should be pre-set and non-adjustable
to operate at a pressure of 3 bar (45 Ibf/in2). It must be
arranged to discharge any water or steam through a pipe
to a safe outlet position.
2. PRESSURE GAUGE - A pressure gauge of minimum
range 0-4 bar (0-60 Ibf/in2) with a fill pressure indicator
must be fitted to the system, preferably at the same
point as the expansion vessel in an easily visible position.
3. EXPANSION VESSEL - An expansion vessel
complying with the requirements of BS 4814 must be
fitted to the system by means of a connection close to
the inlet side of the circulating pump in accordance with
the manufacturers instructions, the connecting pipe being
unrestricted and not less than 15mm (1/2in) nominal size.
The volume of the vessel should be suitable for the
system water content and the nitrogen or air charge
pressure should not be less than the system static head
(See Table. 1).
Further details of sealed system design can be obtained
from BS 5449 and the British Gas publication entitled
'Specifications for Domestic Wet Central Heating
Systems'.
4. FILLING POINT - 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. The sealed
primary circuits may be filled or replenished by means of
a temporary connection between the primary 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. The
filling method adopted must be in accordance with all
relevant water supply regulations and use approved
equipment.
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. MAKE UP SYSTEM - A method of replacing water
lost from the system should be provided either by
means of a make up vessel of not more than 3 litres (5
pints) capacity, mounted above the highest point of the
system, or by re-pressurisation of the system.
6. VENTING - A method of venting the system during
filling and commissioning must be provided by fitting
automatic air vents or by venting manually.
7. HOT WATER STORAGE - The hot water storage
vessel must be of the indirect coil type.
8. COMPONENTS - All components used in the system
must be suitable for operation at 110°C (230°F) and at
the pressure allowed by the safety valve.
Safety
Valve
Pressure
Gauge
Pump
Filling
Point
Air
Vent
3 Litre
Top Up Bottle
(if required)
Radiator
Circuit
Expansion
Vessel
System Drains at
Low Point
Max Boiler Flow
Temp = 82° C
Boiler
Fig. 13
Table. 1
Vessel Charge
Pressure (Bar)
0.5
1.0
1.5
Initial System
Pressure (Bar)
0.5
1.0
1.5
2.0
1.0
1.5
2.0
1.5
2.0
Multiply Total
Water Content Of
System By (Litres)
0.067
0.112
0.207
0.441
0.087
0.152
0.330
0.125
0.265
Method of determining minimum expansion
vessel volume for sealed systems.
System Volume = 75 litres
Vessel Charge Pressure = 1.0 bar
Initial System Pressure = 1.5 bar
75 x 0.152 = 11.4 litres
Expansion Vessel Volume
Example :-
Then :-
NOTE
Where a vessel of the calculated size is not obtainable then
the next available larger size should be used.
Stop
Valve
Double
Check
Valve
Mains
Inlet
CH
Return
Temporary
Hose
Stop
Valve
Fig. 14

7.0 Site Requirements
15
© Baxi Heating UK Limited 2005
7.1 Location
NOTE: Due to the high efficiency 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 boiler must be fitted on a suitable flat and level
surface capable of supporting the weight. Any wall behind
the boiler must be at 90° to the floor to allow case top
cover to fit correctly.
2. The flue must pass through an outside wall or roof and
discharge to atmosphere in a position permitting
satisfactory removal of combustion products and
providing an adequate air supply.
3. The boiler should be fitted within the building unless
otherwise protected by a suitable enclosure i.e. garage or
outhouse.
4. The boiler incorporates a frost protection device. This
will only protect the boiler. To ensure protection of the
system pipework and components it is recommended to
incorporate an appropriate device within the system
controls.
5. If the boiler is fitted in a room containing a bath or
shower, it can only be fitted in Zone 3, (Figs. A & B
shows zone dimensions for a bathtub. For other
examples refer to Section 601 of the Current I.E.E.
Wiring Regulations).
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.
6. 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 Compartment
1. Where the boiler is installed in a cupboard or
compartment, no air vents are required for cooling
purposes providing that the minimum dimensions below
are maintained.
Width 400mm
Height 875mm
Depth 525mm
2. Any compartment should be large enough to house
the boiler only.
NOTE: The ventilation label on the front of the outer
case MUST NOT BE REMOVED when the boiler is
installed in a compartment or cupboard.
Zone 2
Zone 1
Zone 0
Zone 2
Zone 3
Zone 3
Zone 2
Window
Recess
Window
Recess
0.6 m 2.4 m
Ceiling
Outside
Zones
Outside Zones
Zone 3
Zone 3
Zone 2
Zone 2
Zone 1
Zone 0
2.25 m
Zone 2
Window
Recess
3.0 m
2.4 m
0.6 m
Fig. A (Applies in GB ONLY)
Fig. B (Applies in GB ONLY)

7.0 Site Requirements
16 © Baxi Heating UK Limited 2005
7.3 Clearances (Figs. 15 &16)
1. 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. For side flue
installations also See Section 8.1, Figs. 20 & 21.
2. It is recommended that any worktop is removable for
servicing access.
7.4 Gas Supply
1. Check that the information concerning the state of
adjustment given on the data plate is compatible with local
supply conditions.
2. 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”.
3. The connection to the boiler is a 15mm tail on the gas
service cock. The tail protrudes through the boiler rear
panel and is protected by a transit bracket which may be
removed to aid connection.
4. Ensure that the pipework from the meter to the boiler
is of adequate size. (If the boiler is further than 3 metres
from the Gas Meter 22mm pipe should be used). Do not
use pipes of a smaller diameter than the boiler gas
connection.
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 ~ 50Hz fused at 3A.
NOTE: “The method of connection to the electricity
supply must facilitate complete electrical isolation of the
appliance and system”.
Connection may be via a fused double-pole isolator with a
contact separation of at least 3mm in all poles, which must
be in an accessible position to the user and serve the
boiler and system controls only.
There is no method of isolating the boiler at the user
interface.
3. Four core cable is required to supply the boiler as a
permanent live is necessary for the operation of the
condensate pump and frost protection.
850mm
15mm Min
(25mm if under
non removable
worktop)
5mm Min
5mm Min
5mm Min
500mm Min
For Servicing
Purposes
Fig. 15
Fig. 16 In Operation
520mm
390mm

7.0 Site Requirements
17
© Baxi Heating UK Limited 2005
7.6 Condensate Drain - General
Failure to install the condensate discharge pipework
correctly will affect the reliable operation of the boiler.
1. 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.
2. If any further drain pipe is required (additional to that supplied
with the boiler), it should be run in a proprietary material
e.g. PVC, PVC-U, ABS, PVC-C or PP.
3. Metal pipework is NOT suitable for use in condensate
discharge systems.
4. Any pipe fitted externally must be kept as short as possible to
minimise the potential of freezing and must be insulated using
waterproof material.
5. When discharging condensate into a soil stack or waste pipe
the effects of existing plumbing must be considered.
7.7 Condensate Disposal
1. This boiler incorporates an automatic pumped condensate
system. See the graph opposite for available pump flow rates.
2. 3.5 metres of flexible 10mm PVC pipe are supplied with the
boiler. 0.5 metres of this length remains coiled within the boiler
to allow removal of the pump assembly. This must not be
uncoiled to provide extra length.
3. A fitting and securing clip (Fig. B) to accept the 10mm PVC
pipe and connect to 21.5mm overflow pipe is also supplied.
4. The 10mm pipe can be routed to a maximum of 3 metres
vertically and then discharge via gravity or be routed horizontally
(Fig. A). A combination of vertical and horizontal runs is
permissible.
5. The pipe must be supported, either using suitably spaced clips
or run within larger diameter pipe. When using clips take care
not to deform the pipe.
6. When routing the pipe through a wall it must be suitably
sleeved. Also the pipe must not be exposed to sources of heat,
and should be protected in locations where it may be damaged.
7. The pipe should be routed so that any sharp bends, dips and
loops are avoided. A minimum radius of 100mm is
recommended for any bends. No slope is necessary and air
breaks are not required on the pumped part of the condensate
run.
8. If the boiler is fitted in an unheated location the entire length
of condensate pipe should be treated as external, and run within
insulated larger diameter pipe.
1
2
3
4
0
1.5 234
2.5 3.5
Flow (l/min)
Head (metres)
Boiler
Max. Head
3 metres
Alternative Horizontal
Discharge
Gravity Drain min. fall 3°
Min. radius 100mm
Condensate Pump Flow Graph
Fig. A
Note: The point of discharge from
the pumped length of condensate
pipe (point ‘A’) must not be below
the level of the pump, whether
discharging direct into a drain or
into an additional gravity drain.
10mm PVC Pipe
(8.5mm I.D.)
21.5mm Ø O.D. to fit
Overflow Pipe
8.5mm Ø O.D.
Condensate Pipe
Direct Connect
Fitting
Point ‘A’
Securing Clip
Fig. B

7.0 Site Requirement
18 © Baxi Heating UK Limited 2005
7.7 Condensate Disposal (cont.)
9. Ensure that the condensate can discharge freely (without
blockage or restriction of the pipe) into the drain.
10. Examples are shown of condensate pipe methods of
termination:-
i) via an internal discharge branch
(e.g. sink waste) - Fig. C.
ii) to an internal or external soil and vent pipe -
Fig. D.
iii) to a drain or gully - Fig. E. Ensure that the
condensate can discharge freely (without
blockage or restriction of the pipe) into the
drain.
iv) to a soakaway - Fig. F.
From Boiler
Termination to an internal soil and vent pipe
Termination via internal discharge branch e.g
sink waste - downstream
Sink
Pipe must terminate
above water level but
below surrounding surface
Pipe must terminate above
water level but below
surrounding surface
Termination to a drain or gully
Termination to a purpose made
soak-away
Holes in the soak-away must
face away from the building
Fig. C
Fig. D
Fig. E
Fig. F
Direct Connect Fitting
Direct Connect Fitting
From Boiler
From Boiler
From Boiler
Min. 450mm
10° 10°
Branch of Tee to be
± 10° from vertical

7.0 Site Requirements
19
© Baxi Heating UK Limited 2005
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7.8 Flue
NOTE: Due to the high efficiency 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. When siting the flue take into consideration the effect
the plume of water vapour may have on neighbours .
4. Adjacent surfaces close to the flue terminal may need
protection from the effects of condensation.
Alternatively a flue deflector kit (part no. 248167) is
available.
5. For installation of the flue into an internal corner at
the 25mm dimension the flue plume deflector kit (part
no. 248167) must be fitted.
6. * Reduction to the boundary is possible down to
25mm but the flue plume deflector kit (part no. 248167)
must be fitted.
7. 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.
8. If required a suitable terminal guard (part no. 248484)
is available from Baxi for use with the flue deflector. See
also Section 7.11.
9. For fitting under low soffits and eaves it is acceptable
for the flue to project up to 500mm from the face of the
wall to the inside of the air intake. This can be painted if
required using a suitable external paint.
Fig. 17
Fig. 16a
300 min
Terminal
Assembly
Top View Rear Flue
Property Boundary Line
NOTE: The distance from a fanned draught boiler terminal
installed parallel to a boundary may not be less than 300mm
in accordance with the diagram below, unless the flue deflector
kit is used (see 7.7.6 opposite)
Table. 2
Terminal Position with Minimum Distance (Fig. 17) (mm)
AaDirectly below an opening, air brick, opening
windows, etc. 300
BaAbove an opening, air brick, opening window etc. 300
CaHorizontally to an opening, air brick, opening window etc. 300
D Below gutters, soil pipes or drain pipes. 25
E Below eaves. 25
F Below balconies or car port roof. 25
G From a vertical drain pipe or soil pipe. 25
H From an internal (i) or external (ii) corner. (i) 25 (ii) 115
I Above ground, roof or balcony level. 300
J From a surface or boundary line facing a terminal. 600
K From a terminal facing a terminal (Horizontal flue). 1200
From a terminal facing a terminal (Vertical flue). 600
L From an opening in carport (e.g. door, window)
into the dwelling. 1200
M Vertically from a terminal on the same wall. 1500
N Horizontally from a terminal on the same wall. 300
R From adjacent wall to flue (vertical only). 300
S From an adjacent opening window (vertical only). 1000
aIn addition, the terminal should be no nearer than 150 mm 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.
*

7.0 Site Requirements
20 © Baxi Heating UK Limited 2005
7.10 Standard Flue Dimensions
The standard horizontal flue kit allows for flue lengths
between 270mm and 800mm from elbow to terminal
(Fig. 18).
The maximum permissible equivalent concentric flue
length is: 4 metres (Fig. 18a).
NOTE: Each additional 45° flue bend will account
for an equivalent flue length of 0.5m.
eg. 45° = 0.5m, 93° = 2 x 45° = 1m etc.
7.11 Terminal Guard (Fig. 19)
1. When codes of practice dictate the use of terminal
guards, they can be obtained from most Plumbers’ and
Builders’ Merchants.
2. When ordering a terminal guard, quote the boiler
model name and type. Tower Flue Components
(Tel. [phone]) part no. CGDK6BR is suitable.
3. There must be a clearance of at least 50mm
between any part of the terminal and the guard. The
guard should be positioned centrally over the terminal
and fixed as illustrated.
4. The guard must be of a non - corrosive material
(e.g. stainless steel) or plastic coated.
Fig. 18
Fig. 18a
Pictorial examples of flue runs where EQUIVALENT flue length equals 4m
Fig. 19
270mm 800mm
0.5m
1m
0.5m
0.5m