Baxi Solo HE a series Installation and maintenance instructions

© Baxi Heating UK Ltd 2012
Solo HE ARange
Wall Mounted Powered Flue Condensing
Boilers Gas Fired Central Heating Units
Installation & Servicing Instructions
These instructions include the Benchmark Commissioning Checklist
and should be left with the user for safe keeping.

2© Baxi Heating UK Ltd 2012
Natural Gas
Baxi Solo 12 HE A
G.C.No41 075 65
Baxi Solo 15 HE A
G.C.No41 075 66
Baxi Solo 18 HE A
G.C.No41 075 67
Baxi Solo 24 HE A
G.C.No41 075 68
Baxi Solo 30 HE A
G.C.No41 075 69
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.
The Health & Safety Executive operates the ‘Gas Safe Register’,
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Benchmark Logbook is being withdrawn.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.
© Baxi Heating UK Ltd 2012 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 Ltd,
Brooks House, Coventry Road, Warwick. CV34 4LL
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.
0086
ISO 9001
FM 00866
The Benchmark Scheme
Benchmark places responsibilities on both manufacturers and installers. The
purpose is to ensure that customers are provided with the correct equipment for
their needs, that it is installed, commissioned and serviced in accordance with the
manufacturer’s instructions by competent persons and that it meets the
requirements of the appropriate Building Regulations. The Benchmark Checklist
can be used to demonstrate compliance with Building Regulations and should be
provided to the customer for future reference.
Installers are required to carry out installation, commissioning and servicing work
in accordance with the Benchmark Code of Practice which is available from the
Heating and Hotwater Industry Council who manage and promote the Scheme.
Visit www.centralheating.co.uk for more information.

Installer Notification Guidelines
3
© Baxi Heating UK Ltd 2012
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
‘Gas Safe Register’ will issue a
Building Regulations Compliance
Certificate to the property owner
and inform the relevant LABC
You must ensure that the
certificate number issued by
the ‘Gas Safe Register’ is written
onto the Benchmark Checklist
Scheme Members only
Call ‘Gas Safe Register’ on:
0800 408 5577
or log onto:
www.gassaferegister.co.uk
within 10 days
If you notify via the ‘Gas Safe
Register’, the register will issue
the Building Regulations
certificate on members’ 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 Ltd 2012
This company 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 Gas Safe
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).
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 EN 12828 Heating systems in buildings.
BS EN 12831 Heating systems in buildings - calculations of load
BS EN 14336 Installation & commissioning of water based
heating 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 EN 12828 Heating systems in buildings.
BS EN 12831 Heating systems in buildings - calculations of load
BS EN 14336 Installation & commissioning of water based
heating systems.
BS 7074 Expansion vessels and ancillary equipment for
sealed water systems.
BS 7593 Treatment of water in domestic hot water
central heating systems.
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 0086.
Product/Production certified by:
Notified Body 0086.
For GB/IE only.
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 Gas Safe 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”.
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 Gas Safe registered engineers carry an ID card with their licence number and a
photograph. You can check your engineer is registered by telephoning
0800 408 5500 or online at www.gassaferegister.co.uk

Safe Manual Handling
5
© Baxi Heating UK Ltd 2012
General
The following advice should be adhered to, from when first handling the boiler to the final stages of installation, and also during maintenance.
Most injuries as a result of inappropriate handling and lifting are to the back, but all other parts of the body are vulnerable, particularly shoulders, arms and
hands. Health & Safety is the responsibility of EVERYONE.
There is no ‘safe’ limit for one man - each person has different capabilities. The boiler should be handled and lifted by TWO PEOPLE.
Do not handle or lift unless you feel physically able.
Wear appropriate Personal Protection Equipment e.g. protective gloves, safety footwear etc.
Preparation
Co-ordinate movements - know where, and when, you are both going.
Minimise the number of times needed to move the boiler - plan ahead.
Always ensure when handling or lifting the route is clear and unobstructed. If possible avoid steps, wet or slippery surfaces, unlit areas etc. and take special
care on ladders/into lofts.
Technique
When handling or lifting always use safe techniques - keep your back straight, bend your knees. Don’t twist - move your feet, avoid bending forwards and
sideways and keep the load as close to your body as possible.
Where possible transport the boiler using a sack truck or other suitable trolley.
Always grip the boiler firmly, and before lifting feel where the weight is concentrated to establish the centre of gravity, repositioning yourself as necessary.
See section 8.3 of these instructions for recommended lift points.
Remember
The circumstances of each installation are different. Always asses the risks associated with handling and lifting according to the individual conditions.
If at any time when installing the boiler you feel that you may have injured yourself STOP !!
DO NOT ‘work through’ the pain - you may cause further injury.
IF IN ANY DOUBT DO NOT HANDLE OR LIFT THE BOILER - OBTAIN ADVICE OR ASSISTANCE BEFORE PROCEEDING !!

© Baxi Heating UK Ltd 2012
6
1.0 Introduction 7
2.0 General Layout 8
3.0 Appliance Operation 9
4.0 Technical Data 10
5.0 Dimensions and Fixings 11
6.0 System Details 12
7.0 Site Requirements 16
8.0 Flue Options 22
9.0 Plume Displacement 27
10.0 Installation 31
11.0 Electrical 37
12.0 Commissioning the Boiler 39
13.0 Fitting the Outer Case 41
14.0 Servicing the Boiler 42
15.0 Changing Components 45
16.0 Short Parts List 51
17.0 Fault Finding 52
Benchmark Checklist 58
Section Page
Contents
Contents of Pack
The pack contains:-
• Boiler
• Wall Plate
• Template & ‘Quick Fit’ Guide
• Literature Pack
• Fittings Pack

1.0 Introduction
7
© Baxi Heating UK Ltd 2012
Fig. 1
Data Badge
Air Box Door
Lower Door Panel Position of Label
Fig. 2
1.1 Description
1. The Baxi Solo HE Arange are gas fired room sealed fan
assisted condensing central heating boilers.
2. The maximum outputs of the Baxi Solo models are:-
12 HE A- 11.82 kW (Non Condensing)
12.81 kW (Condensing)
15 HE A- 15.24 kW (Non Condensing)
16.49 kW (Condensing)
18 HE A- 17.81 kW (Non Condensing)
19.27 kW (Condensing)
24 HE A- 22.0 kW (Non Condensing)
23.8 kW (Condensing)
30 HE A- 30.18 kW (Non Condensing)
32.61 kW (Condensing)
Note: 30 HE Ais pre-set at 22.0/23.8 kW - see section 10.8
for adjustment details. All boilers automatically adjust output
according to system load.
3. The boiler is designed for use on Natural Gas (G20).
4. The boiler is suitable for fully pumped open vented
central heating and domestic hot water systems and sealed
systems.
5. A label giving details of the model, serial number and Gas
Council number is situated on the rear of the lower door
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 appliance (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.

8© Baxi Heating UK Ltd 2012
2.0 General Layout
2.1 Layout (Figs. 3,4,5 & 6)
1. Wall Plate
2. Flue Elbow
3. Heat Exchanger
4. Burner
5. Air Box
6. Fan Protection Thermostat
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)
1
2
3
4
5
6
7
9
8
10
11
15 14
12
13
16
Fig. 4
Fig. 3
Fig. 5
Fig. 6

3.0 Appliance Operation
9
© Baxi Heating UK Ltd 2012
3.1
1. Switched Live On: When the switched live switches
on if the flow temperature is less than the set point
then pump overrun occurs. When the switched live
switches on if the flow temperature is greater than the
set point then pump overrun occurs.
2. Pump On: The pump is on while the fan, spark
generator and gas valve are off. 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 pump and fan are on while the
spark generator and gas valve are off. After 5 seconds
ignition occurs.
4. Ignition: The pump, 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 pump, 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 pump and fan are on while the
spark generator and gas valve are off. After 5 seconds if
the TRVs are not shut down then pump overrun
occurs. After 5 seconds if the TRVs are shut down then
anti-cycle occurs.
7. Pump Overrun: The pump is on while the fan, spark
generator and gas valve are off. After 1 minute anti-
cycle occurs.
8. Anti-cycle: The pump, fan, spark generator and gas
valve are off. After 3 minutes if the flow temperature is
less than the set point then pump on occurs. After 3
minutes if the flow temperature is greater than the set
point then pump overrun occurs.
9. Ignition Lockout: The pump, fan, spark generator
and gas valve are off. The boiler can only be reset by
manually using the reset button.
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 ?
Flow switch made ?
NO
YES
YES
YES
10 second
Pump On.
All TRVs
shut or Flow temperature
greater than set point ?
5 second
Fan Post Purge.
1 minute
Pump Overrun.
3 minute
Anti-cycle.
NO
YES
YES
YES
NO

4.0 Technical Data
10 © Baxi Heating UK Ltd 2012
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)
Hydraulic Resistance Chart
Appliance Category CAT I 2H
Horizontal
Flue Terminal Diameter 110mm
Dimensions Projection 150mm
Outercase Dimensions
Overall Height Inc Flue Elbow - 750mm
Casing Height - 600mm
Casing Width - 390mm
Casing Depth - 285mm
Weights kg
Packaged Boiler Carton 36.2
Packaged Flue Kit 3.6
Installation Lift Weight 26.0
Connections
Gas Supply - 1/2in BSPT
Central Heating Flow - 22mm
Central Heating Return - 22mm
Condensate Drain - 1 in BSP
Recommended System
Temperature Drop
Condensing 20°C 36°F
Heat Input (Q)(Gross) Max Min
12 model kW 13.34 10.2
15 model kW 16.88 10.2
18 model kW 20.18 10.2
24 model kW 24.50 10.2
30 model kW 33.76 10.2
(see note)
Heat Output (P)
(Non Condensing 70° C Mean Water Temp)
Max Min
12 model kW 11.82 9.14
15 model kW 15.24 9.14
18 model kW 17.81 9.14
24 model kW 22.00 9.14
30 model kW 30.18 9.14
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 80W
External Fuse Rating 3A
Internal Fuse Rating (BS 4265)
Fuse 3.15 AT (PCB)
Inlet Pressure at Gas Valve (Natural Gas)
Min 18.1 mbar
Max 22.5 mbar
(see Section 12.1)
Injector (Natural Gas)
6.5mm Diameter
Clearances
(For unventilated compartments see Section 7.2)
Both Sides 5mm Min
Above Casing 200mm Min
Below Casing 50mm Min
Front (For Servicing) 500mm Min
Front (In Operation) 5mm Min
Appliance Type C13 C33 C53
Nox Class 5
Heat Output (P)
(Condensing 40° C Mean Water Temp)
Max Min
12 model kW 12.81
15 model kW 16.49 10.1
18 model kW 19.27
24 model kW 23.8 10.1
30 model kW 32.61 10.1
Water Content
litres 2.6
pints 4.6
Static Head
max 30 metres (100 ft)
min 1 metre (3.25 ft)
Low Head 0.2m (8 in) min
System Detail
fully pumped open vented & sealed systems
Gas Connection
G1/2” B.S.P. Thread
Controls
boiler thermostat, safety thermostat,
flow switch, electronic flame sensing,
temperature protection thermostat &
condensate blockage sensor
NOTE: The maximum output of the 30
model is factory set at 22.0kW. This can
be altered to 30.18kW - see section 10.8.
For 12 model - The efficiency is 90.5%
For 15 model - The efficiency is 91.3%
For 18 model - The efficiency is 90.4%
For 24 model - The efficiency is 90.9%
For 30 model - 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 0086.
SEDBUK Declaration
Electrical Protection IPX2
CO/CO2 Ratio Up to a maximum
of 0.004
Flow Temperature (adjustable)
55° C to 78° C (± 5° C)
CO2 Level 9% ± 1%
Max Gas Rate (2H - G20 - 20mbar)
(After 10 Mins)
(12) (15) (18) (24) (30)
m3/hr 1.34 1.64 1.94 2.31 2.95
NOTE: All data in this section are nominal values
and subject to normal production tolerances

5.0 Dimensions and Fixings
11
© Baxi Heating UK Ltd 2012
DIMENSIONS
A600mm
B285mm
C390mm
D125mm Ø Min.
E150mm
F96mm
SIDE FLUE (left and right)
For every 1m of horizontal flue
length, the clearance above the top
of the flue elbow should be 27.5mm
to incorporate the 1.5° fall in the flue
from the terminal to the elbow.
The 1.5° fall provided by the elbow
is to allow condensate to run back to
the boiler, for disposal through the
condensate discharge pipe.
Flue length (Y)
up to 1m
1m - 2m
2m - 3m
Clearance (X)
27.5mm
55mm
82.5mm
360° Orientation
Tube Ø 110mm
DC
B
A
E
F
Y
At least
1.5°
X
At least
1.5°
Fig. 7
Fig. 8

6.0 System Details
12 © Baxi Heating UK Ltd 2012
6.1 Water Circulating Systems
1. The appliance 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 (100ft) 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.
• It is recommended that the return pipe is fitted with an
automatic air vent as close to the boiler as is practical.
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 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, Sentinel X300 or X400 or Fernox F3.
They should be used following the flushing agent
manufacturer’s instructions.
• System additives - corrosion inhibitors and flushing
agents/descalers should comply to BS7593 requirements,
e.g. Sentinel X100 and Fernox MB-1 which should be used
following the inhibitor manufacturer’s instructions.
• Full instructions are supplied with the products, for
further information contact Sentinel (0800 389 4670) or
Fernox (0870 870 0362)
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.

6.0 System Details
13
© Baxi Heating UK Ltd 2012
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. The connection on the
boiler are 22mm.
2. A 20 °C (36°F) 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 (20°F).
NOTE: On Solo 30 HE Amodels 28mm pipe should
be used to connect to the boiler flow and return.
3. 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).
6.4 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.
An alternative Low Head Installation (Fig. 12)
2. For heads below 400mm then a combined vent and
feed pipe may be connected. 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 Pump
1. Providing that the cold feed and open vent pipe are
positioned correctly (e.g. the system is not prone to
pumping over, air entrainment etc.) the pump may be
fitted on the primary return pipe.
Typical Low Head Installation
If Conditions Require,
This System Possible
Alternative Low Head Installation
Boiler
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
Automatic Air
Vent 15mm
Cold
Feed
150mm
Max
Return
Pump
Flow
Return
Pump
Flow
Boiler
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

6.0 System Details
14 © Baxi Heating UK Ltd 2012
6.5 System Controls
This boiler does not require a bypass.
This boiler does not require a permanent live.
The pump only needs wiring directly to the boiler for
fully TRV’d systems.
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
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 (or
other device such as a flow switch - a flow switch is
integral to this boiler) should also be provided to switch
off the boiler when there is no demand for heating or
hot water.
4. The interlock for the CH circuit can be provided by
either a Room Thermostat or a fully TRV’d system with
the pump wired back to the boiler without a bypass.
Connection diagrams for both options for Y and S plan
systems are shown.
Y Plan
Diverter
Valve
Cylinder
Stat
Room
Stat
Boiler
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
HW off
LNE
L N P/FE
b
g/y w
o
gr
1
C2
g/y
S Plan
Valve
Cylinder
Stat
Room
Stat
Boiler
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
LNE
L N P/FE
Motor
S Plan
Valve
Motor
o
o
gr
b
g/y
b
gr
br
br
Y Plan
Diverter
Valve
Cylinder
Stat
Boiler
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
HW off
LNE
L N P/FE
b
g/y
o
gr
1
C2
w
g/y
S Plan
Valve
Cylinder
Stat
Boiler
Pump
Timer
230V
50Hz
LNE
L
N
CH on
HW on
LNE
L N P/FE
Motor
S Plan
Valve
Motor
o
o
gr
b
g/y
b
gr
br
br
Y Plan, Room Thermostat System, CH Interlocked By Room Thermostat
At least the Radiator(s) near the Room Thermostat not TRV’d
Pump run from Switched Live
By-pass permitted but not required for Part L1 compliance
S Plan, Room Thermostat System, CH Interlocked By Room Thermostat
At least the Radiator(s) near the Room Thermostat not TRV’d
Pump run from Switched Live
By-pass permitted but not required for Part L1 compliance
Y Plan, Fully TRV’d System, CH Interlocked By Boiler Flow Switch
Room Thermostat should not be fitted
Pump must be run from Boiler P/F connection for Part L1 compliance
By-pass not permitted (must be valved off) for Part L1 compliance
S Plan, Fully TRV’d System, CH Interlocked By Boiler Flow Switch
Room Thermostat should not be fitted
Pump must be run from Boiler P/F connection for Part L1 compliance
By-pass not permitted (must be valved off) for Part L1 compliance
Key to colours
b-Blue
br - Brown
w-White
o - Orange
gr - Grey
g/y - Green/Yellow

6.0 System Details
15
© Baxi Heating UK Ltd 2012
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. 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 valve of
expansion vessel volume for sealed systems
using Baxi Boilers
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
CH
Return
Temporary
Hose
Stop
Valve
Fig. 14

7.0 Site Requirements
16 © Baxi Heating UK Ltd 2012
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 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 7.2).
2. If the boiler is sited in an unheated enclosure then it is
recommended to incorporate an appropriate device for
frost protection in the system controls.
3. If the boiler is fitted in a room containing a bath or
shower it MUST NOT BE fitted in zone 0, 1 or 2, ONLY
within the shaded area (Figs. A & B shows zone
dimensions for a bathtub. For other examples refer to
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.
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 Ventilation of Compartments
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.
Sides 15mm
Top 200mm
Bottom 50mm
Front 30mm
2. If the boiler is installed in a smaller cupboard or
compartment it must be ventilated according to
BS 5440 Part 2 and the minimum clearances given in
section 4.0 “Technical Data” maintained.
3. 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 appliance is
installed in a compartment or cupboard.
Zone 2
Zone 1
Zone 0
Zone 2
Zone 2
Window
Recess
Window
Recess
0.6 m
Ceiling
Outside Zones
Zone 2
Zone 1
Zone 0
2.25 m
0.6 m
Fig. A
Fig. B
In GB Only
In GB Only
Window Recess
Zone 2

7.0 Site Requirements
17
© Baxi Heating UK Ltd 2012
7.3 Clearances (Figs. 15 &16)
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.
3. For unventilated compartments see Section 7.2.
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 1/2in BSPF.
3. Ensure that the pipework from the meter to the
appliance is of adequate size to ensure correct operation.
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”.
Note! There is no method of isolating the boiler, at the
user interface.
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.
WARNING: The PCB Control and Fan
Assembly are 325 Vdc. Isolate at supply
before access.
50mm
600mm
390mm
200mm
5mm Min
5mm Min
5mm
500mm
For Servicing
Purposes
Fig. 15
Fig. 16 In Operation
At least
1.5°
285mm

7.0 Site Requirements
18 © Baxi Heating UK Ltd 2012
7.6 Condensate Drain
FAILURE TO INSTALL THE CONDENSATE
DISCHARGE PIPEWORK CORRECTLY WILL AFFECT
THE RELIABLE OPERATION OF THE BOILER.
CAREFUL CONSIDERATION MUST BE GIVEN TO THE
POSSIBILITY OF THE PIPEWORK BEING SUBJECT TO
FREEZING CONDITIONS AND APPROPRIATE
MEASURES TAKEN TO PREVENT BLOCKAGE.
CORRECT INSTALLATION IN ACCORDANCE WITH
THIS SECTION WILL CONSIDERABLY MINIMISE THE
LIKELIHOOD OF BLOCKAGE AND SUBSEQUENT
BOILER LOCK-OUT.
A CONDENSATE DISCHARGE PUMP AND PIPE ‘TRACE
HEATING’ ARE AVAILABLE AS ACCESSORIES - see
paragraphs 7.7.12 to 7.715 for further details.
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 EXCEPT
when employing a suitable condensate pump in basement
and cellar or similar applications.
The boiler condensate trap incorporates a seal of 75mm,
therefore it is unnecessary to install an air break and trap
in the discharge pipework.
1. The condensate outlet will accept 21.5mm (3/4in) plastic
overflow pipe. It is strongly recommended that this
discharges internally into the household drainage system.
Where this is not possible, discharge into an outside drain is
permissible providing every possible precaution is taken to
prevent freezing.
2. Ensure the discharge of condensate complies with any
national or local regulations in force. BS 6798 & Part H1 of
the Building Regulations give further detailed 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 of the correct
design to prevent sagging.
6. It is advisable that the full length of condensate pipe is run
internally and preferably be less than 3 metres.
7. Internal runs greater than 3 metres or runs in cold areas
should use 32mm waste pipe.
8. External runs MUST be a MINIMUM of 32mm and fully
insulated with material suitable for external use.
9. If the boiler is fitted in an unheated location the entire
condensate discharge pipe should be treated as an external
run and sized and insulated accordingly.
10. 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
and any burrs on cut pipe removed.
21.5mm
2.5° Minimum fall
i) Termination to an internal soil and
vent pipe
450mm min*
Boiler
2.5° Minimum fall
ii) External termination via internal discharge branch
e.g sink waste - downstream*
Sink
Pipe must terminate above
water level but below
surrounding surface. Cut
end at 45°
50mm per metre of pipe run
50mm per metre of pipe run
*450mm is applicable to
properties up to 3 storeys.
For multi-storey building
installations consult BS 6798.
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) downstream of the trap
iii) to a drain or gully
iv) to a purpose made soakaway
v) pumped into an internal discharge branch (e.g. sink waste) downstream of the trap
vi) pumped into an external soil & vent pipe
vii) to a drain or gully with extended external run & trace heating
It is strongly recommended to discharge internally into the household
drainage system. If connecting to a rain water drain, that drain MUST
discharge into a foul drain.
*It is NOT RECOMMENDED
to connect upstream of the
sink or other waste water
receptacle !
32mm Insulation

7.0 Site Requirements
19
© Baxi Heating UK Ltd 2012
7.6 Condensate Drain (cont.)
11. 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.
Boiler
2.5° Minimum fall
iii) Termination to a drain or gully
Boiler
500mm min
2.5° Minimum fall
iv) Termination to a purpose made soakaway
Holes in the soak-away must
face away from the building
50mm per metre of pipe run
50mm per metre of pipe run
Further specific requirements for soakaway
design are referred to in BS 6798.
Pipe must terminate above
water level but below
surrounding surface. Cut
end at 45°

7.0 Site Requirements
20 © Baxi Heating UK Ltd 2012
7.6 Condensate Drain (cont.)
12. A boiler discharge pump is available, ‘MULTIFIT’
part no. 720648301. This pump will dispose of both
condensate & high temperature water from the relief valve.
It has a maximum head of 5 metres. Follow the instructions
supplied with the pump.
13. Condensate Drain Pipe ‘Trace Heating’ Elements are
available in various lengths. ‘MULTIFIT’ part nos.:-
1 metre 720644401
2 metre 720664101
3 metre 720664201
5 metre 720664401*
*Where the drain is between 3 & 5 metres a 5 metre kit can
be used and “doubled back” upon itself.
14. It is possible to fit the element externally on the
condensate drain or internally as detailed in the instructions
provided.
15. The fitting of a ‘Trace Heating’ Element is NOT a
substitute for correct installation of the condensate drain.
ALL requirements in this section must still be adhered to.
Boiler
vi) pumped into an external soil & vent pipe
2.5° Minimum fall
50mm per metre of pipe run
Condensate Pump
Unheated Location
(e.g. Garage)
Basement or similar
(heated)
Boiler
2.5° Minimum fall
50mm per metre of pipe run
Pipe must terminate above
water level but below
surrounding surface. Cut
end at 45°
The ‘Trace Heating’ element
must be installed in accordance
with the instructions supplied.
External runs & those in
unheated locations still require
insulation.
vii) to a drain or gully with extended
external run & trace heating
Boiler
v) pumped into an internal discharge branch
(e.g. sink waste) downstream of the trap
Pipe must terminate above
water level but below
surrounding surface. Cut
end at 45°
2.5° Minimum fall
50mm per metre of pipe run
Condensate Pump
Sink
Basement or similar
(heated)