Baxi Megaflo System 28 HE IE LPG Release note

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© Baxi Heating UK Ltd 2011
Baxi Megaflo System HE IE Range
Gas Fired Wall Mounted Condensing Boiler
Installation & Servicing Instructions
These instructions include the Commissioning Checklist
and should be left with the user for safe keeping.

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2© Baxi Heating UK Ltd 2011
Natural Gas
Baxi Megaflo System 15 HE IE
Baxi Megaflo System 18 HE IE
Baxi Megaflo System 24 HE IE
Baxi Megaflo System 28 HE IE
Baxi Megaflo System 32 HE IE
Propane Gas
Baxi Megaflo System 24 HE IE LPG
Baxi Megaflo System 28 HE IE LPG
© Baxi Heating UK Ltd 2011 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.
ISO 9001
FM 00866
0086

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© Baxi Heating UK Ltd 2011
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.
The installation 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.
Warning - Check the information on the data plate is compatible with local supply
conditions.
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 IE and should
be installed in accordance with the rules in force, and only
used in a suitably ventilated location.
Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
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 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 EN 12828 Heating systems in buildings.
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 0085.
Product/Production certified by:
Notified Bodies 0085 & 0086.
For IE only.

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Safe Manual Handling
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 the
‘Installation’ section 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 !!

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© Baxi Heating UK Ltd 2011
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 11
6.0 System Details 12
7.0 Site Requirements 14
8.0 Flue Options 18
9.0 Plume Displacement 23
10.0 Installation 27
11.0 Commissioning 32
12.0 Completion 34
13.0 Servicing 35
14.0 Changing Components 37
15.0 Setting the Gas Valve 45
16.0 Electrical 46
17.0 Short Parts List 47
18.0 Fault Finding 48
Commissioning Checklist 54
Section Page

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6© Baxi Heating UK Ltd 2011
1.0 Introduction
1.1 Description
1. The Baxi Megaflo System HE IE is a fully automatic gas fired
wall mounted condensing system boiler. It is room sealed and
fan assisted.
2. The boiler is set to give a maximum output of :-
15 models - 15 kW
16.2 kW (Condensing)
18 models - 18 kW
19.4 kW (Condensing)
24 models - 24 kW
25.9 kW (Condensing)
28 models - 28 kW
30.3 kW (Condensing)
32 models - 32 kW
34.4 kW (Condensing)
3. It is designed for use on either Natural Gas (G20), or
Propane (G31) as indicated by the suffix LPG in the model
name. Two Propane models are available, the Baxi Megaflo
System 24 HE IE LPG & 28 HE IE LPG
4. The boiler incorporates a circulating pump and expansion
vessel. It is suitable for use only on fully pumped sealed
systems.
5. The boiler data badge gives details of the model and serial
number, and is situated on the inner door panel. It is visible
when the case front panel is removed (Fig. 1).
6. The boiler model name and serial number are also shown
on the information label on the rear of the lower door panel.
This is for user reference.
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 telescopic flue
kit, part no. 5118069.
9. All systems must be thoroughly flushed and treated with
inhibitor (see section 6.1).
1.2 Contents of Pack
The pack contains:-
• Boiler
• Wall Plate (including taps)
• Set of Pipe Connections
• Template & ‘Quick Fit’ Guide
• Literature Pack
Fig. 1
Control Box
Case Front Panel
Data Badge
Information Label

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© Baxi Heating UK Ltd 2011
2.0 General Layout
2.1 Layout
1. Expansion Vessel
2. Automatic Air Vent
3. Circulation Pump
4. Drain Off Point
5. Pressure Relief Valve
6. Selector Switch
7. Central Heating System Pressure Gauge
8. PCB
9. Control Box
10. Gas Valve
11. Condensate Trap
12. Flame Sensing Electrode
13. Spark Electrode
14. Primary Heat Exchanger
15. Fan Assembly
16. On/Off/Reset Selector Switch
17. Central Heating Temperature Control
18. Calibration Control
19. Venturi
20. Air/Gas Collector
21. Combustion Box Cover & Burner
22. Igniter
23. Burner On Light
24. Central Heating Mode Light
25. Display
1
16 17 18 7
2
1
0
4
3
bar
21
2
3
4
5
6
7
8
9
10
11
12
13
14
15
19
20
22
23
24
25

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3.0 Appliance Operation
3.1 Operating Mode (Fig. 2)
1. With a demand for heating or hot water, the pump
circulates water through the primary circuit. If the pressure is
at least 0.2 bar the ignition sequence will start.
2. 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.
3. When the demand is satisfied the burner is extinguished
and the pump continues to run for a period of 3 minutes
(Pump Overrun).
IMPORTANT: When the selector switch is in the ‘0’
(Off) position the electrical supply to the boiler is
isolated. The boiler will not operate.
3.2 Frost Protection Mode
1. The frost protection mode is integral to the appliance and
functions when the selector switch (see Section 2.1) is in the
ON 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.
3.3 Pump Protection
1. With the selector switch (see Section 2.1) in the ON
position ( ) the pump will automatically operate for 1
minute in every 24 hours to prevent sticking.
1
2
4
5
6
7
8
19
18
9
10 1211
14
13
15
16
17
3
Key
1 Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6Pump
7 Automatic Air Vent
8 Pressure Relief Valve
9 Boiler Drain Point
10 Gas Inlet
11 Boiler Flow
12 Boiler Return
13 Pressure Gauge
14 Automatic By-Pass
15 Water Pressure Sensor
16 Safety Thermostat
17 Temperature Sensor
18 Expansion Vessel
19 Return Temperature Sensor
20 Fan
Boiler Primary Circuit
Fig. 2
20

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© Baxi Heating UK Ltd 2011
4.0 Technical Data
4.1 Megaflo System 15, 18, 24, 28 & 32 HE IE
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Central Heating Primary Circuit
Pressures (Sealed Systems)
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommended Operating Range 1-2
For ‘Semi-Sealed’ Systems it is recommended that
the system is designed to achieve a pressure of
0.2 bar at the boiler (see Section 6.4).
Pump
Available Head See graph below
Expansion Vessel - (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
Temperatures
Flow Temp (adjustable)
25°C to 80°C max (± 5°C)
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 150 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)
*This is the MINIMUM recommended dimension. Greater
clearance will aid installation and maintenance.
Heat Input (Net) Max Min
15 model kW 15.4 4
18 model kW 18.5 4.3
24 model kW 24.7 7
28 model kW 28.9 9.7
32 model kW 32.8 9.7
Heat Output (Non-Condensing)
Max Min
15 model kW 15 3.9
18 model kW 18 4.2
24 model kW 24 6.8
28 model kW 28 9.4
32 model kW 32 9.4
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption
15 model 130W
18 model 140W
24 model 150W
28 & 32 models 160W
Electrical Protection
IPX5D
Internal Fuse Rating F2L
Appliance Category CAT I 2H
Inlet Pressure (Natural Gas - G20)
mbar 20
Injector (Natural Gas - G20)
15 model 4.5mm
18 model 5.7mm
24 model 7.5mm
28 model 12mm
32 model 12mm
Appliance Type C13 C33 C53
Heat Output (Condensing)
Max Min
15 model kW 16.2 4.2
18 model kW 19.4 4.5
24 model kW 25.9 7.4
28 model kW 30.3 10.2
32 model kW 34.4 10.2
Max Gas Rate (Natural Gas - G20)
(After 10 mins)
15 model m3/h 1.69
18 model m3/h 1.95
24 model m3/h 2.61
28 model m3/h 3.1
32 model m3/h 3.48
Condensate Drain
To accept 21.5mm (3/4in) plastic waste pipe
Heat Input (Gross) Max Min
15 model kW 17.1 4.4
18 model kW 20.5 4.8
24 model kW 27.4 7.8
28 model kW 32.1 10.8
32 model kW 36.4 10.8
External Fuse Rating 3A
Weights
15 & 18 24
Packaged Boiler Carton 52.5kg 53.5kg
Installation Lift Weight 43kg 44kg
28 & 32
Packaged Boiler Carton 54.5kg
Installation Lift Weight 45kg
Connections copper tails
Gas Supply - 3/4”
Central Heating Flow - 3/4”
Central Heating Return - 3/4”
Pressure Relief Discharge - 1/2”

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4.0 Technical Data
4.2 Megaflo System 24 & 28 HE IE LPG
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Pump
Available Head See graph below
Expansion Vessel - (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 - 3/4”
Central Heating Flow - 3/4”
Central Heating Return - 3/4”
Pressure Relief Discharge - 1/2”
Temperatures
Flow Temp (adjustable)
25°C to 80°C max (± 5°C)
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
Heat Input (Net) Max Min
24 LPG model kW 24.7 7
28 LPG model kW 28.9 9.7
Heat Output (Non-Condensing)
Max Min
24 LPG model kW 24 6.8
28 LPG model kW 28 9.4
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption
24 LPG model 150W
28 LPG model 160W
Electrical Protection
IPX5D
Internal Fuse Rating F2L
Appliance Category CAT I I 2H3P
Inlet Pressure (Propane - G31)
mbar 37
Injector (Propane Gas - G31)
24 LPG model 7.5mm
28 LPG model 12mm
Appliance Type C13 C33 C53
Heat Output (Condensing)
Max Min
24 LPG model kW 25.9 7.4
28 LPG model kW 30.3 10.2
Max Gas Rate (Propane Gas - G31)
(After 10 mins)
24 LPG model kg/h 1.92
28 LPG model kg/h 2.25
Condensate Drain
To accept 21.5mm (3/4in) plastic waste pipe
Heat Input (Gross) Max Min
24 LPG model kW 27.4 7.8
28 LPG model kW 32.1 10.8
External Fuse Rating 3A
Weights
24 28
Packaged Boiler Carton 53.5kg 54.5kg
Installation Lift Weight 44kg 45kg
Central Heating Primary Circuit
Pressures (Sealed Systems)
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommended Operating Range 1-2
For ‘Semi-Sealed’ Systems it is recommended that
the system is designed to achieve a pressure of
0.2 bar at the boiler (see Section 6.4).
Clearances
Above Casing 200 mm Min
Below Casing 150 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)
*This is the MINIMUM recommended dimension. Greater
clearance will aid installation and maintenance.

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5.0 Dimensions and Fixings
© Baxi Heating UK Ltd 2011
360° Orientation
Flue Ø 100mm
DC
B
A
E
G
F
At least
1.5°
H
Heating
Return
(3/4”)
Heating
Flow
(3/4”)
Pressure Relief
Valve
(1/2”)
Gas
Inlet
(3/4”)
130 mm 130 mm 65 mm
Condensate
Drain
32.5 mm
Tap Rail
Dimensions
A780mm
B345mm
C450mm
D116mm Ø Min.
E185mm
(207mm for 80/125mm
flue systems)
F145mm
G131mm
H180mm

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6.0 System Details
© Baxi Heating UK Ltd 2011
6.1 Central Heating Circuit
1. The appliance is intended for fully pumped sealed systems.
However it can be installed in ‘semi-sealed’ systems also.
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.
6.2 Bypass
1. The boiler is fitted with an automatic integral bypass.
6.3 System Control
1. For optimum operating conditions, the heating system into
which the boiler is installed should include a control system.
2. Such a system will comprise of a timer control and separate
room or cylinder thermostats as appropriate.
3. The boiler should be controlled so that it operates on
demand only.
4. Operation of the system under control of the boiler
thermostat & TRV’s only does not produce the best results.

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6.0 System Details
© Baxi Heating UK Ltd 2011
Fig. 3
Filling Loop for
Sealed Systems
Fig. 4
Stop
Valve
Double
Check
Valve
Mains
Cold
Water
CH
Return
Temporary
Hose
Pressure Relief Valve
Discharge Pipe
Stop
Valve
6.4 System Filling and Pressurising
Sealed Systems
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. The filling method adopted must be in accordance with all
relevant water supply regulations and use approved equipment.
3. Your attention is drawn to the current edition of I.S. 813
“Domestic Gas Installations”.
4. 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.
‘Semi - Sealed’ Systems
1. ‘Semi - Sealed’ systems require the use of a suitable header
tank and ball cock arrangement to charge and provide
subsequent replenishment of the system.
2. The tank must be placed to provide sufficient head in order
to ensure a minimum system pressure of 0.2 bar.
3. A suitable non - return valve must be fitted in the pipework
between the header tank and heating system.
6.5 Expansion Vessel
1. The appliance expansion vessel is pre-charged to 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. Refer to BS 7074
Pt 1. For IE, the current edition of I.S. 813 “Domestic Gas
Installations”.
6.6 Safety Pressure Relief Valve (Fig. 4)
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
1/2” 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.
4, A remote relief valve kit is available to enable the boiler to
be installed in cellars or similar locations below outside ground
level (kit no. 5121379).
Fig. 3a
‘Semi-Sealed’
System
CH
Return
Header Tank
Non-Return
Valve

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7.0 Site Requirements
© Baxi Heating UK Ltd 2011
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
On position.
3. If the boiler is fitted in a room containing a bath or shower
reference must be made to the relevant requirements. 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. 5 & 6)
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.
*This is the MINIMUM recommended dimension. Greater
clearance will aid installation and maintenance.
150mm Min*
780mm
450mm
200mm Min
(300mm Min if
using 80/125mm
flueing system)
5mm Min
5mm Min
450mm Min
For Servicing
Purposes
Fig. 5
Fig. 6
In Operation
5mm Min
At least 1.5°

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7.0 Site Requirement
© Baxi Heating UK Ltd 2011
7.3 Ventilation of Compartments
1. Where the appliance is installed in a cupboard or
compartment, no air vents are required. 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 IE this is the current edition of I.S.
813 “Domestic Gas Installations”.
2. The connection to the appliance is a 3/4” copper tail
located at the rear of the gas service cock (Fig. 7).
3. Ensure that the pipework from the meter to the
appliance is of adequate size, and the demands of any
other gas appliances in the property are taken into
consideration. Do not use pipes of a smaller diameter than
the boiler gas connection (3/4”).
7.5 Electrical Supply
1. External wiring must be correctly earthed, polarised and
in accordance with relevant regulations/rules. 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.
3. When the system includes an indirect domestic hot
water cylinder it is recommended that a cylinder
thermostat is used in conjunction with a 3 port 2 position
valve or 2 port zone valve.
7.6 Bath & Shower Rooms
1. If the boiler is fitted in a room containing a bath or
shower reference should be made to the current edition of
I.S. 813 “Domestic Gas Installations” and the current ETCI
rules.
Fig. 7
Gas Service Cock

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7.0 Site Requirements
© Baxi Heating UK Ltd 2011
7.7 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 & 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. It is advisable to keep the condensate pipe internal.
7. External runs greater than 3 metres or runs in cold areas
should use 32mm waste pipe.
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

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17
7.0 Site Requirements
© Baxi Heating UK Ltd 2011
7.8 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 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.
4. *Reduction to the boundary is possible down to 25mm
but the flue deflector kit (5111068) must be fitted.
IMPORTANT:
• Under car ports we recommend the use of the plume
displacement kit.
• The terminal position must ensure the safe and
nuisance - free dispersal of combustion products.
N
I
I
G
F
M
I
AAF
H
J,K
D
E
H
Likely flue positions requiring
a flue terminal guard
C
RA
I
J,K
I
L
S
B
T
U
Fig. 9
Fig. 8
300 min
Terminal
Assembly
Top View Rear Flue
Property Boundary Line
NOTE: The distance from a fanned draught appliance terminal
installed parallel to a boundary may not be less than 300mm in
accordance with the diagram below
Opening Window
or Door
150mm
MIN.
IMPORTANT: If fitting a Plume
Displacement Flue Kit, the air inlet
must be a minimum of 150mm from
any opening windows or doors (see
Section 9.0).
Plume
Displacement Kit
Air Inlet
Fig. 10
*
Terminal Position with Minimum Distance (Fig. 9) (mm)
A1Directly below an opening, air brick, opening
windows, etc. 300
B1Above an opening, air brick, opening window etc. 300
C1Horizontally to an opening, air brick, opening window etc. 300
D2Below gutters, soil pipes or drain pipes. 25
E2Below eaves. 25
F2Below balconies or car port roof. 25
G2From a vertical drain pipe or soil pipe. 25
H2From an internal or external corner. 25
IAbove ground, roof or balcony level. 300
JFrom a surface or boundary line facing a terminal. 600
KFrom a terminal facing a terminal (Horizontal flue). 1200
From a terminal facing a terminal (Vertical flue). 600
LFrom 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
T Adjacent to windows or openings on pitched and flat roofs 600
U Below windows or openings on pitched roofs 2000
1In 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.
2Only ONE 25mm clearance is allowed per installation. If one of the dimensions
D, E, F, G or H is 25mm then the remainder MUST be as B.S.5440-1.

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18
8.0 Flue Options
© Baxi Heating UK Ltd 2011
Horizontal
Flues
(ii)
(i)
Plume Displacement 60 /100 dia Kit
1M Extensions 45° & 93° elbows
are also available - see Section 9.0
Plume Displacement.
8.1 Horizontal Flue Systems
1. The standard flue is suitable only for horizontal
termination applications.
2. All fittings should be fully engaged. The approximate
engagement is 40mm. Apply soap solution to the seal on
each fitting to aid assembly.
3. Maximum permissible equivalent flue lengths are:-
(60/100)
Horizontal Concentric (15/18 models) 15 metres
(60/100)
Horizontal Concentric (24/28/32 models) 10 metres
(80/125)
Horizontal Concentric (all) 20 metres
4. Any additional “in line” bends in the flue system must be
taken into consideration.
Their equivalent lengths are:-
Concentric Pipes:
135° bend 0.5 metres
93° bend 1.0 metres
Twin Flue Pipe
135° bend 0.25 metres
91.5° bend 0.50 metres
The elbow supplied with the standard horizontal telescopic
flue kit is not included in any equivalent length calculations
NOTE: Flue length is measured from point (i) to (ii) as
shown.
IMPORTANT: All flue systems must be securely
supported at least once every metre. Suitable pipe
supports are available as accessories.
NOTE: Horizontal flue pipes should always be installed with a fall of at least 1.5°
from the terminal to allow condensate to run back to the boiler.
(ii)
(i)
This bend is equivalent to
1 metre
Total equivalent length =
A+B+C+(2x90°Bends)
B
AC
This bend is equivalent to
1 metre

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19
8.0 Flue Options
© Baxi Heating UK Ltd 2011
Vertical
Flues
Vertical
Flues
(Twin Pipe)
(ii)
(i)
(ii)
(i)
8.2 Twin & Vertical Flue Systems
1. Maximum permissible equivalent flue lengths are:-
(60/100) (80/125)
Vertical Concentric 10 metres 20 metres
Vertical Twin Pipe 15 metres
2. Any additional “in line” bends in the flue system must be
taken into consideration.
Their equivalent lengths are:-
Concentric Pipes:
135° bend 0.5 metres
93° bend 1.0 metres
Twin Flue Pipe
135° bend 0.25 metres
91.5° bend 0.50 metres
The elbow supplied with the standard horizontal telescopic
flue kit is not included in any equivalent length calculations
NOTE: Flue length is measured from point (i) to (ii) as
shown.
The total equivalent length for this example is
= 6.5 metres.
1m extension
135°bend
91.5°bend
1m
0.25m
0.5m
5
2
2
5.0m
0.5m
1.0m
AIR DUCT
Noof
fittings/pipes
Sub total
Equivalent
Length Value
Equivalent Length Air Duct = 6.5m
1m extension
135°bend
91.5°bend
1m
0.25m
0.5m
5
2
2
5.0m
0.5m
1.0m
FLUE DUCT
Noof
fittings/pipes
Sub total
Equivalent
Length Value
Equivalent Length Flue Duct = 6.5m
(ii)
(i)
C
Roof
Terminal
A
B
660mm
This bend is equivalent to
1 metre
Total Equivalent Length =
A+B+C+1x90°Bend
All vertical and angled runs must be included,
measured from the boiler adaptor (point i) to the
joint with the flue terminal (point ii). One 91.5°
bend or two 135° bends can be included without
reduction of the flue length.
If further elbows are required the flue length must
be reduced by the following amounts:-
1 metre for each 91.5° bend
0.5 metre for each 45° bend
1m Min to
15m Max
120mm Min
apart
Y
1m Min
to
15m Max
600mm Min
apart
Mini Terminal
on Air Duct
(sited in loft)
Q
T
IMPORTANT: All flue systems must be securely
supported at least once every metre. Suitable
pipe supports are available as accessories.

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20
8.0 Flue Options
© Baxi Heating UK Ltd 2011
Key Accessory Size Code No
FLUE GROUP A
Concentric Flue System 100mm diameter
A3 Telescopic Internal Flue Kit 315-500mm 5119654
A2 Telescopic Flue (incl elbow) 5118069
A Horizontal Flue Terminal (incl elbow) 5118489
B Flue Extension 1000mm 5111074
C Flue Bend 93° 5111075
D Flue Bend (pair) 135° 5111085
U Pipe Support (painted) 100mmØ 5111080
R Vertical Flue Adaptor 5111070
P Wall Liner 5111067
S Flue Terminal Deflector 5111068
FLUE GROUP N
Twin Flue System 80mm diameter
E Flue Extension (pair) 1000mm 5111087
F Flue Bend (pair) 90° 5111072
G Flue Bend (2 pair) 135° 5111086
J Vertical Flue Boiler Adaptor Kit 720089801
H Vertical Flue Adaptor 5111084
W Pipe Support (pair) 80mm 5111081
Y Flue Termination Kit
(horizontal termination) 80mm 5120172
Z Single Terminal 80mm 5121791
Q Adaptor 60/80 5121792
T Pitched Roof Terminal 25°/45° 5106164
FLUE GROUP G
Flue System 80/125mm diameter
A4 Horizontal Flue Kit 5118580
B Straight Extension Kit 1000mm 5118584
D Bend Kit (pair) 135° 5118597
C Bend 91.5° 5118588
U Pipe support 125mm 5118610
FLUE GROUP A, N, G
Vertical Flue Kits
K Vertical Flue Terminal (use with 5111070) 5111078
K1 Vertical Flue Terminal 5118576
L Pitch Roof Flashing 25°/45° 246141
Pitch Roof Flashing 35°/55° 246142
M Roof Cover Plate 246143
N Flat Roof Flashing 246144
A
B
K,K1
R
D
C
N
U,W
S
L
H
J
M
E
GF
P
8.3 ‘MULTIFIT’ Flue Accessories
A2
A3
A4
QT
Y,Z