Baxi Combi 105 HE Release note

© Baxi Heating UK Limited 2005
Baxi Combi 105 HE
Gas Fired Wall Mounted
Condensing Combination Boiler
Installation & Servicing Instructions
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
Baxi Combi 105 HE
G.C.No47 075 18
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Benchmark Logbook is being withdrawn.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.
Potterton 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.
Legislation 4
1.0 Introduction 5
2.0 General Layout 6
3.0 Appliance Operation 7
4.0 Technical Data 8
5.0 Dimensions and Fixings 9
6.0 System Details 10
7.0 Site Requirements 13
8.0 Installation 19
9.0 Commissioning the Boiler 24
10.0 Completion 26
11.0 Servicing the Boiler 27
12.0 Changing Components 29
13.0 Illustrated Wiring Diagram 39
14.0 Fault Finding 40
15.0 Short Parts List 45
Benchmark Checklist 46
Section Page
Contents
© 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
The code of practice for the installation,
commissioning & servicing of central
heating systems.
“Baxi” supports

© Baxi Heating UK Limited 2005
Baxi Combi 105 HE
Gas Fired Wall Mounted
Condensing Combination Boiler
User’s Operating Instructions
Please keep these instructions safe.
Should you move house, please hand
them over to the next occupier.

2© Baxi Heating UK Limited 2005
Natural Gas
Baxi Combi 105 HE
G.C.No47 075 18
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 0051.
Product/Production certified by:
Notified Body 0086.
For GB/IE only.
Where fitted, user label for
optional timer to be applied here
Warranty
heateam the service division of Baxi Heating UK Limited provide a
12 month free warranty for your peace of mind. Once your boiler is
registered with us and in the unlikely event your boiler develops a
fault and your installer is unable to assist, heateam will provide a
free service to you provided the boiler is under 15 months old.
Otherwise heateam will offer a competitive fixed price repair rate
including parts, labour and VAT. To arrange an engineer visit either in
warranty or out, please call heateam on 08706 096 096. It
would help if you had your boiler serial number when you call, the
serial number is shown on the back cover of this guide.
Annual Service
To ensure you receive the maximum efficiency from your boiler we
recommend your boiler has an annual service so you and your family
can continue to enjoy heating and hot water comfort. To arrange an
annual service from one of our Baxi Heating UK Limited heating
experts, please call heateam on 08706 096 096 to arrange a
visit convenient to you.
Benchmark Commissioning Check List
Please ensure that your installer hands you the boiler Installation &
Service Instructions with the “Benchmark” Commissioning Checklist
sections completed. The details in the Checklist will be required in
the event of any warranty work. Keep the instructions in a safe place
and ensure that the Service Interval Record at the back is completed
at each service visit.
12 Months Free Warranty - register today
To receive your 12 months free warranty please complete the form
supplied with the boiler or simply call heateam, the service division
of Baxi Heating UK Limited on 08706 000 653.
© 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
The code of practice for the installation,
commissioning & servicing of central
heating systems.
“Baxi” supports

Legislation
3
© Baxi Heating UK Limited 2005
Codes of Practice, most recent version should be used
IMPORTANT - Installation, Commissioning, Service & Repair
This appliance must be installed in accordance with the manufacturer’s instructions and
the regulations in force. Read the instructions fully before installing or using the
appliance.
In GB, this must be carried out by a competent person as stated in the Gas Safety
(Installation & Use) Regulations.
Definition of competence: A person who works for a CORGI registered company and
holding current certificates in the relevant ACS modules, is deemed competent.
In IE, this must be carried out by a competent person as stated in I.S. 813 “Domestic
Gas Installations”.
Lifting - This product should be lifted and handled by two people. Stooping should be
avoided and protective equipment worn where necessary. Carrying & lifting equipment
should be used as required, e.g. when installing in a loft space.
The addition of anything that may interfere with the normal operation of the appliance
without express written permission from the manufacturer or his agent could invalidate
the appliance warranty. In GB this could also infringe the Gas Safety (Installation and
Use) Regulations.
Warning - Check the information on the data plate is compatible with local supply
conditions.
Benchmark Commissioning Checklist
Please ensure that your installer hands you the boiler Installation & Servicing
Instructions with the Benchmark Commissioning Checklist sections completed. The
details in the Checklist will be required in the event of any warranty work. Keep the
instructions in a safe place and ensure that the Service Interval Record at the back is
completed at each service visit.
All CORGI registered installers carry a CORGI identification card and have a
registration number. You can check your installer is registered by telephoning
0870 4012300 or writing to:-
1 Elmwood,
Chineham Business Park,
Crockford Lane,
Basingstoke. RG24 8WG
or check online at www.corgi-gas-safety.com
Baxi declare that no substances harmful to health are
contained in the appliance or used during appliance
manufacture.
The appliance is suitable only for installation in GB and IE and
should be installed in accordance with the rules in force, and
only used in a suitably ventilated location.
In GB, the installation must be carried out by a CORGI
Registered Installer. It must be carried out in accordance with
the relevant requirements of the:
• Gas Safety (Installation & Use) Regulations.
• The appropriate Building Regulations either The
Building Regulations, The Building Regulations
(Scotland), Building Regulations (Northern Ireland).
• The Water Fittings Regulations or Water Byelaws in
Scotland.
• The Current I.E.E. Wiring Regulations.
Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
In IE, the installation must be carried out by a competent
Person and installed in accordance with the current edition of
I.S. 813 ‘Domestic Gas Installations’, the current Building
Regulations and reference should be made to the current ETCI
rules for electrical installation.
All systems must be thoroughly flushed and treated with
inhibitor.
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.

1.0 Warnings
4© Baxi Heating UK Limited 2005
Gas Tap
Heating Flow, Heating
Return and Mains Water
Inlet
Isolating Valves
Fig. 1
Fig. 2
1.1 In an Emergency
If a water or gas leak occurs or is suspected, the boiler
can be isolated at the inlet valves as follows;
1. Turn off the electrical supply and turn the selector
switch on the facia box to the OFF position.
2. Using a suitable open ended spanner or screwdriver
turn the square on the gas tap to the left to isolate the
gas supply at the boiler (Fig. 1).
3. The isolating valves are positioned under the boiler
and can be closed by turning their taps to the right
towards the wall (Fig. 2).
4. Call your Installer or Service Engineer as soon as
possible.
1.2 In case of gas leaks
1. If a gas leak is found or suspected, turn off the gas
supply at the meter immediately and at the isolating
valve on the boiler if possible. Contact your Gas
Supplier immediately.
1.3 Servicing your Appliance
1. For reasons of safety and economy your appliance
should be serviced annually. Servicing must be
performed by a competent person. Your Installer or
Service Engineer will be able to advise you.
2. Any purpose provided ventilation should be checked
periodically to ensure that it is free from obstruction.
1.4 Electricity Supply
1. THIS APPLIANCE MUST BE EARTHED.
2. A standard 230V ~ 50Hz supply is required. The
appliance must be protected by a 3 amp fuse.
Never Hang Flammable Items Over The Appliance

2.0 Introduction
5
© Baxi Heating UK Limited 2005
2.1 Introduction
1. Your Baxi Combi 105 HE is a gas fired, room sealed,
powered flue condensing combination boiler,
providing central heating for your home and mains fed
domestic hot water to taps and shower. It is fully
automatic and does not have a pilot light. Boiler frost
protection and pump protection are integral features
of the appliance.
2. Priority is given to the hot water mode - when a
hot water tap is turned on the supply of heat to the
central heating circuit is interrupted.
3. Due to the high efficiency and resultant low flue gas
temperature when in condensing mode a white plume
of condensate will be emitted from the terminal. This
will be particularly evident during periods of low
outside temperature.
2.2 Facia Panel
1. The facia panel is behind the hinged lower door
panel. As well as the on/off/reset selector switch,
temperature control knobs and pressure gauge, the
facia incorporates ten neon indicator lights.
2. Neons 12 to 15 indicate the operational status of
the boiler. Neons 6 to 11 have a dual function,
indicating the temperature of the central heating water
when constantly illuminated. If a fault develops the
appropriate neon will begin to flash. Refer to Sections
3.3 to 3.7.
30o40o50o60o70o80o
Reset
Fig. 3
30o40o50o60o70o80o
1. On/Off/Reset Selector Switch
2. Central Heating Temperature Control
3. Hot Water Temperature Control
4. Central Heating System Pressure Gauge
5. Optional Integral Timer Position
Neon Indicators
6. Flame Failure or Blocked Condensate Drain
7. Safety Thermostat Activated (Boiler or Flue)
8. Fault on Fan or Flue
9. Fault on Pump or Low System Pressure
10. Fault on Hot Water Sensor
11. Fault on Central Heating Sensor
12. Power On
13. Domestic Hot Water Mode
14. Central Heating Mode
15. Burner On
When neons 6 to 11 are constantly illuminated, they
indicate the temperature of the central heating water
32145
6 7 8 9 10 11
12 13 14 15
KEY TO FACIA PANEL (Fig. 3)
Hinged Lower
Door Panel
Facia Panel

3.0 Operating the Boiler
6© Baxi Heating UK Limited 2005
3.1 Operating the Boiler
1. Ensure that the electricity and gas supplies are turned
on. Check that the central heating pressure is between 0.5
and 1.0 bar (Fig. 4).
2. Turn the On/Off/Reset selector switch either anti-
clockwise from the off position (Fig. 6) to both central
heating and domestic hot water or clockwise to domestic
hot water only.
3. In either position the green power on indicator
( ) will illuminate (Fig. 5).
4. Position (i) In this position the central heating will
operate according to demand or provide domestic hot
water when a tap or shower is turned on (Fig. 7). Priority
is given to domestic hot water. The central heating/hot
water neon ( ) will illuminate (Fig. 5). Neons 6 to 11
will illuminate as the temperature rises.
5. Position (ii) In this position hot water will be provided
when a tap or shower is turned on (Fig. 8). The hot water
neon ( ) will illuminate (Fig. 5).
6. The boiler will light automatically on demand.
7. The orange burner on neon ( ) will illuminate when
the boiler is operating and the main burner is on (Fig. 5).
IMPORTANT: When the selector switch is in the ‘0’
(Off) position the electrical supply to the boiler is
isolated. The boiler will not operate and the integral
timer (if fitted) will require resetting once the
selector switch is set to either Position (i) or
Position (ii).
30o40o50o60o70o80o
Reset
Reset
Reset
Position (ii)
(Hot Water)
Fig. 7
Fig. 8
Reset
OFF Position
Fig. 6
Fig. 5
Fig. 4
2
1
0
4
3
bar
Power On
Neon Burner On
Neon
Central Heating System
Pressure Gauge
Position (i)
(Central Heating or Hot Water)
On/Off/Reset
Selector Switch
Central
Heating Neon
Domestic
Hot Water
Neon
30o40o50o60o70o80o
6 7 8 9 10 11

3.0 Operating the Boiler
7
© Baxi Heating UK Limited 2005
3.2 Temperature Control
1. Central Heating: The central heating hot water flow
temperature can be adjusted between 30° C (± 5° C)
minimum and 85° C (± 5° C) maximum.
2. Turn the control knob clockwise to increase the
temperature (Fig. 9).
3. In normal winter usage we recommend that the
central heating temperature be set at maximum.
4. Domestic Hot Water: The temperature of the
domestic hot water can be adjusted by turning the
control knob clockwise to increase up to a maximum of
65° C (Fig. 10).
5. The temperature of the water is also dependent on
the water flow rate and the temperature of the mains
coming into the house.
6. By slightly reducing the flow from the tap the
temperature will increase up to the maximum if
required.
7. The flow rate can be reduced down to as low as 2.5
litre/min. The boiler will still recognise the need to heat
the water.
3.3 Flame Failure Reset
1. The red flame failure neon ( ) will illuminate in
the event of the burner failing to light, when incomplete
lighting of the burner occurs or blockage of the
condensate drain (Fig. 11).
2. Turn the selector switch fully anti-clockwise against
the spring pressure to the ‘Reset’ position for at least
two seconds and release (Fig. 12). Set the selector to
the required position to light the boiler.
3. If the flame failure light illuminates repeatedly a fault is
indicated with either the boiler, the gas supply or the
condensate drain. Your installer or Service Engineer
should be contacted as soon as possible.
3.4 Safety Thermostats
1. Your Baxi Combi 105 HE is fitted with additional
safety devices, which shut down the boiler in the event
of the system, the boiler or the flue overheating. The
safety thermostat neon ( ) will light in this instance
(Fig. 11).
2. To reset: Turn the selector fully anti-clockwise against
the spring pressure to the ‘Reset’ position for at least
two seconds and release (Fig. 12). Set the selector to
the required position to light the boiler.
3. If after turning the selector to the ‘Reset’ position the
boiler does not relight or the safety thermostat operates
repeatedly, causing boiler shutdown, a fault is indicated.
Your Installer or Service Engineer should be contacted
as soon as possible.
Reset
Domestic Hot Water
Temperature Control
Fig. 9
Central Heating
Temperature Control
Fig. 10
Reset Position
Fig. 12
30o40o50o60o70o80o
Flame Failure
Neon
Fig. 11
Safety Thermostat
Neon

3.0 Operating the Boiler
8© Baxi Heating UK Limited 2005
3.5 Air Flow Monitor
1. The boiler is fitted with an air pressure sensing device.
This monitors the flue system.
2. If the neon illuminates ( ) it indicates that the flue
or flue terminal is blocked or obstructed in some way,
or that there is an internal fault. If there is no external
blockage of the flue terminal that can be easily removed
contact your Installer or Service Engineer (Fig. 12).
3.6 Pump Fault or Low Pressure
1. The neon ( ) will illuminate if the circulating pump
is faulty or the system pressure drops below the
minimum requirement (Fig. 12).
2. Check the pressure gauge as described in Section 3.9.
If the pressure is in the normal range, a pump fault is
indicated. Contact your Installer or Service Engineer to
determine the nature of the fault.
3.7 Sensor Fault
1. When the ( ) or ( ) neon is illuminated a fault
on the hot water or central heating temperature sensor
is indicated (Fig. 12). Contact your Installer or Service
Engineer.
3.8 Pump Protection
1. With the selector switch in either Position (i) or
Position (ii) (Figs. 13 & 14) the pump will automatically
operate for 1 minute in every 24 hours to prevent
sticking.
30o40o50o60o70o80o
Air Flow
Monitor Neon
Pump/Low
Pressure Neon Sensor Fault
Neons
Reset
Reset
Fig. 12
Fig. 13
Fig. 14

3.0 Operating the Boiler
9
© Baxi Heating UK Limited 2005
3.9 Central Heating System Pressure
1. The water pressure in the central heating system is
indicated by the pressure gauge.
2. With the system cold and the boiler not operating the
pressure should be between 0.5 and 1.0 bar. During
operation the pressure should not exceed 2.5 bar, and
will normally be between 1.0 and 2.0 (Figs. 15 & 16).
3. A pressure of 3 or greater indicates a fault. The safety
pressure relief valve will operate, at a pressure of 3 (Fig.
17). It is important that your Installer or Service
Engineer is contacted as soon as possible.
4. The MINIMUM pressure for correct operation is 0.5. If
the pressure falls below 0.5, this may indicate a leak on
the central heating system (Fig. 18).
3.10 To Shut Off the Boiler
1. For short periods: Turn the selector switch to the OFF
position (Fig. 19).
2. For long periods: Turn off the selector switch (Fig.19),
electricity and gas supplies.
If your home is to be left unoccupied for long
periods during cold weather the boiler and whole
system should be drained unless there is additional
frost protection.
3. Your installer will advise you about frost protection and
draining the system.
IMPORTANT: When the selector switch is in the ‘0’
(Off) position the electrical supply to the boiler is
isolated. The boiler will not operate and the integral
timer (if fitted) will require resetting once the
selector switch is set to either Position (i) or
Position (ii).
3.11 Frost Protection Mode
1. The frost protection feature will operate when the
selector switch is in the central heating and domestic hot
water mode.
The gas and electrical supplies to the boiler must be on
and the system pressure must be within the range
described in Section 3.9.
2. If the system temperature falls below 5°C, then the
boiler will fire until the water temperature has been
raised.
3. Further frost protection can be incorporated by using a
frost thermostat to protect the whole system.
2
1
0
4
3
bar
2
1
0
4
3
bar
2
1
0
4
3
bar
2
1
0
4
3
bar
ON/OFF
Selector Switch
Reset
OFF Position
Fig. 19
Normal Pressure (when cold)
Normal Pressure (operating)
Fig. 15
Fault
Fig. 16
Below Minimum
Fig. 17
Fig. 18
Pressure Gauge

4.0 Clearances and Check List
10 © Baxi Heating UK Limited 2005
4.1 Clearances around the Boiler
(Figs. 20 & 21)
1. The minimum clear spaces needed around the boiler
measured from the casing are as follows:
Top - 200mm
Bottom - 200mm
Left Side - 5mm
Right Side - 20mm/5mm
Front - 5mm (In Operation)
- 450mm (For Servicing)
* NOTE: The boiler can be operated with a clearance
of 5mm at the right. This is also sufficient for routine
maintenance. However a clearance of 20mm is
required if it is necessary to remove the secondary
heat exchanger. This should be considered when
siting the appliance and in the event of any subsequent
alteration in the area of installation.
2. These areas must not be obstructed in any way, and
must be maintained during the regular operation of the
boiler and for routine maintenance. Blocking the
clearance spaces may result in the boiler overheating
and damage may occur.
3. The gas burning compartment of your boiler is
completely sealed from the room in which it is fitted.
Products from the combustion of gas are vented to the
outside through the flue terminal which must be kept
free from obstruction as this would interfere with the
correct operation of the boiler.
4. The boiler may be installed in a cupboard if these
minimum clearances are kept. The compartment should
be large enough to house the boiler and ancillary
equipment only.
5. IT SHOULD NOT BE USED AS A STORAGE
CUPBOARD.
4.2 Check List
1. If a fault develops, or is suspected, call your installer or
Service Engineer as soon as possible.
2. Go through the following check list before you make
contact.
a) Is the electricity supply on ?
b) Is the selector switch on (giving a green “Power ON”
neon) and set for both Central Heating and Domestic
Hot Water ?
c) Is the red “Flame Failure” neon lit ? Turn the
On/Off/Reset selector fully anti-clockwise.
d) Is the gas supply on ?
e) Is the mains water supply turned on ?
f) Is the system pressure correct ?
g) Are the boiler temperature controls set high enough ?
h) Is the time clock (if fitted) calling for central heating ?
i) Is the room thermostat (if fitted) set high enough ?
j) Are the radiator valves open ?
780mm
450mm
200mm Min
20mm/5mm Min
See * NOTE:
5mm Min
5mm Min
450mm Min
For Servicing
Purposes
Fig. 20
Fig. 21
In Operation
200mm Min

5.0 Care of the Boiler
11
© Baxi Heating UK Limited 2005
5.1 Cleaning the Outercase
The painted panels should be wiped with a damp cloth
and then dried completely. DO NOT USE ABRASIVE
CLEANING AGENTS.
5.2 Servicing and Repair of your Boiler
Servicing & Repairs of the boiler should only be
carried out by a CORGI Registered Installer or
other Competent Person
1. heateam can service and repair your boiler if your
installer is not able to.
2. In the unlikely event of a breakdown our
Baxi Heating UK Limited trained heating experts will
quickly get your heating and hot water working again. If
your boiler is out of its free 12 month warranty period,
heateam can provide a competitive fixed price repair
rate including parts, labour and VAT.
3. To find out more call heateam on 08706 096 096,
open Monday to Friday 8am - 6pm, weekends and bank
holidays 8.30am - 2pm, closed on Christmas and New
Years Day. An appointment convenient for you can be
arranged. It will help if you have your boiler serial
number when you call, the serial number is shown on
the back cover of this guide.
5.3 Spare Parts
1. Once outside the guarantee period any spare parts
may be obtained through approved Baxi Heating UK
Limited stockists if required.
2. Quote the boiler name, model number (found on the
reverse of the facia cover) and where possible the part
number when ordering spares. A short parts list is
included in the Installation and Servicing Instructions.
No Heating/HotWate r
User to check
fault diagnosis
Contact your installer
Installer unable
to rectify fault
Contact heateam
Important information
you need to arrange
an appointment:
- Product serial number
- ake and model
- Installer details
- Proof of purchase
Contact
heateam
08706 096 096
Installer contacts
Help-line

© Baxi Heating UK Limited 2005 Comp No5111810 - Iss 3 - 01/06
Label
Hinged Lower
Door Panel
Users Operating
Instruction Label
Baxi Heating UK Limited
Brownedge Road Bamber Bridge Preston Lancashire PR5 6UP
After Sales Service 08706 096 096 Technical Enquiries 08706 049 049
Website www.baxi.co.uk
company
Serial Number
Date of Installation
Installer Details (name, address and contact number(s)
Please complete the boxes below
heateam
heateam is the national customer service division of Baxi
Heating UK Limited providing a free warranty service within 12
months of installation of your boiler. If your installer is unable to
rectify your boiler fault, by contacting one of our friendly advisors
we can arrange an engineer if required.
When calling heateam it would be helpful if you could have the
following information to hand:
1 boiler serial number.
2 boiler make and model number.
3 Your installer name and address details.
4 Proof of purchase (if you do not have the boiler serial
number).
heateam will verify the boiler age via the serial number and offer
a free warranty service within 12 months of installation of the
boiler. If you are unable to provide this information or the boiler
has been installed for over 15 months, heateam will charge a
competitive rate for the repair. The engineer when visiting will
verify if the boiler is under the free 12 months warranty service, in
this case heateam will provide a full refund.
If you have contacted your installer and they are unable to assist
you at this time, please contact heateam.
heateam is open Monday to Friday 8am - 6pm, weekends and
bank holidays 8.30am - 2pm, closed on Christmas and New Years
Day.
Telephone [phone]*
* To aid in continuous improvement and staff training, calls
to this line may be monitored or recorded.
All descriptions and illustrations provided in this leaflet have been carefully
prepared but we reserve the right to make changes and improvements in our
products which may affect the accuracy of the information contained in this
leaflet. All goods are sold subject to our standard Conditions of Sale which are
available on request.
DDMYY
M

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 writen onto the
Benchmark Checklist
Scheme Members only
Call CORGI on: 0870 88 88 777
or log onto:
www.corgi-notify.com
within 10 days
If you notify via CORGI Scheme,
CORGI will then notify the
relevant Local Authority
Building Control Scheme
on member's behalf
Complete the
Benchmark Checklist
Install and Commission this
appliance to manufacturer's
instructions
Competent Person's
Self Certification Scheme Building Control

Legislation
4© Baxi Heating UK Limited 2005
Codes of Practice, most recent version should be used
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. Stooping should be
avoided and protective equipment worn where necessary. Carrying & lifting equipment
should be used as required, when installing in a loft space.
The addition of anything that may interfere with the normal operation of the appliance
without express written permission from the manufacturer or his agent could invalidate
the appliance warranty. In GB this could also infringe the Gas Safety (Installation and
Use) Regulations.
Warning - Check the information on the data plate is compatible with local supply
conditions.
Baxi declare that no substances harmful to health are
contained in the appliance or used during appliance
manufacture.
The appliance is suitable only for installation in GB and IE and
should be installed in accordance with the rules in force, and
only used in a suitably ventilated location.
In GB, the installation must be carried out by a CORGI
Registered Installer. It must be carried out in accordance with
the relevant requirements of the:
• Gas Safety (Installation & Use) Regulations.
• The appropriate Building Regulations either The
Building Regulations, The Building Regulations
(Scotland), Building Regulations (Northern Ireland).
• The Water Fittings Regulations or Water Byelaws in
Scotland.
• The Current I.E.E. Wiring Regulations.
Where no specific instructions are given, reference should be
made to the relevant British Standard Code of Practice.
In IE, the installation must be carried out by a competent
Person and installed in accordance with the current edition of
I.S. 813 ‘Domestic Gas Installations’, the current Building
Regulations and reference should be made to the current ETCI
rules for electrical installation.
All systems must be thoroughly flushed and treated with
inhibitor (see section 6.2).
In GB the following Codes of Practice apply:
Standard Scope
BS 6891 Gas Installation.
BS 5546 Installation of hot water supplies for
domestic purposes.
BS 5449 Forced circulation hot water systems.
BS 6798 Installation of gas fired hot water boilers.
BS 5440 Part 1 Flues.
BS 5440 Part 2 Ventilation.
BS 7074 Expansion vessels and ancillary equipment
for sealed water systems.
BS 7593 Treatment of water in domestic hot water
central heating systems.
In IE the following Codes of Practice apply:
Standard Scope
I.S. 813 Domestic Gas Installations.
The following 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.
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 0051.
Product/Production certified by:
Notified Body 0086.
For GB/IE only.

1.1 Description
1. The Baxi Combi 105 HE is a fully automatic gas fired
wall mounted condensing combination boiler. It is room
sealed and fan assisted, and will serve central heating and
mains fed domestic hot water.
2. The boiler is set to give a maximum output of
31.0 kW (condensing).
3. It is designed for use on Natural Gas (G20) and can be
converted to use Propane.
4. The boiler is suitable for use only on fully pumped
sealed heating systems. Priority is given to domestic hot
water.
5. The boiler data badge gives details of the model, serial
number and Gas Council number and is situated on the
control box. It is visible when the case front panel is
removed (Fig. 1).
6. The boiler is intended to be installed in residential /
commercial / light industrial E.M.C. environments on a
governed meter supply only.
7. The boiler must be installed with one of the purpose
designed flues such as the standard horizontal flue kit,
part no. 5111073.
8. All systems must be thoroughly flushed and treated
with inhibitor (see section 6.2).
1.2 Optional Extras
Various flue extensions, bends, vertical flue kits,
control accessories etc. are available as optional
extras. These are detailed in a separate publication.
1.0 Introduction
5
© Baxi Heating UK Limited 2005
Data Badge
Fig. 1
Control Box
Case Front Panel

2.0 General Layout
6© Baxi Heating UK Limited 2005
2.1 Layout
1. Air Pressure Switch
2. Expansion Vessel
3. Burner Manifold
4. Automatic Air Vent
5. DHW Plate Heat Exchanger
6. Circulation Pump
7. Drain Off Point
8. Pressure Relief Valve
9. Optional Integral Timer
10. Central Heating System Pressure Gauge
11. PCB
12. Control Box
13. 3-Way Valve Assembly
14. Condensate Trap
15. Flame Sensing Electrode
16. Spark Electrode
17. Burner
18. Primary Heat Exchanger
19. Fan Assembly
20. Secondary Heat Exchanger
21. On/Off/Reset Selector Switch
22. Central Heating Temperature Control
23. Hot Water Temperature Control
24. Flame Failure or Blocked Condensate Drain
25. Safety Thermostat Activated (Boiler or Flue)
26. Fault on Fan or Flue
27. Fault on Pump or Low System Pressure
28. Fault on Hot Water Sensor
29. Fault on Central Heating Sensor
30. Power On
31. Domestic Hot Water Mode
32. Central Heating Mode
33. Burner On
When neons 24 to 29 are constantly illuminated, they
indicate the temperature of the central heating water.
19
18
17
14
15
16
13
12 11
10 9
21 22 23 10 9
7
6
3
4
5
8
2
1
30o40o50o60o70o80o
Reset
30o40o50o60o70o80o
24 25 26 27 28 29
30 31 32 33
20

3.0 Appliance Operation
7
© Baxi Heating UK Limited 2005
NOTE: All delay timers mentioned in 3.1 and 3.2 are
overridden by domestic hot water demand.
3.1 Central Heating Mode (Fig. 2)
1. With a demand for heating, the pump circulates water
through the primary circuit. At a pre-determined flow
rate the central heating flow switch operates, initiating
the ignition sequence.
2. The main burner ignites at low rate, then the gas valve
controls the gas rate to maintain the heating
temperature measured by the temperature sensor.
3. When the flow temperature exceeds the setting
temperature, a 3 minute delay occurs before the burner
relights automatically (anti-cycling). The pump continues
to run during this period.
4. When the demand is satisfied the burner is
extinguished and the pump continues to run for a
period of 3 minutes (Pump Overrun).
3.2 Domestic Hot Water Mode (Fig. 3)
1. Priority is given to the domestic hot water supply. A
demand at a tap or shower will override any central
heating requirement.
2. The flow of water will operate the DHW flow switch
which requests the 3 way valve to change position. This
will allow the pump to circulate the primary water
through the DHW plate heat exchanger.
3. The burner will light automatically and the
temperature of the domestic hot water is controlled by
the temperature sensor.
4. When the domestic hot water demand ceases the
burner will extinguish and the diverter valve will remain
in the domestic hot water mode, unless there is a
demand for central heating.
IMPORTANT: When the selector switch is in the
‘0’ (Off) position the electrical supply to the boiler
is isolated. The boiler will not operate and the
integral timer (if fitted) will require resetting once
the selector switch is set to either Position (i) or
Position (ii).
3.3 Frost Protection Mode
1. The frost protection mode is integral to the appliance
and functions only with the selector switch (see Section
2.1) in the domestic hot water and central heating
position. If the system temperature falls below 5° C then
the boiler will fire on its minimum setting until a flow
temperature of 30° C is reached. Further protection can
be incorporated by using a system frost thermostat.
3.4 Pump Protection
1. With the selector switch (see Section 2.1) in either
the central heating or central heating and domestic hot
water position the pump will automatically operate for 1
minute in every 24 hours to prevent sticking.
1
2
4
5 6
7
8
9
10 11
1213141516
17
18
19
20
21
22
23
24
25
26
3
1 Primary Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Plate Heat Exchanger
9 Flow Sensor with Filter
10 Pressure Relief Valve
11 Boiler Drain Point
12 Heating Return
13 Cold Water Inlet On/Off Valve and Filter
14 Gas Inlet
15 Domestic Hot Water Outlet
16 Heating Flow
17 Pressure Gauge
18 Hydraulic Differential Pressure Sensor Microswitch
19 Automatic By-Pass
20 Hydraulic Differential Pressure Sensor
21 Diverter Valve Assembly
22 Domestic Hot Water Flow Priority Assembly
23 Domestic Hot Water Flow Priority Microswitch
24 Safety Thermostat
25 Central Heating Temperature Sensor
26 Expansion Vessel
27 Domestic Hot Water Temperature Sensor
28 Secondary Heat Exchanger
Key
Central Heating Circuit
Domestic Hot Water Circuit
Fig. 3
1
2
4
5 6
7
8
9
10 11
1213141516
17
18
19
20
21
22
23
24
25
26
3
Fig. 2
27
27
28
28

4.0 Technical Data
8© Baxi Heating UK Limited 2005
4.1 Combi 105 HE
Flue Terminal Diameter 100mm
Dimensions Projection 125mm
Outercase Dimensions
Casing Height - 780mm
Overall Height Inc Flue
Elbow - 965mm
Casing Width - 450mm
Casing Depth - 345mm
Clearances
Above Casing 200 mm Min
Below Casing 200 mm Min
Front 450 mm Min (For Servicing)
Front 5 mm Min (In Operation)
L.H. Side 5 mm Min
R.H. Side 5 mm Min (In Operation)
20mm Min (See Note*)
*NOTE: The boiler can be operated with a
clearance of 5mm at the right. This is also
sufficient for routine maintenance. However a
clearance of 20mm is required if it is necessary to
remove the secondary heat exchanger. This
should be considered when siting the appliance
and in the event of any subsequent alterations in
the area of installation
Weights kg
Packaged Boiler Carton 54
Installation Lift Weight 44
Central Heating Primary Circuit
Pressures
bar
Safety Discharge 3
Max Operating 2.5
Min Operating 0.5
Recommend Operating 1-2
DHW Circuit bar
Pressures
Max Operating 8
Min Operating 0.2
Min Operating Pressure
at 13.2 l/min 0.96
Flow Rates l/min
DHW Flow Rate
@ 30°C Rise 14.1
DHW Flow Rate
@ 35°C Rise 12.1
Min Working
DHW Flow Rate 2.5
Pump
Available Head See graph below
Expansion Vessel - (For Central Heating
only. Integral with appliance)
bar
Min Pre-charge Pressure 0.5
litre
Max Capacity of
CH System 125
Primary Water Content 1.2
of Boiler (unpressurised)
Connections copper tails
Gas Supply - 22mm
Central Heating Flow - 22mm
Central Heating Return - 22mm
Cold Water Mains Inlet - 15mm
DHW Flow - 15mm
Pressure Relief Discharge - 15mm
Temperatures
C.H. Flow Temp (adjustable)
35°C to 85°C max (± 5°C)
D.H.W. Flow Temp (adjustable)
35°C to 65°C max (± 5°C)
dependent upon flow rate
Heat Input CH
Max Min
kW 30.5 11.9
Heat Output CH (Non-Condensing)
Max Min
kW 29.6 11
Electrical Supply 230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption 180W
External Fuse Rating 3A
Internal Fuse Rating
Fuse 2A Fast Blow to BS 4265
Appliance Category CAT II 2H 3P
Inlet Pressure (Natural Gas - G20)
mbar 20
Burner Injector (Natural Gas - G20)
15 x 1.25mm Diameter
Burner Pressure (Natural Gas - G20)
Max Rate Min Rate
mbar 12.1 ± 0.5 2.1 ± 0.2
Appliance Type C12 C32
NOxClass 3
Electrical Protection IPX5D
This value is used in the UK Government’s Standard Assessment
Procedure (SAP) for energy rating of dwellings. The test data from
which it has been calculated have been certified by 0051.
SEDBUK Declaration For Combi 105 HE
The seasonal efficiency (SEDBUK) is 87.3% (89.4% LPG)
Band B
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
4.5
LPG Propane - G31
Burner Injector 15 x 0.77mm diameter
Burner Pressure
Propane mbar
Inlet Pressures
mbar
Max Rate
32.3 ± 0.5
Min Rate
5.2 ± 0.2
37
Heat Output CH (Condensing)
Max Min
kW 31 11.3
Heat Input DHW
Max
kW 30.5
Heat Output DHW
Max
kW 29.6
Condensate Drain 1” BSP
Max Gas Rate (Natural Gas - G20)
(After 10 mins)
m3/h 3.22