Baxi Combi 105 HE Operation instructions

© Baxi Heating UK Ltd 2007
Baxi Combi 105 HE
Gas Fired Wall Mounted
Condensing Combination Boiler
User’s Operating Instructions &
Important Warranty Information
Please keep these instructions in a safe place.
If you move house, please hand them over to the next occupier.

2© Baxi Heating UK Ltd 2007
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
© Baxi Heating UK Ltd 2007 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, 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 Ltd 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 Ltd 2007
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
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 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 Ltd 2007
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. Using a suitable open ended spanner, turn the square
nut on the gas tap through 90° (1/4turn) in a clockwise
direction to isolate the gas supply at the boiler (Fig. 1).
2. The isolating valves are positioned under the boiler
and can be closed by turning their taps to the right
towards the wall (Fig. 2).
3. 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 Ltd 2007
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 Ltd 2007
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 Ltd 2007
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 Ltd 2007
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 Ltd 2007
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 Ltd 2007
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 Ltd 2007
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 Spare Parts
1. Once outside the guarantee period any spare parts
may be obtained through approved Baxi Heating UK Ltd
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.

© Baxi Heating UK Ltd 2007 Comp No5111810 - Iss 5 - 3/07
Label
Hinged Lower
Door Panel
Users Operating
Instruction Label
9.0 Warranty & Service
BAXI
A Trading Division of Baxi Heating UK Ltd
Brooks House, Coventry Road, Warwick. CV34 4LL
After Sales Service 08700 60 30 60 Technical Enquiries 08706 049 049
Website www.baxi.co.uk
e&oe
company
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.
Serial Number
Date of Installation
Installer Details (name, address and contact number(s))
Please complete the boxes below
DDMYY
M
Standard Warranty Term & Conditions
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 of Baxi Heating UK Ltd on
08706 000 653.
Our promise to you
If you experience a fault with your new boiler, we aim to provide a safe and
high quality repair service supported by our dedicated national network of
highly skilled engineers. If your installer can’t resolve the problem for you, we
will do everything we can to get an engineer out to you as quickly as possible.
Nothing in this warranty will affect your statutory consumer rights.
What you need to do if you experience a problem with your heating system
or the operation of the boiler
You should always contact your installer first, because the fault may not be
related to the boiler. If your installer confirms that the fault is within the boiler
it self and he/she can’t repair it, our friendly customer service team is on hand
to help. Simply call our service division heateam on 08700 60 30 60 to book
an engineer visit or for any general advice that you may need. Our contact
centre is open Monday to Friday 8am - 6pm, weekends and Bank Holidays
8.30am - 2pm, excluding Christmas Day and New Years Day.
When calling heateam it would be helpful if you could have the following
information to hand:-
1 boiler serial number (see opposite).
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).
What this warranty covers
Free of charge repair or replacement of components found to be faulty from
manufacture.
Free of charge replacement of the complete unit provided always that the
failure is related to a manufacturing fault that cannot be repaired or is
uneconomic to repair.
The warranty runs for 12 months from the date your product is installed.
What this warranty does not cover
Repairs to boilers which haven’t been installed and commissioned properly,
and as set out in the installation instructions (this includes the need to flush the
system effectively and add a suitable corrosion inhibitor).
Any damage caused by hard water scale deposits and/or aggressive water
resulting from corrosion.
Any other defects or failures, either in the connected heating system or
outside of the boiler itself.
Faults caused by inadequate supply of electricity, gas or water to the property.
Installations within commercial settings for which this boiler was not designed.
Reimbursement of any third party repair or replacement costs that we haven’t
been told about or agreed with you in advance.
Compensation for consequential losses (e.g. loss of earnings, business losses,
stress and inconvenience) arising from a production breakdown, including
repair delays caused by factors outside our reasonable control.
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 Ltd heating experts, please call to arrange a
visit convenient to you.