Baxi Combi 105 He Quick Start Guide 5111809 Install

2014-11-12

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Baxi Combi 105 HE

Gas Fired Wall Mounted

Condensing 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 Ltd 2011

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.

The Health & Safety Executive operates the ‘Gas Safe Register’, a

self-certification scheme for gas heating appliances.

These arrangements represent a change from the situation whereby

compliance with Building Regulations was accepted as being

demonstrated by completion of the Benchmark Logbook (which was

then left on site with the customer).

With the introduction of Self Certification Schemes, the Benchmark

Logbook is being withdrawn. However, a similar document in the form

of a commissioning checklist and service interval record is incorporated

at the back of these instructions.

This company is a member of the Benchmark initiative and fully supports

the aims of the programme. Its aim is to improve the standards of

installation and commissioning of central heating systems in the UK and

to encourage the regular servicing of all central heating systems to

ensure safety and efficiency.

Building Regulations require that installations should comply with

manufacturer's instructions. It is therefore important that the

commissioning checklist is completed by the installer. The relevant

section of Building Regulations only relates to dwellings. Therefore the

checklist only applies if the appliance is being installed in a dwelling or

some related structure.

The flowchart opposite gives guidance for installers on the process

necessary to ensure compliance with Building Regulations.

Legislation 4

1.0 Introduction 6

2.0 General Layout 7

3.0 Appliance Operation 8

4.0 Technical Data 9

5.0 Dimensions and Fixings 10

6.0 System Details 11

7.0 Site Requirements 14

8.0 Flue Options 18

9.0 Plume Displacement 23

10.0 Installation 27

11.0 Commissioning the Boiler 32

12.0 Completion 34

13.0 Servicing the Boiler 35

14.0 Changing Components 37

15.0 Illustrated Wiring Diagram 47

16.0 Fault Finding 48

17.0 Short Parts List 53

Benchmark Checklist 54

Section Page

Contents

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,

Brooks House, Coventry Road, Warwick. CV34 4LL

Full acknowledgement of author and source must be given.

WARNING: Any person who does any unauthorised act in relation to a copyright work may be liable to

criminal prosecution and civil claims for damages.

0086

ISO 9001

FM 00866

The Benchmark Scheme

Benchmark places responsibilities on both manufacturers and installers. The

purpose is to ensure that customers are provided with the correct equipment for

their needs, that it is installed, commissioned and serviced in accordance with the

manufacturer’s instructions by competent persons and that it meets the

requirements of the appropriate Building Regulations. The Benchmark Checklist

can be used to demonstrate compliance with Building Regulations and should be

provided to the customer for future reference.

Installers are required to carry out installation, commissioning and servicing work

in accordance with the Benchmark Code of Practice which is available from the

Heating and Hotwater Industry Council who manage and promote the Scheme.

Visit www.centralheating.co.uk for more information.

Installer Notification Guidelines

Choose Building

Regulations Notification

Route

Contact your relevant Local

Authority Building Control

(LABC) who will arrange

an inspection or contact

a government approved

inspector

LABC will record the data

and will issue a

certificate of compliance

‘Gas Safe Register’ will issue a

Building Regulations Compliance

Certificate to the property owner

and inform the relevant LABC

You must ensure that the

certificate number issued by

the ‘Gas Safe Register’ is written

onto the Benchmark Checklist

Scheme Members only

Call ‘Gas Safe Register’ on:

0800 408 5577

or log onto:

www.GasSafeRegister.co.uk

within 10 days

If you notify via the ‘Gas Safe

the Building Regulations

certificate on members’ behalf

Complete the

Benchmark Checklist

Install and Commission this

appliance to manufacturer's

instructions

Competent Person's

Self Certification Scheme

Building Control

Complete the

Benchmark Checklist

Install and Commission this

appliance to manufacturer's

instructions

Legislation

4© Baxi Heating UK Ltd 2011

IMPORTANT - Installation, Commissioning, Service & Repair

This appliance must be installed in accordance with the manufacturer’s instructions and

the regulations in force. Read the instructions fully before installing or using the

appliance.

In GB, this must be carried out by a competent person as stated in the Gas Safety

(Installation & Use) Regulations.

Definition of competence: A person who works for a Gas Safe registered company

and holding current certificates in the relevant ACS modules, is deemed competent.

In IE, this must be carried out by a competent person as stated in I.S. 813 “Domestic

Gas Installations”.

The addition of anything that may interfere with the normal operation of the appliance

without express written permission from the manufacturer or his agent could invalidate

the appliance warranty. In GB this could also infringe the Gas Safety (Installation and

Use) Regulations.

Warning - Check the information on the data plate is compatible with local supply

conditions.

This company declare that no substances harmful to health

are contained in the appliance or used during appliance

manufacture.

The appliance is suitable only for installation in GB and IE and

should be installed in accordance with the rules in force, and

only used in a suitably ventilated location.

In GB, the installation must be carried out by a Gas Safe

Registered Installer. It must be carried out in accordance with

the relevant requirements of the:

• Gas Safety (Installation & Use) Regulations.

• The appropriate Building Regulations either The

Building Regulations, The Building Regulations

(Scotland), Building Regulations (Northern Ireland).

• The Water Fittings Regulations or Water Byelaws in

Scotland.

• The Current I.E.E. Wiring Regulations.

Where no specific instructions are given, reference should be

made to the relevant British Standard Code of Practice.

In IE, the installation must be carried out by a competent

Person and installed in accordance with the current edition of

I.S. 813 ‘Domestic Gas Installations’, the current Building

Regulations and reference should be made to the current ETCI

rules for electrical installation.

All systems must be thoroughly flushed and treated with

inhibitor (see section 6.2).

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 Bodies 0051 & 0086.

For GB/IE only.

All Gas Safe registered engineers carry an ID card with their licence number and a

photograph. You can check your engineer is registered by telephoning

0800 408 5500 or online at www.gassaferegister.co.uk

Codes of Practice - refer to the most recent version

In GB the following Codes of Practice apply:

Standard Scope

BS 6891 Gas Installation.

BS 5546 Installation of hot water supplies for domestic

purposes.

BS EN 12828 Heating systems in buildings.

BS EN 14336 Installation & commissioning of water based

heating systems.

BS 6798 Installation of gas fired hot water boilers.

BS 5440 Part 1 Flues.

BS 5440 Part 2 Ventilation.

BS 7074 Expansion vessels and ancillary equipment for

sealed water systems.

BS 7593 Treatment of water in domestic hot water

central heating systems.

In IE the following Codes of Practice apply:

Standard Scope

I.S. 813 Domestic Gas Installations.

The following 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.

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 !!

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. 5118489.

8. All systems must be thoroughly flushed and treated

with inhibitor (see section 6.2).

1.0 Introduction

6© Baxi Heating UK Ltd 2011

Data Badge

Fig. 1

Control Box

Case Front Panel

2.0 General Layout

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.

12 11

10 9

21 22 23 10 9

30o40o50o60o70o80o

Reset

bar

30o40o50o60o70o80o

24 25 26 27 28 29

30 31 32 33

3.0 Appliance Operation

8© Baxi Heating UK Ltd 2011

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.

5 6

1213141516

1 Primary Heat Exchanger

2 Burner

3 Ignition Electrode

4 Flame Sensing Electrode

5 Gas Valve

6Pump

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

5 6

1213141516

Fig. 2

4.0 Technical Data

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)

30°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 C52

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

200 400 600 800 1000 1200

0.5

1.5

2.5

3.5

Metre (wg)

Flow Rate (l/h)

Pump - Available Head

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

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

5.0 Dimensions and Fixings

10 © Baxi Heating UK Ltd 2011

Dimensions

A780mm

B345mm

C450mm

D116mm Ø Min.

E185mm

F190mm

G131mm

360° Orientation

Flue Ø 100mm

Domestic Hot

Water Outlet

(15mm)

Cold Water

Inlet

(15mm)

Heating

Return

(22mm)

Heating

Flow

(22mm)

Pressure Relief

Valve

(15mm)

Gas

Inlet

(22mm)

65 mm 65 mm 65 mm 65 mm 65 mm

Tap Rail

At least 1.5o

28mm

Condensate

Drain

6.0 System Details

6.1 Information

1. The Baxi Combi 105 HE Condensing Combination Boiler is

‘Water Byelaws Scheme - Approved Products’.

To comply with the Water Byelaws your attention is drawn to

the following installation requirements and notes (IRN).

a) IRN 001 - See text of entry for installation

requirements and notes.

b) IRN 302 - Byelaw 14.

2. Reference to the WRc publications, ‘Water fittings and

materials directory’ and ‘Water supply byelaws guide’ give full

details of byelaws and the IRNs.

6.2 Central Heating Circuit

1. The appliance is suitable for fully pumped SEALED

SYSTEMS ONLY.

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.

6.3 Bypass

1. The boiler is fitted with an automatic integral bypass.

6.4 System Control

1. The boiler is designed for use in a heating system that

incorporates external controls, i.e. a minimum of a timer

device.

2. Suitable timer kits are available as optional extras.

3. For optimum operating conditions and maximum

economy the fitting of a programmable room thermostat,

is recommended.

6.0 System Details

12 © Baxi Heating UK Ltd 2011

6.5 System Filling and Pressurising

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. There are connection points on the mains cold water

inlet and central heating return isolating taps (Fig. 5) to

which the optional filling loop kit (Part No. 248221) can

be assembled.

3. The filling method adopted must be in accordance with

all relevant water supply regulations and use approved

equipment.

4. Your attention is drawn to,

for GB: guidance G24.2 and recommendation R24.2 of

the Water Regulations Guide.

for IE: the current edition of I.S. 813. “Domestic Gas

Installations”.

5. 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.

6.6 Expansion Vessel

(Central Heating only)

1. The appliance expansion vessel is pre-charged to 0.5

bar. Therefore, the minimum cold fill pressure is 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. For GB refer to

BS 7074 Pt 1. For IE, the current edition of

I.S. 813 “Domestic Gas Installations”.

6.7 Pressure Relief Valve (Fig. 6)

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.

2. The pressure relief discharge pipe should be not less

than 15mm 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. 4

Fig. 6

Stop

Valve

Double

Check

Valve

DHW

Mains

Inlet

Return

Temporary

Hose

Pressure Relief Valve Discharge Pipe

Filling Loop

Fig. 5

Stop

Valve

6.0 System Details

6.8 Domestic Hot Water Circuit (Fig. 7)

1. All DHW circuits, connections, fittings, etc. should be

fully in accordance with relevant standards and water

supply regulations.

2. Your attention is drawn to:

for GB: Guidance G17 to G24 and recommendation R17

to R24 of the Water Regulations Guide.

for IE: the current edition of I.S. 813. “domestic Gas

Installations”.

3. The Water Regulations recommendations for England

and Wales prohibits backflow from appliances into the

wholesome water supply due to thermal expansion.

However this type of instantaneous combination boiler,

with less than 15 litres of stored capacity, does not

require any backflow prevention device as any thermal

expansion is accommodated within the appliance.

It is possible in certain circumstances that other cold

water demands (e.g. washing machines, flushing of W.C.s)

may affect the DHW function of the boiler. In these

instances the fitting of a backflow prevention device and

expansion vessel is recommended.

4. Also if there is an existing check valve, loose jumpered

stop cock, water meter or water treatment device

already fitted to the wholesome water supply connected

to the boiler domestic hot water (DHW) inlet supply

then a suitable expansion device may be required.

5. The boiler’s maximum working mains pressure is 8 bar,

therefore all pipework, connections, fittings, etc. should

be suitable for pressures in excess of 8 bar. A pressure

reducing valve must be fitted for pressures in excess of 8

bar. The manufacturer of any outlet fittings, such as a

shower valve, may require a lower maximum pressure.

The pressure reduction must take account of all fittings

connected to the DHW system.

6.9 Showers

1. If a shower control is supplied from the appliance it

should be of the thermostatic or pressure balanced type.

Thermostatic type shower valves provide the best

comfort and guard against water at too high a

temperature. Existing controls may not be suitable - refer

to the shower valve manufacturer.

6.10 Hard Water Areas

1. If the area of the installation is recognised as a HARD

WATER AREA then a suitable device should be fitted to

treat the mains water supply to the boiler. Contact your

Water Distribution Company for advice on suitable

devices.

Boiler

Other Tap

Outlets

Expansion

Vessel*

To Hot

Taps

Check

Valve*

Pressure Reducer

Valve*

Stop Tap

Fig. 7

*See 6.8 for instances when

these items may be required

7.0 Site Requirements

14 © 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 domestic hot water and central heating position to

give frost protection.

3. If the boiler is fitted in a room containing a bath or

shower reference must be made to the relevant

requirements.

In GB this is the current I.E.E. Wiring Regulations and

Building Regulations.

In IE reference should be made to the current edition of

I.S. 813 “Domestic Gas Installations” and the current ETCI

rules.

4. If the boiler is to be fitted into a building of timber frame

construction then reference must be made to the current

edition of Institute of Gas Engineers Publication IGE/UP/7

(Gas Installations in Timber Framed Housing).

7.2 Clearances (Figs. 8 & 9)

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, access during routine

maintenance 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.

* 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.

200mm Min

780mm

450mm

200mm Min

20mm/5mm Min

See * NOTE:

5mm Min

450mm Min

For Servicing

Purposes

Fig. 8

Fig. 9

In Operation

7.0 Site Requirements

7.3 Ventilation of Compartments

1. Where the appliance is installed in a cupboard or

compartment, no air vents are required.

2. BS 5440: Part 2 Clause 4.2 refers to room sealed

appliances installed in compartments. 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 GB this is BS 6891. In IE this is the

current edition of I.S. 813 “Domestic Gas Installations”.

2. The connection to the appliance is a 22mm copper

tail located at the rear of the gas service cock (Fig. 10).

3. Ensure that the pipework from the meter to the

appliance is of adequate size. Do not use pipes of a

smaller diameter than the boiler gas connection

(22mm).

7.5 Electrical Supply

1. External wiring must be correctly earthed, polarised

and in accordance with relevant regulations/rules. In GB

this is the current I.E.e. Wiring Regulations. In IE

reference should be made to the current edition of

ETCI rules.

2. The mains supply is 230V ~ 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.

Fig. 10

Gas Service Cock

7.0 Site Requirements

16 © Baxi Heating UK Ltd 2011

7.6 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 terminates in a 1” BSP nut and seal

for the connection of 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

External termination to a drain or gully

Boiler

500mm min

2.5° Minimum fall

External termination to a purpose made soak-away

Holes in the soak-away must

face away from the building

50mm per metre of pipe run

7.0 Site Requirements

7.7 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 GB recommendations

are given in BS 5440 Pt 1. For IE recommendations are given

in the current edition of I.S. 813 “Domestic Gas

Installations”.

2. If the terminal discharges onto a pathway or passageway,

check that combustion products will not cause a nuisance

and that the terminal will not obstruct the passageway.

3. 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 (part no. 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.

AAF

J,K

Likely flue positions requiring

a flue terminal guard

J,K

Fig. 11

Fig. 12

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. 12a

Terminal Position with Minimum Distance (Fig. 11) (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

I Above ground, roof or balcony level. 300

J From a surface or boundary line facing a terminal. 600

K From a terminal facing a terminal (Horizontal flue). 1200

From a terminal facing a terminal (Vertical flue). 600

L From an opening in carport (e.g. door, window)

into the dwelling. 1200

M Vertically from a terminal on the same wall. 1500

N Horizontally from a terminal on the same wall. 300

R From adjacent wall to flue (vertical only). 300

S From an adjacent opening window (vertical only). 1000

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.

8.0 Flue Options

18 © Baxi Heating UK Ltd 2011

8.1 Horizontal Flue Systems

1. The standard flue is suitable only for horizontal

applications.

2. Maximum permissible equivalent flue lengths are:-

Horizontal Concentric 3m

3. 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 flue is

not included in any equivalent length calculations.

NOTE: Flue length is measured from point X to Y

as shown.

IMPORTANT: All flue systems must be securely

supported at least once every metre. Suitable pipe

supports are available as accessories.

Horizontal

Flues

Plume Displacement Kit 60 /100 Ø

1M Extensions, 45° & 93° elbows

are also available - see Section 9.0

NOTE: Horizontal flue pipes should always be installed with at least a 1.5° fall

from the terminal to allow condensate to run back to the boiler.

This bend is equivalent to

1 metre

Total equivalent length =

A+B+C+2x90°Bends

This bend is equivalent to

1 metre

8.0 Flue Options

Vertical

Flues

(Twin Pipe)

Vertical

Flues

The total equivalent length for this example is

= 6.5 metres.

1m extension

135°bend

91.5°bend

0.25m

0.5m

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

0.25m

0.5m

5.0m

0.5m

1.0m

FLUE DUCT

Noof

fittings/pipes Sub total

Equivalent

Length Value

Equivalent Length Flue Duct = 6.5m

Roof

Terminal

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 X) to the

joint with the flue terminal (point Y). 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 135° bend

8.2 Twin & Vertical Flue Systems

1. Maximum permissible equivalent flue lengths are:-

Vertical Concentric 3m

Vertical Twin Pipe 12m*

* Both the air and flue duct can be up to 12 metres

long each.

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 flue is

not included in any equivalent length calculations

NOTE: Flue length is measured from point X to Y

as shown.

IMPORTANT: All flue systems must be securely

supported at least once every metre. Suitable pipe

supports are available as accessories.

8.0 Flue Options

20 © 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) 100mm 5111080

R Vertical flue adaptor (use with 5111078) 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 5111079

H Vertical flue adaptor 5111084

W Pipe support (pair) 80mm 5111081

FLUE GROUP A, N,

Vertical Flue Kits

K Vertical flue terminal (use with 5111070) 5111078

K1 Vertical flue terminal 5118576

L Lead tile 25°/50° 5122151

M Roof cover plate 246143

N Flat roof flashing 246144

K, K1

U,W

8.3 Flue Accessories

8.0 Flue Options

For Twin Flue Systems fit the adaptors as follows:-

8.4 Flue Duct Adaptor

1. Engage the flue duct adaptor on the boiler adaptor,

making sure that it is pushed down as far as possible.

8.5 Air duct adaptor

1. Undo the screws securing the blanking plate to the boiler

top panel. Discard the plate.

2. There are three restrictor plates supplied in the kit. One

marked ‘23’ and one marked ‘27’, which can be discarded.

The third restrictor MUST be positioned as shown in the

diagram below.

3. Take one of the gaskets supplied in the kit and place on

the boiler top panel.

4. Align the appropriate restrictor as shown. Position the

second gasket over the restrictor.

5. Using the screws previously removed secure the inlet

adaptor to the top panel.

6. Continue to fit the twin flue system.

Flue Duct Adaptor

Boiler Adaptor

Air Duct Adaptor

Gasket

Restrictor

Gasket

Position of Restrictor

Blanking Plate

8.0 Flue Options

22 © Baxi Heating UK Ltd 2011

Fig. 13

Fig. 14

100mm 685mm

Push Fit Adaptor

Air Duct

Flue Duct

Cut the same

amount off the

Air Duct &

Flue Duct

Approx

1425mm

8.6 For Roof Terminals

1. In the case of a pitched roof 25 - 50 degrees, position the lead

tile to replace/flash over existing roof tiling. Make an aperture in

the roof suitable for the lower tube of the roof terminal and

ensure the integrity of the roof cover is maintained. The

adjustable plastic collar can either be positioned on the lead tile

or the lower tube of the roof terminal prior to the final

positioning of the vertical flue through the tile. Check the collar is

correctly located to suit required roof pitch (either 25° to 38° or

37° to 50°). From inside the roof adjust the flue to a vertical

position and secure to the roof structure with the clamp supplied.

2. For flat roof installations the aluminium flashing must be

incorporated into the roof covering and the appropriate aperture

made in the roof decking. The vertical flue is lowered onto the

flashing making sure the collar of the flue locates securely with the

flashing. (A mastic seal may be necessary). From inside the roof,

adjust the flue to a vertical position and secure to the roof

structure with the clamp supplied.

8.7 Flue Dimensions

The standard horizontal flue kit allows for flue lengths between

100mm and 685mm from elbow to terminal (Fig. 13).

The maximum permissible equivalent flue length is: 3 metres

NOTE: Each additional 45° of flue bend will account for an

equivalent flue length of 0.5m.

eg. 45° = 0.5m, 90° = 2 x 45° = 1m etc.

8.8 Flue Trim

1. The rubber flue trim supplied may be fitted to either the

outside wall or on the inner wall of installation.

8.9 Terminal Guard (Fig. 14)

1. When codes of practice dictate the use of terminal guards, they

can be obtained from most Plumbers’ and Builders’ Merchants.

2. There must be a clearance of at least 50mm between any part

of the terminal and the guard.

3. When ordering a terminal guard, quote the appliance name and

model number.

4. The flue terminal guard should be positioned centrally over the

terminal and fixed as illustrated.

8.10 Flue Deflector (Fig. 13a)

1. If required a flue deflector is available from your Baxi stockist.

2. Push the flue deflector over the terminal end and rotate to the

optimum angle for deflecting plume. Secure the deflector to the

terminal with screws provided.

Flue Deflector

Fig. 13a

9.0 Plume Displacement

9.1 Plume Displacement Kit (Fig. 14b)

Kit No 5118638

Content of kit

1 0.9m 60/100 Concentric Flue

1 1m 60 Dia Exhaust Flue Pipe

1 Adaptor

2 60 Dia Support Brackets

1 93° Elbow/Plume Outlet Assembly

1 Flexible Flue Trim

3 “O” Rings

1 ‘Jubilee Clip

1 Boiler Elbow

1. This kit is recommended for installations where the

condensate plume emitted from the flue may cause a nuisance

or affect the surroundings.

2. The terminal must be positioned outside the building with

the air inlet facing downward and outlet connection upwards.

3. The plume outlet must always be at least 45° to the wall,

with the ‘peak’ uppermost to prevent rain entry (Figs. 15 &

16), and be at least 2 metres above ground level. It must be

secured as shown in Fig. 12a. The plume outlet must also be

at least 500mm from the air inlet in any direction (Fig. 16).

NOTE: The outlet must be positioned so that any

condensate plume is directed away from adjacent surfaces.

There must be a constant fall along the entire length of the

flue system from the outlet back to the boiler.

4. It is possible to reduce or increase (with the addition of

extensions) the length of either or both the 60/100 concentric

and 60Ø exhaust.

5. Standard concentric flue extension kits may be added

between the boiler elbow and the terminal assembly.

6. The minimum length of the concentric flue is 100mm when

measured from the edge of the flue elbow.

IMPORTANT: The maximum equivalent length of

concentric flue is:- 1.5 metres

Additional bends may be fitted in the concentric flue, but

the equivalent length must be reduced by 1 metre (93°

elbow) or 0.5 metres (45° elbow).

7. 60Ø 1 metre extensions (including support bracket), and

additional 93° & 45° elbows are available. Any additional 93°

& 45° elbows must be accounted for when calculating flue

lengths.

NOTE: Permitted positions of the plume outlet relative to

doors, windows etc. are the same as for conventional

concentric flues as detailed in the main Installation &

Servicing Instructions and BS5440 Pt. 1. It is NOT

necessary to fit a terminal guard over the air inlet or the

plume outlet.

Air Inlet at Bottom

‘Peak’ Uppermost

Fig. 15

Fig. 16

500mm Min.

45°

Outlet must be at

least 45° from

wall face

93° Elbow/Plume

Outlet Assembly

60Ø Exhaust

Flue Pipe

60Ø Support

Bracket

60Ø Support

Bracket

Flexible Flue

Trim

60/100Ø

Concentric Flue

Adaptor

O Ring

‘Jubilee’ Clip

0.9 metres

Fig. 14b

Fig. 14a

Elbow

9.0 Plume Displacement

24 © Baxi Heating UK Ltd 2011

Concentric 60/100 Flue

60Ø Exhaust

Fig. 17

60 Ø Exhaust (metres) X

Concentric 60/100 Flue (metres) Y

105 HE

Fig. 18

60 Ø Exhaust (metres) X

Concentric 60/100 Flue (metres) Y

105 HE

60 Ø Exhaust (metres) X

Concentric 60/100 Flue (metres) Y

105 HE

Flue Length - Worked Example

Baxi Combi 105 HE

In Fig. 18 opposite an additional 93° elbow has been included

in the 60Ø exhaust. with 2 x 1metre extensions which have

been cut to 0.25metres and fitted. The waste is discarded.

To calculate total length:-

2 x 0.25 metre Lengths = 0.5 metres

1 x 93° Elbow = 1 metre

Total 60Ø Exhaust = 1.5 metres

After consulting the table in Example 3 it can be determined

that the concentric flue could be up to approximately 0.5

metres long.

Concentric Flue

Support

Bracket

93° Elbow

Extension

Additional Accessories

A - 93° Elbow 5117381

B - 45° Elbow (Pair) 5117382

C - 1 metre 60Ø Extension 5117380

9.2 Determining Permissible Lengths

In the graph the solid line diagonal represents the

relationship between the concentric flue assembly (and any

extensions) and the 60Ø exhaust (and any extensions or

additional bends).

Example 1 - Not Permissible

If, for instance, a concentric length of 1.25 metres was

required and the 60Ø exhaust needed to be 1 metres the

graph shows that this combination would NOT be

permissible as the intersection point would be above the

solid diagonal line.

Example 2 - Flue Lengths OK

Where both lengths have been determined they can be

applied to the graph to check that the installation is

permissible. For example, if it was known that 0.5 metres of

concentric flue and 1 metre of 60Ø exhaust were required,

the values could be applied to the graph as shown in

Example 2.. As the point of intersection of the dotted lines is

below the solid diagonal line, the combination of lengths is

shown to be acceptable.

Example 3 - Flue Lengths OK

In the example shown, assume that the concentric part of

the flue needs to be 1 metres long. Find the position of ‘1’ on

the horizontal axis of the graph and then project upwards to

the solid diagonal line. This is represented by the vertical

thick dotted line. Where this dotted line intersects with the

solid diagonal line on the graph, project across to the vertical

axis. As can be seen this corresponds with 1 metres.

Therefore, the total equivalent length of the 60Ø exhaust

can be up to 1 metres. Any elbow equivalences must be

accounted for i.e. 93° elbows are equal to 1 metre, each 45°

elbow to 0.5 metres.

Example 1

Flue Lengths - Not Permissible

Example 2

Flue Lengths - OK

Example 3

Flue Lengths - OK

9.0 Plume Displacement

Min. 2 metres

Fig. 19

Fig. 24

30mm

Fig. 21

Fig. 23

Fig. 22

Adaptor

50mm

Flue Trim

Position of ‘Jubilee’ Clip

screw

Fig. 20

Spigot

9.3 General Fitting Notes

1. Cut a hole in the external wall which the concentric flue

assembly will pass through. The hole should allow the flue

to fall back to the boiler at an angle of at least 1.5°.

2. When completed the terminal must be at least 2 metres

above ground level (Fig. 19).

3. Measure and cut to size the concentric assembly and any

extensions that are being used.

4. Insert the concentric assembly through the hole from

outside the building.

5. If required, the flexible flue trim should be fitted prior to

this as it cannot be fitted after. Use the large ‘Jubilee’ clip to

secure the trim to the flue (See Fig. 20, trim shown

dotted), with the screw part of the clip at the bottom.

6. Connect any extensions or elbows that are being used

to the concentric assembly. Engage the extension, elbow

or concentric assembly in the boiler flue elbow. Fit the

boiler flue elbow to the boiler adaptor.

7. Ensure that the concentric assembly and any extensions

fall back to the boiler at an angle of at least 1.5° and that

the external air inlet is to the bottom.

8. Use suitable brackets to support the concentric

assembly and any extensions, and make good inside and

outside.

9. The 60Ø exhaust can now be fitted. Slide the adaptor

over the plain end of the 60Ø exhaust (Fig. 22) and engage

the exhaust in the terminal. Slide the adaptor down over

the spigot. Mark and drill the adaptor, using a 2mm bit, as

shown in Fig. 21. Secure the adaptor to the spigot using

one of the screws supplied.

10. If it is necessary to shorten the 60Ø exhaust or any of

the extensions, the excess material must be cut from the

plain end of the pipe.

11. Determine the position of the 60Ø exhaust and mark

on the wall a suitable position for the support bracket. If

extensions are being used, a support bracket is supplied in

each kit.

12. Drill the wall, and fit the bracket(s) using the plug and

screw provided.

13. Mark and drill the 60Ø exhaust, using a 2mm bit, as

shown in Fig. 23. Complete the installation of the 60Ø

exhaust, securing in the brackets.

14. Fit the 93° elbow/plume outlet and secure with the

two remaining screws supplied. Ensure the plume outlet is

at least 45° to the wall and that the ‘peak’ is uppermost

(Fig. 24).

9.0 Plume Displacement

26 © Baxi Heating UK Ltd 2011

9.3 General Fitting Notes (cont.)

15. For aesthetic purposes it is permissible to route the

60Ø exhaust in an enclosed box, but the air inlet and

plume outlet MUST remain in free air.

16. It is also possible to separate the plume outlet from

the 93° elbow to allow the flue to be installed as shown

in Fig. 25.

17. To do this, first slacken the two screws retaining the

plume outlet to the elbow, and remove the outlet

(Fig. 26). The elbow can now be used to connect the

vertical to horizontal 60Ø exhaust (Fig. 25). Retighten

the screws in the elbow.

18. The outlet can now be fitted into the female end of

an 60Ø extension piece. It must be secured using two

of the screws supplied in the bag with the ‘Jubilee’ clip.

19. Mark the female end of the extension at 30mm as

shown in two positions, directly opposite each other

(Fig. 27).

20. Using a suitable bit (e.g. 2mm), drill through the

extension and outlet. Secure using two of the screws

supplied.

21. The remaining screw must be used to secure the

adaptor to the concentric terminal.

22. When the plume outlet is positioned under a

balcony or other projection (Fig. 28) it must protrude at

least 200mm (it is not necessary to extend it further

than this).

23. When under balconies or projections it is

permissible to rotate the concentric flue length up to

70°, clockwise or anti-clockwise (Fig. 29), if there is

insufficient space to connect vertically.

24.This will allow the connection of the exhaust to the

outlet spigot.

25. All other minimum & maximum dimensions must be

adhered to, and the air inlet positioned such that it will

not be subject to rain entry.

500mm Min.

200mm Min.

30mm

Fig. 26

Fig. 27

Fig. 25

Fig. 28

Plume Outlet Elbow

70°

Fig. 29

Outlet Spigot

Concentric Flue Length

(shown end-on)

10.0 Installation

10.1 Initial Preparation

The gas supply, gas type and pressure must be

checked for suitability before connection (see Section

7.4).

1. After considering the site requirements

(see Section 7.0) position the fixing template on the

wall ensuring it is level both horizontally and vertically.

2. Mark the position of the two most suitable fixing slots

for the wall plate and boiler lower fixing holes. It is

preferable to use the horizontal fixing slots.

3. Mark the position of the centre of the flue hole (rear

exit). For side flue exit, mark as shown (Fig. 30).

4. Note the shaded area on the template. Pipework

may be routed upwards behind the boiler, providing it

does not conflict with the shaded area.

5. If required, mark the position of the gas and water

pipes. Remove the template.

6. Cut the hole for the flue (minimum diameter

116mm).

7. Drill the wall as previously marked to accept the wall

plugs supplied. Secure the wall plate using the fixing

screws.

8. Using a spirit level ensure that the plate is level

before finally tightening the screws.

9. Connect the gas and water pipes to the valves on the

wall plate using the copper tails supplied. Ensure that

the sealing washers are fitted between the connections.

10.2 Flushing

1. Connect a tube to the central heating flow or return

pipe (Fig. 31).

2. Flush thoroughly (see System Details, Section 6.2).

10.3 Preparing The Boiler

1. Remove all packaging.

2. Stand the boiler on its base by using the rear lower

edge as a pivot.

NOTE: A small amount of water may drain from

the boiler in the upright position.

Fig. 30

Fig. 31

190mm

For Side Flue Exit

Central Heating Return

Flushing Tube Wall Plate

10.0 Installation

28 © Baxi Heating UK Ltd 2011

10.4 Fitting The Boiler

1. Remove the sealing caps from the boiler connections.

2. Lift the boiler using the lower edges. The boiler should

be lifted by TWO PEOPLE. Engage the slots at the top

rear of the boiler on the wall plate (Fig. 32). See ‘Safe

Manual Handling’ on page 5.

3. Insert the sealing washers between the valves and

pipes on the wall plate and the boiler connections. The

rubber washers must be used on the gas connection.

4. Tighten all the connections.

10.5 Fitting the Pressure Relief

Discharge Pipe (Fig. 33)

1. Remove the discharge pipe from the kit.

2. Determine the routing of the discharge pipe in the

vicinity of the boiler. Make up as much of the pipework as

is practical, including the discharge pipe supplied.

3. The pipework must be at least 15mm diameter and

run continuously downwards to a discharge point outside

the building. See section 6.7 for further details.

4. Utilising one of the sealing washers, connect the

discharge pipe to the adaptor and tighten the nut.

5. Complete the discharge pipework and route it to the

outside discharge point.

IMPORTANT: Make all soldered joints before

connecting to the pressure relief valve.

10.6 Condensate Drain (see section 7.6)

1. Connect the condensate drain using the 1” BSP nut

and seal supplied.

Ensure the discharge of condensate complies with any

national or local regulations in force (see British Gas

“Guidance Notes for the Installation of Domestic Gas

Condensing Boilers”.

2. The condensate outlet terminates in a 1” BSP nut and

seal for the connection of 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.

Fig. 33

Fig. 32

Pressure Relief Valve

Wall Plate

Discharge Pipe

Suggested Lifting Points

shown as shaded area

10.0 Installation

10.7 Fitting The Flue

HORIZONTAL FLUE

1. The standard flue is suitable for lengths between

100mm minimum and 685mm maximum, as measured

from the edge of the flue elbow outlet to the joint

between the terminal and air duct (Fig. 34).

2. Locate the flue elbow on the adaptor at the top of

the boiler. Set the elbow to the required orientation

(Fig. 35).

NOTE: The flue elbow is angled at 93 degrees to

ensure a fall back to the boiler.

3. Measure the distance from the outside wall face to

the elbow. This dimension will be known as ‘X’ (Fig. 36).

4. To dimension ‘X’ add 50mm. This dimension to be

known as ‘Y’.

IMPORTANT: Check all dimensions before cutting.

Wall Thickness

(X)

Wall Thickness

(X)

Fig. 36

Flue Elbow

Adaptor

Fig. 34

100mm 685mm

Fig. 35

10.0 Installation

30 © Baxi Heating UK Ltd 2011

10.7 Fitting the Flue (Cont)

5. Mark dimension ‘Y’ on the flue as shown (Fig. 37).

Carefully cut the waste material from the flue, ensuring

that the ducts are square and free from burrs.

6. The inner flue duct support bracket may be in the

waste portion of the flue. In this case retrieve the

bracket before discarding the waste.

7. Take the inner flue support bracket (if not already

fitted) and engage it over the flue duct. This will

centralise the flue and air ducts, and ease assembly

(Fig. 38).

8. Insert the flue through the hole in the wall. Fit the

elbow to the boiler adaptor, ensuring that it is pushed

fully in.

9. Draw the flue back through the wall and engage it in

the elbow. It may be necessary to use soap solution or

similar to ease assembly of the elbow adaptor and flue

(Fig. 39).

10. Make good between the wall and air duct outside

the building.

11. Fit the flue trim if required, and if necessary fit a

terminal guard (see Section 8.8 & 8.9).

VERTICAL FLUE

1. Only a flue approved with the Baxi Combi 105 HE

can be used.

Flue Elbow

Fig. 39

Inner Flue Support Bracket

Fig. 38

Flue

Waste

Fig. 37

10.0 Installation

10.8 Making The Electrical Connections

To connect the mains input cable proceed as follows:-

1. Slacken the facia securing screws and lift the

outercase panel so that its locating tabs are clear of the

facia. Remove the panel.

2. Completely undo the screws securing the facia panel

and hinge it down (Fig. 40).

3. Remove the control box cover securing screws.

Disengage the barbs on the control box from the

cover. Remove the cover (Fig. 41).

4. Slacken the cable clamp on the LH side of the boiler

chassis (Fig. 42). Insert the cable through the clamp and

route it to the terminal block.

5. Slacken the screws in the terminal block, connect

the input cable, and tighten the screws.

6. If an external control is to be connected it can be

done at this point. Run the input cable from the

external control through the second cable clamp on

the boiler chassis. Refer to the instructions supplied

with the control.

7. To connect external control(s) remove the link

between terminals 1 & 2. The 230V supply at terminal

1 must be connected to the external control. The

switched output from the external control must be

connected to terminal 2 (Fig. 43).

NOTE: If the room thermostat being used

incorporates an anticipator it MUST be wired as

shown in Fig. 43

IMPORTANT: The external control MUST be

suitable for 230V switching.

8. Ensure that both mains input and, where fitted,

external control input cables have sufficient slack to

allow the control box to drop down. Tighten the cable

clamp(s) on the boiler chassis.

9. If the optional integral timer is to be used it should

be fitted at this point. Refer to the instructions supplied

with the timer. NOTE: An external frost thermostat

cannot be used with the integral timer.

10.9 Preliminary Electrical Checks

1. Prior to commissioning the boiler preliminary

electrical system checks should be carried out.

2. These should be performed using a suitable meter,

and include checks for Ground Continuity,

Resistance to Ground, Short Circuit and Polarity.

Always fit fast

blow 2A fuse

Fused supply 3A

230V ~ 50Hz

Live (brown)

Neutral (blue)

Earth (green/yellow)

230V

g/y

Frost Thermostat

Room Thermostat

External Clock

230 V

Selector /

Reset Switch

External

Controls N

br b

Pump

Hydraulic Differential Pressure Switch

DHW Flow Priority Microswitch

Safety Overheat Thermostat

Flue Thermostat

Central Heating

NTC Sensor

Gas Valve

Spark Electrode

Condensate Trap

Flame Sensing Electrode

br b

Fan

Pressure Switch

PCB

DHW

NTC Sensor

Gas Valve Modulator

Fig. 42

Fig. 41

Fig. 43

Fig. 44

Fig. 40

Terminal Block

Fuse

Cable Clamp

Control Box Cover

Facia Panel

Functional Flow Diagram

Key to Wiring

b - blue

br - brown

bk - black

r - red

g - green

IMPORTANT: If an integral timer is fitted to the boiler

an external frost thermostat wired as shown will not

operate correctly. Only external timers may be used in

such installations, as in the diagram.

11.0 Commissioning the Boiler

32 © Baxi Heating UK Ltd 2011

11.1 Commissioning the Boiler

1. Reference should be made to BS 5449 Section 5

when commissioning the boiler.

2. At the time of commissioning, complete all relevant

sections of the Benchmark Checklist at the rear of this

publications.

3. Open the mains water supply to the boiler.

4. Open all hot water taps to purge the DHW system.

5. Ensure that the filling loop is connected and open,

then open the heating flow and return valves on the

boiler.

6. Open the screw on the automatic air vent (Fig. 45).

7. The system must be flushed in accordance with BS

7593 (see Section 6.2) and the flushing agent

manufacturers instructions.

8. Pressurise the system to 1.0 bar then close and

disconnect the filling loop.

9. Turn the gas supply on and purge according to in GB

BS 6891 and in IE I.S. 813 “Domestic Gas Installations”.

10. Test for gas soundness.

11. If at any time during commissioning it is required to

terminate a particular cycle, e.g. the pump overrun

period, turn the selector to the OFF position and then

back to either ( ) or ( ) (Fig. 47).

Automatic Air

Vent

Pressure Gauge

Screw

bar

Fig. 45

Selector Switch

Central Heating

Temperature Control

Hot Water

Temperature Control

Fig. 46

30o40o50o60o70o80o

Reset

bar

Pump

Fig. 47

Power On

Neon

11.0 Commissioning the Boiler

OUT

MIN

Pressure Test Point

Sealing Screw

Gas Valve

Fig. 48

Selector Switch

Central Heating

Temperature Control

Hot Water

Temperature Control

30o40o50o60o70o80o

Reset

bar

Fig. 51

Power On

Neon

Pressure Gauge

bar

Fig. 50

11.2 Checking the Burner Pressure

1. Turn on the gas and electrical supplies to the boiler

and ensure that all external controls are calling for heat.

2. Set the temperature controls to maximum and the

selector switch to the Off position (Fig. 51).

3. Slacken the pressure test point sealing screw on the

gas valve and connect a pressure gauge (Fig. 48).

4. Undo the screws securing the inner door panel. Lift

the panel slightly to disengage it from the studs on top

of the case.

5. Turn the selector switch fully anticlockwise against the

spring pressure to the reset position and hold for 2

seconds to reset the boiler (Fig. 51).

6. Turn the selector switch to the Cental Heating and

Domestic Hot Water position ( ). The power On

neon ( ) will illuminate (Fig. 51).

7. Turn a hot water tap on to give a flow rate of at least

10l/min.

8. The pressure should be :-

NG 12.1mbar

Propane 32.3mbar

If not, check that the gas supply pressure is correct

(Natural Gas 20mbar, and Propane 37mbar).

9. The pressure can be adjusted if required.

10. To check and set minimum pressure first remove

one of the modulator wires.

Adjusting the Pressure (Fig 49)

11. Remove the plastic protection cap from the

pressure adjustment nuts on the valve.

12. The smaller nut (5mm) adjusts minimum pressure

and the larger nut (8mm) maximum pressure.

13. Using a suitable spanner adjust the relevant nut until

the correct pressure is achieved.

14. Once the pressure has been set turn the boiler off

and disconnect the pressure gauge.

15. Tighten the pressure test screw and refit the

modulator to the valve. Reassemble in reverse order.

Fig. 49

Plastic

Protection

Cap

Modulator

Wire Maximum Rate

Adjustment Nut

Minimum Rate

Adjustment Nut

NOTE: Gas Valve Electrical

Plug/Igniter not shown for clarity.

12.0 Completion

34 © Baxi Heating UK Ltd 2011

12.1 Completion

1. Hinge the facia panel upwards and refit the case front

panel. Tighten the securing screws (Fig. 52).

2. Instruct the user in the operation of the boiler and

system, explaining the operational sequence.

3. Carefully read and complete all sections of the

Benchmark Commissioning Checklist at the rear of this

publication that are relevant to the appliance and

installation. These details will be required in the event of

any warranty work. The publication must be handed to

the user for safe keeping and each subsequent regular

service visit recorded.

4. For IE, it is necessary to complete a “Declaration of

Conformity” to indicate compliance with I.S. 813. An

example of this is given in I.S. 813 “Domestic Gas

Installations”. This is in addition to the Benchmark

Commissioning Checklist.

5. Hand over the Users Operating, Installation and

Servicing Instructions, giving advice on the necessity of

regular servicing.

Fig. 52

Facia Panel

Case Front Panel

13.0 Servicing the Boiler

13.1 Annual Servicing

1. For reasons of safety and economy, it is

recommended that the boiler is serviced annually.

Servicing must be performed by a competent person.

2. After servicing, complete the relevant Service Interval

Record section of the Benchmark Commissioning

Checklist at the rear of this publication.

3. Ensure that the boiler is cool.

4. Ensure that both the gas and electrical supplies to

the boiler are isolated.

5. Slacken the screws securing the facia panel. Lift the

outercase panel so that its securing tabs are clear of the

facia. Remove the panel (Fig. 53).

6. Remove the screws securing the inner door panel. Lift

the panel slightly to disengage it from the studs on top

of the case (Fig. 54).

7. Note the positions of the two sensing tubes on the

fan spigot and three wires on the fan motor and

remove them (Fig. 55).

8. Slacken the screws on the fan spigot outlet pipe

clamps. Ease the clamps inwards over the pipe.

9. Draw the outlet pipe away from the boiler.

10. Remove the four screws securing the combustion

box door and remove the door (Fig. 54).

Fan Wires Fan

Sensing

Tubes

Case Front Panel

Ease Fan Spigot Outlet

Pipe Clamps Inwards

Fig. 53

Facia Panel Securing

Screws

Fig. 54

Fig. 55

Inner Door

Panel

Combustion

Box Door

Fan Spigot

Outlet Pipe

13.0 Servicing the Boiler

36 © Baxi Heating UK Ltd 2011

13.1 Annual Servicing (Cont)

11. Ease the front edge of the left hand baffle upwards,

disengaging the spring clip. Disengage the tab on the

baffle from the slot in the fan hood (Fig. 56).

12. Undo the screws securing the fan and hood to the

appliance back panel. Draw the assembly forwards

(Fig. 57).

13. Undo the screws securing the burner to the injector

manifold. Draw the burner out of the combustion box,

pulling the electrode grommets from the slots in the

combustion box lower panel (Fig. 58).

14. Disconnect the electrode leads and grommets from

the electrodes. Completely remove the burner (Fig. 58).

15. Brush any deposits from the injectors. Do not use a

pin or wire to clean them.

16. Brush the burner blades and venturis and clean the

combustion box.

17. Ensure that the heat exchanger fins are clear of any

obstruction.

NOTE: If necessary the secondary heat exchanger

may be dismantled - see section 14.24.

DHW Filters (Fig. 60)

18. If the flow of domestic hot water is diminished, it

may be necessary to clean the filters.

19. Initially check the cold water inlet tap filter.

20. Turn the tap off. Undo the blanking cap and remove

the thread bush (Fig. 59).

21. Extract the filter and rinse thoroughly in clean water.

Reassemble and check the flow. If required clean the

manifold filter as described below.

22. Undo the filter cartridge from the inlet/return

manifold.

23. Dismantle the cartridge and carefully remove the

flow regulator and filter gauze. Rinse them thoroughly in

clean water and reassemble in reverse order.

24. Check that the pressure vessel charge is 0.5bar and

reassemble in reverse order of dismantling and

recommission.

25. Turn the selector switch fully anticlockwise against

the spring pressure to the reset position and hold for 2

seconds to reset the boiler.

26. Complete the relevant Service Interval Record

section of the Benchmark Commissioning Checklist at

the rear of this publication and then hand it back to the

user.

Spring Clip

Fan and Hood

Assembly

Baffle Tab

Burner

Electrode

Grommets

Fig. 56

Fig. 58

Fig. 57

Fig. 59

Threaded

Bush

Cold Water

Inlet Tap

Blanking Cap

Cartridge

Body

Filter Gauze

Flow

Regulator

Venturi

Inlet/Return Manifold

Fig. 60

14.0 Changing Components

IMPORTANT: When changing components ensure

that both the gas and electrical supplies to the

boiler are isolated before any work is started.

When the new component has been fitted turn the

selector switch fully anticlockwise against the spring

pressure to the ‘Reset’ position and hold for 2

seconds to reset the boiler before recommissioning.

See Section 13.1 “Annual Servicing” for removal of case

panel, door etc.

14.1 Fan (Figs. 62 & 63)

1. Note the positions of the two sensing tubes on the

outlet elbow and three wires on the fan motor and

remove them.

2. Slacken the screws on the fan spigot outlet pipe

clamps. Ease the clamps inwards over the pipe.

3. Draw the outlet pipe away from the boiler.

4. Remove the four screws securing the combustion box

door and remove the door.

5. Ease the front edge of the left hand baffle upwards,

disengaging the spring clip. Disengage the tab on the

baffle from the slot in the fan hood.

6. Undo the screws securing the fan hood to the

appliance back panel, and draw the fan and hood

assembly forwards.

7. Remove the screws and spring washers securing the

fan to the hood.

8. Fit the new fan to the hood using the screws and

spring washers previously removed.

9. Reassemble in reverse order of dismantling.

14.2 Pressure Switch (Fig. 61)

1. Remove the fan as described in section 14.1.

2. Note the positions of the two sensing tubes and

three wires and remove them.

3. Remove the two screws holding the pressure switch

to the bracket on the combustion box top panel.

4. Fit the new pressure switch and reassemble all

components in reverse order of dismantling.

Fan Hood

Spring Washer

Securing Screw

Pressure

Switch

Sensing

Tubes

Pressure

Switch Wires

Fig. 61

Fan Wires Fan

Sensing

Tubes

Ease Fan Spigot Outlet

Pipe Clamps Inwards

Fig. 62

Fan Spigot

Outlet Pipe

Spring Clip

Baffle Tab

Fan

Fig. 63

14.0 Changing Components

38 © Baxi Heating UK Ltd 2011

14.3 Heat Exchanger (Fig. 64)

1. Remove the fan as described in section 14.1.

2. Drain the primary circuit. Prise the three pipe

connecting clips off the joints in the flow and return

pipes. Remove the heat exchanger return pipe.

3. Lift the heat exchanger to disconnect the flow pipe

joint. Withdraw it from the appliance, taking care not to

damage the rear insulation piece.

4. Fit the new heat exchanger.

5. Reassemble in reverse order of dismantling, and

repressurise the system.

14.4 Burner (Fig. 65)

1. Remove the four screws securing the combustion box

door and remove the door.

2. Undo the screws securing the burner to the injector

manifold. Draw the burner out of the combustion box,

pulling the electrode grommets from the slots in the

combustion box lower panel.

3. Disconnect the electrode leads and grommets from

the electrodes. Completely remove the burner.

4. Undo the screws securing the electrodes to the

burner. Examine the condition of the electrodes,

replacing if necessary. Fit the electrodes to the new

burner.

5. Engage the burner location brackets over the studs on

the injector manifold and reassemble in reverse order.

Burner

Electrode

Grommets

Electrode

Leads

Electrodes

Fig. 64

Heat Exchanger

Pipe Connecting

Clips

Fig. 65

Flow Pipe

Heat Exchanger

Return Pipe

14.0 Changing Components

14.5 Injectors (Fig. 66)

1. Remove the burner as described in Section 14.4.

2. Undo the screws securing the injector manifold to

the inlet elbow and remove the manifold.

3. Unscrew and replace injectors as required and

examine the sealing gasket, replacing as necessary.

Reassemble in reverse order.

14.6 Electrodes (Fig. 66)

1. Remove the four screws securing the combustion

box door and remove the door.

2. Undo the screws securing the burner to the

injector manifold. Draw the burner out of the

combustion box, pulling the electrode grommets from

the slots in the combustion box lower panel.

3. Disconnect the lead and grommet from the

electrode being replaced. Undo the securing screw

and withdraw the electrode to the burner.

4. Reassemble in reverse order.

14.7 Insulation (Fig. 67)

1. Remove the four screws securing the combustion

box door and remove the door.

2. Slide the side insulation pieces carefully out of their

carriers.

3. To replace the rear insulation piece it is necessary

to remove the heat exchanger as described in Section

14.3 and slide out the side pieces.

4. The combustion box door insulation piece can be

replaced by carefully bending up the two retaining

tabs.

5. Replace all insulation pieces and reassemble in

reverse order.

13.8

Injector

Manifold Inlet Elbow

Gasket

Injector

Burner

Electrode

Grommets

Electrode

Leads

Side Insulation

Rear Insulation

Front Insulation

Combustion Box

Door

Side Insulation

Electrodes

Fig. 66

Fig. 67

14.0 Changing Components

14.8 Gas Valve (Fig. 68)

1. Undo the nut on the gas feed pipe under the boiler.

2. Completely undo the securing screws and hinge the

facia panel down.

3. Disconnect the wires from the valve modulator and

the ignition lead from the spark generator. Disconnect

the pressure sensing pipe from the valve. Undo the

screw securing the spark generator electrical plug to the

valve and disconnect the plug.

4. Pull the earth wire off the spade terminal on the valve.

5. Remove the screws securing the inlet pipe flange to

the boiler bottom panel and those securing the outlet

manifold to the burner manifold.

6. Remove the valve from the boiler.

7. Note the orientation of the inlet pipe and outlet

manifold. Undo the securing screws and remove the

pipe and manifold.

8. Examine the ‘O’ ring seals for damage, replacing as

necessary.

9. Fit the inlet pipe and outlet manifold to the new valve,

ensuring that the ‘O’ ring seals are in place.

10. Reassemble in reverse order and check the burner

pressure (Section 11.2).

14.9 Central Heating Temperature Sensor

(Fig. 69)

1. Ease the retaining tab on the sensor away and

disconnect the electrical plug.

2. Unscrew the sensor from it’s pocket and reassemble

in reverse order. The plug will only fit one way.

14.10 Safety Thermostat (Fig. 69)

1. Pull the electrical connections off the thermostat.

2. Remove the screws securing the thermostat to the

mounting plate on the flow pipe.

3. Reassemble in reverse order. The thermostat is not

polarised - either wire can fit either terminal on the

thermostat.

14.11 DHW Temperature Sensor (Fig. 70)

1. Turn off the mains water supply and draw off the

residual domestic hot water.

2. Ease the retaining tab on the sensor away and

disconnect the electrical plug.

3. Unscrew the sensor from the plate heat exchanger

manifold. Examine the sealing washer,replacing if

necessary.

4. Reassemble in reverse order. The plug will only fit one

way.

Gas Valve

Inlet Pipe

Gas Feed

Pipe

Electrical Plug

Central Heating

Temperature Sensor

Safety Thermostat

Flow Pipe

Fig. 68

Fig. 69

DHW Temperature

Sensor

Fig. 70

Plate Heat

Exchanger

Modulator

Wires

Ignition

Lead

Earth Wire

14.0 Changing Components

14.12 Pump - Head Only (Fig. 71)

1. Drain the primary circuit and remove the socket

head screws securing the pump head to the body and

draw the head away.

2. Undo the screw on the pump wiring cover and

remove the cover. Using a suitable flat bladed screw

driver press the cable securing levers downwards to

release each wire after noting their position.

3. A standard Grundfos 15-60 replacement head can

now be fitted. Connect the wiring to the new head.

The pump speed must be set to 3 (Fig. 72).

4. Reassemble in reverse order.

14.13 Pump - Complete (Fig. 73)

1. Drain the primary circuit and unscrew the automatic

air vent from the pump body. Undo the two screws

securing the body to the pipe and manifold and draw

the pump forwards.

2. Undo the screw on the pump wiring cover and

remove the cover. Using a suitable flat bladed screw

driver press the cable securing levers downwards to

release each wire after noting their position.

3. Connect the wiring to the new pump. Examine the

‘O’ ring seals on the return pipe and manifold, replacing

if necessary.

4. Fit the air vent to the pump body and reassemble in

reverse order.

14.14 Automatic Air Vent (Fig. 73)

1. Drain the primary circuit and unscrew the automatic

air vent from the pump body.

2. Examine the ‘O’ ring seal, replacing if necessary, and

fit it to the new automatic air vent.

3. Reassemble in reverse order.

Pump Setting

Pump Wiring

Cover

Socket Headed

Screw

Pump Head

Pump Body

Pump Wiring

Cover

Automatic Air

Vent

Fig. 71

Fig. 73

Fig. 72

14.0 Changing Components

14.15 Pressure Gauge (Figs. 74 & 75)

1. Drain the primary circuit and undo the nut on the

pressure gauge capillary.

2. Remove the timer cover and ease the timer wiring

aside. Undo the screws securing the gauge retaining

bracket.

3. Remove the bracket and gauge assembly. Depress

the barbs on the side of the gauge and remove the

retaining bracket.

4. Reassemble in reverse order.

14.16 Expansion Vessel (Fig. 76)

1. To replace the expansion vessel it is necessary to

remove the boiler from the wall.

Note: Alternatively a vessel of equivalent

capacity can be fitted on the system return

pipe as close as possible to the boiler.

2. Drain the system and undo all gas, water and

condensate drain connections. Remove the flue elbow.

3. Lift the boiler off the wall plate and lay it on it’s side

on a clean flat surface.

4. Undo the nut on the vessel outlet spigot, and

remove the locknut and spring washer securing the

spigot to the boiler chassis.

5. Undo the screws and remove the appliance upper

cross member. Slide the expansion vessel out of the

retaining clips.

6. Reassemble in reverse order. Fully recommission

the appliance and system.

14.17 Condensate Trap (Fig. 77)

1. Disconnect the two sensing wires from the trap

connections.

2. Squeeze together the wire spring clip to release and

ease the inlet pipe from the trap spigot.

3. Undo the nut securing the condensate drain pipe to

the trap. Disconnect the pipe and sealing washer.

4. From underneath the boiler remove the screws

securing the trap bracket.

5. Remove the trap and bracket from the boiler. Undo

the locknut securing the trap to the bracket.

6. Reassemble in reverse order.

Pressure Gauge

Timer Cover

Pressure Gauge

Capillary

Gauge Retaining

Bracket

Expansion Vessel

Retaining Clip

Vessel Outlet Spigot

Boiler Chassis

Lock Nut Spring

Washer

Fig. 74

Fig. 75

Fig. 76

Inlet Pipe

Sensing Wires

Condensate

Trap

Wire Spring

Clip

Bracket

Condensate

Drain Pipe

Fig. 77

14.0 Changing Components

14.18 Pressure Relief Valve (Fig. 78)

1. Drain the primary circuit.

2. Disconnect the discharge pipe from the valve. Using a

suitable hexagon key undo the grub screw sufficiently to

release the valve.

3. Note the orientation of the valve, rotate it and

withdraw it from the manifold.

4. Fit the new valve and ‘O’ ring seal and set to the

previously noted orientation. Reassemble in reverse

order.

14.19 P.C.B. (Fig. 80)

1. Note the settings of the temperature control knobs.

Rotate the knobs fully anticlockwise and carefully pull

them off the drive pins.

2. Completely undo the screws securing the control box

cover and release the cover retaining barbs from their

slots. Disengage the rear of the cover from the control

box hinge pin (Fig. 79).

3. Note the position of all plugs and wires on the P.C.B.

and disconnect them.

4. Undo the securing screws and remove the P.C.B.

Transfer the control knob drive pins to the new P.C.B.

and turn them fully anticlockwise.

5. Reassemble in reverse order, ensuring that the

temperature controllers are reset to their previous

positions.

14.20 Selector Switch (Fig. 80)

1. Note the setting of the selector switch knob and

carefully pull it off the facia.

2. Completely undo the screws securing the control box

cover and release the cover retaining barbs from their

slots. Disengage the rear of the cover from the control

box hinge pin (Fig. 79).

3. Note the position of the electrical connections and

the orientation of the switch. Remove the electrical

connections.

4. Remove the screws securing the switch to the facia

panel.

5. Fit the new switch, ensuring that it is correctly

positioned and reassemble in reverse order.

Pressure Relief Valve

Grub Screw

‘O’ ring seal

Discharge Pipe

Control Box Cover

P.C.B.

Selector

Switch

Facia

Selector Switch Knob

Temperature Control Knobs

Fig. 78

Fig. 79

Fig. 80

Drive Pins

14.0 Changing Components

14.21 Plate Heat Exchanger (Fig. 81)

1. Drain the primary circuit.

2. While supporting the heat exchanger undo the

screws securing it to the brass manifolds.

3. Withdraw the heat exchanger upwards and to the

left of the gas valve, taking care not to damage any

wires or controls.

Seals

4. There are four rubber seals between the manifolds

and heat exchanger which may need replacement.

5. Ease the seals out of the manifold. Replace carefully,

ensuring that the seal is inserted into the manifold

parallel and pushed fully in.

6. When fitting the new heat exchanger note that the

left hand location stud is offset towards the centre

more than the right hand one.

7. Reassemble in reverse order.

14.22 Diverter Valve Assembly

(Figs. 82 & 83)

The diverter valve assembly comprises of a central

heating pressure differential valve and a domestic hot

water pressure differential valve. These are connected

to a manifold which is joined to the plate heat

exchanger.

DHW Pressure Differential Valve (Fig. 83)

1. Drain the primary circuit.

2. Undo the screw securing the microswitch bracket to

the valve (Fig. 82).

3. Disconnect the two sensing pipes and slacken the

grub screws securing the valve to the diverter manifold.

4. Draw the valve away from the diverter manifold. The

valve may now be replaced or split to examine the

diaphragm.

5. To examine the diaphragm hold the valve body

securely and carefully remove the six screws. The

diaphragm spring will force apart the two halves of the

valve.

6. Remove the plastic disc and pushrod assembly.

Carefully examine the diaphragm and replace it if there

is any damage.

7. Reassemble in reverse order.

Plate Heat Exchanger

Rubber Seal

DHW Pressure

Differential Valve

Microswitch

Bracket

Grub Screws

Diverter Manifold

Sensing Pipes

Plastic Disc

Pushrod

Diaphragm

Spring

Diaphragm

Fig. 81

Fig. 82

Fig. 83

14.0 Changing Components

14.22 Diverter Valve Assembly (Cont)

Pressure Differential Valve (Fig. 84)

1. Remove the pressure differential valve as described

in 14.22.

2. From the brass diverter manifold undo the nut on

the heating flow pipe. Remove the screw securing the

diverter manifold to the appliance lower bracket.

3. Disconnect the pressure gauge capillary from the

diverter manifold and remove the two wires from the

microswitch.

4. Prise off the spring clip securing the by-pass pipe to

the diverter manifold and disconnect the sensing pipe.

5. Ease the diverter manifold out of the plate heat

exchanger manifold. Remove the assembly from the

appliance.

6. Undo the screw securing the microswitch bracket

to the valve body. The sensor may now be dismantled

to examine the diaphragm.

7. To examine the diaphragm hold the assembly

securely and carefully remove the four screws. The

diaphragm spring will force the two halves of the valve

apart.

8. Carefully examine the diaphragm and replace it if

there is any damage.

9. Reassemble in reverse order.

CH Pressure Microswitch (Fig. 84)

1. Remove the two wires from the Pressure

microswitch.

2. Undo the screw securing the microswitch bracket

to the valve body.

3. Reassemble in reverse order.

14.23 Flow Regulator (Figs. 85 & 86)

1. Undo the filter cartridge from the inlet/return

manifold.

2. Unscrew the venturi and remove the flow regulator.

3. Check the cleanliness of the filter gauze, rinsing

thoroughly in clean water as necessary. Fit the new

flow regulator and reassemble in reverse order.

Pressure Gauge

Capillary

Heating Flow

Pipe

Spring Clip

By-pass Pipe

Sensing Pipe

Diaphragm

Diverter Manifold

Microswitch / Bracket

Central Heating Pressure

Differential Valve

Fig. 84

Cartridge

Body

Filter Gauze

Flow

Regulator

Venturi

Inlet/Return Manifold

Fig. 85

Fig. 86

14.0 Changing Components

14.24 Secondary Heat Exchanger (Fig. 87)

1. Drain the primary circuit

2. Undo the four screws securing the right hand case

panel. Remove the panel.

3. Prise the connecting clips from the heat exchanger

return pipe and the boiler return pipe. Remove the

pipes.

4. Slacken the screws on the left hand fan spigot outlet

pipe clamp. Ease the clamp to the right.

5. Remove the nut securing the elbow to the secondary

heat exchanger. Draw the elbow and outlet pipe

forwards.

6. Remove the secondary heat exchanger from the

outer drum by easing it forward.

7. Reassemble in reverse order of dismantling.

14.25 Flue Overheat Thermostat (Fig. 88)

NOTE: The flue overheat thermostat includes a

reset button. Check that the thermostat will not

reset before replacing.

1. Remove the fan spigot outlet pipe from the fan and

elbow.

2. Pull the two wires off the terminals on the flue

overheat thermostat. Unscrew the thermostat from the

adaptor in the outlet elbow.

3. Reassemble in reverse order of dismantling.

Ease Fan Spigot Outlet

Pipe Clamps Inwards

Fan Spigot

Outlet Pipe

Overheat Thermostat

Fan Spigot Outlet

Pipe Clamp

Fan Spigot

Outlet Pipe

Secondary

Heat Exchanger

Outer Drum

Boiler Return Pipe

Pipe Connecting Clip

Elbow

Heat Exchanger

Return Pipe

Fig. 87

Fig. 88

15.0 Illustrated Wiring Diagram

- brown

- black

- blue

- red

- green

- green / yellow

- white

g/y

Optional Timer

Domestic Hot Water

Temperature Sensor

Reset Selector Switch

Control PCB

A1 A2 A3

bk r

212 3

341

2344

6789

Central Heating

Temperature Sensor

Fan

Gas Valve

Overheat Stat

Hydraulic Differential

Pressure Switch

Domestic Hot Water Flow

Priority Pressure Switch

Flame

Mains Input

Fuse

Link

g/y

g/ybbr

Sensing

Electrode

Pump

bbk b b b

bk bkbr

bkbrbr

Flue Stat

1234

Condensate

Trap

g/y

16.0 Fault Finding

Carry out initial fault finding checks

1. Check that gas, water and electrical supplies are available at the boiler. Electrical supply = 230V ~ 50 Hz.

CH water system pressurised to 0.5 bar when the boiler is cold. The preferred minimum gas pressure is 19.5mbar (natural gas), or 36mbar (propane).

2. Carry out electrical system checks, i.e. Ground Continuity, Resistance to Ground, Short Circuit and Polarity with a suitable meter.

NOTE: These checks must be repeated after any servicing or fault finding.

3. Ensure all external controls are calling for heat and check all external and internal fuses. Before any servicing or replacement of parts ensure the gas and

electrical supplies are isolated.

Refer to Section 15.0 “Illustrated Wiring Diagram” for position of numbered terminals

Central Heating - Follow operational sequence

Turn selector to

neon illuminated

Primary flow switch operated

Fan runs at max speed

Burner goes out

Turn thermostat

to max.

Pump runs

Air pressure

switch proved

neon flashing

Burner on neon

illuminated

Burner output

modulates until set

temperature is reached

Spark at ignition electrodes

for up to 10 seconds

Go to section ‘A’

neon flashing

Go to section ‘B’

neon flashing

Go to section ‘C’

Go to sections ‘J’ & ‘M’

neons flashing

Go to section ‘D’

neon flashing

Go to section ‘E’

Replace PCB

Turn selector to the reset

position. If the neon does

not extinguish go to

sections H & K

Go to section ‘F’

neon flashing

Go to sections ‘I’ & ’L’

Go to section ‘G’

Fan stops Pump stops Operation sequence correct

neon flashing

Turn selector to reset

position. If regular resetting is

required or appliance still

does not operate

investigation is necessary

External controls and, where

fitted, integral timer calling for

heat

Ensure controls are set to

demand and verify the

contacts are closed

Burner extinguishes

after 10 seconds

YES

YES YES YES

NO NO

YES

NOTE: When instructed to turn the

selector to the reset position turn the

selector switch fully anticlockwise against

the spring pressure to ‘Reset’ position and

hold for 2 seconds to reset the boiler.

16.0 Fault Finding

Domestic Hot Water - Follow operational sequence

Turn selector to

neon illuminated

Primary flow switch operated

Fan runs at max speed

Pump runs

Turn thermostat to max.

Open DHW tap fully. DHW

flow switch operated

Primary water is diverted

from CH system to DHW

heat exchanger and flow

microswitch operated

neon illuminated

Continuity across DHW flow

microswitch terminals and

PCB - A5 connector

terminals 5 & 6

Air pressure switch proved

neon flashing

Burner on neon

illuminated

Spark at ignition electrodes

for up to 10 seconds

Go to section ‘A’

neon flashing

Go to section ‘B’

neon flashing

Go to section ‘C’

Go to sections ‘J’ & ‘M’

neons flashing

Go to section ‘D’

Replace PCB

Go to section ‘F’

neon flashing

Go to sections ‘I’ & ‘L’

DHW flow valve

senses no flow.

Primary water diverted to

CH system. DHW flow

switch released off

Close DHW tap

Burner goes out

Diverter valve spindle

assembly faulty

Pump stops Operation sequence correct

neon flashing

Turn selector to reset

position. If regular resetting is

required or appliance still

does not operate

investigation is necessary

neon flashing

Go to section ‘E’

Burner extinguishes

after 10 seconds

YES

Fan stops

NO YES YES

YES

DHW flow rate more than

2.5l/min.

Is mains water

filter and differential

assembly clean?

DHW flow valve diaphragm

damaged

DHW flow valve rod

obstructed

Replace DHW flow

microswitch

Replace PCB

Replace diaphragm

YES

NO Reduce the DHW flow rate.

If burner does not modulate

clean DHW temperature

sensor and DHW heat

exchanger. If modulation

does not occur go to section

‘G’

Burner output modulates to

maintain temperature set at

thermostat

Turn selector to the reset

position. If the neon does

not extinguish go to

sections H & K

16.0 Fault Finding

Fault Finding Solutions Sections A to E

Is there 230V at:

Main terminals L and N Check electrical supply

1. NO

Main terminal fuse Replace fuse

Replace PCB

neon

illuminated

2. YES

Selector terminals a & b and a

& 3. PCB - A4 connector

terminals 4 & 5

Check wiring

Replace selector

3. NO

Pump Replace pump

1. NO

PCB - A4 connector terminals 3 & 6 Replace PCB

2. NO

Change pump supply cable

YES

CH system pressure 0.5 to 1.5 bar Re-pressurise system

1. NO

Primary flow valve diaphragm damaged Replace diaphragm

Flow valve rod obstructed

3. YES

Check the tap of the automatic air

vent is opened Open the automatic air vent

2. NO

YES

Continuity across flow

microswitch and PCB - A5

connector terminals 7 & 8

Replace microswitch

1. NO

Primary temperature sensor faulty.

Cold resistance approx. 11K ohms

(resistance reduces with increase in temp.)

Replace sensor

YES

Fan connections correct at fan.

PCB - A2 connector, is 230V

across terminals 5 & 7

Fan jammed or faulty winding

Replace PCB

Replace fan

YES

If pump jammed, release

16.0 Fault Finding

Check and correct if necessary

1. Electrical and pressure tube connections

2. Blockage of pressure tubes

3. Restriction in flue

4. Venturi

Replace air pressure

switch

Gas at burner Ensure gas is on and purged

Replace PCB

Replace gas valve

neon flashing

PCB - A1 connector has 230V AC

across terminals 2 & 4

YES

Turn selector switch

to ‘Reset’ position

YES

Replace PCB

Check and correct if necessary

1. Ignition electrode and lead

2. Electrode connection

3. Spark gap and position

230V at Main PCB - A1

connector across terminals

3 & 4. Check wiring

YES

Replace gas valve

electrical plug &

igniter assembly

YES

Check the burner setting pressure of the

gas valve

(see Section 9.2 of Commissioning)

Voltage at modulating coil of gas valve is:

Max. burner press.approx 9V DC (13V DC LPG)

Min. burner press.approx 1V DC

Current at modulating coil of gas valve is:

(Use an instrument with average function for this

measure)

30 ÷ 230 mA DC (45 ÷ 310 mA DC LPG)

Replace gas valve

NO Replace PCB

16.0 Fault Finding

Check and correct if necessary

1. Flame sensing electrode and lead connections

2. Electrode position

Flame current should be 1 μA approx.

Replace PCB

YES

Replace flame sensing electrode

YES

Ensure that mains input terminal L

is Live (230V) and N is Neutral

(0V)

Check terminal 1 of ON/OFF/RESET selector is in

connection with PCB - A4 connector terminal 2

Check electrical continuity across terminals 1 & a of

ON/OFF/RESET selector when turned to ‘Reset’ position

Replace ON/OFF/RESET selector

Replace PCB

YES

Replace safety

thermostat

YES

Overheat thermostat operated or

faulty, i.e. continuity across

thermostat terminals

Allow to cool. Continuity

across thermostat terminals

more than 1.5 ohm

If checks in section I are completed successfully, blockage

of the condensate drain or trap may have occurred

If checks in section J are completed successfully, the flue

overheat thermostat may have operated. Press the reset

button on the flue overheat thermostat. If the boiler does

not relight or repeatedly cuts out. Check the operation of

the flue system or replace the flue overheat thermostat

17.0 Short Parts List

Short Parts List

Key G.C. Description Manufacturers

No. No. Part No.

22 H01106 Fan 5112430

23 E66385 Pressure Switch 5137530

32 H01070 Heat Exchanger 5112431

41 H01072 Burner 5112770

44 H01103 Injector 5112376

59 E66 408 Electrode Lead 248037

63 E66 411 Spark or Sensing

Electrode 247384

72 E66539 Pump 248042

101 E66 432 3-Way Valve Assy. 248061

131 342 571 Temperature Sensor 247394

135 E66 439 Safety Thermostat 248079

140 E94426 Gas Valve 5107339

154 H01109 PCB 5112380

169 E66 453 Pressure Gauge 248090

327 E66408 Igniter/Gas Valve Cable 5112385

A H01108 Flue Overheat

Thermostat 5112395

22 140

154

135

101

169

131

371

Failure to install and commission according to the manufacturer’s instructions and complete this Benchmark Commissioning Checklist will invalidate the warranty. This

does not affect the customer’s statutory rights.

If yes, and if required by the manufacturer, has a water scale reducer been ﬁtted?

CONDENSING BOILERS ONLY

The condensate drain has been installed in accordance with the manufacturer’s instructions and/or BS5546/BS6798 Yes

If the condensate pipe terminates externally has the pipe diameter been increased and weatherproof insulation ﬁtted? Yes

Service Record

It is recommended that your heating system is serviced regularly and that the appropriate Service Interval Record is completed.

Service Provider

Before completing the appropriate Service Record below, please ensure you have carried out the service as described in the

manufacturer’s instructions.

Always use the manufacturer’s speciﬁed spare part when replacing controls.

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Operative ID No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Date:

Engineer Name:

Company Name:

Telephone No.

Gas Safe Register No.

Comments:

Signature:

Service 1 Service 2

Service 3 Service 4

Service 5 Service 6

Service 7 Service 8

Service 9 Service 10

BAXI

A Trading Division of Baxi Heating UK Ltd (3879156)

Brooks House, Coventry Road, Warwick. CV34 4LL

After Sales Service 0844 871 1525 Technical Enquiries 0844 871 1555

Website www.baxi.co.uk

e&oe

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.

Baxi Combi 105 He Quick Start Guide 5111809 Install

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