Baxi MainEco Combi 24 Manual

These instructions include the Benchmark Commissioning Checklist and should be left with the
user for safe keeping. They must be read in conjunction with the Flue Installation Guide.
United Kingdom
en
24-28-35 / 18-24
Installation and Service Manual
Wall Mounted Gas Condensing Boiler
Baxi MainEco Combi and System

Dear customer,
Thank you for purchasing this appliance.
Please read this manual carefully before using the product and keep it in a safe place for future reference.
In order to ensure continued safe and efficient operation we recommend that the product is regularly maintained. Our Service
and After Sales organization can assist with this.
We hope you will receive many years of satisfactory service.

Contents
1.1 Building Regulations and the Benchmark
Commissioning Checklist ....................................6
1.2 The Benchmark Scheme ......................................6
1.3 Installer Notification Guidelines ..........................7
2Introduction ................................................................................................8
2.1 Symbols used .......................................................8
2.2 Abbreviations ........................................................8
2.3 General ..................................................................8
2.3.1 Manufacturer’s liability .............................................8
2.3.2 Installer’s liability .....................................................9
2.3.3 User’s liability ..........................................................9
2.4 Homologations ....................................................10
2.4.1 Certifications .........................................................10
2.4.2 Additional Directives ..............................................10
3 Safety instructions and recommendations ............................................11
3.1 Safety instructions .............................................11
3.2 Recommendations ..............................................11
4 Technical description ..............................................................................13
4.1 General description ............................................13
4.2 Main parts ............................................................13
4.3 Skeleton Diagrams .............................................14
4.4 Operating principle .............................................14
4.4.1 Gas/air setting .......................................................14
4.4.2 Combustion ...........................................................15
4.4.3 Heating and domestic hot water production ..........15
4.4.4 Control system ......................................................15
4.4.5 Adjustment ............................................................15
4.4.6 Regulation of the water temperature .....................16
4.4.7 Protection against low water or no
circulation ..............................................................16
4.4.8 Overheat temperature protection ..........................16
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4.5 Circulating pump (Available pump head) .........16
4.6 Technical specifications ....................................17
5 Installation ................................................................................................19
5.1 Regulations governing installation ...................19
5.2 Choice of the location ........................................20
5.2.1 Type plate .............................................................20
5.2.2 Location of the boiler .............................................20
5.3 Main dimensions .................................................22
5.4 Positioning the boiler .........................................23
5.5 Hydraulic connections .......................................23
5.5.1 Flushing the system ..............................................24
5.5.2 Water flow rate ......................................................24
5.5.3 Connection of the heating circuit ...........................24
5.5.4 Connection of the water circuit for domestic
use ........................................................................25
5.5.5 Connecting the expansion vessel .........................25
5.5.6 Connecting the safety valve discharge pipe ..........26
5.5.7 Connecting the condensate discharge pipe ..........26
5.5.8 Automatic air bleed ...............................................28
5.6 Gas connection ...................................................29
5.7 Connections for the air and exhaust
pipes ....................................................................29
5.7.1 Classification .........................................................29
5.7.2 Outlets ...................................................................30
5.7.3 Lengths of the air/flue gas pipes ...........................31
5.7.4 Additional Directives ..............................................32
5.7.5 Connection of the combustion gas exhaust
pipe .......................................................................32
5.8 Electrical connections ........................................32
5.8.1 Control unit ............................................................32
5.8.2 Recommendations ................................................33
5.8.3 Access to the connector block / Boiler HMI ...........34
5.8.4 Connection options ...............................................34
5.9 Electrical diagram ...............................................38
5.10 Filling the system ...............................................38
5.10.1 Water treatment ....................................................38
5.10.2 Filling the condensate trap ....................................39
5.10.3 Filling the system ..................................................40
5.10.4 Venting the system ................................................41
Contents
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6 Commissioning ........................................................................................42
6.1 Control panel .......................................................42
6.2 Check points before commissioning ................43
6.2.1 Preparing the boiler for commissioning .................43
6.2.2 Hydraulic circuit .....................................................43
6.2.3 Electrical connections ...........................................43
6.3 Commissioning the boiler ..................................43
6.4 Gas settings ........................................................45
6.4.1 Gas circuit .............................................................45
6.4.2 Checking combustion ............................................45
6.4.3 Setting the air/gas ratio .........................................48
6.5 Finalizing work ....................................................49
6.6 Parameter descriptions ......................................50
7 Switching off the boiler ............................................................................52
7.1 Installation shutdown .........................................52
7.2 Antifreeze protection ..........................................52
8 Checking and maintenance .....................................................................53
8.1 General instructions ...........................................53
8.2 Standard inspection and maintenance
operations ...........................................................53
8.2.1 Open the boiler ......................................................53
8.2.2 Checking the hydraulic pressure ...........................54
8.2.3 Checking the expansion vessel .............................54
8.2.4 Checking the ionization current .............................54
8.2.5 Checking the DHW transfer capacity ....................55
8.2.6 Checking the flue gas discharge and the air
supply ....................................................................55
8.2.7 Checking combustion ............................................55
8.2.8 Checking the automatic air vent ............................55
8.2.9 Checking the condensate trap ..............................56
8.2.10 Checking the burner and cleaning the heat
exchanger .............................................................57
8.3 Specific maintenance operations ......................58
8.3.1 Replacing the ionization/ignition electrode ............58
8.3.2 Replacing the 3-way valve ....................................59
8.3.3 Cleaning the plate heat exchanger .......................59
8.3.4 Cleaning the domestic water cartridge ..................60
8.3.5 Replacement of the expansion vessel ..................60
8.3.6 Re-assembling the boiler ......................................61
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9 Troubleshooting .......................................................................................63
9.1 Error codes ..........................................................63
9.2 Shutdowns and lock-outs ..................................63
9.2.1 Blocking .................................................................63
9.2.2 Lock out .................................................................65
10 Spare parts ................................................................................................70
10.1 General ................................................................70
10.2 Spare parts ..........................................................70
11 Appendix ...................................................................................................71
11.1 User instruction card ..........................................71
11.2 Gas boiler system commissioning
checklist ..............................................................72
11.3 Service record .....................................................73
Contents
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EC declaration of conformity
The device complies with the standard type described in the EG
declaration of conformity. It was manufactured and commissioned in
accordance with European directives.
The original declaration of conformity is available from the
manufacturer.

1.1 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.
This can be achieved via a Competent Persons Self
Certification Scheme as an option to notifying the Local
Authority directly.
The Health & Safety Executive operates the ’Gas Safe
Register’, a selfcertification scheme for gas heating
appliances.
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.
1.2 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.
R000725-A
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1.3 Installer Notification Guidelines
R000696-01
Choose Building
Regulations Notification
Route
Contact your relevant Local
Authority Building Control
(LABC) who will arrange
an inspection or contact
a government approved
inspector
LABC will record the data
and will issue a
certificate of compliance
‘Gas Safe Register’ will issue a
Building Regulations Compliance
Certificate to the property owner
and inform the relevant LABC
You must ensure that the
certificate number issued by
the ‘Gas Safe Register’ is written
onto the Benchmark Checklist
Scheme Members only
Call ‘Gas Safe Register’ on:
0800 408 5577
or log onto:
www.gassaferegister.co.uk
within 10 days
If you notify via the ‘Gas Safe
Register’, the register will issue
the Building Regulations
certificate on members’ behalf
Complete the
Benchmark Checklist
Install and Commission this
appliance to manufacturer's
instructions
Competent Person's
Self Certification Scheme
Building Control
Complete the
Benchmark Checklist
Install and Commission this
appliance to manufacturer's
instructions
Baxi MainEco Combi and System 24 - 28 - 35 / 18 - 24
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2 Introduction
2.1 Symbols used
In these instructions, various danger levels are employed to draw the
user’s attention to particular information. In so doing, we wish to
safeguard the user’s safety, highlight hazards and guarantee correct
operation of the appliance.
DANGER
Risk of a dangerous situation causing serious physical
injury.
WARNING
Risk of a dangerous situation causing slight physical
injury.
CAUTION
Risk of material damage.
Signals important information.
¼Signals a referral to other instructions or other pages in the
instructions.
2.2 Abbreviations
4LTH: Low temperature heating
4DHW: Domestic hot water
4HRU: Heat Recovery Unit
4PCU: Primary Control Unit - Electronic system to control burner
function
4SCU: Secondary Control Unit - Additional electronic system
2.3 General
2.3.1. Manufacturer’s liability
Our products are manufactured in compliance with the requirements
of the various applicable European Directives. They are therefore
delivered with [ marking and all relevant documentation.
2. Introduction Baxi MainEco Combi and System 24 - 28 - 35 / 18 - 24
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