Baxi 800 Combi 2 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
800 Combi 
24 - 30 - 36
Installation and Service Manual & Boiler Fiche
High-efficiency wall-hung condensing gas boiler

Dear Customer,
Thank you very much for buying this appliance.
Please read through the manual carefully before using the product, and keep it in a safe place for later reference. In order to
ensure continued safe and efficient operation we recommend that the product is serviced regularly. Our service and customer
service organisation can assist with this.
We hope you enjoy years of problem-free operation with the product.

Contents
800 Combi 2 3
Contents
1 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 General safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5 Liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.5.1 Manufacturer's liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.5.2 Installer's liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.5.3 User's liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 About this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Symbols used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1 Symbols used in the manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3 Technical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1
3.2 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
3.2.2 Features of the temperature sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
3.3 Dimensions and connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4 Description of the product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.2 Operating principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.1 Air-gas adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.2.2 Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.3 Heating and domestic hot water production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.4 Schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Main components........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.4 Control panel description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4.1 Description of the control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.5 Contents of the package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.6 Accessories & options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5 Before installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1 Installation standards and rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5.2.1 Gas supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2.2 Electrical supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3 Flow rate/head at the plate characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4 Abbreviations/glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.1 Benchmark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.1 Building regulations and the benchmark commissioning checklist. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
1.1.2 The benchmark scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.3 Installer notification guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4 Specific safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4.1 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Homologations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
3.1.1 Safety, performance & quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.2 Certifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.3 Gas category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1.4 Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2.3 Hard water area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.2.4 Bypass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2.5 System control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2.6 Treatment of water circulating systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2.7 Showers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.8 Expansion vessel (CH only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.9 Safety pressure relief valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2.1 Technical information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2.2 Additional documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Contents
6.6 Draining the installation . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.2 Checklist before commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.3 Commissioning procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.4 Gas settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.4.1 Checking the working gas inlet pressure and gas rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.4.2 Combustion parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.4.3 LPG conversion procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.5 Final instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1 Use of the control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.2 Assembly . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.2.1 Fitting the pressure relief discharge pipe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.2.2 Connecting the condensate drain . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
6.3 Air supply/flue gas connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
6.3.1 Connecting the flue/chimney . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
6.4 Electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6.5 Filling the installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
6.5.1 Flushing the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
6.5.2 Filling the installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
6.5.3 Filling the condensate trap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.4 Choice of the location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.4.1 Location of the boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.6.1 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.5 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
5.4.2 Bath and shower rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.4.3 Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.4.4 Condensate drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.4.5 Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4.6 Flue/chimney location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4.7 Horizontal flue/chimney systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.4.8 Flue/chimney trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.4.9 Terminal guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.4.10 Flue/chimney deflector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.4.11 Flue/chimney accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.6 Unpacking and initial preparation . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
5.6.2 Initial preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
6.4.1 Accessing the electrical connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
6.4.2 Connecting the room thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
6.4.3 Service connection (SERVICE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
6.4.4 Connecting on wall outdoor sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.4.5 Connecting the outside sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
6.4.6 Identifying label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.4.4 Service settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.5.1 Handover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.1.1 Browsing the menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1.2 Running the automatic detection function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1.3 Information menu display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.4.12 Data plate and boiler service level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.7.1 Filling information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.7 Connecting diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
5.7.2 Domestic hot water circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
8.1.4 Counter menu display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4 800 Combi 2
7.4.5 Adjusting the gas valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

800 Combi 2 5
Contents
12.2 Recommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
13 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
13.1 Disposal and recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
10 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
10.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
10.2 Maintenance message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
10.2.1 Service notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
10.2.3 Resetting the upcoming maintenance message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
10.3 Periodic check and maintenance procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
10.3.1
Checking the water pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
10.3.2
Checking the expansion vessel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
10.3.3
Checking the flue gas discharge and the air supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10.3.4
Checking the combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10.3.5
Checking the automatic air vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10.3.6
Cleaning the siphon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10.3.7
Checking the burner and cleaning the heat exchanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
10.3.8 Electrode distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10.3.9
Water unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
10.3.10
Removing limescale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
10.4 Specific maintenance operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
10.4.1 Detection/ignition electrode replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
10.4.2 Dismantling the water-water exchanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
10.4.3 Flow and return sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
10.4.5 Replacing the 3-way valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
11 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
11.1 Temporary and permanent faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
11.2 Error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
12 Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
12.1 Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
10.4.6 Pressure sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
9 Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
9.1 Accessing the settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
9.2 List of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
9.3 Setting the parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
9.3.1 Setting the heating curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
8.3 Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.4 Degassing function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.5 Frost protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.3.1 Switching off the heating and domestic hot water (DHW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
9.4 Reading out measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
9.5 Reading counters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
10.2.2 Resetting the displayed maintenance message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
8.2 Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.2.1 Procedure for first start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.2.2 Changing the heating flow temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.2.3 Changing the domestic hot water (DHW) temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9.2.1 Resetting factory settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
10.4.4 Replacing the return valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
9.4.1 Statuses and sub-statuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Annual servicing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
10.3.11
10.3.12
Cleaning/replacing the DHW filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
10.4.7
10.4.8
10.4.9
10.4.11
10.4.12
10.4.10
10.4.13
Hall effect sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Safety pressure relief valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
Diverter valve motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Replacing the expansion vessel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Replacing the PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Pump replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Setting an uncalibrated gas valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

1 Safety
1.1 Benchmark
1.1.1 Building Regulations and the Benchmark Commissioning
Checklist
Building Regulations (England & Wales) require notification of the installa-
tion 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 self
certification 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 installa-
tion and commissioning of central heating systems in the UK and to en-
courage the regular servicing of all central heating systems to ensure
safety and efficiency.
Building Regulations require that installations should comply with manu-
facturer’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 in 1.1.3 gives guidance for installers on the process neces-
sary to ensure compliance with Building Regulations.
1.1.2 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 ref
erence.
Installers are required to carry out installation, commissioning and servic
ing 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 infor
mation.
Fig.1 Benchmark
AD-3000725-01
1 Safety
6 800 Combi 2

1.1.3 Installer Notification Guidelines
Fig.2 Installer Notification Guidelines
AD-3000696-01
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
1 Safety
800 Combi 2 7

1.2 General safety instructions
Danger
This boiler can be used by children aged 8 years and above and
by persons with reduced physical, sensory or mental capabilities
or lack of experience and knowledge when they have been given
supervision or instruction concerning the safe use of the device
and understand the resulting risks. Children must not be allowed
to play with the appliance. Cleaning and user maintenance must
not be carried out by children without supervision.
Danger
If you smell gas:
1. Do not use a naked flame, do not smoke, do not operate elec
trical contacts or switches (doorbell, light, motor, lift, etc.).
2. Shut off gas supply.
3. Open the windows.
4. Trace possible leaks and seal them immediately.
5. If the gas leak is before the gas meter, contact the supplier
6. Telephone the National Gas Emergency Service on:- 0800
111 999.
Danger
If you smell flue gases:
1. Switch off the boiler.
2. Open the windows.
3. Trace possible leaks and seal them immediately.
Warning
Do not touch the flue gas pipes. Depending on the boiler settings,
the temperature of the flue gas pipes may exceed 60 oC.
Warning
Do not touch the radiators for long periods. Depending on the boil-
er settings, the temperature of the radiators may exceed 60 oC.
Warning
Take precautions with the domestic hot water. Depending on the
boiler settings, the domestic hot water temperature may exceed
65 oC.
Danger
Before any work, switch off the mains supply to the boiler.
Caution
After maintenance or repair work, check the entire heating installa
tion to ensure that there are no leaks.
1.3 Recommendations
Warning
Installation and maintenance of the boiler must be carried out by a
qualified installer in accordance with local and national regula
tions.
Warning
If the mains lead is damaged, it must be replaced by the original
manufacturer, the manufacturer's dealer or another suitably skilled
person to prevent hazardous situations from arising.
Warning
Always disconnect the mains supply and close the main gas tap
when working on the boiler.
1 Safety
8 800 Combi 2

Caution
Make sure the boiler can be reached at all times.
The boiler must be installed in a frost-free area.
In the case of a fixed connection to the power cord, you must al
ways install a main double pole switch with an opening gap of at
least 3 mm (EN 60335-1).
Drain the boiler and central heating system if you are not going
to use your home for a long time and there is a chance of frost.
The frost protection does not work if the boiler is out of opera
tion.
The boiler protection only protects the boiler, not the system.
Check the water pressure in the system regularly. If the water
pressure is lower than 0.8 bar, the system must be topped up
(recommended water pressure between 1 and 2 bar).
Important
Keep this document near to the boiler.
Important
Casing panels may only be removed for maintenance and servic
ing purposes. Refit all panels when maintenance work and servic
ing are complete.
Note
Instruction and warning labels must never be removed or covered
and must be clearly legible throughout the entire service life of the
boiler. Replace damaged or illegible instruction and warning labels
immediately.
Note
The boiler must not be modified in any way.
1.4 Specific safety instructions
1.4.1 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 should-
ers, arms and hands. Health & Safety is the responsibility of EVERY-
ONE.
There is no "safe" limit for one person - 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 unobstruc
ted. 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 pos
sible.
Where possible transport the boiler using a sack truck or other suitable
trolley.
1 Safety
800 Combi 2 9

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 recom
mended lift points.
Remember
The circumstances of each installation are different. Always assess the
risks associated with handling and lifting according to the individual con
ditions.
If at any time when installing the boiler you feel that you may have in
jured 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 !
1.5 Liabilities
1.5.1 Manufacturer's liability
Our products are manufactured in compliance with the requirements of the
various Directives applicable. They are therefore delivered with the
marking and any documents necessary. In the interests of the quality of
our products, we strive constantly to improve them. We therefore reserve
the right to modify the specifications given in this document.
Our liability as manufacturer may not be invoked in the following cases:
Failure to abide by the instructions on installing the appliance.
Failure to abide by the instructions on using the appliance.
Faulty or insufficient maintenance of the appliance.
1.5.2 Installer's liability
The installer is responsible for the installation and initial commissioning of
the appliance. The installer must observe the following instructions:
Read and follow the instructions given in the manuals provided with the
appliance.
Install the appliance in compliance with prevailing legislation and stand
ards.
Carry out initial commissioning and any checks necessary.
Explain the installation to the user.
If maintenance is necessary, warn the user of the obligation to check the
appliance and keep it in good working order.
Give all the instruction manuals to the user.
1.5.3 User's liability
To guarantee optimum operation of the system, you must abide by the fol
lowing instructions:
Read and follow the instructions given in the manuals provided with the
appliance.
Call on a qualified professional to carry out installation and initial com
missioning.
Get your installer to explain your installation to you.
Have the required inspections and maintenance carried out by a quali
fied installer.
Keep the instruction manuals in good condition close to the appliance.
1 Safety
10 800 Combi 2

This manual is intended for installers and service engineers of
Baxi 800 Combi 2 boilers.
2.3 Symbols used
2.3.1 Symbols used in the manual
This manual uses various danger levels to draw attention to special
instructions. We do this to improve user safety, to prevent problems and to
guarantee correct operation of the appliance.
Danger
Risk of dangerous situations that may result in serious personal
injury.
Danger of electric shock
Risk of electric shock.
Warning
Risk of dangerous situations that may result in minor personal
injury.
Caution
Risk of material damage.
Important
Please note: important information.
See
Reference to other manuals or pages in this manual.
2 About this manual
2.1 General
2.4 Abbreviations/Glossary
BS
CH
DHW
GB
British Standard
Central heating
Domestic hot water
Great Britain
HHIC Heating and Hotwater Industry Council
Hi
Hs
IE
PCU
Pn
Pnc
SU
Lower heating value (LHV)
Higher heating value (HHV)
Ireland
PCB for managing burner operation
Nominal output
Condensing output
Safety PCB
2 About this manual
2.2 Additional documentation
These Installation & Service Instructions must be read in conjunction with
the Flue Accessories Fitting Guide supplied in the Literature Pack.
Various timers, external controls, etc. are available as optional extras. Full
details are contained in the relevant sales literature.
800 Combi 2 11

3 Technical specifications
3.1 Homologations
3.1.2 Certifications
Tab.1 Certifications
CE certificate number 0085CU0338
NOx class 6
Boiler type C13, C33
3.1.3 Gas category
Gas category Gas type Supply pressure (mbar)
I2H G20 (H natural gas) 20
3 Technical specifications
3.1.4 Standards
Codes of Practice — refer to the most recent version
Tab.3 In GB the following Codes of Practice apply:
3.1.1 Safety, Performance & Quality
This boiler has been assessed by an appropriate Notified Body and shown
to meet the requirements of all Directives and Regulations as applicable.
These Directives and Regulations lay down requirements for the safety
and efficiency of the appliance, together with its design, construction and
use of materials. They also require the production process to be covered
by an approved and monitored system of quality assurance.
Tab.2 Gas category, type and supply pressure
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
12831
Heating systems in buildings — Calculation of load.
BS EN
14336
Installation & commissioning of water based heating sys
tems.
BS 6798 Installation of gas fired hot water boilers.
BS 5440
Part 1
Flues.
BS 5440
Part 2
Ventilation.
Important
This appliance is suitable for G20 gas containing up to
20% hydrogen (H2). Due to variations in the percentage
of H2, the percentage of O2 may vary over time. (For
example: 20% of H2 in the gas may lead to a 1.5%
increase of O2 in the flue gases) The gas valve may
need to be adjusted more accurately. This must be
adjusted using standard O2 values for the gas used.
12 800 Combi 2
I3P G31 (P LPG) 37
UKCE certificate number 748353
G.C. nos. 824-2: 47-077-63 830-2: 47-077-64 836-2: 47-077-65

3 Technical specifications
Tab.4 In IE the following Code of Practice apply:
Standard Scope
IS 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
12831
Heating systems in buildings — Calculation of load.
BS EN
14336
Installation & commissioning of water based heating sys
tems.
BS 7074 Expansion vessels and ancillary equipment for sealed wa
ter systems.
BS 7593 Treatment of water in domestic hot water central heating
systems.
3.2 Technical data
Tab.5 Technical settings for combination heaters with boilers
3.2.1 Technical information
Important
All data in these sections are nominal and subject to normal pro
duction tolerances.
BS 7074 Expansion vessels and ancillary equipment for sealed wa
ter systems.
BS 7593 Treatment of water in domestic hot water central heating
systems.
BS 4814 Specification for Expansion Vessels using an internal dia
phragm, for sealed hot water systems.
IGE/UP/
7/1998
Guide for gas installations in timber framed housing.
Standard Scope
&RPEL &RPEL
&RQGHQVLQJERLOHU <HV <HV
/RZWHPSHUDWXUHERLOHU 1R 1R
%ERLOHU 1R 1R
&RPEL
<HV
1R
1R
800 Combi 2 13

3 Technical specifications
&RPEL &RPEL
&RJHQHUDWLRQVSDFHKHDWHU 1R 1R
&RPELQDWLRQKHDWHU <HV <HV
5DWHGKHDWRXWSXW
3UDWHG N:
8VHIXOKHDWRXWSXWDWUDWHGKHDWRXWSXWDQG
KLJKWHPSHUDWXUHVHWWLQJ
3 N:
8VHIXOKHDWRXWSXWDWRIUDWHGKHDWRXWo
SXWDQGORZWHPSHUDWXUHVHWWLQJ
3 N:
6HDVRQDOVSDFHKHDWLQJHQHUJ\HIILFLHQF\ ŠV 
8VHIXOHIILFLHQF\DWUDWHGKHDWRXWSXWDQGKLJK
WHPSHUDWXUHVHWWLQJ
Š 
8VHIXOHIILFLHQF\DWRIUDWHGKHDWRXWSXW
DQGORZWHPSHUDWXUHVHWWLQJ
Š 
$X[LOLDU\HOHFWULFLW\FRQVXPSWLRQ
)XOOORDG
HOPD[ N:
3DUWLDOORDG HOPLQ N:
6WDQGE\PRGH
36% N:
2WKHULWHPV
+HDWORVVRQVWDQGE\ 3VWE\ N:
,JQLWLRQEXUQHUSRZHUFRQVXPSWLRQ
3LJQ N:
$QQXDOHQHUJ\FRQVXPSWLRQ
4+( *-
6RXQGSRZHUOHYHOLQGRRUV /:$ G%
1LWURJHQR[LGHHPLVVLRQV 12[ PJN:K
'RPHVWLFKRWZDWHUSDUDPHWHUV
'HFODUHGORDGSURILOH
'DLO\HOHFWULFLW\FRQVXPSWLRQ 4HOHF N:K
$QQXDOHOHFWULFLW\FRQVXPSWLRQ $(& N:K
:DWHUKHDWLQJHQHUJ\HIILFLHQF\
'DLO\IXHOFRQVXPSWLRQ
4IXHO N:K
$QQXDOIXHOFRQVXPSWLRQ
$)& *-
 /RZWHPSHUDWXUHPHDQVIRUFRQGHQVLQJERLOHUV r&IRUORZWHPSHUDWXUHERLOHUV r&DQGIRURWKHUKHDWHUV r&UHWXUQWHPSHUDWXUH
DWKHDWHULQOHW
 +LJKWHPSHUDWXUHVHWWLQJPHDQVr&UHWXUQWHPSHUDWXUHDWERLOHULQOHWDQGr&IORZWHPSHUDWXUHDWERLOHURXWOHW.
&RPEL
1R
<HV
7DE6 *HQHUDO
&RPEL &RPEL
5DWHGKHDWLQSXW4QIRUGRPHVWLFKRWZDWHU N: .7
5DWHGKHDWLQSXW4QIRUKHDWLQJ N: 
5HGXFHGKHDWLQSXW4Qr& N: 
5DWHGKHDWRXWSXW3QIRUGRPHVWLFKRWZDWHU N: 4.0
5DWHGKHDWRXWSXW3Qr&IRUKHDWLQJ N: 
5DWHGKHDWRXWSXW3Qr&IRUKHDWLQJ N: 8
5HGXFHGKHDWRXWSXW3Qr& N: 
5HGXFHGKHDWRXWSXW3Qr& N: 
5DWHGHIILFLHQF\r&+L  
&RPEL
36.9
30.9
5.75.7
6.0 7.4
30.0 36.0
 
6.3 7.6
5 7.2
55
27.1 27.1
14 800 Combi 2
20 25 25
20.0 25.0 25.0
6.7 8.4 8.4
949494
88.2 88.1 88.1
99.0 98.8 98.8
0.004 0.004 0.004
0.04 0.04 0.04
777762
0.046 0.061 0.071
0.008 0.009 0.009
XLXLXL
0.1380.1400.146
303132
20.43820.547
161616
515150
313132
20.473
000

3 Technical specifications
7DE7 &KDUDFWHULVWLFVRIWKHKHDWLQJFLUFXLW
&RPEL &RPEL
0D[LPXPSUHVVXUH EDU
0LQLPXPSUHVVXUH EDU  
7HPSHUDWXUHUDQJHIRUKHDWLQJFLUFXLW r& - -
:DWHUFDSDFLW\RIH[SDQVLRQYHVVHO O  
7DE8 &KDUDFWHULVWLFVRIWKHGRPHVWLFZDWHUFLUFXLW
&RPEL &RPEL
0LQLPXPSUHVVXUH EDU  
0D[LPXPSUHVVXUH EDU  
0LQLPXPG\QDPLFSUHVVXUH EDU  
0LQLPXPZDWHUIORZ OPLQ  
6SHFLILFIORZ' OPLQ 5
7HPSHUDWXUHUDQJHIRUGRPHVWLFZDWHUFLUFXLW r&
'RPHVWLFZDWHUSURGXFWLRQZLWK˂7 r& OPLQ
'RPHVWLFZDWHUSURGXFWLRQZLWK˂7 r& OPLQ
7DE9 &RPEXVWLRQFKDUDFWHULVWLFV
&RPEL &RPEL
*JDVFRQVXPSWLRQ4PD[ PK 61
*JDVFRQVXPSWLRQ4PLQ PK 
'LDPHWHURIFRD[LDOGLVFKDUJHSLSHV PP  
)OXHJDVPDVVIORZUDWHPD[ NJVHF 
)OXHJDVPDVVIORZUDWHPLQ NJVHF 
7DE10 (OHFWULFDOFKDUDFWHULVWLFV
&RPEL &RPEL
3RZHUVXSSO\YROWDJH 9  
3RZHUVXSSO\IUHTXHQF\ +]  
5DWHGHOHFWULFSRZHU : 85
7DE11 2WKHUFKDUDFWHULVWLFV
&RPEL
+XPLGLW\SURWHFWLRQUDWLQJ(1 ,3 ;' ;';'
1HWZHLJKWZKHQHPSW\ILOOHGZLWKZDWHU NJ 
'LPHQVLRQVKHLJKWZLGWKGHSWK PP  
6&RPEL
2.5

-

&RPEL




&RPEL

&RPEL


&&RRPPEELL &RPEL
;'

3.26
63
3.9
78
3
88
4
4.3
7
4
91
29/31 30/31
7.2
800 Combi 2 15
2.52.5
35-6035-60 35-60
17.614.1 21.0
12.210.2 15.0

3.3 Dimensions and connections
Fig.3 Dimensions and connections
3 Technical specifications
3.2.1 Features of the temperature sensors
7DE3 7HPSHUDWXUHIORZKHDWLQJFLUFXLWUHWXUQVHQVRU17&.%HWD k2KP# r&
7HPSHUDWXUH>r&@           
5HVLVWDQFH>˖@           
7DE4 )OXHJDVWHPSHUDWXUHVHQVRU17&.%HWD N2KP# r&
7HPSHUDWXUH>r&@            
5HVLVWDQFH>˖@            
ಧಧಧಧಧ!            
ಧಧಧಧಧ!            
7DE2 7HPSHUDWXUHVHQVRURXWGRRUVHQVRU17&%HWD N2KP# r&
7HPSHUDWXUH>r&@            
5HVLVWDQFH>˖@            







&RQGHQVDWHRXWOHW
+HDWLQJFLUFXLWIORZILWWLQJ*ರ
3UHVVXUHUHOLHI & drain
'+:'RPHVWLF+RW:DWHURXWOHWILWWLQJ*ರ
*DVLQOHWILWWLQJ*ರ
'RPHVWLFFROGZDWHULQOHWILWWLQJ*ರ
+HDWLQJFLUFXLWUHWXUQILWWLQJ*
Cable gland
Boiler ID inc. serial number
8
16 800 Combi 2
9

Fig.4 Paper template
3 Technical specifications
800 Combi 2 17

3.4 Electrical diagram
Fig.5 Boiler electrical wiring diagram
3 Technical specifications
Tab.15Electrical connections
X1
Power supply:
L: Live 230 V – 50 Hz
N: Neutral
: Earthing connector
X2 Fan supply (FAN)
X3 Gas valve (GV)
X4 Pump power supply
X5 3-way valve motor power supply
X6 Earth connections
X7
Sensors:
Limit thermostat (ST)
Installation return temperature (SRT)
Installation flow temperature (SFL)
Flue gas temperature (FS)
X8
Sensors:
DHW flowmeter (HS)
Heating circuit pressure switch (SP)
Pump PWM signal (PWM PUMP)
X9 CAN connection
X10 Service interface
X17 Open Therm room unit (OT)
X17 Outside sensor (OS)
X17 External tank sensor - accessory (BS)
X15 Boiler stoppage (with open contact)
RT Room thermostat contact (230 V)
18 800 Combi 2

The purpose of this gas-fuelled condensing boiler is to heat water to a
temperature that is lower than boiling point at atmospheric pressure. It
must be connected to a heating installation and to a domestic hot water
distribution system that is compatible with its power and performance
ratings. Features of this boiler:
Low pollutant emissions,
High-efficiency heating,
Combustion products discharged through a concentric connector,
Front control panel with display,
Lightweight and compact.
4.2 Operating principle
4.2.1 Air-gas adjustment
The air is drawn in by the fan and gas injected directly at the height of the
venturi. The fan revolution speed is regulated automatically by the
electronic board based on the adjustment settings. The gas and air are
mixed in the manifold. The gas/air ratio ensures that the quantity of gas
and air are adjusted correctly to always obtain optimal combustion. The
gas/air mixture is fed into the burner at the front of the exchanger.
Here, the electric igniter triggers the mixture with a series of sparks that
burn, producing thermal energy.
4.2.2 Combustion
The burner heats the heating water circulating in the heat exchanger.
When the temperature of the combustion gas is lower than the dew point
(around 55 °C), the water vapour contained in the combustion gas
condenses in the flue gas side of the heat exchanger. The heat recovered
during this condensation process (the latent heat or condensing heat) is
also transferred to the heating water. Once cooled, the combustion gases
are discharged through the exhaust pipe. The condensed water is
discharged through a siphon.
4.2.3 Heating and domestic hot water production
In boilers used for heating and for producing domestic hot water, an
integrated plate heat exchanger heats the domestic water. The heated
water is then channelled to the heating installation or to the plate heat
exchanger via a three-way valve. A flow sensor detects that a hot water
tap has been turned on and communicates this to the PCB, which
switches the three-way valve to the hot water position and activates the
pump. The three-way valve is spring-loaded and only consumes electricity
when switching from one position to another. Precedence is given to a
heat request in domestic water mode.
4 Description of the product
4.1 General description
800 Combi 2 19
4 Description of the product

4 Description of the product
 6FKHPDWLFGLDJUDP











+HDWH[FKDQJHUKHDWLQJ
:DWHUXQLW
3ODWHKHDWH[FKDQJHU'+:
6DIHW\YDOYH
+HDWLQJIORZ
'+:RXWOHW*
'+:LQOHW*
+HDWLQJUHWXUQ
3XPSKHDWLQJFLUFXLW
0RWRULVHGWKUHHZD\YDOYH
Filling link
 0ain&omponents
1. Flue Adaptor
2. Expansion vessel valve
3. Expansion vessel
4. Air-gas collector
5. Fan
6. Gas valve
7. DHW plate to plate heat exchanger
8. DHW flow sensor
9. Pump
10. Control panel/facia/PCB's
11. Cable gland
12. Safety pressure relief valve & drain
13. Condensate trap
14. 3 way valve motor
15. Electrode
16. Burner flange
17. Silencer
)LJ66FKHPDWLFGLDJUDP
BO-0000191
1
3
76
2
M
58
9
4
10
11
)LJ7)XQFWLRQDOGLDJUDP
20 800 Combi 2