A.O. Smith SGS-28 Troubleshooting guide

0311753
Innovation has a name.
Installation, User and Service
Manual
Condensing High Efficiency
Gas-Solar Water Heater
SGS - 28/30/50/60/80/100/120
SGS
3017 - Changes Reserved.

A.O. Smith UK, Unit B8 Amstrong Mall,
Southwood Business Park, Farnborough, Hampshire GU14 0NR
www.aosmith.co.uk
“A.O. Smith Water Heaters” is a trading name of Advance Services (Sales) Ltd. Reg.
your installer

Preface
Copyright
Copyright © 2016 A.O. Smith Water Products Company
All rights reserved.
Nothing from this publication may be copied, reproduced and/or published by means of
printing, photocopying or by whatsoever means, without the prior written approval of A.O.
Smith Water Products Company.
A.O. Smith Water Products Company reserves the right to modify specifications in this
manual.
Trademarks
Brand names in this manual are registered trademarks of their respective owners.
Warranty
Refer to the appendix Warranty (see section 12.9) for the warranty provisions.
Liability
A.O. Smith accepts no liability for claims from third parties caused by:
unauthorized use
use other than stated in this manual
use other than in accordance with the General Conditions registered at the Chamber
of Commerce.
For more information, refer to the General Conditions. These are available on request, free
of charge.
We believe that this manual provides you with accurate and complete descriptions of all
relevant components. If you, nonetheless find errors or inaccuracies in this manual, please
inform A.O. Smith. This helps us to further improve our documentation.
Compliance
To safely produce domestic hot water, the design and construction of the SGS water
heaters is in accordance with:
the European Gas Appliance Directive (GAD).
the European Standard for Gas–fired storage water heaters for the production of
domestic hot water (EN89).
The European ECO-Design Directive.
The European Energy Labeling Directive
Refer to the appendix Declaration of conformity.
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0311753_SGS_28-120_II_UKUK_V2.0 , 2017-05-03 3

Regulations
Gas Safety (installations and Use) Regulations 1998 (as
amended).
It is law that all gas appliances are installed by competent persons, in accordance with the
above regulations. Failure to install appliances correctly could lead to prosecution. It is in
your own interest and that of safety, to ensure that this law is complied with.
The installation of the water heater MUST be in accordance with the relevant requirements
of the Gas Safety Regulations, Building Regulations, IEE Regulations and the Water Supply
(water fittings) Regulations. The installation should also be in accordance with any
relevant requirements of the HSE, local gas region and local authority and the relevant
recommendations of the following documents:
British and European Standards
BS 6891:
Installation of low pressure gas pipework of up to 35 mm (R1¼) in domestic
premises (2nd family gas) - Specification. Note: for lager installations see IGE/UP/2
below.
BS 6798:
Specification for installation and maintenance of gas-fired boilers of rated input not
exceeding 70 kW net.
BS 6644:
Specification for installation of gas-fired hot water boilers of rated inputs between 70
kW (net) and 1.8 MW (net) (2nd and 3rd family gases).
BS 6700:
Design, installation, testing and maintenance of services supplying water for
domestic use within buildings and their cartilages - Specifications
BS EN 806-2:
Specification for installations inside buildings conveying water for human
consumption. Part 2: Design.
BS 5546:
Specification for installation of hot water supplies for domestic purposes, using gas-
fired appliances of rated input not exceeding 70 kW.
BS 5440:
Flueing and ventilation for gas appliances of rated input not exceeding 70 kW net
(1st, 2nd and 3rd family gases).
Part 1: Specification for installation of gas appliances to chimneys and for
maintenance of chimneys.
Part 2: Specification for installation and maintenance of ventilation for gas
appliances.
Institute of Gas Engineers and Managers (IGEM) Publications
IGE/UP/1:
Soundness testing and purging of industrial and commercial gas installations.
IGE/UP/1A:
Soundness testing and direct purging of small low pressure industrial and commercial
natural gas installations.
IGE/UP/2:
Gas installation pipework, boosters and compressors on industrial and commercial
premises.
IGE/UP/10:
Installation of flued gas appliances in industrial and commercial premises.
CIBSE Publications
Guide G:
Public Health Engineering
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Contact information
If you have any comments or questions, please contact:
A.O. Smith Water Products Company
Adress: PO Box 70
5500 AB Veldhoven
The Netherlands
Telephone: 0870 - AOSMITH (free)
0870 - 267 64 84
General: [phone]
Fax: [phone]
E-mail: [email protected]
Website: www.aosmith.co.uk
In the event of problems with your gas, electricity or water supply connections, contact
your supplier.
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6

About this manual
Scope
This manual gives information about safe and correct use of the water heater and how
installation, maintenance and service activities have to be done correctly. You must obey
the instructions in this manual.
Caution
Read this manual carefully before you start the water heater. It can cause personal injury
and damage to the water heater when you do not read the manual and/or do not obey
the instructions.
The purpose of this manual is to:
describe the working principles and layout of the water heater
explain the safety devices
highlight possible hazards
describe the use of the water heater
describe the installation, service and maintenance of the water heater
This manual has two parts:
An User part that describes the correct usage of the water heater.
An Installation, Maintenance and Service part, that describes the correct installation
and maintenance procedures.
Target group
The information in this manual applies to three target groups:
users
installation engineers
service and maintenance engineers
The User part is intended for the (end) users. The Installation, Maintenance and Service
part is intended for the installation engineers and the service and maintenance engineers.
Notation conventions
This manual uses the following text conventions:
Numbers between parentheses e.g. (1), refer to elements in a figure that are
described by the text.
Texts displayed on the user interface always are shown similar to the characters in
the display, for example WEEK PROGRAM, SETTINGS.
Buttons are always shown between brackets, for example: [ ], [ENTER], [RESET].
Cross-references to sections, tables, figures etc. are underlined and written as (see
section "..."). In the digital version, the cross-references function as hyperlinks that
can be used to navigate through the manual by clicking on them. Example: Safety
(see section 2).
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0311753_SGS_28-120_II_UKUK_V2.0 , 2017-05-03 7

This manual contains the following text styles/symbols for situations that may endanger
users/engineers, cause damage to equipment or need special attention:
Note
A note gives more information on a topic.
Caution
Obey the caution instructions to prevent damage of the water heater.
Warning
Obey the warning instructions to prevent danger of personal injury, and serious damage
to the water heater.
Document identification
Article number Language Version
0311753 EN 2.0
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Table of Contents
Preface........................................................................................ 3
Copyright.......................................................................... 3
Trademarks....................................................................... 3
Warranty...........................................................................3
Liability.............................................................................3
Compliance....................................................................... 3
Regulations....................................................................... 4
Contact information............................................................ 5
About this manual....................................................................... 7
Scope............................................................................... 7
Target group..................................................................... 7
Notation conventions.......................................................... 7
Document identification.......................................................8
User part.................................................................. 13
1 Introduction.............................................................................. 15
2 Safety........................................................................................17
3 Interface................................................................................... 19
3.1 Operator interface............................................................ 19
3.2 Explanation of icons.......................................................... 19
3.3 Control switch.................................................................. 20
3.4 Buttons........................................................................... 20
3.5 PC connection.................................................................. 21
3.6 Status of the water heater................................................. 21
3.6.1 Operating modes.............................................................. 21
3.6.2 Error conditions................................................................22
3.6.3 Service conditions.............................................................23
3.6.4 Anode warning................................................................. 23
3.6.5 Q/T Sensor warning.......................................................... 23
3.6.6 Collector temperature warning........................................... 23
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4 Use............................................................................................ 25
4.1 Turn on the water heater...................................................25
4.1.1 The appliance's heating cycle............................................. 25
4.2 Turn off the water heater...................................................27
4.2.1 Turn off for a short period..................................................27
4.2.2 Isolate from the mains...................................................... 27
4.2.3 Turn off for a long period...................................................28
4.3 Main menu...................................................................... 28
4.3.1 Notation conventions for menu-related instructions............... 28
4.3.2 Switching to ON mode.......................................................29
4.3.3 Setting the water temperature........................................... 29
4.3.4 Week program................................................................. 30
4.3.5 Starting and stopping the week program............................. 30
4.3.6 Changing the appliance's standard week program................. 30
4.3.7 Adding times to a week program........................................ 33
4.3.8 Deleting times from a week program...................................34
4.3.9 Extra period.....................................................................35
4.3.10 Settings.......................................................................... 37
Installation, Maintenance and Service part.............. 41
5 Introduction.............................................................................. 43
5.1 About the water heater..................................................... 43
5.2 The appliance's heating cycle............................................. 43
5.3 Working principle..............................................................43
5.4 Operating cycle................................................................ 45
6 Safety........................................................................................47
6.1 Safety instructions............................................................47
6.2 Instructions on the water heater.........................................48
6.3 Safety devices..................................................................49
6.3.1 Protection for the water heater...........................................49
6.3.2 Safety of the installation....................................................50
6.3.3 Protection for the solar heating system................................51
6.3.4 Safety of the solar heating system...................................... 51
6.4 Environmental aspects...................................................... 52
6.4.1 Recycling.........................................................................52
6.4.2 Disposal.......................................................................... 52
7 Installation............................................................................... 53
7.1 Packaging........................................................................53
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7.2 Conditions....................................................................... 53
7.2.1 Ambient conditions........................................................... 53
7.2.2 Maximum floor load.......................................................... 53
7.2.3 Water composition............................................................54
7.2.4 Working clearances...........................................................54
7.2.5 Storage tank working clearances........................................ 55
7.3 Installation diagram..........................................................56
7.4 Water connections............................................................ 57
7.4.1 Unvented water connections.............................................. 57
7.4.2 Vented water connections..................................................58
7.5 Gas connection.................................................................59
7.6 Solar heating system........................................................ 59
7.7 Venting system................................................................ 59
7.7.1 C13/C33 concentric systems.............................................. 61
7.7.2 C13/C33 parallel systems.................................................. 62
7.7.3 C43/C53/C63 systems.......................................................64
7.8 Electrical connections........................................................ 65
7.8.1 Preparation......................................................................66
7.8.2 Mains power.................................................................... 66
7.8.3 Optional electrical connections............................................67
7.8.4 Electrical connection of the solar heating system...................68
7.9 Commissioning.................................................................70
7.9.1 Filling..............................................................................70
7.9.2 Procedure for checking the supply pressure..........................72
7.9.3 Procedure for checking the gas control valve pressure........... 74
7.9.4 CO2 adjustment............................................................... 75
7.9.5 Switching pressure measurement....................................... 77
7.9.6 Turn on the water heater...................................................78
7.10 Decommisioning...............................................................78
7.10.1 Turn off the water heater...................................................78
7.10.2 Draining.......................................................................... 78
8 Conversion of gas type.............................................................. 81
9 Settings.....................................................................................83
9.1 Operator interface............................................................ 83
9.2 Service program...............................................................83
9.2.1 Hysteresis....................................................................... 83
9.2.2 Display the error history.................................................... 84
9.2.3 Display the water heater history......................................... 84
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9.2.4 Display the selected water heater....................................... 84
9.2.5 Setting the service interval................................................ 85
9.2.6 Service mode...................................................................85
9.2.7 Setting legionella prevention.............................................. 86
9.2.8 Solar heating system configuration..................................... 87
9.2.9 Setting the central heating configuration..............................89
10 Maintenance.............................................................................. 91
10.1 Preparation......................................................................91
10.2 Water-side maintenance....................................................92
10.2.1 Descale the tank.............................................................. 92
10.2.2 Clean the condensate drain................................................93
10.3 Gas-side maintenance....................................................... 93
10.3.1 Clean the burner.............................................................. 93
10.3.2 Clean the heat exchanger.................................................. 93
10.4 Solar collector maintenance............................................... 94
10.5 Finalization...................................................................... 94
11 Troubleshooting........................................................................ 95
11.1 Errors and warnings..........................................................95
11.1.1 General errors..................................................................96
11.1.2 Displayed errors............................................................... 97
11.1.3 Warnings....................................................................... 102
12 Appendices.............................................................................. 105
12.1 Technical details............................................................. 105
12.2 Dimensions.................................................................... 109
12.3 Gas details.....................................................................113
12.4 Week program card.........................................................115
12.5 Electrical wiring diagram..................................................117
12.6 Electrical wiring diagram solar heating system.................... 119
12.7 Menu structure............................................................... 120
12.8 Declaration of conformity.................................................121
12.9 Warranty....................................................................... 122
Index...................................................................................... 125
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User part
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1 Introduction
The SGS water heater stores and heats water for sanitary purposes.
Cold water enters the bottom of the tank through the water inlet (1). The heated water
leaves the tank at the top through the hot water outlet (2). To operate the water heater,
the operator interface (3) and control switch (4) are used.
Fig. SGS water heater
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2
3
4
1. Water inlet
2. Water outlet
3. Operator interface
4. Control switch
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2 Safety
A.O. Smith cannot be held responsible for damages or injuries leading back to:
Failure to follow the instructions provided in this manual.
Carelessness during use or maintenance of the water heater.
Every user has to study the user part of this manual and has to follow the instructions in
this part of the manual strictly. Do not change the sequence of the actions to be done.
This manual has to be available for the user and service engineer all the time.
Warning
If you smell gas:
Shut off the mains gas supply valve!
Avoid causing sparks! Do not use any electrical equipment or switch, i.e. no
telephones, plugs or bells!
No naked flames! No smoking!
Open windows and doors!
Warn occupants and leave the building!
After leaving the building, alert the gas distribution company or your
installation engineer.
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Caution
Do not store or use chemical substances in the room where the water heater is installed
because of the risk of explosion and corrosion of the water heater. Some propellants,
bleaching agents and degreasing agents etc. disperse of explosive vapors and/or cause
accelerated corrosion. If the water heater is used in a room where such substances are
stored or used, the warranty will be void.
Caution
Installation, maintenance and service may only by carried out by a qualified engineer.
Caution
The water heater is not intended for use by persons with reduced physical, sensory or
mental capacities, or who lack the necessary experience or knowledge. When the person
responsible for their safety is supervising them or has explained to them how the water
heater should be used, these persons can use the water heater.
Caution
This water heater is not intended to be used by children. Always supervise children, and
make sure that they do not play with the water heater.
Note
Regular maintenance extends the service life of the water heater. To determine the
correct service interval, the service and maintenance engineer has to do a check on both
the water and gas side of the water heater three months after installation. Based on this
check, the best service interval can be determined.
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18 User part

3 Interface
3.1 Operator interface
The operator interface is completely menu-driven, and comprises:
a 4-line display with 20 characters per line;
6 buttons for controlling the water heater (below the display);
6 graphical symbols (above the display);
a connector for a service PC;
a control switch.
The buttons are divided into three groups:
Navigation buttons:
Buttons for UP [ ], and DOWN [ ];
Enter: [ENTER].
Reset button: [RESET].
The main menu (see section 4.3): [ ];
The service program: [ ].
This chapter is specifically intended for the service and maintenance engineer and
installation engineer.
In this manual, the display of the operator interface is shown as in the figure, both with
and without icons.
3.2 Explanation of icons
The table explains the meanings of the icons.
Name Explanation
Heat demand Heat demand detected
Purge Pre- and post-purge using fan
Pressure switch Pressure switch is closed
Glow (Pre)glow
Gas control valve Gas control valve open/ignition
Flame detection Water heater operational
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Name Explanation
Solar heating system Solar energy is heating the water
3.3 Control switch
The control switch of the controller turns the water heater ON and OFF. Note that in the
OFF position the water heater remains electrically live, in order for the continuous pump
to stay running.
After switching on, the text INTERNAL CHECK appears on the display for about 10
seconds. The main menu (see section 4.3) then appears. If no selection is made in the
main menu, the water heater automatically switches to the OFF mode (see section 3.6.1).
Note
To electrically isolate the water heater, you must use the isolator between the water
heater and the mains power supply.
3.4 Buttons
The use of these buttons is explained with the help of the figure showing the main menu
(see section 4.3).
The buttons are:
Buttons for UP [], and DOWN [ ];
Enter: [ENTER];
Reset button: [RESET].
The arrows and indicate that you can scroll up and/or down. Use [ ] and [ ] to
scroll.
The cursor ® points to the option to be activated. In the display as shown in the figure,
you can scroll through the main menu.
The main menu comprises: OFF, ON, WEEK PROGRAM, EXTRA PERIOD and
SETTINGS. You have to scroll down further to see the options EXTRA PERIOD and
SETTINGS.
The selected option is confirmed using [ENTER].
Pressing [RESET] takes you back one page in a menu and discards all options selected in
the current menu.
Note
[RESET] is also used to reset the water heater following an error.
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