A.O. Smith SGS-28 Troubleshooting guide

0311183
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
3015 - Changes Reserved.

your installer
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.

E1
Errata
The amendments below apply to:
the preparation of the electrical connection of the solar heating control (3.12.1 "Preparation");
finishing maintenance (15.6 "Finalizing maintenance");
the electrical diagram of the solar heating control (17.4 "Electrical diagram solar heating system").
These instructions supersede the previous instructions of the solar heating control.
3.12.1 Preparation
Remove the cover (snap-on type) from the terminal block of the solar heating control.
This has the following terminals:
0311615 R0.0
15.6 Finalizing
maintenance
To finalize the maintenance, carry out the following steps:
1. Fill the water heater (5 "Filling").
2. Start the water heater (9 "Starting the water heater").
3. Check the CO2value (3.12.3 "CO2adjustment").
4. Check the switching pressure of the pressure switch. (3.12.4 "Switching pressure
measurement")
5. Erase the message SERVICE REQUIRED. The displayed message can be reset in
either of two ways:
Temporary reset: To postpone the message, press RESET once. The message
will reappear on the display 7 days later.
2.Full reset: To fully reset the message, press and hold both RESET and ENTER
at the same time for 5 sec.
On completion of the full reset of the message, the message below will appear on the
display. This message will NOT be shown after a temporary rest of the message.

E2
17.3 Electrical diagram Electrical diagram
solar heating
system
0309687b R2.0
1 = brown, 2 = blue, 3 = yellow / green, 4 = black, 5 = white, 6 = grey / beige, 7 = green, 8 = yellow

E3
TERMINAL BLOCK CONNECTIONS
Earth
N Neutral
L Live input of the controller
L3Live input for the solar heating system modulating pump
PWM+ PWM+ stuursignaal t.b.v. aansturing pomp zonnesysteem
PWM- PWM- stuursignaal t.b.v. aansturing pomp zonnesysteem
COMPONENTS
AA Controller
BB[VAC] Solar heating system pump (modulating) (230 VAC)
BB[PWM] Solar heating system pump (modulating) (PWM-signal)
CC Temperature sensor (S1- solar collector)
DD Temperature sensor (S2- tank)
EE Combined Q/T sensor
(incl. temperature sensor S4- solar collector return)
FF Communication between the water heater controller and the solar
Heating system controller (BUS-link)
GG Temperature sensor (S3- top of storage tank)
K Double-pole isolator
CONTROLLER CONNECTIONS
J12 Connection of combined Q/T sensor (1-2-3-4)
J13 Connection of temperature sensor S1(2-4)
J14 Connection of temperature sensor S2(2-4) and temperature sensor S3
(1-3)
J16 Connection of BUS-link communication
J18 Connection of PWM-signal solar heating system pump
F2 Fuse (T 3.15A - 250 V)

Instruction manual SGS 3
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Read this manual carefully Warning
Read this manual carefully before starting the water heater. Failure to read
the manual and to follow the printed instructions may lead to personal injury and
damage to the water heater.
Copyright © 2013 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
stated in this manual.
Trademarks Any brand names mentioned in this manual are registered trademarks of their
respective owners.
Liability A.O.Smith Water Products Company accepts no liability for claims from third
parties arising from unauthorised use, use other than that stated in this manual,
and use other than in accordance with the General Conditions registered at the
Chamber of Commerce.
Refer further to the General Conditions. These are available on request, free of
charge.
Although considerable care has been taken to ensure a correct and suitably
comprehensive description of all relevant components, the manual may
nonetheless contain errors and inaccuracies.
Should you detect any errors or inaccuracies in the manual, we would be
grateful if you would inform us. This helps us to further improve our
documentation.
More information If you have any comments or queries concerning specific aspects related to the
water heater, then please do not hesitate to contact:
A.O.Smith Water Products Company
PO Box 70
5500 AB Veldhoven
The Netherlands
Telephone: (free) 0870-AOSMITH
0870-2676484
General: [phone]
Fax: [phone]
E-mail: [e-mail]
Website: www.aosmith.co.uk
In the event of problems with your gas, electricity or water supply connections,
please contact the supplier/installation engineer of your installation.

4Instruction manual SGS
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Instruction manual SGS 5
Contents
1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.1 About the water heater - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.2 What to do if you smell gas- - - - - - - - - - - - - - - - - - - - - - - - - 9
1.3 Regulations - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.4 Target groups - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 10
1.5 Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 11
1.6 Notation conventions- - - - - - - - - - - - - - - - - - - - - - - - - - - 11
1.7 Overview of this document - - - - - - - - - - - - - - - - - - - - - - - - 12
2 Working principle of the water heater - - - - - - - - - - - - - 13
2.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 13
2.2 General working principle of the water heater - - - - - - - - - - - - - - - 13
2.3 Water heater operating cycle - - - - - - - - - - - - - - - - - - - - - - - 15
2.4 Protection for the water heater - - - - - - - - - - - - - - - - - - - - - - 16
2.5 Safety of the installation - - - - - - - - - - - - - - - - - - - - - - - - - 17
2.6 Protection for the solar heating system - - - - - - - - - - - - - - - - - - 18
2.7 Safety of the solar heating system - - - - - - - - - - - - - - - - - - - - 19
3 Installation - - - - - - - - - - - - - - - - - - - - - - - - - - - 21
3.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21
3.2 Packaging - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21
3.3 Ambient conditions- - - - - - - - - - - - - - - - - - - - - - - - - - - - 21
3.4 Technical specifications - - - - - - - - - - - - - - - - - - - - - - - - - 23
3.5 Installation diagram - - - - - - - - - - - - - - - - - - - - - - - - - - - 29
3.6 Unvented water connections - - - - - - - - - - - - - - - - - - - - - - - 30
3.7 Vented water connections - - - - - - - - - - - - - - - - - - - - - - - - 30
3.8 Gas connection - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 31
3.9 Solar heating system- - - - - - - - - - - - - - - - - - - - - - - - - - - 32
3.10 Air supply and chimney flue discharge - - - - - - - - - - - - - - - - - - 32
3.11 Electrically connecting the water heater- - - - - - - - - - - - - - - - - - 38
3.12 Electrical connection of the solar heating system - - - - - - - - - - - - - 42
3.13 Check the supply pressure, gas control valve pressure, CO2value and
switching pressure - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45
4 Conversion to a different gas category - - - - - - - - - - - - 53
4.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 53
5 Filling - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 55
5.1 Filling unvented installations - - - - - - - - - - - - - - - - - - - - - - - 55
5.2 Filling vented installations - - - - - - - - - - - - - - - - - - - - - - - - 56
5.3 Filling solar heating system- - - - - - - - - - - - - - - - - - - - - - - - 56
6 Draining - - - - - - - - - - - - - - - - - - - - - - - - - - - - 59
6.1 Draining unvented installations - - - - - - - - - - - - - - - - - - - - - - 59
6.2 Draining vented installations - - - - - - - - - - - - - - - - - - - - - - - 60
6.3 Draining solar heating system - - - - - - - - - - - - - - - - - - - - - - 60
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Contents
6Instruction manual SGS
7 The control panel - - - - - - - - - - - - - - - - - - - - - - - - 63
7.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 63
7.2 Control - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 63
7.3 Explanation of icons- - - - - - - - - - - - - - - - - - - - - - - - - - - - 63
7.4 ON/OFF switch on controller - - - - - - - - - - - - - - - - - - - - - - - 63
7.5 Navigation buttons - - - - - - - - - - - - - - - - - - - - - - - - - - - - 63
7.6 PC connection - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 64
8 Status of the water heater - - - - - - - - - - - - - - - - - - - 65
8.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65
8.2 Operating modes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65
8.3 Error conditions - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 66
8.4 Service condition - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 67
8.5 Anode warning - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 67
8.6 Q/T Sensor warning - - - - - - - - - - - - - - - - - - - - - - - - - - - - 67
8.7 Collector temperature warning- - - - - - - - - - - - - - - - - - - - - - - 67
9 Starting the water heater - - - - - - - - - - - - - - - - - - - - 69
9.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 69
9.2 Starting the appliance - - - - - - - - - - - - - - - - - - - - - - - - - - - 69
9.3 The appliance's heating cycle - - - - - - - - - - - - - - - - - - - - - - - 69
10 Shutting down - - - - - - - - - - - - - - - - - - - - - - - - - 71
10.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 71
10.2 Decommissioning the water heater for a short period- - - - - - - - - - - - 71
10.3 Isolating the water heater from the mains - - - - - - - - - - - - - - - - - 71
10.4 Decommissioning the water heater for a long period - - - - - - - - - - - - 71
11 Main menu - - - - - - - - - - - - - - - - - - - - - - - - - - - 73
11.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 73
11.2 Notation convention for menu-related instructions - - - - - - - - - - - - - 73
11.3 Switching to "ON mode" - - - - - - - - - - - - - - - - - - - - - - - - - - 73
11.4 Setting the water temperature - - - - - - - - - - - - - - - - - - - - - - - 73
11.5 Week program - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 74
11.6 Starting and stopping the week program - - - - - - - - - - - - - - - - - - 74
11.7 Changing the appliance's standard week program - - - - - - - - - - - - - 74
11.8 Adding times to a week program- - - - - - - - - - - - - - - - - - - - - - 76
11.9 Deleting times from a week program- - - - - - - - - - - - - - - - - - - - 77
11.10 Extra period- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 78
11.11 Settings- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 79
12 Service program - - - - - - - - - - - - - - - - - - - - - - - - 81
12.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 81
12.2 Setting the hysteresis - - - - - - - - - - - - - - - - - - - - - - - - - - - 81
12.3 Displaying the error history - - - - - - - - - - - - - - - - - - - - - - - - 81
12.4 Displaying the water heater history - - - - - - - - - - - - - - - - - - - - 81
12.5 Display the selected water heater - - - - - - - - - - - - - - - - - - - - - 82
12.6 Setting the service interval - - - - - - - - - - - - - - - - - - - - - - - - 82
12.7 Service mode - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 82
12.8 Setting legionella prevention- - - - - - - - - - - - - - - - - - - - - - - - 83
12.9 Solar heating system configuration - - - - - - - - - - - - - - - - - - - - 83
12.10 Setting the central heating configuration - - - - - - - - - - - - - - - - - - 84

Instruction manual SGS 7
13 Errors- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 85
13.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 85
13.2 Troubleshooting table for general errors - - - - - - - - - - - - - - - - - 86
13.3 Troubleshooting table for displayed errors - - - - - - - - - - - - - - - - 89
13.4 Warnings on the display - - - - - - - - - - - - - - - - - - - - - - - - - 98
14 Service interval - - - - - - - - - - - - - - - - - - - - - - - - - 99
14.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 99
14.2 Determining service interval - - - - - - - - - - - - - - - - - - - - - - - 99
15 Performing maintenance - - - - - - - - - - - - - - - - - - - - 101
15.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 101
15.2 Preparation for maintenance - - - - - - - - - - - - - - - - - - - - - - - 101
15.3 Water-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - 102
15.4 Gas-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - 103
15.5 Solar collector maintenance - - - - - - - - - - - - - - - - - - - - - - - 104
15.6 Finalizing maintenance- - - - - - - - - - - - - - - - - - - - - - - - - - 104
16 Warranty (certificate) - - - - - - - - - - - - - - - - - - - - - - 105
16.1 General warranty - - - - - - - - - - - - - - - - - - - - - - - - - - - - 105
16.2 Tank warranty - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 105
16.3 Conditions for Installation and use - - - - - - - - - - - - - - - - - - - - 105
16.4 Exclusions - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 106
16.5 Scope of the warranty - - - - - - - - - - - - - - - - - - - - - - - - - - 106
16.6 Claims - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 106
16.7 Obligations of A.O.Smith - - - - - - - - - - - - - - - - - - - - - - - - - 106
17 Appendices- - - - - - - - - - - - - - - - - - - - - - - - - - - 107
17.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 107
17.2 Menu structure- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 108
17.3 Electrical diagram for the appliance- - - - - - - - - - - - - - - - - - - - 110
17.4 Electrical diagram, solar heating system - - - - - - - - - - - - - - - - - 112
17.5 Declaration of conformity - - - - - - - - - - - - - - - - - - - - - - - - - 114
17.6 Week program card - - - - - - - - - - - - - - - - - - - - - - - - - - - 115