A.O. Smith 28 30 50 60 Supplement

WATER PRODUCTS
COMPANY
A DIVISION OF A. O. SMITH CORPORATION
XTRA HIGH EFFICIENCY
XTRAHIGHEFF
ICIENCY
XTRAHIGHEFF
ICIENCY
Installation
User and
Service Manual
28
30
50
60
Release R.1.3UK

your installer
www.aosmithinternational.com

Release R.1.3 UK 3
Warning
Read this manual carefully before first using the water heater. Failure to read
this manual and to follow the instructions in this manual may lead to
accidents, personal injury, and damage to the appliance.
Copyright
Copyright 2003 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 improper use other than that stated in this manual and in
accordance with the General Conditions registered at the Eindhoven Chamber
of Commerce.
Refer further to the General Conditions. These are available on request, and
without 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 to receive notification. This helps us to further improve our
documentation.
More information
If you have any comments or queries concerning any aspect related to the
appliance, then please do not hesitate to contact A.O. Smith Water Products
Company.
A.O. Smith
Postbus 70
5500 AB Veldhoven
The Netherlands
Freephone: 008008 AOSMITH
008008 2 67 64 84
General: [phone]
Sales: [phone]
Help desk: [phone]
Fax: [phone]
E-mail: [e-mail]
Internet: www.aosmithinternational.com
In the event of problems with connecting to the gas, electricity or water supply,
please contact your installation’s supplier/installer.

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Table of contents
1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.1 About the appliance - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.2 What to do if you smell gas- - - - - - - - - - - - - - - - - - - - - - - - - 9
1.3 Regulations - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.4 Target groups - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 10
1.5 Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 10
1.6 Forms of notation - - - - - - - - - - - - - - - - - - - - - - - - - - - - 10
1.7 Overview of this document - - - - - - - - - - - - - - - - - - - - - - - - 11
2 Functioning of the appliance - - - - - - - - - - - - - - - - - - 13
2.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 13
2.2 Functional description of the appliance - - - - - - - - - - - - - - - - - - 13
2.3 The appliance’s heating cycle - - - - - - - - - - - - - - - - - - - - - - 14
2.4 Protection for the appliance - - - - - - - - - - - - - - - - - - - - - - - 14
2.4.1 Water temperature protection - - - - - - - - - - - - - - - - - 15
2.4.2 Gas control - - - - - - - - - - - - - - - - - - - - - - - - - - 15
2.4.3 Fan - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15
2.4.4 Pressure switch - - - - - - - - - - - - - - - - - - - - - - - - 15
2.4.5 Ionisation rod - - - - - - - - - - - - - - - - - - - - - - - - - 16
2.5 Safety of the installation - - - - - - - - - - - - - - - - - - - - - - - - - 16
2.5.1 Unvented installation - - - - - - - - - - - - - - - - - - - - - 16
2.5.2 Vented installation- - - - - - - - - - - - - - - - - - - - - - - 16
2.5.3 T&P valve - - - - - - - - - - - - - - - - - - - - - - - - - - - 16
3 Installation - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.2 Packaging - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.3 Environmental conditions- - - - - - - - - - - - - - - - - - - - - - - - - 17
3.3.1 Humidity and ambient temperature- - - - - - - - - - - - - - - 18
3.3.2 Maximum floor loading - - - - - - - - - - - - - - - - - - - - 18
3.3.3 Water composition - - - - - - - - - - - - - - - - - - - - - - 18
3.3.4 Working clearances - - - - - - - - - - - - - - - - - - - - - - 18
3.4 Technical specifications - - - - - - - - - - - - - - - - - - - - - - - - - 20
3.5 Installation diagram - - - - - - - - - - - - - - - - - - - - - - - - - - - 23
3.6 Water connections, Unvented - - - - - - - - - - - - - - - - - - - - - - 25
3.6.1 Cold water side - - - - - - - - - - - - - - - - - - - - - - - - 25
3.6.2 Hot water side - - - - - - - - - - - - - - - - - - - - - - - - - 25
3.6.3 Circulation pipe - - - - - - - - - - - - - - - - - - - - - - - - 25
3.6.4 Condensation drainage - - - - - - - - - - - - - - - - - - - - 25
3.7 Water connections, Vented- - - - - - - - - - - - - - - - - - - - - - - - 26
3.7.1 Cold water side - - - - - - - - - - - - - - - - - - - - - - - - 26
3.7.2 Hot water side - - - - - - - - - - - - - - - - - - - - - - - - - 26
3.7.3 Circulation pipe - - - - - - - - - - - - - - - - - - - - - - - - 26
3.7.4 Condensation drainage - - - - - - - - - - - - - - - - - - - - 26
3.8 Gas connection - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 26
3.9 Air supply and flue gas discharge- - - - - - - - - - - - - - - - - - - - - 27
3.9.1 Concentric wall flue terminal - - - - - - - - - - - - - - - - - - 28
3.9.2 Concentric roof flue terminal - - - - - - - - - - - - - - - - - - 29
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3.10 Electrical connection - - - - - - - - - - - - - - - - - - - - - - - - - - - 30
3.10.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 30
3.10.2 Preparation- - - - - - - - - - - - - - - - - - - - - - - - - - - 30
3.10.3 Mains voltage - - - - - - - - - - - - - - - - - - - - - - - - - 31
3.10.4 Isolating Transformer - - - - - - - - - - - - - - - - - - - - - - 32
3.10.5 Continuous pump- - - - - - - - - - - - - - - - - - - - - - - - 32
3.10.6 program-controlled pump - - - - - - - - - - - - - - - - - - - - 32
3.10.7 Extra ON mode switch (“Tank ON”) - - - - - - - - - - - - - - - 32
3.10.8 Connecting extra error signal (“Alarm OUT”) - - - - - - - - - - 33
3.11 Checking the supply pressure and burner pressure - - - - - - - - - - - - 33
3.12 Conversion to a different gas category - - - - - - - - - - - - - - - - - - - 35
4 Filling and draining - - - - - - - - - - - - - - - - - - - - - - - 39
4.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 39
4.2 Filling the appliance - - - - - - - - - - - - - - - - - - - - - - - - - - - - 39
4.2.1 Filling unvented installations - - - - - - - - - - - - - - - - - - 39
4.2.2 Filling vented installations- - - - - - - - - - - - - - - - - - - - 39
4.3 Draining the appliance - - - - - - - - - - - - - - - - - - - - - - - - - - 41
4.3.1 Draining unvented installations - - - - - - - - - - - - - - - - - 41
4.3.2 Draining vented installations - - - - - - - - - - - - - - - - - - 41
5 The control panel - - - - - - - - - - - - - - - - - - - - - - - - 43
5.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 43
5.2 Operating - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 43
5.3 Explanation of the icons - - - - - - - - - - - - - - - - - - - - - - - - - - 44
5.4 ON/OFF switch of ThermoControl - - - - - - - - - - - - - - - - - - - - - 44
5.5 Navigation buttons - - - - - - - - - - - - - - - - - - - - - - - - - - - - 44
5.6 PC connection. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 44
6 Status of the appliance - - - - - - - - - - - - - - - - - - - - - 45
6.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45
6.2 Operating modes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45
6.3 Error conditions - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 46
6.4 Service condition - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 47
7 Starting up and shutting down - - - - - - - - - - - - - - - - - 49
7.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49
7.2 Starting up - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49
7.3 Shutting down- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49
7.3.1 Shut the appliance down for a brief period (“OFF mode”) - - - - 50
7.3.2 Disconnect the appliance from the mains - - - - - - - - - - - - 50
7.3.3 Shut the appliance down for a longer period- - - - - - - - - - - 50
7.4 The appliance’s heating cycle - - - - - - - - - - - - - - - - - - - - - - - 51
8 Main menu - - - - - - - - - - - - - - - - - - - - - - - - - - - 53
8.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 53
8.2 Notational convention for menu-related instructions - - - - - - - - - - - - 53
8.3 Switching into “ON mode” - - - - - - - - - - - - - - - - - - - - - - - - - 54
8.4 Setting the water temperature - - - - - - - - - - - - - - - - - - - - - - - 54
8.4.1 Setting the water temperature via SETPOINT MENU - - - - - - 54
8.4.2 Setting water temperature during ON mode - - - - - - - - - - - 54

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8.5 Week programme - - - - - - - - - - - - - - - - - - - - - - - - - - - - 55
8.5.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 55
8.5.2 Starting up and shutting down the week program- - - - - - - - 55
8.5.3 Changing the appliance’s standard week program - - - - - - - 55
8.5.4 Adding times to a week program - - - - - - - - - - - - - - - - 57
8.5.5 Deleting times from a week program - - - - - - - - - - - - - - 58
8.6 Extra period - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 60
8.6.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 60
8.6.2 Programming an extra period - - - - - - - - - - - - - - - - - 60
8.7 Settings - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 61
8.7.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 61
8.7.2 Setting menu language - - - - - - - - - - - - - - - - - - - - 61
8.7.3 Setting day and time- - - - - - - - - - - - - - - - - - - - - - 62
8.7.4 Displaying appliance specifications - - - - - - - - - - - - - - 62
9 Service program - - - - - - - - - - - - - - - - - - - - - - - - 65
9.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65
9.2 Setting the hysteresis - - - - - - - - - - - - - - - - - - - - - - - - - - 65
9.3 Displaying the error history - - - - - - - - - - - - - - - - - - - - - - - - 65
9.4 Displaying the appliance history - - - - - - - - - - - - - - - - - - - - - 66
9.5 Display the selected appliance - - - - - - - - - - - - - - - - - - - - - - 66
9.6 Setting the pump on/off - - - - - - - - - - - - - - - - - - - - - - - - - 66
9.7 Setting the service interval - - - - - - - - - - - - - - - - - - - - - - - - 66
9.8 Setting the display contrast- - - - - - - - - - - - - - - - - - - - - - - - 67
9.9 Setting the backlight time- - - - - - - - - - - - - - - - - - - - - - - - - 67
9.10 Setting the display scroll speed- - - - - - - - - - - - - - - - - - - - - - 67
10 Troubleshooting - - - - - - - - - - - - - - - - - - - - - - - - 69
10.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 69
10.2 Troubleshooting table for general errors - - - - - - - - - - - - - - - - - 70
10.3 Troubleshooting table for displayed errors - - - - - - - - - - - - - - - - 72
11 Maintenance frequency - - - - - - - - - - - - - - - - - - - - 83
11.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 83
11.2 Determining service interval - - - - - - - - - - - - - - - - - - - - - - - 83
12 Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - 85
12.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 85
12.2 Preparation for maintenance - - - - - - - - - - - - - - - - - - - - - - - 85
12.3 Water-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - 87
12.3.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 87
12.3.2 Checking the anodes - - - - - - - - - - - - - - - - - - - - - 87
12.3.3 Descaling and cleaning the tank - - - - - - - - - - - - - - - - 87
12.3.4 Cleaning condensation water discharge - - - - - - - - - - - - 87
12.4 Gas-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - 87
12.4.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 87
12.4.2 Cleaning the burner - - - - - - - - - - - - - - - - - - - - - - 87
12.4.3 Cleaning the orifice - - - - - - - - - - - - - - - - - - - - - - 88
12.4.4 Cleaning heat exchanger - - - - - - - - - - - - - - - - - - - 88
12.5 Finalising maintenance- - - - - - - - - - - - - - - - - - - - - - - - - - 88
13 Warranty (Certificate)- - - - - - - - - - - - - - - - - - - - - - 89
13.1 General warranty - - - - - - - - - - - - - - - - - - - - - - - - - - - - 89

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13.2 Tank warranty- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 89
13.3 Installation and conditions of use - - - - - - - - - - - - - - - - - - - - - 89
13.4 Exclusions - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 89
13.5 Scope of the warranty - - - - - - - - - - - - - - - - - - - - - - - - - - - 90
13.6 Claims - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 90
13.7 Limitation of liability A.O. Smith - - - - - - - - - - - - - - - - - - - - - - 90
A Appendices - - - - - - - - - - - - - - - - - - - - - - - - - - - 91
A.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 91
A.2 Electrical diagram BFC - - - - - - - - - - - - - - - - - - - - - - - - - - 92
IX Index - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 95

About the appliance
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1 Introduction
1.1 About the appliance This manual describes how to install, service and use the BFC appliance. The
BFC appliance is a condensing room-sealed water heater with a fan in the air
intake. A concentric chimney connector is fitted standard to the appliance.
Alternatively, the appliance can be connected using a parallel system.
Installation types possible with this appliance are C13, C33, C43, C53 and C63.
The information in this manual is applicable to types: BFC 28, BFC 30, BFC 50
and BFC 60.
The manner of construction and features of the appliance are in conformance
with the European standard for gas-fired storage water heaters for the
production of domestic hot water (ES 89). The appliances are therefore
compliant with the European Directive for Gas Appliances, and have the right to
bear the CE mark.
Warning
Read this manual carefully before starting up the water heater. Failure to
read the manual and to follow the printed instructions may lead to personal
injury and damage to the appliance.
1.2 What to do if you
smell gas Warning
Whenever there is a smell of gas:
No naked flames! No smoking!
Avoid causing sparks! Do not use any electrical equipment or switch, i.e. no
telephones, plugs or bells!
Shut off the mains gas supply!
Open windows and doors!
Warn occupants and leave the building!
After leaving the building, alert the gas distribution company or installer.
1.3 Regulations As the (end) user, installer or service and maintenance engineer, you must
ensure that the entire installation complies, as a minimum, with the official local:
• building regulations;
• energy supplier’s directives for existing gas installations;
• directives and technical guidelines for natural gas installations;
• safety requirements for low-voltage installations;
• regulations governing the supply of drinking water;
• regulations governing ventilation in buildings;
• regulations governing the supply of air for combustion;
• regulations governing the discharge of products of combustion;
• requirements for installations that consume gas;
• regulations governing indoor waste water disposal;
• regulations imposed by fire service, power companies and municipality;
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Furthermore, the installation must comply with the manufacturer’s instructions.
nRemark
Later amendments and/or additions to all regulations, requirements and
guidelines published on or prior to the moment of installing, will apply to the
installation.
1.4 Target groups The three target groups for this manual are:
• (end) users;
•installers;
• service and maintenance engineers.
Symbols on each page indicate the target groups for whom the information is
intended. See Table 1.1.
1.5 Maintenance A service should be carried out at least once a year, both on the water side and
on the gas side. Maintenance frequency depends, among other things, on the
water quality, the average burning time per day and the set water temperature.
nRemark
To determine the correct maintenance frequency, it is recommended to
arrange for the service and maintenance engineer to check the appliance on
both the water and gas side, three months after installation. Based on this
check, the best maintenance frequency can be determined.
nRemark
Regular maintenance extends the service life of the appliance.
1.6 Forms of notation The following notation is used in this manual:
nRemark
Important information
cNote
Ignoring this information can lead to the appliance being damaged.
Warning
Failure to carefully read this information may lead to danger of personal
injury, and serious damage to the appliance.
Table 1.1 Target group symbols
Symbol Target group
g(End) user
iinstaller
sService and maintenance engineer

Overview of this document
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1.7 Overview of this
document
Table 1. 2 provides an overview of the contents of this document.
Table 1.2 Contents of document
Chapter Target groups Description
2 Functioning of the
appliance gis This chapter describes how the appliance functions.
3 Installation is This chapter describes the installation activity to be completed
before you actually start up the appliance.
4 Filling and draining gis This chapter describes how to fill and drain the appliance.
5 The control panel gis This chapter describes the general control of the appliance
using the display.
6 Status of the appliance gis This chapter describes the status (mode or condition) that the
appliance may have, and possible actions to take.
7 Starting up and shutting
down gis This chapter describes how to start up the appliance, and how to shut it down for a brief or long period of time. The general
heating cycle of the appliance is also described.
8 Main menu gis Describes the main menu of the display. This is the actual
menu for the user, however the installer and service and
maintenance engineers will also need to use this menu.
9 Service program is Describes the service menu. It is mainly intended for the
installer and service and maintenance engineers. End users
may also refer to this chapter for additional information about
the appliance.
10 Troubleshooting gis This chapter is mainly intended for the installer and the service
and maintenance engineer. It describes appliance errors.
These errors are indicated on the display. A troubleshooting
table of possible causes and solutions is provided. End users
may also refer to this chapter for additional information about
the appliance.
11 Maintenance frequency gs This chapter describes how to determine the optimum
frequency at which to carry out maintenance. Both the end
user and the service and maintenance engineer are
responsible for regular maintenance. They need to reach clear
agreement on this.
nRemark
If the appliance is not regularly maintained, the warranty
will become void.
12 Maintenance sThis chapter sets out the maintenance tasks to be carried out
during a service.
13 Warranty (Certificate) gis This chapter states the warranty terms and conditions.

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Introduction
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2 Functioning of the
appliance
2.1 Introduction Topics covered in this chapter:
•Functional description of the appliance;
•The appliance’s heating cycle;
•Protection for the appliance;
•Safety of the installation.
2.2 Functional
description of the
appliance
Figure 2.1 shows a cut-away view of the appliance.
Legend
aplastic top cover
bhot water outlet
celectrical connection block
dThermoControl
epressure switch
fcontrol panel
gtemperature sensor T1
hcombustion chamber
ianode
jtank
kheat exchanger
linspection and cleaning
opening
mtemperature sensor T2
ncold water inlet
odrain valve
pgas control
qburner
rfan
sair supply hose
tglow igniter
uionisation rod
vchimney pipe
wsiphon
xPU insulation layer
IMD-0070
Figure 2.1 Cut-away view of the appliance
k
i
a
p
c
e
u
b
o
r
x
q
h
f
d
j
n
t
v
w
s
g
l
m
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Functioning of the appliance
14 Instruction Manual BFC
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In this appliance the cold water enters the bottom of the tank via the cold water
inlet n. The tap water, heated by the combustion chamber hand heat
exchanger k, leaves the tank through the hot water outlet b. Once the
appliance is completely filled with water, it remains constantly under water
supply pressure. As hot water is drawn from the appliance, cold water is
immediately added.
The air required for combustion is forcibly delivered to the burner qby the
fan r. The gas is fed to the burner qvia the gas control p. Thanks to the
modulated supply of gas and air, the optimum gas/air mixture is always
achieved. The special construction of the burner causes the mixture to form a
vortex (the cyclone effect), before it becomes ignited. Because of this vorticity,
ignition at the glow igniter tis improved, and the combustion efficiency is also
optimised. Through the special design of the heat exchanger k, the flue gases
are first led downwards via the combustion chamber, then upwards again via the
heat exchanger, then once more downwards beside the water in the tank. In this
process, the flue gases gradually become cooler. Because the cooled flue
gases flow alongside the cold water below in the tank, they start to condense.
This condensation causes latent heat energy to be released, which is
transferred to the cooler water, and thereby increases the performance of the
unit. The water of condensation yielded by this process is discharged via the
siphon w.
The PU insulation layer xprevents heat loss. The inside of the tank is
enamelled to protect against corrosion. The magnesium anodes iprovide
extra protection against corrosion.
For use during maintenance, the appliance has a inspection and cleaning
opening l.
2.3 The appliance’s
heating cycle
The entire appliance is controlled (and monitored) by theThermoControl d. The
temperature sensor T1 g(in the top of the tank j) and the temperature sensor
T2 m(in the bottom of the tank) measure the water temperature. These
temperatures are sent to the ThermoControl. Based on these two observations,
the ThermoControl calculates a net water temperature: Tnet. The value of Tnet
lies between the temperatures measured at the top and bottom of the tank. As
soon as Tnet falls below the set water temperature (Tset), the ThermoControl
registers a ‘heat demand’. The gas control pis opened, and the gas is mixed
with air. This mixture is ignited by the glow igniter tand the water becomes
heated. As soon as Tnet rises above Tset, the heat demand ends, and the
ThermoControl stops the heating cycle.
Both when registering and ending the heat demand, the ThermoControl
assumes a certain margin. We refer to this margin as the hysteresis (see
paragraph ’9.2 Setting the hysteresis’).
2.4 Protection for the
appliance
The ThermoControl monitors the water temperature and ensures safe
combustion. This is achieved by:
• the Water temperature protection;
• the Gas control;
• the Fan;
• the Pressure switch;
• the Ionisation rod.

Protection for the appliance
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2.4.1 Water temperature protection
With temperature sensor T1 gand temperature sensor T2 m, the
ThermoControl monitors three temperatures which are important for safety.
Table 2. 1 explains the functioning of the temperature sensors.
2.4.2 Gas control
The ThermoControl opens the gas control so that gas can be supplied to the
burner. As a safety measure, the gas control has two valves. Both valves shut
off the gas supply.
Smooth ignition is achieved by opening the gas control with a delay (‘softlite’).
2.4.3 Fan
The fan provides an optimum air supply when there is a heat demand. A safety
aspect is that the fan ensures that any gases present in the combustion
chamber get removed, both before and after combustion. We refer to this as
pre- and post-purge.
The fan speed is continuously monitored by the ThermoControl. The
ThermoControl takes control if the speed of rotation varies too much from the
value set.
2.4.4 Pressure switch
The pressure switch ensures the discharge of flue gases and the supply of
incoming air during the pre-purge and normal running of the appliance. The
standard position of the pressure switch is open. When sufficient pressure
differential is reached, the pressure switch closes. However, in the event of a
fault, the pressure switch will be tripped open, and the heating cycle will be
interrupted.
Table 2.1 Temperature protection
Protection Description
Against frost
(T1< 5°C or T2< 5°C)
The frost protection cuts in. The water is heated to 20°C.
For maximum water temperature
(T1> 85°C or T2> 85°C)
The high-limit safeguard serves to prevent overheating and/or excessive
formation of scale in the appliance. Should the high-limit safeguard be
activated, the heating is halted. This causes the water in the tank to cool down.
Once the water has cooled sufficiently (T1< 78 °C), the ThermoControl resets
the appliance.
For extra safety
(T1> 93°C or T2> 93°C)
A lockout error of the water heater controller takes place. The controller must
be manually reset before the appliance can resume operation (see paragraph
’6.3 Error conditions’). The reset may only be performed once T1< 78°C.

Functioning of the appliance
16 Instruction Manual BFC
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Table 2.2 shows the trip point per appliance.
nRemark
The trip point of the pressure switch is not adjustable.
2.4.5 Ionisation rod
To ensure that no gas will flow when there is no combustion, an ionisation rod
has been fitted. The ThermoControl uses this rod for flame detection, by means
of ionisation detection. The ThermoControl cuts in, the instant it detects that
there is a gas flow but no flame.
2.5 Safety of the instal-
lation
In addition to the appliance’s standard safety monitoring, the appliance must
also be protected by an expansion vessel, pressure overflow valve, non-return
valve and a T&P valve.
Use of an expansion vessel, a pressure relief valve and/or a pressure reducing
valve depends on the type of installation: unvented or vented.
2.5.1 Unvented installation
With an unvented installation, a pressure relief valve and expansion vessel
prevent excessive pressure in the tank. This prevents damage being caused to
the enamelled coating (in the appliance) or to the tank. A non-return valve
prevents excessive pressure in the water supply system. This valve also
prevents water from flowing backwards from the tank into the cold water supply
system. The pressure reducing valve protects the installation against an
excessively high water supply pressure (> 8 bar). These components are fitted
to the cold water pipe. See paragraph ’3.6.1 Cold water side’.
2.5.2 Vented installation
With a vented installation, excess pressure is taken up by the open water
reservoir. The level of the water reservoir determines the maximum working
pressure in the tank, which may not exceed 8 bar. The installation must also be
fitted with an overflow from the hot water pipe, which discharges into the water
reservoir. See paragraph ’3.6.2 Hot water side’.
2.5.3 T&P valve
A T&P valve is only mandatory in an ‘unvented’ installation. However,
A.O. Smith also recommends the use of a T&P valve in ‘vented’ installations.
A T&P valve monitors the pressure in the tank, and the water temperature at the
top of the tank. If the pressure in the tank becomes excessive (>10 bar) or the
water temperature is too high (>97°C), the valve will open. The hot water will
immediately flow out of the tank. Because the appliance is under water supply
pressure, cold water will automatically flow into the tank. The valve remains
open until the unsafe situation has been averted. A connecting point for a T&P
valve is standard on the appliance. See paragraph ’3.6.2 Hot water side’.
Table 2.2 Pressure switch trip points
Applianc
e
Pressure differential [Pa]
Closing Opening
BFC 28 > 635 < 605
BFC 30 > 855 < 825
BFC 50 > 885 < 855
BFC 60 > 1085 < 1055

Introduction
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3 Installation
Warning
The installation should be carried out by an approved installer in compliance
with the general and local regulations imposed by the gas, water and power
supply companies and the fire service.
The appliance may only be installed in a room which complies with the
requirements stated in national and local ventilation regulations.
Refer also to paragraph ’1.3 Regulations’.
3.1 Introduction This chapter describes the installation activities to be carried out before the
appliance may be started up, namely:
•Packaging;
•Environmental conditions;
•Technical specifications;
•Water connections, Unvented;
•Water connections, Vented;
•Gas connection;
•Air supply and flue gas discharge;
•Electrical connection;
•Checking the supply pressure and burner pressure;
•Conversion to a different gas category.
nRemark
Starting up the appliance is described in chapter ’7 Starting up and shutting
down’.
3.2 Packaging To avoid damaging the appliance, remove the packaging carefully. We
recommend unpacking the appliance at or near its intended location.
cNote
The appliance may only be manoeuvred in an upright position. Take care
that the appliance is not damaged after unpacking.
3.3 Environmental
conditions The BFC appliance is a room-sealed appliance. Installation types possible with
this appliance are C13, C33, C43, C53 and C63. This makes it possible to install
the appliance in either a closed or an open boiler room.
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Installation
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3.3.1 Humidity and ambient temperature
The boiler room must be frost-free, or be protected against frost. Table 3.1
shows the environmental conditions that must be adhered to, for correct
functioning of the electronics present in the appliance to be guaranteed.
3.3.2 Maximum floor loading
In connection with the appliance’s weight, take account of the maximum floor
loading, see Tabl e 3 . 2 .
3.3.3 Water composition
The appliance is intended for heating drinking water. The drinking water must
comply with the regulations governing drinking water for human consumption.
Table 3.3 shows these requirements.
nRemark
If the water specifications deviate from those stated in Table 3. 3 , then the
tank protection cannot be guaranteed.
See also chapter ’13 Warranty (Certificate)’.
3.3.4 Working clearances
For access to the appliance it is recommended that the following clearances
are observed (see Figure 3.2):
• AA: around the appliance’s control column and cleaning openings: 100 cm.
• BB: around the appliance itself: 50 cm.
• Above the appliance (room to replace the anodes):
- 100 cm if using fixed anodes, or
- 50 cm if using flexible anodes.
Table 3.1 Humidity and ambient temperature specifications
Humidity and ambient temperature
Humidity max. 93% RH at +25°C
Ambient temperature Functional: 0 ≤t ≤60°C
Table 3.2 Weight specifications related to maximum floor loading
Weight of the appliance filled with water
BFC 28 392 kg
BFC 30, BFC 50, BFC 60 593 kg
Table 3.3 Water specifications
Water composition
Hardness
(alkaline earth ions)
> 1.00 mmol/l:
• German hardness >5.6° dH
• French hardness > 10.0° fH
• British hardness > 7.0° eH
Conductivity > 125 µS/cm
Acidity (pH value) 7.0 < pH value < 9.5

Environmental conditions
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If the available clearance is less than 100 cm, flexible magnesium anodes
may be ordered from A.O. Smith, the installer / supplier.
nRemark
When installing the appliance, be aware that any leakage from the tank and/
or connections can cause damage to the immediate environment or floors
below the level of the boiler room. If this is the case, then the appliance
should be installed above a wastewater drain or in a suitable metal leak tray.
The leak tray must have an appropriate wastewater drain and must be at
least 5cm deep with a length and width at least 5cm greater than the
diameter of the appliance.
Figure 3.1 Working clearances
IMD-0073
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3.4 Technical
specifications
The appliance is supplied without accessories. Check the dimensions and other
specifications for the accessories to be used, based on Figure 3.2 and
Table 3.6.
Figure 3.2 Plan and elevation of the appliance
IMD-0073