A.O. Smith BFM 50, BFM 30, BFM 80 User Manual
MODELS
BFM 30
BFM 50
BFM 80
INSTALLATION INSTRUCTIONS AND
USERS MANUAL
UNITED KINGDOM
CLOSED COMBUSTION WA TER HEA TER
INTRODUCTION
Read the installation instructions before installing the water heater. Read the user-instructions before lighting the water
heater. If these instructions are not followed carefully, this may lead to explosion and/or fire and can cause material
damages and/or physical harm.
Installation and commissioning should be carried out by a registered installer. The type of gas and standard values
which the water heater (from factory) is set on, are stated on the type plate.
The BFM-models fall under the instrument category; C13/C33. These water heaters are provided with an ignition system.
A. O. SMITH DOES NOT ACCEPT ANY RESPONSIBILITY FOR GUARANTEE, SERVICE PROVISION AND/OR PRODUCT
LIABILITY IN CASE OF UNAUTHORISED PRODUCT MODIFICATION OR REPAIRS.
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CONTENTS PAGE
1. GENERAL
1.1 Water heater description ..................................................................................................................... 5
1.2 Technical safety equipment ................................................................................................................ 6
1.2.1 Gas control .......................................................................................................................................... 6
1.2.2 Control box...........................................................................................................................................6
1.2.3 Burner automat ................................................................................................................................... .6
1.2.4 Air proving switch................................................................................................................................. 6
1.2.5 Gas control valve ................................................................................................................................. 6
1.3 Technical description ..........................................................................................................................8
1.3.1 Measurements ....................................................................................................................................8
1.3.2 Technical data ................................................................................................................................... 10
2. FOR THE INSTALLER
2.1 Installation instructions ..................................................................................................................... 11
2.1.1 Installation .........................................................................................................................................11
2.1.2 Water connection ............................................................................................................................... 1 1
2.1.3 Condensation drain...........................................................................................................................14
2.1.4 Gas connection ................................................................................................................................. 14
2.1.5 Flue connection (concentric) ............................................................................................................. 1 4
2.1.6 Electrical connection ......................................................................................................................... 16
2.2 Turning the water heater on ..............................................................................................................1 9
2.2.1 Filling the water heater ......................................................................................................................1 9
2.2.2 Turning the water heater on .............................................................................................................. 19
2.2.3 Setting up the pilot flame...................................................................................................................1 9
2.3 Turning the water heater off............................................................................................................... 19
2.4 Usage/temperature control ...............................................................................................................19
2.5 Checking the gas pressures ............................................................................................................ 20
2.6 Conversion to another gas ................................................................................................................2 1
2.7 Maintenance ...................................................................................................................................... 2 2
2.8 Anode ................................................................................................................................................. 22
2.9 Descale procedure............................................................................................................................22
2.10 Condensation....................................................................................................................................23
2.11 Spare parts ........................................................................................................................................ 23
3. FOR THE USER
3.1 Instructions for use ............................................................................................................................ 2 4
3.1.1 Warning ............................................................................................................................................. 24
3.1.2 Filling the water heater ......................................................................................................................24
3.1.3 Turning the water heater on .............................................................................................................. 24
3.2 Usage ................................................................................................................................................2 4
3.3 Turning the water heater off...............................................................................................................2 4
3.4 Maintenance ......................................................................................................................................2 4
4. FAULT FINDING AND CORRECTION
4.1 Fault finding userl .............................................................................................................................. 2 5
4.2 Fault finding installer ......................................................................................................................... 26
4.3 Detailed fault finding installer ............................................................................................................ 27
5. WARRANTY
5.1 Guarantee in general ........................................................................................................................ 3 1
5.2 Guarantee of the tank ........................................................................................................................31
5.3 Conditions for installation and use ................................................................................................... 31
5.4 Exclusions ......................................................................................................................................... 31
5.5 Range of the guarantee .....................................................................................................................3 1
5.6 Claims ............................................................................................................................................... 3 1
5.7 No other guarantee or warranty either expressed or implied is
made on behalf of A.O. Smith Water Products Company.................................................................3 1
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Figure 1
1) TOP-BOX 9) VENTILATION FAN
2) AIR PROVING SWITCH 10) ANODE
3) TEMPERATURE REGULATOR 11) FLUE TUBES
ON/OFF SWITCH 12) FLUE BAFFLE
RESET-KNOB 13) DIAPHRAGM
4) BURNER CONTROLLER 14) INSULATION
5) GAS VALVE 15) BURNER
6) MANIFOLD / INJECTORS 16) AIR DIFFUSION PLATE
7) PILOT BURNER 17) CONDENSATE DRAIN
8) HORIZONTAL AIR INLET
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1. GENERAL
1.1 Description of the appliance
Construction and fitting out of the storage appliance
comply with the European Standard for gas fired hot
water storage appliances for sanitary use (EN89). The
appliance thereby satisfies the requirements of the
European Directive for Gas Appliances, and is therefore
entitled to bear the CE mark.
The BFM appliance is an enclosed appliance with a
fan in the air inlet ( appliance category C13 or C33 ). The
appliance is designed for a concentric flue
configuration. A diaphragm, across which the pressure
difference can be measured, is fitted in the air inlet
system. When the control thermostat calls for heat, the
burner control unit carries out a zero position check. The
fan is subsequently switched on and, at a signal from
the pressure difference switch, the pre-ventilation
period (minimally 30 seconds) commences. Following
the pre-ventilation period the burner control unit
switches on the ignition transformer whereby the first
gas valve (the pilot) opens. On receiving an ionisation
signal from the ignition burner, the second (main
burner) gas valve opens. The appliance is now in
operation.
Technically this appliance falls into gas category
II
; the appliance is therefore suitable for natural
2L3P
gas as well as propane and butane gases. The storage
appliance is suitable for working pressures to 8 bar. A
connection is provided for the optional fitting of an extra
safety feature, the temperature and pressure valve. The
interior of the tank is enamelled for corrosion protection,
and a number of magnesium anodes are fitted to the
tank for the same purpose.
A thick polyurethane insulating layer between the tank
and its steel casing prevents unnecessary heat loss. If
the storage appliance is completely filled with water it is
under continual mains pressure. When hot water is
tapped off the appliance, cold water is immediately
introduced. Turbulence strips are placed in the fire tubes for the efficient transfer of heat. The flue gases pass
their heat to the water by conduction and radiation. The
flue gases are led to the flue via the top box. The burner
bed consists of a number of bar burners. An injector is
screwed into the manifold ahead of each burner, which
ensures correct mixing of gas and primary air through
injection into the burner inlet venturi. Secondary air is
drawn between the bar burners. An air distribution plate,
which also functions as a radiant heat shield, is fitted
below the burners. Any condensation water produced is
captured beneath the combustion chamber and led
away via a siphon (see illustration 1).
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1.2 Technical safety equipment
1.2.1 Gas control
The water heaters are equipped with a gas control
valve which regulates the flow of gas to the burner. The
combination gas control is equipped with a safety valve,
gas control valve, pilot safety valve and burner control
(on a standard natural gas setting)
1.2.2 Control box
For safety purposes, water heaters are always fitted
with three thermostats: a control thermostat, a high-limit
thermostat and an overheat thermostat.
The desired water temperature is set with the control
thermostat. To protect against freezing, the control
thermostat is also fitted with frost protection which
ignites the burner when the water temperature drops to
o
C, irrespective of the thermostat’s temperature
20
setting. The overheat thermostat prevents the water
reaching too high a temperature.
Should both control and high-limit thermostats
malfunction, the overheat thermostat will automatically
shut down the water heater.
The control thermostat can be set at settings 1-4
(approx. 40°C to 73°C). The frost protection ignites the
burner if the water temperature drops below 20°C. The
switch temperature of the high-limit thermostat is 84°C;
the overheat thermostat cuts in at 93°C. The sensor for
the control/frost thermostat is located at the level of the
control switch; the sensors for the high-limit and
overheat thermostats are located near the top of the
water heater.
The control box is fitted with an ON/OFF switch (I/0).
At setting I, the gas control operates on the basis of heat
demand from the control thermostat. At setting 0 the
water heater is switched off. The burner will only ignite
on the basis of heat demand from the frost protection.
When the control thermostat calls for heat, the water
heater checks all controls are in the off position. Power
is then switched to the ventilation fan. Immediately the
air pressure switch opens. The purge cycle starts. This
runs for between 30 and 60 seconds after which the
safety valve opens and the spark generator is operated.
Gas flows to the pilot burner where it is ignited by the
spark generator. The ionization probe now detects the
flame, switches off power to the spark generator and
opens the main gas valve.A softlite staged ignition
control prevents explosive ignition by allowing a small
percentage of total gas rate into the combustion
chamber initially followed by the full rate when
combustion is established. When the water temperature
reaches the set point the water heater is turned off.
If the flame extinguishes whilst in operation both the
safety (pilot) valve and the gas valve will close
immediately. If the control thermostat is still calling for
heat the burner automation will repeat the ignition
procedure.
continues to work.
- An interlocking of the burner automation can be
cancelled out by pressing the reset knob. If the
procedure does not succeed immediately, wait at
least 15 seconds before pressing the interlocking
knob again.
If the flame detection falls out during normal
operation, the burner automation will automatically
repeat its ignition procedure. As long as a flame is
detected within the safety period of 50 seconds, the
automation will continue to repeat the ignition procedure.
As soon as the water temperature has reached the
set value, the burner automation will close the gas
valves.
The control column has a potential-free contact for
external error message.
1.2.3. Ventilation fan
The ventilation fan is installed in the top-box. When
heat is required the ventilation fan is switched on by the
burner automation. The fan switches off when the main
burner has extinguished. The fan can be removed from
the top box via the access panel.
1.2.4 Air proving switch
The air proving switch ensures that there is sufficient
air flow for the safe operation of the water heater. If the
airflow falls below the preset value this will be detected
by the air proving switch and the gas supply to both the
ignition and main burners will be closed. The air proving
switch is preset and cannot be adjusted.
Air proving switches BFM-units
Unit Pstart Poff
(Pa) (Pa)
BFM 30 250 220
BFM 50 250 220
BFM 80 230 205
The air proving switch must always be fitted with the
connection points downwards!
The air pressure differential switch must always be fitted
with the connection points at the bottom, while the pipe
with the letter H must be connected to the point P1. Pipe
L goes to connection P2.
1.2.5 Gas control
The water heaters are provided with a gas valve that
regulates the gas supply to the burners.
The gas control has a safety valve and a gas valve
and hence has a B/D-configuration. The position of both
valves can be regulated by the burner automation. To
ensure improved ignition the gas control valve opening
mechanism is fitted with a delay (softlite).
- If no flame is detected within the safety time of
50 seconds, the burner automation will interlock and
the reset knob will light up.
- As long as the air proving switch does not operate
(remains closed), the burner automation will remain
in the waiting position, while the ventilation fan
6
Figure 2 - Positioning ventilation
Figure 3 - Differential pressure switch
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1.3 Technical description
1.3.1 Measurements
See figure 4
Size BFM 30 BFM 50 BFM 80
A 1995 1995 2020
B 1795 1795 1820
C 600 600 600
D 520 520 525
E 600 600 590
F 1640 1640 1655
G 1360 1360 1360
H 630 630 625
K 710 710 710
L 1000 1000 1000
M 755 755 755
N 80/125 100/150 130/200
1 Cold water inletRP1½
2 Hot water outletRP 1½
3 Gas valve RP ¾
4 Drain valve ¾"-14 NPT
5 T&P-connection (temperature- and pressure valve) 1"-14 NPT
All dimensions in mm, rounded up to the nearest 5 mm.
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Figure 4
IMD-0057-R0
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1.3.2 Technical data
Heater category:II
2H3+
Description Unit BFM 30 BFM 50 BFM 80
DATA NATURAL GAS G 20
Nominal gas inlet pressure mbar 20 20 20
Burner pressure mbar 12.5 12.5 12.5
Input kW 29 47 75
Output to water kW 27 42 68
Gas consumption* m3/h 3.0 4.7 7.9
Diameter main injector m m 2.60 2.50 2.70
Diameter injector ignition burner mm 0.56 / 0.41 0.56 / 0.41 0.56 / 0.41
Heating time ∆T=45°C mi n 35 25 12
DATA PROPANE/BUTANE G 30 - G 31 G30 G31 G30 G31 G30 G31
Nominal gas inlet pressure mbar 30 37 30 37 30 37
Input kW 29 28 46 44 75 71
Gas consumption kg/h 2.3 2.1 3.6 3.3 5.8 5.3
Diameter main injector m m 1.45 1.40 1.50
Diameter injector ignition burner m m 0.25 0.25 0.25
GENERAL
Storage capacity litre 309 298 2 53
Number of bar burners - 3 5 7
Number of anodes - 2 2 4
Number of flue tubes - 5 7 16
Water connections - Rp11/2 Rp11/2 Rp11/2
Gas connection - Rp3/4 Rp3/4 Rp3/4
Drain connection - 3/4" - 14 NPT 3/4" - 14 NPT 3/4" - 14 NPT
Anode - 3/4" - 14 NPT 3/4" - 14 NPT 3/4" - 14 NPT
Connection T&P-plug** - 1” - 14 NPT 1” - 14 NPT 1” - 14 NPT
Maximum working heat bar 8 8 8
Empty weight kg 27 0 290 3 50
* Gas usage at 1013,25 mbar and 15 °C.
** For a leak-tight connection European coupling pieces with pipe screw-thread according to ISO 228/1 or ISO 7/1 can be
used on the NPT-connection nipples.
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