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Installation and Operating Instructions
Gas Instantaneous Water Heater
Safety instructions:
If you smell gas:
- Do not operate any electrical switches.
- Do not telephone from inside the danger area.
- Turn off the gas cock.
- Open windows and ventilate room.
6 720 607 527 ZA (05.02) JS
- From outside, call the gas company and your approved
installer.
Do not use or store easily combustible materials in the vicinity
of the appliance.
W11..B...
W14..B...
W18..B...
With electronic ignition and triple safety system
consisting of ionisation detector, flue gas monitor
and heat exchanger temperature sensor.
Installation and servicing of the appliance may only be
carried out by an approved technician.
The appliance should be regularly serviced in order to ensure
that it remains in perfect and safe working order.
If there is a risk of freezing, the appliance must be switched
off and drained. If the appliance has not been drained during
a cold spell, when it is switched on again check that it
produces hot water. If problems occur, contact your installer
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Contents
W 11 B
23
31
S…
W 14 B
23
31
S…
W 18 B
23
31
S…
1. Technical Characteristics and Dimensions
1.1 General Description ......................................................... 2
1.2 Explanation of Model Code ............................................ 2
1.3 Accessories ........................................................................ 2
1.4 Dimensions ......................................................................... 3
1.5 Appliance design ............................................................... 3
1.6 Circuit diagram ..................................................................4
1.7 Technical characteristics ................................................. 4
2. Preconditions for installation
2.1 Regulations .........................................................................5
2.2 Location .............................................................................. 5
2.3 Fixing the appliance.......................................................... 5
2.4 Water connection ............................................................. 5
1. Technical Characteristics and Dimensions
1.1 General Description
The appliance is easy to operate as it is ready to use at the
press of a button.
2.5 Gas connection ................................................................. 5
2.6 Flue....................................................................................... 5
2.7 Commissioning .................................................................. 5
3. Operation and maintenance
3.1 Function .............................................................................. 6
3.2 Water temperature control .............................................. 6
3.3 Appliance adjustments ..................................................... 6
3.4 Maintenance ...................................................................... 6
3.5 Flue gas safety device ..................................................... 6
3.6 Converting to a different gas type ................................ 6
3.7 Troubleshooting ................................................................. 7
4. Operation .................................................................................. 8
1.2 Explanation of Model Code
Guaranteed safety provided by:
- Gas-tight ionisation detector that prevents escape of gas
if there is no flame.
- Flue gas safety device that switches off the appliance if
the flue is not functioning properly.
- Temperature limiter which protects the heat exchanger
against overheating.
Electronic ignition controlled by opening of water valve.
Absence of a permanent pilot flame make it more
economical than conventional appliances.
Semi-permanent pilot flame functions only during the time
between opening of the water valve and activation of the
main burner.
Heat exchanger has no tin/lead lining.
Automatic water valve made of glass-fibre reinforced
polyamide, 100% recyclable.
Automatic control of water flow maintains constant flow rate
even with fluctuating supply pressure.
Green LED indicates burner condition.
W Gas instantaneous water heater
11 Flow rate (l/min)
B Electronic ignition powered by 1.5 V batteries
23 Natural gas type H
31 LPG (butane/propane)
S... Country code
1.3 Accessories (Included with Appliance)
- Sleeves and hooks for wall-mounting.
- Set of two batteries, 1.5 V type R
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1.5 Dimensions
Dimensions A B C D E F G H (Ø)
(mm) Natural Gas LPG
W11..B...
310 580 228 112,5 463 60 25
W14..B... 350 655 228 132,5 510 95 30
W18..B... 425 655 334 132,5 540 65 30
1/2"
1. Outer case
2. Hole for fixing to wall
3. Observation window
4. Temperature control
5. LED indicator for battery
charge level
6. On/Off switch
7. Output control
8. Gas connection
9. Flue socket
10. Draught diverter with flue
gas monitor
11. Heat exchanger
12. Automatic gas valve
13. Igniter unit
14. Battery compartment
15. LED indicator for burner
status
1.6 Appliance design
Fig. 3
Fig. 2
1. Heat exchanger
2. Ionisation detector
3. Main burner
4. Injector
5a. Testing point for burner pressure
5b. Testing point for supply pressure
6. Slow ignition valve
7. Temperature control
8. Venturi
9. Water valve
10. Flow restrictor
11. Water filter
12. Cold water supply pipe
13. Diaphragm
14. Microswitch
15. Main gas valve
16. Regulating screw
17. Gas inlet
18. Gas filter
19. Battery compartment
20. Hot water pipe
21. Igniter unit
22. On/Off switch
23. LED indicator for battery charge level
24. Servo valve
25. Output control
26. Gas valve
27. Gas valve for pilot burner
28. Pilot burner injector
29. Igniter electrode
30. Pilot burner
31. Temperature limiter
32. Flue gas safety device
33. LED indicator for burner status
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1.7 Circuit diagram
Technical Data Symbol Unit W11 W14 W18
Rated max. heat output
P
n
Btu/h 65570 80595 104165
Rated min. heat output
P
min
Btu/h 31420 40300 52082
Output (modulation range) Btu/h 31420 - 65570 40300 - 80595 52082 - 104165
Rated max. heat input
Q
n
Btu/h 74450 92210 117825
Rated min. heat input
Q
min
Btu/h 36200 46105 58912
Supply pressure:
Natural gas mbar (kPa) 20 (2.0) 20 (2.0) 20 (2.0)
LPG (butane/propane) mbar (kPa) 28 (2.8) 28 (2.8) 28 (2.8)
Consumption:
Natural gas G20
m3/h
2.2 2.77 3.5
LPG (butane/propane) G30/G31 kg/h 1.75 2.2 2.79
Number of injectors 12 14 18
Max. water pressure**
p
w
psi 170 170 170
Temperature control at maximum setting
Temperature increase °C 50 50 50
Flow rate l/min 5.5 7 8.8
Min. operating pressure
p
wmin
psi 2.0 3.0 3.0
Temperature control at minimum setting
Temperature increase °C 25 25 25
Flow rate l/min 11 14 17.6
Min. operating pressure bar 0.2 0.2 0.2
Draught requirement mbar 0.015 0.015 0.015
Flow rate g/s 13 17 22
Temperature °C 160 170 180
Output and heat
demand
Gas supply
specifications *
Flue
specifications
***
Water system specifications
1.8 Technical characteristics
1 Servo valve (normally open)
2 Diaphragm valve
3 Main valve (normally closed)
4 Ionisation detector
5 Igniter electrode
6 Flue gas safety device
7 Temperature limiter
8 Igniter unit
9 LED indicator for battery charge level
10 LED indicator for burner status
11 On/Off switch
12 Batteries, 1.5 V
13 Microswitch
Fig. 4
* Hi 15°C - 1013 mbar - dry : Natural gas 34.2 MJ/m3 (9.5 kWh/m3)
** This figure must not be exceeded taking account of water expansion
LPG: Butane 45.7 MJ/kg (12.7 kWh/kg) Propane 46.4 MJ/kg (12.9 kWh/kg)
*** At maximum rated heat output
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2. Preconditions for installation
The appliance can only be sold in the countries mentioned
in the type plate.
2.1 Regulations
Any local by-laws and regulations pertaining to installation
and use of gas-heated appliances must be observed. Please
refer to the laws that should be attended in South Africa.
2.2 Location
The appliance should be sited in a well ventilated room where
it will not be exposed to temperatures below freezing.
To prevent corrosion, the combustion air must not contain
any corrosive substances. Substances classed as corrosionpromoting include halogenated hydrocarbons such as are
found in solvents, paints, adhesives, aerosol propellants and
various household cleaners. Appropriate measures should
be taken where necessary.
With the exception of the flue pipe, the surface temperature
of the appliance is below 85 °C. No special safety measures
are therefore necessary.
Site appliance as shown in Fig. 5.
Always site appliance in a location not exposed to
temperatures below freezing. If this is not possible, the
appliance must be switched off and drained and the batteries
removed whenever there is a risk of freezing.
Danger: the appliances are designed to prevent flame reflow.
In case you suspect anything unusual in the appliance
operation, please shut down gas and water cocks, and call
an approved technician to check the local conditions.
To prevent flame reflow in outdoor installations please make
sure that a wind/rain protection is fitted.
To prevent flame reflow in indoor installations please make
sure that a wind/rain protection is fitted at the end of the
secondary flue.
Select pipe diameter to suit output of instantaneous water
heater being installed.
Fit gas service cock as close to appliance as possible.
Caution: This is a low pressure gas appliance. A SA certified
2.8 kPa low pressure regulator must be fitted.
2.6 Flue
It is absolutely essential that all instantaneous water heaters
are connected to a suitably dimensioned flue pipe by means
of a gas-tight connection.
The flue pipe should be made of galvanised iron, aluminium,
stainless steel or fibre concrete. Fit as shown in Fig. 5.
A flexible or rigid pipe should be used, fit it inside the flue
socket. The external diameter of the pipe should be slightly
smaller than the dimension specified in the appliances
dimensions table.
wind/rain
protection
2.3 Fixing the appliance
Remove the temperature control and the output control.
Remove the outer case by sliding it forwards and then lifting
upwards.
Fix the appliance using the sleeves and hooks supplied so
that it is vertical.
Never allow the appliance to rest against water or gas
pipes.
2.4 Water connection
It is advisable to drain the appliance before installing it as
any dirt or grit inside it could reduce the water flow rate and,
in extreme cases, could completely clog up the appliance.
Mark hot water and cold water pipes so as to prevent
confusion.
Connect pipe to automatic water valve using the connecting
kit supplied.
To prevent problems caused by sudden pressure fluctuations
in the water supply, it is advisable to fit a non-return valve to
the water outlet.
2.5 Gas connection
Take care to ensure dirt is not allowed to enter gas inlet.
Make sure that the type of gas specified on the appliance
type plate is the same as that supplied by the gas authorities.
Fig. 5
2.7 Commissioning
Turn on the gas and water cocks and check all connections
for leaks.
The two 1.5 V type R batteries supplied must be correctly
fitted (Fig. 6).
Check flue gas safety device good functioning, proceed as
explained in section 3.5.
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3. Operation and maintenance
Sealed parts must not be interfered with.
3.1 Function
This water heater is fitted with automatic electronic ignition
that provides for easy commissioning.
All that is required is to press the On/Off switch (Fig. 6).
The appliance will then ignite automatically as soon as a
hot water tap is turned on. The pilot flame ignites first and
then, about four seconds later, the main burner; the pilot
flame subsequently goes out after about 20 seconds.
Consequently, the appliance is substantially more
economical because the pilot flame only remains lit until
the main burner ignites, in contrast with conventional
appliances on which the pilot flame remains alight constantly.
After successful ignition, positioning it according to your
output requirement. The further to the left you position the
output control the higher the output, and consequently the
higher the consumption of gas. Maximum output is obtained
when the slide control is to the far left.
In order to optimise energy consumption, adjust slide control
position to supply the minimum output required.
If there is air in the gas pipe when the appliance is
commissioned, this can cause ignition failure. In such cases,
the hot water tap should be turned off and then on again so
that the appliance repeats the ignition cycle. The procedure
should be repeated as necessary until the gas pipe is purged
of air.
Danger: the area in front of the burner can reach very high
temperatures, and there is a risk of burning on contact.
connecting pipes should be descaled.
Check the gas and water valves for leaks and carry out a
complete function check.
If components need to be replaced, use only genuine Bosch
spare parts.
3.5 Flue gas safety device
The recommition must be done from a qualified technician
only.
The flue gas safety device must not under any circumstances
be switched off, simulated or replaced by any other
component.
Operation and safety precautions
The flue gas safety device checks the effectiveness of flue
gas extraction by the flue. If it is inadequate, the appliance
switches off automatically so that the combustion fumes do
not escape into the room in which the appliance has been
installed. The flue gas safety device resets after a coolingdown period.
If the appliance shuts down while in operation, ventilate the
room. Wait about 10 minutes then restart the appliance. If
the problem recurs, call an engineer. The user must never
make any modifications to the appliance.
Maintenance*
If faults occur on the flue gas safety device, proceed as
follows:
- Undo flue gas safety device fixing screw.
- Unplug igniter unit connector
Replace damaged component with new one and refit using
the reverse of the procedure set out in the table above.
3.2 Water temperature control
The water temperature control is used to adjust the water
flow rate, and thereby the water temperature, to the desired
setting.
Turning the control clockwise reduces the water flow rate
and increases the temperature; turning the control anticlockwise increases the water flow rate and reduces the
temperature.
If the temperature is set only as high as required, energy
consumption is reduced and the likelihood of scale deposits
in the heat exchanger minimised.
3.3 Appliance adjustments
All instantaneous water heaters are factory-adjusted and
require no further adjustment.*
Water heaters that use LPG (liquefied petroleum gas, i.e.
butane/propane) are set to the operating pressure stated
on the identification plate (28 mbar).
Natural gas appliances are set to a Wobbe Index of 15 kWh/
m3 and a supply pressure of 20 mbar.
* Sealed components must not be tampered with.
3.4 Maintenance
The appliance should only be serviced by an approved
engineer.
A complete overhaul should be carried out after two years.
The overhaul should involve thoroughly cleaning the heat
exchanger, burner, pilot burner and automatic water valve
filter.
If necessary, the inside of the heat exchanger and the
Function check*
Flue gas safety device function check:
- Disconnect flue pipe
- Replace with pipe (about 50 cm long) with sealed end
- Fit pipe vertically
- Start up appliance at rated output and set temperature
control to maximum temperature.
Under those conditions, the appliance should shut down
after two minutes. Remove temporary pipe and reconnect
flue pipe.
* This work may only be carried out by an approved engineer.
3.6 Converting to a different gas type
Use only the genuine Bosch conversion kit. Conversion
may only be carried out by an approved technician.
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3.7 Troubleshooting
Fault Possible Cause Solution
Appliance does not ignite. Batteries flat, incorrectly fitted or switch set to
Off
Check position and refit/replace.
Pilot flame lights slowly/with difficulty Batteries flat. Replace.
Red LED flashes
Water not hot enough Check position of water temperature control and
adjust to obtain desired hot water temperature
Water not hot enough, no flame Gas supply dynamic pressure too low Check gas cylinder governor and replace if
incompatible or damaged
Check whether gas cylinder (butane) is freezing
when appliance is in operation and re-site in
warmer location if necessary
Flame goes out while appliance is in
operation
Temperature limiter has tripped Wait 10 minutes then restart appliance. If
problem recurs, call an approved technician.
Flue gas safety device has tripped Ventilate room. Wait 10 minutes then restart
appliance. If problem recurs, call an approved
technician.
Reduced water flow rate Inadequate inlet flow rate Check and adjust.
Dirt in water service cock or mixer unit Check and clean.
Automatic water valve clogged Clean filter.*
Heat exchanger clogged (scale) Clean and descale as necessary.*
Installation, servicing and repairs may only be carried out by an approved engineer.
The following table illustrates only a few solutions to straightforward problems.
The operations marked with “*” may only be carried out by an approved technician
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4. Operation
Turn on all gas and water taps
Purge air from pipes
Insert two 1.5 V type R 20 batteries
in battery compartment
Safety precautions for use of batteries:
- Do not dispose of batteries with normal
household waste, take them to a recycling
site instead.
- Do not re-use worn out batteries.
- Use only batteries of the specified type
G667_092
Switching on/off
Press “
“ switch to switch
appliance on/off
If the red LED starts flashing,
replace batteries
G181_272
Green LED off = Main burner off
Green LED on = Main burner on
- On (I)
- Off (0)
G181_273
Low water temperature
Lower output
High water temperature
Higher output
Temperature adjustmentStarting up
Turning control anti-clockwise
increases water flow rate and
reduces water temperature
Turning control clockwise
reduces water flow rate and
increases water temperature
Fig. 6
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