Installation and Operating Instructions
Gas Instantaneous Water Heater
Safety instructions:
If you smell gas:
- Do not operate any electrical switches.
6 720 607 526 ZA (05.02) JS
- Do not telephone from inside the danger area.
- Turn off the gas cock.
- Open windows and ventilate room.
- 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..P...
W14..P...
W18..P...
With piezo ignition and double safety
system consisting of 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.
page page
W 11 P
23
31
S…
W 14 P
23
31
S…
W 18 P
23
31
S…
1. Technical Characteristics and Dimensions ............... 2
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 Technical characteristics ................................................. 4
2. Preconditions for installation ........................................... 5
2.1 Regulations .........................................................................5
2.2 Location .............................................................................. 5
2.3 Fixing the appliance.......................................................... 5
2.4 Water connection ............................................................. 5
Index
2.5 Gas connection ................................................................. 5
2.6 Flue....................................................................................... 5
2.7 Comissioning ...................................................................... 5
3. Operation and maintenance ............................................. 6
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. Technical Characteristics and Dimensions
1.1 General Description
This water heater is fitted with a piezo system.
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.
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.
Gas valve with adjustable output via a slide control.
1.2 Explanation of Model Code
W Gas instantaneous water heater
11 Flow rate (l/min)
P Piezo ignition
23 Natural gas type H
31 LPG (butane/propane)
S... Country code
1.3 Accessories (Included with Appliance)
- Sleeves and hooks for wall-mounting
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1.4 Dimensions
Dimensions
A B C D E F G H (Ø)
(mm) Natural Gas LPG
W11..P...
310 580 228 112,5 463 60 25
W14..P...
350 655 228 132,5 510 95 30
W18..P...
425 655 334 132,5 540 65 30
1/2"
1. Front cover
2. Hole for fixing to wall
3. Observation window
4. Temperature control
5. Output control
6. Gas connection
7. Exhaust pipe union
8. Draught diverter with flue gas
monitor
9. Heat exchanger
10. Automatic gas valve
11. Piezo
12. Water valve
1.5 Appliance design
Fig. 2
1. Heat exchanger
2. Main burner
3. Injector
4. Slow ignition valve
5. Temperature control
6. Venturi
7. Water valve
8. Water throttle
9. Water filter
10. Membrane
11. Cold water pipe
12. Magnetic valve
13. Gas supply pipe
14. Gas filter
15. Regulating screw
16. Pilot filter
17. Piezo
18. Hot water pipe
19. Output control
20. Igniter button
21. Main gas valve
22. Gas valve for pilot burner
23. Pilot burner injector
24. Gas valve
25. Jet pressure testing point
26. Thermocouple
27. Igniter electrode
28. Temperature limiter
29. Flue gas safety device
Fig. 3
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1.6 Technical characteristics
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
m3/h
2.2 2.77 3.5
LPG (butane/propane) 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 50.0 50.0 50.0
Flow rate l/min 5.5 7 8.8
Min. operating pressure
p
wmin
psi 2.0 2.0 3.0
Temperature control at minimum setting
Temperature increase °C 25 25 25
Flow rate l/min 11 14 17.6
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 *
Water system specifications
Flue
specifications
***
* Hi 15°C - 1013 mbar - dry : Natural gas 34.2 MJ/m3 (9.5 kWh/m3)
LPG: Butane 45.7 MJ/kg (12.7 kWh/kg) Propane 46.4 MJ/kg (12.9 kWh/kg)
** This figure must not be exceeded taking account of water expansion
*** 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. 4.
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 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. 4.
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. 4
2.7 Commissioning
Turn on the gas and water cocks and check all connections
for leaks.
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 piezo ignition that provides
for easy commissioning.
In first place it must dislocate the output control of the off
position to the ignition position (see fig. 5).
Press in the slide control knob and subsequently press the
piezo button. Release the slide control after about 15
seconds, if the pilot flame does not stay alight, repeat the
operation.
Ignition may not be successful due to the presence of air
inside the gas supply pipe, especially if first connected or
after long inactive periods. In this case, keep the output
control knob fully depressed until the gas pipe has been
totally purged.
Slide the gas control slide fully to the right to obtain maximum
output. Sliding the gas control slide to the left reduces the
output.
In order to optimise energy consumption, adjust the output
control to supply the minimum output required.
After following these procedures, ignition of the main burner
will automatically take place whenever you turn on a hot
water tap, since the pilot burner is permanently alight.
When you want to switch off the heater, move the slide
control to the far left. After a few seconds the pilot flame
will go out.
If there is a risk of freezing, switch off the appliance and
drain the appliance.
Danger: the area in front of the burner can reach very high
temperatures, and there is a risk of burning on contact.
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 (2,8 kPa).
Natural gas appliances are set to a Wobbe Index of 15 kWh/
m3 and a supply pressure of 2.0 kPa.
* Sealed components must not be tampered with.
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
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.
- Undo magnetic unit connector
- Remove thermocouple.
Replace damaged component with new one and refit using
the reverse of the procedure set out in the table above.
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.
3.4 Maintenance
The appliance should only be serviced by an approved
engineer.
A complete overhaul should be carried out after two years.
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3.7 Troubleshooting
Problem Cause Solution
Pilot flame stay alight. Blocked pilot burner. Clean.*
Several atempts required to turn pilot
flame on.
Yellow pilot flame.
Flame goes out while appliance is in
operation.
Flue gas safety device has tripped Ventilate room. Wait 10 minutes then restart
appliance. If problem recurs, call an approved
technician.
Temperature limiter has tripped. Wait 10 minutes then restart appliance. If
problem recurs, call an approved technician.
Water not hot enough. Check output selector position and regulate
according with needs.
Water not hot enough, weak 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 resite in warmer location if necessary.
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
Ignition:
Release the slide control knob
after approximately 15 seconds
Press the piezo igniter
Output Control:
output decrease output increase
Depress slide control knob
and hold it in
Repeat these steps if the flame does not stay alight
Temperature adjustment
Turning control anti-clockwise
increases water flow rate and
reduces water temperature
Switching off:
Turning control clockwise
reduces water flow rate and
increases water temperature
Move slide control to the far left
Fig. 5
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