Bosch PROTANKLESS GWH 345/450 ESR - Manual (Page 30)

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Maintenance and service
5 Maintenance and service
The unit should be checked once a year by a gas
technician. If repairs are needed, the repairs should be
done by a gas technician
To remove front cover
B Loosen the two Philips head screws (as shown in
Fig. 2).
B Pull control panel upwards and then pull it
downwards.
B Lift front cover panel upward and remove.
Yearly maintenance
Refer to diagrams on pages 35 and 36.
• Inspect venting system for leaks, blockage or other
damage
• Unclip 4 access clips and remove cover to inspect
and clean burner assembly
• Manual operation of the pressure relief valve to insure
correct operation
• If flow is reduced or error AA is activated, flush the
heat exchanger with a descaling solution if mineral
build up is evident. Scale build up will shorten the life
of the water heater and is not covered by warranty.
Descale heat exchanger thoroughly and repeat
annually depending on mineral content of ground
water.
5.1 Service mode
The service mode provides diagnostic information to
the technician with a variety of real time parameters.
See Table 15 for the parameters and their respective
meaning.
Accessing the service mode
B Switch on the equipment.
B Press and hold the reset button
B Rotate the hot water temperature sensor dial to
the minimum and to the maximum.
Now the appliance is in the Service Mode.
Selecting parameter
B Rotate the recirculating water temperature selector
(left dial) to scan the different parameters.
Rotating clockwise accesses the next parameter
(increasing).
Once the desired parameter number has been
selected, the digital display will change to the value
stored in that parameter.
Adjusting parameters
B Rotate hot water temperature selector dial to
change the value of the parameter (only parameter
03 and 22).
Warning: Always turn off the electrical
power supply, turn off the manual gas
valve and turn off the manual water shut
off valves whenever servicing.