Control Unit Diagnostics - Bosch GWH C 920 ES Instruction Manual

Maintenance and service
6.7

Control unit diagnostics

1. Press ON/OFF button to turn off the appliance.
2. Press and hold "Program"
ON/OFF button to turn appliance ON.
3. Release the button when '188' appears on the
display. The display should read 'P2' when the
program button is released. If not, repeat process.
4. Press and release the
panel until the display reads 'P4'. You are now in the
diagnostic mode of the control board.
5. When the display reads 'P4', press and release the
button once again and the display should read
'E'.
6. Use the and
cycle through different diagnostic modes available.
7. Once in the selected diagnostic mode of your
choice, press and release the
the diagnostic information.
B EXAMPLE: to read the flow rate in gallons per minute
while the unit is flowing water, cycle to the '3d' mode
and press the button. A reading of 25 on the
display would indicate the heater is reading a flow
rate of 2.5 gallons/minute.
B Once the information is obtained, press the
button again to return to the diagnostic mode menu
and scroll to addition diagnostic information.
8. Press ON/OFF button to turn OFF the appliance and
back ON again to return heater to normal function.
40
button and press
button on the control
buttons on the control unit to
button to display
Diagnostic menu
E Entry/Exit into sub-modes
Set-point temperature
0d
1d Inlet water temperature (°F)
2d Outlet water temperature (°F)
3d Water flow (gallons/min)
Gas type (LP or NG)
4d
5d Fan speed (Hz)
Burner power (%)
6d
7d Maximum power (kW)
Back flow temperature (°C)
8d
9d Exhaust temperature (°C)
Most recent error/failure
1F
2F 2nd most recent error
3F 3rd most recent error
4F 4th most recent error
5th most recent error
5F
6F 6th most recent error
7F 7th most recent error
8F 8th most recent error
9th most recent error
9F
10F 10th most recent error
Table 19
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