Bosch Greentherm T9800 SEO199 Installation And Operating Instructions Manual page 48

Problem solving
Display Description
F7 Electronic control unit internal error.
F8 Electronic control unit internal error.
F9 Gas valve driver internal fault.
FA Gas leakage in the gas path (gas valve or gas
manifold shut-off valves).
FC Control buttons pressed for more than 30s.
Display shows Power demand lower than appliance minimum
but without output power.
existence of solar
thermal system.
Display shows
and water
temperature low.
Display shows "--" Display is not communicating with Electronic
Control Unit.
High pitch noise Combustion flame with gas in excess or lack of air. ▶ Check if gas type is correct ( section 6.7).
(whistling)
Low pitch noise Combustion flame with air in excess or lack of gas. ▶ Check if gas type is correct ( section 6.7).
with vibration
(rumbling)
1) only to be carried out by qualified contractors.
2) see temperature resistance charts in fig. 47 and 48.
Table 20
Note: If the appliance is locked for safety reasons, information is shown on the display to give more information on the problem.
Once the problem is solved, you may have to reset the error (press and hold
inside the appliance or in the remote control.
48
Solution
▶ Reset error (press and hold on/off button for 3
seconds).
If the problem persists:
▶ Replace electronic control unit.
▶ Reset error (press and hold on/off button for 3
seconds).
If the problem persists:
▶ Replace electronic control unit.
▶ Check gas valve wire connections.
If the problem persists:
▶ Replace the wire connections and/or electronic
control unit.
▶ Replace the gas valve and/or gas manifold.
▶ After gas valve and/or gas manifold replacement
perform gas and air tuning ( section 8.11).
▶ Release the button.
▶ Increase hot water flow.
▶ increase setpoint temperature.
▶ Reset the appliance by unplugging it for some
seconds (at least 10) and plug it back in.
▶ Replace the display and/or wire connections and/or
electronic control unit.
▶ Check gas inlet pressure ( section 4.13).
▶ Perform gas and air tuning ( section 8.11).
▶ Check gas inlet pressure ( section 4.13).
▶ Perform gas and air tuning ( section 8.11).
button for 3 seconds). To restart the appliance,
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