Bosch Greentherm T9900 SE 160 Installation And Operating Instructions Manual page 68

Problem solving
Display Description
AA Condensing unit flue gases temperature [16]
above 392 °F (200 °C) and/or flue gases
temperature [15] above 145 °F (63 °C) at the
exhaust sensor [15]. Appliance regulates power to
protect against overheating.
BB Fan calibration triggered due to missed ignitions.
BC Successive fan calibration with similar learned
values.
C1 Flue blockage detected during startup due to
insufficient combustion air.
C2
C3 Flow sensor [14] does not detect water
recirculation.
C5 Bypass water valve [8] disconnected or damaged. ▶ Check bypass water valve wire connections.
C7 Fan [2] disconnected or damaged.
C8 Main water valve [22] disconnected or damaged. ▶ Check main water valve wire connections.
C9 Barometric pressure sensor damaged.
CA Water flow above 9.2gpm.
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Solution
▶ Descale appliance ( section 7.3).
▶ Check gas inlet pressure ( section 4.13).
▶ Perform gas and air tuning ( section 8.12).
▶ Check gas inlet pressure ( section 4.13).
▶ Perform gas and air tuning ( section 8.12).
▶ Reset error (touch and hold on/off button for 3
seconds).
If the problem persists:
▶ Check air intake and exhaust pipes and terminals for
obstructions and reset the error.
▶ Check if flue length is according to specification
(section 4.6) and reset the error.
▶ Perform gas and air tuning ( section 8.12).
▶ Check pump and connections.
▶ Check recirculation circuit for any blockage.
If the problem persists:
▶ Replace the bypass water valve and/or wire
connections. After valve replacement, proceed with
bypass water valve calibration (section 6.7).
▶ Check fan wire connections.
▶ Reset error (touch and hold on/off button for 3
seconds)
If the problem persists:
▶ Replace the fan and/or wire connections.
▶ Proceed with main water valve calibration.
If the problem persists:
▶ Replace main water valve and/or wire connections.
After valve replacement, proceed with main water
valve calibration (section 6.7).
▶ Reset error (touch and hold on/off button for 3
seconds).
If the problem persists:
▶ Replace electronic control unit (ECU).
▶ Disconnect the appliance and purge hydraulic circuit
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to remove air.
▶ Install water flow restrictor.
▶ Check water pressure does not exceed 150psi
(section 3.2).
Greentherm T9900 SE/i – 6 720 813 635 (2019/03)
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