Bosch Greentherm T9900 SE 160, Installation And Operating Instructions Manual

Page: 68 / 80

Problem solving
Greentherm T9900 SE/i – 6 720 813 635 (2019/03) 68
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. ▶ Descale appliance (

section 7.3).
1)
BB Fan calibration triggered due to missed ignitions. ▶ Check gas inlet pressure (

section 4.13).
1)
▶ Perform gas and air tuning (

section 8.12).
1)
BC Successive fan calibration with similar learned
values. ▶ Check gas inlet pressure (

section 4.13).
1)
▶ Perform gas and air tuning (

section 8.12).
1)
C1
C2
Flue blockage detected during startup due to
insufficient combustion air. ▶ 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).
1)
C3 Flow sensor [14] does not detect water
recirculation. ▶ Check pump and connections.
1)
▶ Check recirculation circuit for any blockage.
C5 Bypass water valve [8] disconnected or damaged. ▶ Check bypass water valve wire connections.
1)
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).
1)
C7 Fan [2] disconnected or damaged. ▶ 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.
1)
C8 Main water valve [22] disconnected or damaged. ▶ Check main water valve wire connections.
1)
▶ 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).
1)
C9 Barometric pressure sensor damaged. ▶ Reset error (touch and hold on/off button for 3
seconds).
If the problem persists:
▶ Replace electronic control unit (ECU).
1)
CA Water flow above 9.2gpm. ▶ Disconnect the appliance and purge hydraulic circuit
to remove air.
1)
▶ Install water flow restrictor.
1)
▶ Check water pressure does not exceed 150psi
(

section 3.2).
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