Bosch Therm 6000 S Installation And Operating Instructions Manual page 38

38 | Problem solving
Display Cause
EA No flame ionization detected
with water flow.
EC Ionization failure during
operation.
F7 Ionization error at standby.
FA Gas leakage error, gas valve
circuit not closing properly.
Table 21
* By installer or service technician only.
6 720 800 095 (2015/11)
Solution
1. Verify that all manual gas shut off valves are open.
2. Check gas type.
3. Check gas pressure.
4. Reset error code and open a water tap to cycle the heater in an effort
to purge air. Cycling hot water tap on and off multiple times may be
necessary. If heater still faults with EA error code, have a licensed gas
technician properly purge air out of the gas line leading to the water
heater.
5. Check three wire connections on the lower front of the heat exchanger
are secure.
6. Check venting specifications are met. Improper venting may cause
premature failure of the flame sensor rod.
7. Check that the minimum power fan speed has been adjusted to the
proper value. See chapter 8.6.
8. Observe inside the viewing window of the heat exchanger when a hot
water tap is opened. Sparking should be followed by a steady blue flame.
If flame is unstable/yellow with proper gas pressure, confirm CO
readings.
1. Check gas type.
2. Check gas pressure.
3. Check three wire connections to ignition group on the lower front of
the heat exchanger are secure.
4. Verify that venting specifications are met. Improper venting may cause
premature failure of the flame sensor rod.
5. Check that the minimum power fan speed has been adjusted to the
proper value. See chapter 8.6.
6. Check and adjust CO readings.
2
1. Loose connection to the flame ionization rod. Verify that the thinner
wire leading from the control unit is securely connected to the set of
electrodes located on the lower front of the heat exchanger.
2. Flame ionization rod or control unit may be damaged. Call the
Technical Assistance.
1. Disconnect power supply cord and check wire connections on gas
valve and the two connectors on the control board.
2. Flow water out of a hot water tap above the minimum activation point
(1.9 l/m). Measure voltage at the gas valve wire plug connection. The
voltage should measure 24VDC between the left pair of wires and 24VDC
between the right pair of wires when the unit is operating. If voltage is not
proper, call the Technical Assistance.
3. Gas valve may be defective, call the Technical Assistance.
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Therm 6000S