Bosch Therm 8000 S GWHC 27 CTDE Installation And Operating Instructions Manual page 44

44 | Problem solving
Display Cause
No ame ionization detected
with water ow.
Ionization failure during
operation.
Ionization error at standby.
Gas leakage error, gas valve
circuit not closing properly.
Table 25
* By installer or service technician only.
6 720 680 174 (2012/09)
Solution
1. Verify that all manual gas shut o 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 e ort
to purge air. Cycling hot water tap
necessary. If heater still faults with EA error code, have a licensed gas
technician properly purge air out of
heater.
5. Check three wire connections on the lower front of the heat
exchanger are secure.
6. Check venting speci cations ar
premature failure of the ame 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
water tap is opened. Sparking should be followed by a steady blue
ame. If ame is unstable/yellow wi
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 speci catio
cause premature failure of the ame 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 CO2 readings.
1. Loose connection to the ame ioni
wire leading from the control unit is
electrodes located on the lower front of the heat exchanger.
2. Flame ionization rod or contro
Technical Assistance.
1. Disconnect power supply cord an
valve and the two connectors on the control board.
2. Flow water out of a hot water ta
(1.9 l/m). Measure voltage at the ga
voltage should measure 24VDC between the left pair of wires and
24VDC between the right pair of wire
voltage is not proper, call the Technical Assistance.
3. Gas valve may be defective, call the Technical Assistance.
on and o multiple times may be
the gas line lead ing to the water
e met. Improper venting may cause
of the heat exchanger when a hot
th proper gas pressure, con rm CO2
ns are met. Improper venting may
zation rod. Verify that the thinner
securely connected to the set of
l unit may be damaged. Call the
d check wire connections on gas
p above the minimum activation point
s valve wire plug connection. The
s when the unit is operating. If
Therm 8000 S