Problem solving
Display | Cause | Solution | |
| No flame ionization detected with | 1. | Verify that all manual gas shut off valves are open. |
| water flow. | 2. | Check gas type, see Fig. 2, page 6. |
3.Reset error code and open a water tap to cycle the heater in an effort to purge air on new installations. 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.
4.Check three wire connections to ignition group on the lower front of the heat exchanger are secure.
5.Check gas pressure, see chapter 3.12, page 27.
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 page 18.
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 or yellow with proper gas pressure, confirm CO2 readings per section 6.4.
Ionization failure during operation. | 1. | Check gas type, see Fig. 2, page 6. |
| 2. | Check three wire connections to ignition group on the lower |
| front of the heat exchanger are secure. | |
| 3. | Check venting specifications are met. Improper venting may |
| cause unstable burner flames and loss of flame ionization. | |
| 4. Check that the minimum power fan speed has been adjusted to | |
| the proper value. See page 18. | |
| 5. | Check gas pressure, see section 3.12, page 27. |
| 6. | Check and adjust CO2 readings, see section 6.4, page 33. |
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Ionization error at standby. | 1. | Loose connection to the flame ionization rod. Verify that the |
| thinner wire leading from the control unit is securely connected to | |
| the flame sensor located on the lower front of the heat exchanger. | |
| See Fig. 64, page 49. | |
| 2. | Flame ionization rod or control unit may be damaged. Contact |
| Bosch Water Heating for further instruction. | |
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Gas leakage error, gas valve circuit | 1. Disconnect power supply cord and check wire connections on | |
not closing properly. | gas valve and the two connectors on the control board. | |
| 2. Flow water out of a hot water tap above the minimum activation | |
| point of 0.65 GPM. 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, contact Bosch Water | |
| Heating for further instruction. | |
| 3. Gas valve may be defective, contact Bosch Water Heating for | |
| further instruction. | |
Table 20
* By installer or service technician only.
44 | 6 720 608 542 |