Bosch 830 ES Installation And Operating Instructions Manual page 62

Problem solving
Display Cause
(Flashing) Water flow signal over
specified maximum value.
Water flow > 10 gallon/min.
(Status message).
Over-temperature
detected by outlet
temperature sensor.
Temperature > 185°F
Cold water temperature
sensor fault.
Backflow temperature
sensor over 309°F.
The appliance will close the
burner and lock (non-
volatile).
Overheat sensor (ECO)
open circuit (resets when
cooler temperatures are
detected 220°F/104 °C).
No flame ionization
detected with water flow.
62
Solution
1. Disconnect power supply cord and check wire connections on water valve and the
two connectors on the control board, see fig. 74, page 75.
2. Excessive water pressure and flow. Ensure water pressure is less than 150psi and
flow rate is below 10 gallons per minute.
1. In areas where water has a high mineral content, periodic descaling may be
necessary. See chapter 7.3, page 53 for directions.
2. Check sensor (ref. page 64, chapter 10).
1. Check connector on wires coming from top of water valve for a secure connection.
See fig. 67, page 68.
2. Sensor may trip if water temperature drops below 36°F (2°C). Protect heater from
freezing conditions as any damage due to freezing conditions is not covered under
warranty.
3. Check sensor (ref. page 65, chapter 11).
1. Check inlet/outlet vent pipes.
2. Check if secondary fan connections are disconnected.
3. Check if venting specifications are met. Long vent lengths, venting with more than
three elbows, blocked vent or combination venting may cause this failure. See
chapter 4.3, page 15.
4. Call Bosch Water Heating for further instructions.
1. Disconnect power supply cord and check wire connections on the overheat sensor
(fig. 67, page 68) and the two connectors on the control board.
2. Check white wire connections at the overheat sensor. Clean terminals with an eraser.
If badly corroded, replace sensor and wire harness.
3. Check that venting specifications are met. Long vent lengths, venting with more than
three elbows, blocked vent or combination venting may cause this failure.
4. In areas where water has a high mineral content, periodic descaling may necessary,
see chapter 7.3, page 53.
5. Unplug power supply cord to the water heater. Open a hot water tap for several
minutes to allow cold water to pass through heat exchanger. Close hot water tap and
disconnect lead wires to overheat sensor. Using a multimeter, check continuity through
overheat sensor contacts. Replace sensor if open.
1. Verify that all manual gas shut off valves are open.
2. Check gas type. See fig. 2, page 12.
3. 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.
4. Check three wire connections on the lower front of the heat exchanger are secure.
5. Check gas pressure. See chapter 4.14, page 46.
6. Check venting specifications are met. Improper venting may cause premature failure
of the flame sensor rod. See chapter 4.3, page 15.
7. Check that the minimum power fan speed has been adjusted to the proper value. See
page 30.
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 CO2 readings per chapter 7.4, page 53.
830 ES – 6 720 644 936 (2021/08)