Bosch Therm 6000 S - Page 38

6 720 800 095 (2014/05) Therm 6000S
38 | Problem solving
Hot water temperature sensor
(NTC) at the exit of the
appliance detect a high
temperature of the hot water.
Temperature > 85°C
1. Check the correct position and xation of the NTC sensor.
2. Check the electric connections and connectors of the hot water
temperature sensor. Clean terminals. If the terminals are rusted, replace
the sensor and cables. Check resistance (see Fig. 3, [2]).
3. Clean the water lter, any dirty in the faucets and also all the water
lters of the installation.
4. In areas where water has a high mineral content, periodic descaling
may necessary.
Cold water temperature sensor
fault.
1. Check connector on wires coming from top of watervalve for a secure
connection.
2. Sensor may trip if water temperature drops below 2 °C. Protect heater
from freezing conditions as any damage due to freezing conditions is not
covered under warranty.
3. Check sensor.
Backow temperature sensor
over 150 °C.
The appliance will close the
burner and lock (non-volatile).
1. Check inlet/outlet vent pipes.
2. Check if secondary fan connections are disconnected.
3. Check if venting specications are met. Long vent lengths, venting
with more than three elbows, blocked vent or combination venting may
cause this failure.
4. Call the Technical Assistance.
Overheat sensor (ECO) open
circuit (resets when cooler
temperatures are detected
104 °C).
1. Disconnect power supply cord and check wire connections on the
overheat sensor and the two connectors on the control board. see Fig. 2,
[7].
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 specications are met. Long vent lengths, venting
with more than three elbows, blocked vent or combination venting may
cause this failure.
4. Clean the water lter, any dirty in the faucets and also all the water
lters of the installation.
5. In areas where water has a high mineral content, periodic descaling
may necessary.
6. Unplug power supply cord to the water heater. Open a hot water tap
fo
r 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.
Display Cause Solution
Table 21
* By installer or service technician only.