Problem Solving; 10.1 Problem/Cause/Solution - Bosch Therm 6000 S Installation And Operating Instructions Manual

10

Problem solving

10.1 Problem/Cause/Solution

To remove error code from the display, press
the reset button.
Display Cause
A2 Fault in the flue gas limiter.
Temperature above 110 °C
inside the cabinet.
A3 Resistance connections are not
correct.
A4 Backflow temperature sensor
defect - happens if sensor is
disconnected or short circuit.
A7 Outlet temperature sensor fault
(Temperature below 0 °C or
above 98 °C).
Table 21
* By installer or service technician only.
Therm 6000S
Solution
1. Check continuity of the flue gas limiter (normally closed).
2. Check for flue gas leakage around the top and bottom seals of heat
exchanger, use mirror to check around the rear as well as the viewing
window.
3. Check venting specifications are met. Long vent lengths, venting with
more than three elbows, blocked vent or combination venting may cause
this failure.
4. Check that flue gas limiter connector and spade connections are
secure.
5. Unplug heater and check the wiring harness connections on the
control board.
1. Check resistance connection, see Fig. 2, [9].
1. Check backflow temperature sensor connection, see Fig. 2, [13].
2. Replace exhaust temperature sensor.
1. Check red wire connections at hot water temperature sensor. Clean
terminals with an eraser. If badly corroded, replace sensor and wire
harness.
2. Sensor may trip if water temperature drops below 0 °C to protect
heater from freezing conditions. Any damage due to freezing conditions
is not covered under warranty.
3. Clean the water filter, any dirty in the faucets and also all the water
filters of the installation.
4. In areas where water has a high mineral content, periodic descaling
may necessary.
5. Check sensor.
Problem solving | 35
6 720 800 095 (2015/11)