07/2009 - Art. Nr. 13 022 182A
20
Malfunction diagnosis and repair
In the event of a malfunction, first check
that the prerequisites for correct
operation are fulfilled:
1.
Is there any current?
2.
Is there gas pressure?
3.
Is the gas shut-off valve open?
4.
Are all control and safety devices,
such as the boiler thermostat, low
water detector, limit switches, etc.
correctly set?
If the malfunction is still present, refer to
the table below.
Important safety components must not
be repaired; these components must be
replaced by parts with the same part
number.
Only use original spare parts
.
Switch off the power supply
before carrying out
maintenance or cleaning
Note:
After any work on the system:
• Under normal operating conditions
(doors closed, cover fitted, etc.),
check combustion and check the
individual lines for leaks.
• Record the results in the relevant
documents.
Observation
Cause
Corrective action
Burner does not start after thermostatic closure.
No malfunction indicated on the control and
safety unit.
Drop in supply voltage or power failure.
Control unit malfunction.
Check the cause of the drop in voltage or the
power failure.
Replace the control unit.
No heat requested.
Thermostats defective or incorrectly adjusted
Adjust the thermostats, replace if necessary.
The burner starts briefly when switched on,
then switches off and the red indicator light
comes on.
Control unit has been locked intentionally.
Unlock the unit.
Burner does not start.
Air pressure switch: not in rest position.
Incorrect adjustment
Contact welded
Readjust the pressure switch.
Replace the pressure switch.
Burner does not start.
Gas pressure normal
Insufficient gas pressure.
Gas pressure switch wrongly set or defective
Check gas lines.
Clean filter.
Check the gas pressure switch or replace the
gas train.
Burner blower starts up.
Burner does not start.
Air pressure switch: Contact does not close.
Check the pressure transmitter (foreign bodies)
and wiring.
Burner blower starts up.
Burner does not start.
Flaring during pre-ventilation or pre-ignition.
Check the valve. Check flame monitoring.
The burner starts, the ignition switches on, then
failure
No flame at the end of the safety time.
Gas throughput set incorrectly.
Malfunction in flame monitoring system
No ignition sparks.
Electrode(s) short-circuited.
Ignition cable(s) damaged or defective.
Igniter defective.
Control and safety unit
Solenoid valves do not open.
Valves jamming.
Adjust the gas flow stage
Check the condition of the cell.
Check the condition of the flame detection
circuit connections (cable).
Adjust, clean or replace the electrodes.
Connect or replace the cable(s).
Replace the igniter.
Replace the control unit.
Check the cabling between the control unit and
external components.
Replace the gas train.
Replace the valves.
The burner switches off during operation.
Air pressure switch: contact opens during start-
up or during operation.
Flame failure during operation.
Adjust or replace the pressure switch.
Check the flame detection cell circuit.
Check or replace the control and safety unit.
Troubleshooting
Gas operation
Summary of Contents for NC12 B117
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