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19
220562A
Diagram 8.2
Diagram 8.3
8 F a u l t F i n d i n g
8.1 Fire Front Ignition
Remove the ash pit cover, front fret and fuel effect beds
and pieces.
Refer to diagram 8.1 “Fire Front Ignition Fault Finding”,
diagram 8.4 and 8.5.
8.2 Thermocouple
To test a thermocouple, a meter with a range of 0 to
30mV is required together with a thermocouple
interrupter test unit similar to the British Gas Minitest 6
Multimeter and Interrupter.
Refer to fault finding diagram 8.3 and diagnosis graph,
diagram 8.2.
Closed Circuit Voltage (millivolts)
DIAGNOSIS GRAPH FOR FIRE
THERMOCOUPLE CIRCUIT
Open Circuit Voltage (millivolts)
01234567891011
7
8
9
10
11
12
13
14
15
16
17
ABC
0065M
Disconnect appliance thermocouple from the gas tap. Check that all connections are
clean and in good condition. Fit test meter interrupter into the magnet unit. Fit appliance
thermocouple into the test meter interrupter.
NO
YES
Hold down control tap in ignition position. Ignite burner, allowing thermocouple to attain
operating temperature. Measure the OPEN CIRCUIT voltage.
Is voltage greater
than 7mV?
Faulty thermocouple.
Replace.
Note the open circuit reading then measure the CLOSED CIRCUIT voltage. Note this voltage.
Referring to the diagnosis graph, mark the open circuit voltage on the VERTICAL axis,
and the closed circuit voltage on the HORIZONTAL axis. Note the point where these
two values intersect on the graph.
THERMOCOUPLE
CIRCUIT IS
SATISFACTORY
In which area of the
graph is the intersect
Faulty thermocouple.
Replace.
Faulty magnet unit in gas tap.
Replace gas tap
B
A
C
0086M
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