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9
221045A
3 F a u l t F i n d i n g
Diagram 3.5
CONNECTION
'D'
MULTIFUNCTIONAL
CONTROL
BOILER
OVERHEAT CUTOFF
CONNECTION 'E'
CONNECTION
'C'
CONNECTION
'B'
CONNECTION
'A'
With the boiler cold, check connections of the thermocouple, boiler overheat cut-off and multifunctional
control. Disconnect overheat cutoff connectors at points A and B at the multifunctional control,
see diagram 3.5. Test continuity of the overheat cutoff. Is there continuity?
Re-connect boiler overheat cutoff to points
A and B. Disconnect thermocouple at point
D of the mulitfunctional control. Test continuity
between point C and the body of the multi-
functional control. Is there continuity?
Test continuity of thermocouple between inner
connection point D and point E.
Is there continuity?
Thermocouple and boiler overheat
circuit satisfactory.
Faulty cutoff connectors into
multifunctional control, either at A or
C. Renew where faulty.
Faulty boiler overheat cutoff, renew.
Faulty thermocouple, renew.
YES
YES
NO
NO
NO
YES
Diagram 3.4
3.2 Pilot Burner and Ignition System
Symptom: The pilot burner will not light or stay alight.
Test the pilot burner and ignition system as shown in
diagram 3.3.
3.3 Thermocouple and Overheat Cutoff
Symptom: The pilot burner fails to stay alight.
On completion of initial checks, as Section 3.1.
Test the thermocouple, overheat cutoff and thermocouple
connectors, as described in Fault Finding diagram 3.4
and shown in diagram 3.5.
Check the millivoltage of the thermocouple closed
circuit at points “A” and “E”, this should be within the
range of 6 to 11mV, see diagram 3.5.
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