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FAULT FINDING
mini HE --- Installation & Servicing
57
yes
yes
no
Is LED 1 and LED 2
on and LED 3
flashing?
Is LED 1 on and
LED 2 flashing?
no
Continued f rom
page 55 of fault
finding
yes
yes
no
no
Is there continuity of
overheat thermostat
wiring at PCB
connection?
Has th e main
overheat thermostat
operated? (Check
continuity)
Replace fau lty gas
valve
Allow boiler to cool
and press re---set
Repair or r eplace
damaged wiring
yes
yes
no no
Is the harness in
short c ircuit?
Allow the boiler to
cool. Is the
resistance of the flue
temperature probe
< 600 Ω ?
Replace fau lty wiring
Replace the probe
and press the reset
button
Check the
recuperator
yes
yes
no no
Is the continuity o f
thefluetemperature
probe harness OK?
Remove the flue
temperature probe.
Is the r esistance of
the probe > 30 KΩ ?
Replace faul ty PCB
Replace the probe
and press the reset
button
Replace fau lty wiring
yes
no
yes
Is LED 1 and LED 2
flashing and LED 3
on?
Is LED 1 on and
LED 2 and LED 3
flashing?
Wait for 1 minute. Is
the fan still running?
no no
yes
Is there 230V at
the fan
connections?
Replace fau lty fan.
no
no
yes
yes
Repair or r eplace
faulty wiring.
Is there continuity of the
Air Pressure Switch
harness?
Is there continuity
betweenNCandCatthe
Air Pressure Switch?
Replace fau lty Air
Pressure Switch.
Replace faul ty PCB
Repair or r eplace
faulty flame
detection signal
connection harness.
Refer to frame 49.
yes
yes
yes
no
no
no
no
no
yes
yes
Are the sensing
pipes undamaged
and connected?
Is there continuity
across C and NO on
the Air Pressure
Switch?
Clear flue
Repair or r eplace
venturi
Is th e burner on?
Istheflueclearand
venturi O.K?
Replace sensing
pipes.
Repair or r eplace
faulty wiring.
Is the A ir Pr essure
Switch harness
continuity O.K?
Replace fau lty Air
Pressure Switch
Replace faul ty PCB
yes
no
Is LED 1, LED 2
and L ED 3 on?
yes
Replace fau lty
PCB
FAULT FINDING