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FAULT FINDING
54
mini HE --- Installation & Servicing
Continued from
page 52 of fault
finding. Is there at
least one of the
LEDs flashing?
Is LED 1 flashing with
LED 2 on ?
When the pump
runs does the
spindle of the water
flow detector
extend to operate
the micro switch?
Refer to frame 63.
Replace fau lty
diaphragm and clean
housing of debris, if any.
refer to frame 64.
Continued on page
55 of fault finding
no
yes
no no
no no
no
no
no
no
no
yes
yes
yes
yes
yes
yes
yes
yes
Check resista nce o f
DHW temperature
probe. Is it between
12 kΩ and 1.5 kΩ ?
Check resista nce o f
CH temperature
probe. Is it between
12 kΩ and 1.5 kΩ ?
Are LED2 and LED 3
flashing?
Replace fau lty
thermistor
Are LED2 flashing
and L ED 3 on?
Replace fau lty
thermistor
Repair or r eplace
faulty wiring
Repair or r eplace
faulty wiring
Remove the pump
nut. Does the pump
rotate f reely when
turned)
Replace fau lty pump
Re---pressurise
system and vent
Is the heating circuit
pressurised t o at least
1 bar and fully vented
of air?
Is the continuity o f
the micro switch
harness O.K?
Replace faulty micro
switch
Is there continuity
between C and NO
contacts on micro
switch when the
switch is operated?
Repair or r eplace
faulty wiring
Replace faul ty PCB
yes
FAULT FINDING