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FAULT FINDING
52
mini HE --- Installation & Servicing
77 FAULT FINDING
WARNING
Care must be taken when conducting fault finding tests to
guard against the risk of electric shock.
230 Vac is t he nominal UK supply voltage. This may vary
between 253 V ac and 196 V ac.
When checking continuity ensure po wer is off to the
appliance.
With a fast pulse showing on LED 1 the boiler will continue to
operate with a reduced performance in some fault conditions.
Before commencing fault finding please check the follo wing:
Are all wiring connectio ns OK ?
Are the function selector settings correct
(Refer to frame 35, 36 and 39)
Pay attention t hat if the boiler locks out five times in an hour, it
is not sufficient to press the reset button to re---start the boiler
but it is necessary to disconnect the boiler from the main
supply and, after reconnect it, to press the reset button.
yes
no
Continued on page
54 of fault finding.
Adjust the burner
pressure. refer to
frame 35. Can th e max
burner pressure* be
achieved?
Continued
from page 56.
Remove the motor
assembly, with 230V at
the connections is the
spindle visible? Refer
to frame 76.
Dismantle the DHW
detector valve. Refer to
frame 66 and clean.
When re --- assembled
with DHW taps closed,
does the heating flow
pipe become warm?
Continued on page
53 of fault finding.
no no
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nonononono
no no
no
no
no
nono
yes
yes
yes
yes
yes
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yes
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yes
yes
yes yes
yes
yes
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no
yes
START
Ensure the room thermostat (if fitted) and programmer are calling for heat
Also that all services are on and the selector switch is set to heating*
Are only the two
green leds on front
fascia flashing
together or
alternately?
Isthereatleastoneof
the led flashing?
Is there 230V between
Live and Earth at th e
mains connection in
the c ontrol box?
Rectify external
wiring fault
Is there continuity
across the fuses on
the PCB?
Replace f au l ty fuses
and check for wiring
fault
With the boiler in heating
mode, what is the
maximum bur ner
pressure with boiler and
system cool ?
(pressure values are
giveninTable2page4
Is the gas inlet
pressure > 17 mbar?
Rectifygassupplyfault
Is there 230V at th e
Live connection to PCB
pin 4 ?
Repair or r eplace
wiring fault
Is there at least 15V dc
at the connections on
modu lator coil?
Replace faul ty PCB
Is m odulator harness
continuity O.K?
Repair or r eplace
faulty wiring
Replace faul ty PCB
Adjust max ’ stop’ on Gas
Valvetoachievethemax
burner pressure*
Does the heating
flow pipe become
warm quickly?
Is it a
system
boiler?
Is there a
DHW tap
open?
Disconnect DHW
flow sensor wiring.
Does the heating
flow pipe now
become warm?
Is there 230V
between Blue
and Brown at
the 3 ---way
valve
connection?
Close
DHW
tap
Is the continuity
of the 3 --- way
valve harness
O.K?
Repair or
replace
faulty
wiring
Replace faulty PCB
Replace fau lty
motor assembly
Replace fau lty valve
body assembly
Replace the D HW flow
detector sensor body.
Does the heating f low
become warm?
Faulty sensor now
replaced
Replace the faulty
DHW detector
valve
* see Table 2 at page 4 for the correct v alue
Are only the two green
leds on front fascia
flashing alternatively?
yes
no
Wait 60 seconds
FAULT FINDING