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5.5
C.H. MODE - FAULT FINDING
Start from cold
Rotary switch set to WINTER position.
Room thermostat (if fitted) calling for heat and all D.H.W. taps off.
C.H. thermostat set to maximum position.
Clock in the on position (if fitted).
No
Is there power
Make
at the external
power
socket?
available
Yes
Is fuse
Yes
at mains
plug OK?
No
Replace fuse in
mains plug
Put a jumper on
Replace
the room thermo-
the fuse
stat connection
No
No
Yes
Is there a jumper
on the room
Is fuse
0,6 A OK?
thermostat
connection?
Yes
Check pump
connection
Fit correctly the
ignition electrode
Does the boiler
lock-out without
No
starting the
burner?
The gap between
ignition electrode
and hood
is correct?
Yes
Yes
Check for continu-
No
Is there a spark
ity between ignition
at the ignition
electrode and igni-
electrode?
tion transformer
Yes
No
Is the gas
Check the
available?
gas supply
Yes
No
Check the
Is there voltage at
connection on
the gas valve?
the fan PCB
Yes
Replace the
gas valve
NOTE:
After completing fault finding reset the room thermostat (if fitted) to the required setting. If the appliance will not function check the wiring
to the clock and if necessary, replace the clock.
Yes
Does
Turn the clock
the pump
in the right
start?
position
No
No
Is the clock in
Replace
the correct
the clock
band time?
Yes
No
Make it free to
rotate
Check the
time clock does
his contacts
open and close
when the clock
turns?
Is pump shaft
free to rotate?
Yes
No
Yes
Is there voltage
Replace
available
the pump
to the pump?
No
No
The ignition of the
burner is noisy
The boiler
lock-out
starting
the burner
Check the settings
of the gas valve
and "POT. ACC."
trimmer
Yes
Is the ionisation
probe
connected to the
main PCB?
Yes
No
Restore the
connection
Fit correctly the
ionistation probe
Yes
Does
the fan
start?
No
Is there voltage
available
to the fan?
No
Yes
Replace
the fan
No
Check the
power supply
cable
Yes
No
Yes
After the ignition
sequence does
the fan operate
Yes
at minimum
speed for
1 minute?
No
Remove the
"ANN. RIT." jumper
No
Does the boiler
remain in
pre-purge mode?
Yes
No
Is smoke
Replace the
pressure switch
smoke pressure
closed?
switch
Yes
No
Is limit
Replace the
thermostat
limit thermostat
calling for heat?
Yes
Yes
Is the micro-switch
Loose the screw
on the diverter
on the flow
valve locked?
switch cover
No
Yes
Does the
micro-switch
Check the
operate correctly?
connections of:
smoke pressure
switch, limit
No
thermostat and
flow switch
in the PCB
Replace the
control board
microswitch
No
Check:
Does the fan
speed decrease
2) C.H.
reducing the flow
thermistor
temperature
setting on
3) PCB control
the C.H. knob?
board
Yes
No
Does the
boiler switch
OFF before
achieving the
temperature?
Yes
Boiler is
satisfactory
17
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