16
5.6
D.H.W. MODE - FAULT FINDING
Start from cold - rotary switch set to SUMMER position, D.H.W. thermostat set to maximum, and all D.H.W. taps OFF.
NOTE:
When commissioning the boiler, please check the polarity in case the pump and the fan are running but the burner does not fire.
Is there power
at the external
socket?
Make
power
available
Open any tap.
Is there an
adequate flow
rate of D.H.W.
available?
Does the
microswitch of the
divertor valve
operate correctly?
Does
the fan
start?
Is fuse
at mains
plug OK?
Clean or replace
the divertor valve
Is there voltage
available
to the fan?
Does the boiler
remain in
pre-purge mode?
Replace fuse in
mains plug
Does
the pump
start?
Replace
the fan
Is limit
thermostat
calling for heat?
Replace the
limit thermostat
Make it free to
rotate
Replace the
microinterruptor
Check the
power supply
cable
Is the micro-switch
on the diverter
valve locked?
Is pump shaft
free to rotate?
Check pump
connection
Is fuse
0,6 A OK?
Replace
the fuse
Does the
micro-switch
operate correctly?
Replace the
microswitch
Replace
the pump
Loose the screw
on the flow
switch cover
Does the boiler
lock-out without
starting the
burner?
The boiler
lock-out
starting
the burner
Does the fan
speed decrease
reducing the flow
temperature
setting on the
D.H.W. knob?
Check:
2) C.H.
thermistor
3) PCB control
board
The ignition of the
burner is noisy
Does the
boiler switch
OFF before
achieving the
temperature?
Check the settings
of the gas valve
and “POT. ACC.”
trimmer
Is there a spark
at the ignition
electrode?
Is the ionisation
probe
connected to the
main PCB?
Check the
gas supply
Check for continu-
ity between ignition
electrode and igni-
tion transformer
The gap between
ignition electrode
and hood
is correct?
Fit correctly the
ignition electrode
Is the gas
available?
Restore the
connection
Fit correctly the
ionistation probe
Boiler is
satisfactory
Check the
connection on
the fan PCB
Is there voltage at
the gas valve?
Replace the
gas valve
Yes
No
No
Yes
No
No
Yes
No
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
No
Yes
No
Yes
Yes
Yes
No
No
Yes
No
Yes
Check the
connections of:
limit thermostat
and flow switch
in the PCB
control board
Yes
No
No
No
No
No
Yes
No
Yes
Yes
Yes
No
No
No
Is there voltage
available
to the pump?
No
Yes
Yes
No
Yes
Yes