6.5
Central Heating - Fault Finding
Start from cold set to WINTER position.
Room thermostat calling for heat.
C.H. thermostat set to maximum position.
NOTE:
After completing fault finding reset the room thermostat to the required setting.
Is there power
at the external
socket?
Make
power
available
Does
the pump
start?
After 20 seconds
from start of the
pump is the green
led flashing?
Is flow water
switch closed?
Does
the fan
start?
Is there a spark
at the ignition
electrode?
Is fuse
at mains
plug OK?
Is there power
at L and N
terminals?
Is the green
led on?
Check flow
water switch
and the C.H.
water filter
Flue fault.
Check air pressure
switch and
connections
After 20 seconds
from start of the
fan, is the green
led flashing?
Replace fuse
on the PCB
Replace fuse in
mains plug
Check wire
connections
to L and N
terminals
Is the T/S clock in
the correct
band time?
Check the
T/S time clock.
Do the contact
open and close
when the clock
turns?
Is there 230V AC
available at the
fan terminals?
Replace the PCB
Check: gap
between the
electrode and
burner, conditions
of the electrode
and ignition
transformer.
Does it spark
now?
Turn the clock
to the right
position
Close room
thermostat
contact
Replace
the fan
Is there voltage
available
to the pump?
Replace
/clock
the thermostat
Check pump
connection
Is pump shaft
free to rotate?
Replace
the pump
Make it free to
rotate
Has the PCB
ignition
locked-out after
10 seconds
without flame
at the burner?
Has the PCB
ignition
locked-out after
10 seconds
with flame
at the burner
before lock?
Check: gap
between the
electrode and
burner, conditions
of the electrode
and ignition
transformer.
Does it now
detect the flame?
Can the burner
pressure be
reduced by the
C.H. adjuster?
Does the burner
pressure reduce
as the temperature
rises towards max.?
Check:
1) C.H.
thermistor
2) PCB control
board
After two minutes
(safety time +
C.H. delay time),
is the burner
pressure set to
the maximum?
Is there
voltage at the
modulator?
Does the boiler
switch off before
achieving the tem-
perature?
Is the gas
available?
Open the
gas cock
Is L and N
polarity correct?
Replace the
modulator
Replace the PCB
Is the safety
thermostat OK?
Replace the
safety
thermostat
Correct
Replace the
C.H. thermistor
Is there
voltage available
to the gas valve?
Replace the
gas valve
Check the
connection
Boiler is
satisfactory
Yes
No
Is the room
thermostat
contact closed?
Yes
No
Yes
No
Yes
No
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
No
No
No
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
No
No
No
No
Yes
Yes
Yes
No
Yes
No
No
Yes
No
No
No
No
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Summary of Contents for sime 30e
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