19
6.7
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.
Is there power
at the external
socket?
Make
power
available
Does
the pump
start?
Does
the fan
start?
Is there a spark
at the ignition
electrode?
Is fuse
at mains
plug OK?
Replace
fuse in
mains plug
Replace fuse on
the PCB
Is the green
led on?
After 20 seconds
from start of the
pump is the green
led flashing?
Smoke fault.
Check smoke pres-
sure switch and
his connection
After 20 seconds
from start of the
fan, is the green
led flashing?
Make it
free to
rotate
Is there power
at L and N
terminals?
Check wire
connections
to L and N
terminals
Is there
voltage available
at the pump?
Is flow water
switch closed?
Check flow
water switch
Check: gap
between the
electrode and
burner, conditions
or the electrode
and ignition
transformer.
Does it spark
now?
Is pump
shaft free
to rotate?
Open any
D.H.W. tap
to give flow
2.8 l/min.
Can you
get the desired
flow at the
D.H.W. taps?
Are microswitches
of divertor valve
operated?
Check pump
connection
Is there 230V ac
available at the fan
terminals?
Replace the PCB
Replace the
pump
Replace the
divertor valve
Replace the fan
Clean or replace
filter at inlet of
hydraulic group
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?
Is the gas
available?
Open the
gas cock
Is the safety
thermostat OK?
Replace the
safety thermostat
Is there voltage
available to
the gas valve?
Set properly
the connection
Replace the
gas valve
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
Yes
Yes
No
Yes
No
No
Yes
No
No
No
No
Yes
Yes
No
Yes
No
No
No
Yes
Yes
No
Yes
Yes
Yes
No
No
No
Yes
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
D.H.W. adjuster?
Does the burner
pressure reduce
as the temperature
rises towards max.?
Check:
1) C.H.
thermistor
2) PCB control
board
Is the burner
pressure set to
the maximum?
Is there
voltage at the
modulator?
Replace the
C.H. thermistor
Does the boiler
switch off before
achieving the tem-
perature?
Is L and N
polarity right
on the plug?
Replace the
modulator
Replace the PCB
Turn the plug
Boiler is
satisfactory
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
No
No
No
No
Yes
No
No
No
Summary of Contents for Murelle 25 BF
Page 24: ...Format C installation and servicing instructions...
Page 53: ...26...
