Quick start manual

39
14.0 Fault Finding
Domestic Hot Water - Follow operational sequence
Turn selector to
neon illuminated
Primary flow switch
operated
Fan runs at max speed
Pump runs
Turn thermostat to
max. Open DHW tap fully.
DHW flow switch operated
Primary water is diverted
from CH system to DHW
heat exchanger and flow
microswitch operated
neon illuminated
Continuity across DHW
flow microswitch terminals
and PCB - A5 connector
terminals 5 & 6
Air pressure switch
proved
neon flashing
Burner on neon
illuminated
Spark at ignition
electrodes for up to 10
seconds
Go to section ‘A’
neon flashing
Go to section ‘B’
neon flashing
Go to section ‘C’
Go to section ‘J’
neons flashing
Go to section ‘D’
Replace PCB
Turn the selector to the
reset position. If the light
does not extinguish go to
section H & K
Go to section ‘F’
neon flashing
Go to section ‘I’
DHW flow valve
senses no flow.
Primary water diverted to
CH system. DHW flow
switch released off
Close DHW tap
Burner goes out
Diverter valve spindle
assembly faulty
Pump stops
Operation sequence
correct
neon flashing
Turn selector to reset
position. If regular
resetting is required or
appliance still does not
operate investigation is
necessary
neon flashing
Go to section ‘E’
Burner extinguishes
after 10 seconds
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
Fan stops
NO
YES
YES
YES
YES
NO
NO
DHW flow rate more than
2.5l/min.
Is mains water
filter and differential
assembly clean?
DHW flow valve
diaphragm damaged
DHW flow valve rod
obstructed
Replace DHW flow
microswitch
Replace PCB
Replace diaphragm
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO
Reduce the DHW flow
rate. If burner does not
modulate clean DHW
temperature sensor and
DHW heat exchanger. If
modulation does not occur
go to section ‘G’
Burner output modulates
to maintain temperature
set at thermostat
NO
NO