Baxi Main Combi 24 HE Installation And Service Instructions Manual page 49

Domestic Hot Water - Follow operational sequence
Turn selector to
neon illuminated
YES
Turn thermostat to max.
Open DHW tap fully. DHW
flow switch operated
YES
Primary water is diverted
from CH system to DHW
heat exchanger and flow
microswitch operated
YES
Pump runs
YES
Primary flow switch operated
YES
Fan runs at max speed
YES
Air pressure switch proved
YES
Spark at ignition electrodes
for up to 10 seconds
YES
Burner on neon
illuminated
YES
Burner extinguishes
after 10 seconds
NO
Burner output modulates to
maintain temperature set at
thermostat
YES
Close DHW tap
YES
DHW flow valve
senses no flow.
Primary water diverted to
CH system. DHW flow
switch released off
YES
Burner goes out
© Baxi Heating UK Ltd 2011
NO
Go to section 'A'
Is mains water
filter and differential
assembly clean?
YES
NO
DHW flow rate more than
2.5l/min.
Continuity across DHW flow
microswitch terminals and
NO
PCB - M1 connector
terminals 13 & 14 (terminals
12-14 open)
NO
Go to section 'B'
NO
Go to section 'C'
Turn the selector switch to
NO
the 'Reset' position and hold
for at least 2 seconds. If
regular resetting is required,
or appliance still does not
operate investigation is
necessary
NO
Go to section 'E'
NO
neon illuminated
NO
Replace PCB
NO
Go to section 'F'
YES
Go to section 'I'
Reduce the DHW flow rate.
NO
If burner does not modulate
clean temperature sensor and
DHW heat exchanger. If
modulation does not occur
go to section 'G'
NO
Diverter valve spindle
assembly faulty
NO
Fan stops
16.0
Replace diaphragm
YES
YES
DHW flow valve diaphragm
damaged
NO
DHW flow valve rod
obstructed
NO
Replace DHW flow
microswitch
YES
Replace PCB
Go to section 'J', 'L' & 'D'
Turn the selector to the reset
YES
position. If the light does not
extinguish go to section
H & K
YES
Pump stops
Fault Finding
YES
Operation sequence correct
49