15.0
Fault Finding
53
© Baxi Heating UK Limited 2005
Check isolation valve and
gas supply.
Remove gas valve & check inlet
filter for blockage. Otherwise
incorrect gas supply to boiler.
YES
NO
Ignition Lockout
YES
YES
NO
NO
Is there
gas at gas valve inlet ?
Reset lockout.
Is there gas flow ?
(check at the meter)
Replace spark or flame
detection probe.
Is spark or
flame detection probe
damaged ?
Is there at
least 18mbar dynamic
at gas valve inlet ?
Set spark gap to 3.5mm.
Is spark gap
between 3 and 4mm ?
NO
YES
NO
YES
Rectify wiring.
Is
wiring from PCB
to spark probe & flame
detection probe
OK ?
NO
YES
Replace gas valve.
NO
YES
Replace PCB.
Remove
5-way connector
from gas valve. Is there 240Vdc
between F & G during ignition ?
Remove
the larger of the two
6-way PCB connectors. Is there
continuity from F to I
& from G to H ?
Lead from PCB to gas
valve faulty.
YES
NO
G
F
I
H
Off
On
Off
On
ON
LED
Lights
Clear blockage & dry
sensors.
Is condensate
trap blocked or water on
terminals ?
YES
NO
Is the burner
blocked or damaged ?
Replace PCB.
NO
Clean burner or replace
as necessary.
YES