Baxi Combi 105 HE Installation & Servicing Instructions Manual page 56

I
Ensure that mains input terminal L
is Live (230V) and N is Neutral
(0V)
YES
Check and correct if necessary
1. Flame sensing electrode and lead connections
2. Electrode position
Flame current should be 1 μA approx.
J
Overheat thermostat operated or
faulty, i.e. continuity across
thermostat terminals
YES
K
Check terminal 1 of ON/OFF/RESET selector is in
connection with PCB - A4 connector terminal 2
Check electrical continuity across terminals 1 & a of
ON/OFF/RESET selector when turned to 'Reset' position
L
If checks in section I are completed successfully, blockage
of the condensate drain or trap may have occurred
M
If checks in section J are completed successfully, the flue
overheat thermostat may have operated. Press the reset
button on the flue overheat thermostat. If the boiler does
not relight or repeatedly cuts out. Check the operation of
the flue system or replace the flue overheat thermostat
44
© Baxi Heating UK Limited 2005
Allow to cool. Continuity
NO
across thermostat terminals
more than 1.5 ohm
Replace PCB
14.0
YES
Replace PCB
NO
Replace flame sensing electrode
YES
NO
Replace ON/OFF/RESET selector
YES
Replace PCB
Fault Finding
Replace safety
thermostat