© Baxi Heating UK Ltd 2008
39
Air Proving Lockout
Lockout Burner Mains
Check for blockages in the condensate
system, the flue system and the heat
exchangers
The APS is not maintaining its signal.
This has occurred 4 times from a switched
live being present and the burner being lit
Lockout Burner Mains
This indication can be activated by two faults:
1) Flow direction is checked after 1 minute of burner fire. If the casting thermistor reads
a higher temperature than the flow thermistor, the fault occurs. This does not cause a lockout.
2) Adequate circulation is checked continuously during burner fire. If the casting thermistor
exceeds 80C the fault occurs. A lockout is activated if this happens 4 times.
Water Circulation Lockout
Refer to the boiler wiring diagram
Yes
No
Fill system with water and
bleed out all air
Is the system
full of water
Yes
No
Is the pump
running
Yes
No
Reset
lockout
Is there 230V at
the terminal block
(Pump L and N) ?
Pump or pump wiring fault
Yes
No
Check the
continuity of the
Pump L and N
wiring from the
terminal block
to PCB
Wiring from terminal block
to PCB faulty
Replace PCB
No
No
Yes
Yes
Open bypass/TRV's
and check for blockages
Is there
sufficient water
flow around the
system ?
Is the
flow in the
right direction
Rectify flow and return
pipework
Replace PCB
on
flashing
flashing
on
off
off
Fig. 47