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© Baxi Heating UK Ltd 2007
16.0 Fault Finding
Carry out initial fault finding checks
1. Check that gas, water and electrical supplies are available at the boiler. Electrical supply = 230V ~ 50 Hz.
CH water system pressurised to 0.5 bar when the boiler is cold. The preferred minimum gas pressure is 19.5mbar (natural gas), or 36mbar (propane).
2. Carry out electrical system checks, i.e. Ground Continuity, Resistance to Ground, Short Circuit and Polarity with a suitable meter.
NOTE: These checks must be repeated after any servicing or fault finding.
3. Ensure all external controls are calling for heat and check all external and internal fuses. Before any servicing or replacement of parts ensure the gas and
electrical supplies are isolated.
Refer to Section 15.0 “Illustrated Wiring Diagram” for position of numbered terminals
Central Heating - Follow operational sequence
Turn selector to
neon illuminated
Primary flow switch operated
Fan runs at max speed
Burner goes out
Turn thermostat
to max.
Pump runs
Air pressure
switch proved
neon flashing
Burner on neon
illuminated
Burner output
modulates until set
temperature is reached
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 sections ‘J’ & ‘M’
neons flashing
Go to section ‘D’
neon flashing
Go to section ‘E’
Replace PCB
Turn selector to the reset
position. If the neon does not
extinguish go to sections H &
K
Go to section ‘F’
neon flashing
Go to sections ‘I’ & ’L’
Go to section ‘G’
Fan stops 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
External controls and, where
fitted, integral timer calling for
heat
Ensure controls are set to
demand and verify the
contacts are closed
Burner extinguishes
after 10 seconds
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
YES
YES YES YES
NO
NO NO
NO
NO
NO
NO
NO
NO
NO
YES
NO
NOTE: When instructed to turn the
selector to the reset position turn the
selector switch fully anticlockwise against
the spring pressure to ‘Reset’ position and
hold for 2 seconds to reset the boiler.