Fault Finding - Baxi Combi 105e Installation And Servicing Instructions

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), 27mbar
(butane) 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 13.0 "Illustrated Wiring Diagram" for position of numbered terminals
Central Heating - Follow operational sequence
Turn selector to
neon illuminated
YES
Turn thermostat
to max.
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 until set
temperature is reached
YES
Burner goes out
38
NO
Go to section 'A'
neon flashing
Go to section 'B'
YES
External controls and,
NO
where fitted, integral timer
calling for heat
NO
neon flashing
Go to section 'C'
NO
neon flashing
NO
neons flashing
Go to section 'D'
NO
neon flashing
Go to section 'E'
NO
neon flashing
NO
Replace PCB
NO
Go to section 'F'
YES
neon flashing
Go to section 'I'
NO
Go to section 'G'
YES
Fan stops

14.0 Fault Finding

Ensure controls are set to
NO
demand and verify the
contacts are closed
Turn selector to reset
position. If regular
YES
resetting is required or
appliance still does not
operate investigation is
necessary
Turn selector to the reset
YES
position. If the neon does
not extinguish go to
sections H & K
YES
Pump stops
NOTE: When instructed to turn the
selector to the reset position turn the
selector switch fully anticlockwise
against the spring pressure to
position R and hold for 2 seconds to
reset the boiler.
Go to section 'J'
YES
Operation sequence
correct