Baxi BAXI COMBI INSTANT 105 HE, Installation & Servicing Instructions Manual

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14.0 Fault Finding
42
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 13.0 “Illustrated Wiring Diagram” for position of numbered terminals
Domestic Hot Water - Preheating Function - Follow operational sequence
Turn On/Off/Reset selector to
position.
neon illuminated.
Turn preheat control to on.
Preheating function starts after
25 seconds.
neon flashing.
Primary water diverted to
DHW preheating circuit.
Pump runs.
Primary flow switch operated.
Fan runs at maximum speed.
Air pressure switch proved.
Spark at ignition electrode for
up to 10 seconds.
Burner lights.
Burner output modulates to
minimum heat input until a
temperature of 75°C is
detected by central heating
NTC sensor.
Burner extinguishes.
Go to section ‘A’.
External controls and where
fitted, integral timer calling for
heat.
Go to section ‘L’.
Ensure controls are set to
demand and verify the contacts
are closed.
Go to section ‘M’.
neon flashing.
Go to section ‘B’.
neon flashing.
Go to section ‘C’.
neon flashing.
neon flashing.
Go to section ‘D’.
Go to section ‘J’ or ‘O’.
neon flashing.
Go to section ‘E’.
neon flashing.
Turn selector to the reset
position. If the neon does not
extinguish go to sections H and
K.
Change main PCB.
Burner extinguishes after 10
seconds.
Go to section ‘F’.
neon flashing.
Go to section ‘I’ & ‘N’.
Go to section ‘G’.
Fan stops.
Pump continues to
run for 30 seconds.
Operation sequence
correct
YES
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES YES
YES
NO
YES
NO
YES
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.
Turn selector to reset
position. If regular resetting is
required or appliance still
does not operate
investigation is necessary
YES