Fault Finding - Baxi Combi Instant 80e Installation & Servicing Instructions Manual

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
Domestic Hot Water - Preheating Function - Follow operational sequence
Turn On/Off/Reset selector
to position.
neon illuminated.
YES
Turn preheat control to on.
Preheating function starts
after 25 seconds.
neon flashing.
YES
Primary water diverted to
DHW preheating circuit.
YES
Pump runs.
YES
Primary flow switch
operated.
YES
Fan runs at maximum
speed.
YES
Air pressure switch proved.
YES
Spark at ignition electrode
for up to 10 seconds.
YES
Burner lights.
YES
Burner extinguishes after
10 seconds.
NO
Burner output modulates to
minimum heat input until a
temperature of 75°C is
detected by central heating
NTC sensor.
YES
Burner extinguishes.
40
NO
Go to section 'A'.
External controls and
NO
where fitted, integral timer
calling for heat.
NO
Go to section 'M'.
NO
neon flashing.
Go to section 'B'.
NO
neon flashing.
Go to section 'C'.
NO
neon flashing.
Turn the selector to reset.
NO
neon flashing.
Go to section 'D'.
NO
neon flashing.
Go to section 'E'.
NO
neon flashing.
NO
Go to section 'F'.
NO
neon flashing.
Go to section 'I'.
NO
Go to section 'G'.
YES
Fan stops.
14.0

Fault Finding

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.
YES
Go to section 'L'.
Ensure controls are set to
NO
demand and verify the
contacts are closed.
Go to section 'J'.
Turn selector to the reset
YES
position. If the neon does
not extinguish go to
sections H and K.
NO
Change main PCB.
YES
Pump continues to
run for 30 seconds.
YES
Operation
sequence correct