Baxi Combi Instant 80e Installation & Servicing Instructions Manual page 41

Domestic Hot Water - Follow operational sequence
Turn On/Off/Reset selector
to position.
neon illuminated.
YES
Primary water diverted to
DHW preheating circuit.
YES
Turn preheat control to on.
Preheating function starts
after 25 seconds.
neon flashing.
YES
Open DHW tap fully. DHW
flow switch operated.
YES
Primary water is diverted
from preheating circuit to
DHW heat exchanger.
neon illuminated
YES
Pump runs
YES
Primary flow switch
operated
YES
Fan runs at max 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
maintain temperature set at
preheat control.
YES
Close DHW tap.
YES
DHW flow valve senses no
flow. DHW flow switch
released off.
YES
Preheating function
restarts.
neon flashing
YES
YES
Burner goes out.
NO
Go to section 'A'.
NO
Go to section 'M'.
External controls and
NO
where fitted, integral timer
calling for heat.
NO
DHW flow rate more than
2.5 l/min.
Continuity across DHW flow
NO
microswitch terminals and
PCB - A5 connector
terminals 5 & 6
NO
neon flashing
Go to section 'B'
NO
neon flashing
Go to section 'C'
NO
neon flashing
NO
neon flashing
Go to section 'E'
NO
neon flashing
NO
Go to section 'F'.
YES
Reduce the DHW flow rate.
If burner does not modulate
clean DHW temperature
NO
sensor and DHW heat
exchanger. If modulation
does not occur go to
section 'G'.
Ensure controls are set to
demand and verify the
controls are closed.
NO
External controls and where
NO
fitted, integral timer calling
for heat.
Fan stops.
Go to section 'L'.
YES
Ensure controls are set to
NO
demand and verify the
contacts are closed.
Is mains water filter and
YES
differential assembly
clean?
NO
Replace DHW flow
microswitch.
YES
Replace main PCB
Turn the selector to reset.
If regular resetting is
YES
required or appliance still
does not operate
investigation is necessary.
Go to section 'D'
NO
YES
neon flashing
Go to section 'I'
YES
Go to section 'L'.
YES
Pump continues to
run for 30 seconds.
14.0 Fault Finding
YES
DHW flow valve diaphragm
neons flashing
Turn selector to the reset
position. If the neon does
NO
YES
Operation
sequence correct
Replace diaphragm.
YES
damaged.
NO
DHW flow valve rod
obstructed.
Go to section 'J'.
not extinguish go to
sections H and K.
Change main PCB.
41