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10. Trouble shooting
11.1 CARRY OUT INITIAL FAULT FINDING CHECKS
1. Check that gas, water and electrical supplies are available at the
water heater.
Electrical supply = 120V - 60 Hz,
DHW fl ow rate is more than 2.5 litre/min.
2. Carry out electrical system checks, i.e. Ground Continuity, Resistance
to Ground, Short Circuit and Polarity with a suitable meter.
Follow operational sequence
Turn selector to
neon illuminated
YES
Turn
thermostat
to max. Open DHW tap fully.
DHW flow switch operated
neon illuminated
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 illumina-
ted
YES
Burner extinguishes
after 10 seconds
NO
Burner output modulates to
maintain temperature set at
thermostat
YES
Close DHW tap
YES
DHW flow sensor senses no
flow.
YES
Burner goes out
NO
Go to section 'A'
Continuity across DHW flow
sensor terminals
YES
NO
DHW flow rate more than
2.5l/min.
Continuity across DHW flow
NO
microswitch terminals and
PCB - A5 connector terminals
5 & 6
NO
neon flashing
NO
Go to section 'B'
NO
neon flashing
Go to section 'D'
NO
neon flashing
NO
Replace PCB
NO
Go to section 'E'
YES
neon flashing
Go to section 'H'
NO
Reduce the DHW flow rate.
If burner does not modulate
clean DHW temperature
sensor and heat exchanger. If
modulation does not occur go
to section 'F'
YES
Fan stops
Note: These checks must be repeated after any servicing or fault
fi nding.
3. Check all external and internal fuses.
Before any servicing or replacement of parts ensure the gas and
electrical supplies are isolated.
NO
Replace DHW flow sensor
YES
Replace PCB
YES
Go to section C, D, I
Turn the selector to the reset
YES
position. If the light does not
extinguish go to section G &
L
YES
Operation sequence correct
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