24
Follow operational sequence
Turn selector to
neon illuminated
Fan runs at max speed
Turn thermostat
to max. Open DHW tap fully.
DHW flow switch operated
neon illuminated
Continuity across DHW flow
microswitch terminals and
PCB - A5 connector terminals
5 & 6
Air pressure switch proved
neon flashing
Burner on neon illumina-
ted
Spark at ignition electrodes
for up to 10 seconds
Go to section ‘A’
Go to section C, D, I
Go to section ‘B’
Replace PCB
Turn the selector to the reset
position. If the light does not
extinguish go to section G &
L
Go to section ‘E’
neon flashing
Go to section ‘H’
Close DHW tap
Burner goes out
DHW flow sensor senses no
flow.
Operation sequence correct
neon flashing
neon flashing
Go to section ‘D’
Burner extinguishes
after 10 seconds
YES
YES
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
Fan stops
YES
YES
YES
YES
NO
NO
DHW flow rate more than
2.5l/min.
Continuity across DHW flow
sensor terminals
Replace DHW flow sensor
Replace PCB
NO
YES
NO
NO
NO
NO
NO
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’
Burner output modulates to
maintain temperature set at
thermostat
NO
NO
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.
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.
Содержание NIAGARA
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