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11. Trouble shooting
11.1 CARRY OUT INITIAL FAULT FINDING CHECKS
1. Check that gas, water and electrical supplies are available at the
boiler.
Electrical supply = 120V - 60 Hz,
CH water system pessurised to (7.25/14.5) p.s.i. - (0.5/1) bar when the
boiler is cold. DHW fl ow rate is more than 2.5 litre/min.
2. Carry out electrical system checks, i.e. Ground Continuity, Resistance
Central Heating - Follow operational sequence
Turn selector to
neon illuminated
YES
Turn
thermostat
to max.
Pump runs
YES
Primary flow switch
operated
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
illuminated
YES
Burner extinguishes
after 10 seconds
NO
Burner output
modulates until set
temperature is reached
YES
Burner goes out
NO
Go to section 'A'
neon flashing
Go to section 'B'
YES
External controls and,
NO
where fitted, integral timer
calling for heat
NO
neon flashing
Go to section 'C'
NO
neon flashing
NO
neons flashing
Go to section 'D'
NO
neon flashing
Go to section 'E'
NO
neon flashing
NO
Replace PCB
NO
Go to section 'F'
YES
neon flashing
Go to section 'I'
NO
Go to section 'G'
YES
Fan stops
to Ground, Short Circuit and Polarity with a suitable meter.
Note: These checks must be repeated after any servicing or fault
fi nding.
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.
Ensure controls are set
NO
to demand and verify the
contacts are closed
Turn selector to reset
position. If regular
YES
resetting is required or
appliance still does not
operate investigation is
necessary
Turn selector to the reset
YES
position. If the neon does
not extinguish go to
sections H & K
YES
Pump stops
35
Go to section 'J'
YES
Operation sequence
correct
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