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27
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The boiler will now enter the combustion analy-
sis mode (CO mode) for a period of 15 minutes,
signified by the LED flashing Yellow. During
this time, the boiler will remain on full gas.
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Once the flue gas analysis has been made, turn
the shaft back to the required position and
replace the mode selector knob.
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Remove the probe and replace the sealing
screw.
7.5
CHECKING THE EXPANSION VESSEL
Carry out the component removal procedure as
described in 6.4. You must ensure that the boiler
is completely drained of water.
Using a suitable pressure gauge, remove dust
cap on expansion vessel and check the charge
pressure. The correct charge pressure should be
1.0 bar ± 0.1 bar.
If the charge pressure is less, use a suitable
pump to increase the charge.
NOTE
You must ensure the drain valve is in the open
position whilst re-charging takes place. Replace
the dust cap and carry out the relevant commis-
sioning procedure (section 5).
7.6
EXTERNAL FAULTS
Before carrying out any faultfinding or compo-
nent replacement, ensure the fault is not attribut-
able to any aspect of the installation.
7.6.1
INSTALLATION FAULTS
7.7
ELECTRICAL CHECKS
Any electrical checks must be carried out by a
suitably qualified person.
7.7.1
EARTH CONTINUITY TEST
Isolate the appliance from the electrical supply,
and using a suitable multi-meter carry out a
resistance test. Connect test leads between an
appliance earth point and the earth wire of the
appliance supply cable. The resistance should be
less than 1 OHM. If the resistance is greater than
1 OHM check all earth wires and connectors for
continuity and integrity.
7.7.2
SHORT CIRCUIT CHECK
Isolate the appliance from the electrical supply,
and using a suitable multi-meter, carry out a short
circuit test between the Live & Neutral connec-
tions at the appliance terminal strip (fig.16).
Repeat above test on the Live & Earth connec-
tions at the appliance terminal strip (fig.16).
NOTE
Should it be found that the fuse has failed but no
fault is indicated, a detailed continuity. Check will
be required to trace the fault. A visual inspection of
components may also assist in locating the fault.
7.7.3
POLARITY CHECK
With the appliance connected to the electrical
supply and using a suitable multimeter, carry out
the following voltage tests:
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Connect test leads between the Live & Neutral
connections at the appliance terminal strip
(fig.16). The meter should read approximately
230V ac. If so proceed to next stage. If not, see
7.7.4.
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Connect test leads between the Live & Earth
connections at the appliance terminal strip
(fig.16). The meter should read approximately
230V ac. If so proceed to next stage. If not, see
7.7.4.
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Connect test leads between the Neutral &
Earth connections at the appliance terminal
strip (fig.16). The meter should read approxi-
mately 0 - 15Vac. If so polarity is correct. If not,
see 7.7.4.
Fig. 41
Air
analysis
outlet
Fumes
analysis
outlet
Fig. 42
Symptom
Possible causes
No ignition
Check wiring
Check electrical supply
No hot water
Check hot/cold pipe
work is not reversed
No central heating
Check wiring of room thermostat
and/or other external controls
Frequency
Faults/Status
ON every 6-secs
At stand-by with no faults
Flashing 8-times a second
SARA function active
ON every 0.5-secs
Temporary fault, e.g.:
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APS fault
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low water pressure
Solid
Active for heat/DHW request
GREEN LED
Frequency
Faults/Status
ON every 0.5-secs
CO function active
Solid
DHW thermistor fault (see 7.2.5.2)
YELLOW LED
Frequency
Faults/Status
ON every 0.5-secs
Final fault, e.g.:
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water pressure switch
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condense pressure switch
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fan/flue problem
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limit thermostat
Solid
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primary NTC open/short circuit
RED LED
