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24
7.4.3
COMPLETION
On completion of the combustion analysis check
and/or any gas valve adjustment, set the HTG
trimmer to the corresponding value as detailed in
the fan speed table. Refit the 3-selector knobs
and move the mode selector to the OFF position.
Remove the test probe from the test point and
refit the sealing screw/s and/or cap.
IMPORTANT
A GAS SOUNDNESS CHECK MUST BE
CARRIED OUT IF ANY GAS CARRYING
COMPONENTS HAVE BEEN REMOVED,
REPLACED, OR DISTURBED.
7.5
COMBUSTION ANALYSIS TEST
A combustion analysis check can easily be carried
out on the appliance via the test points located
on the top of the appliance (see 7.4).
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Insert the flue gas analyser probe into the flue
gas test point (see fig. 31).
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Operate the boiler in CO mode and compare
the values with those shown in section 2 (Nat.
Gas) or section 10 (LPG). If different adjust the
gas valve according to 7.4.1, 7.4.2, & 7.4.3.
7.6
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
commissioning procedure (section 5).
7.7
EXTERNAL FAULTS
Before carrying out any faultfinding or component
replacement, ensure the fault is not attributable
to any aspect of the installation.
7.7.1
INSTALLATION FAULTS
7.8
ELECTRICAL CHECKS
Any electrical checks must be carried out by a
suitably qualified person.
7.8.1
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.
Symptom
Possible cause
No display/ignition
Check wiring/check
electrical supply
No hot water
Check external controls
No heating
Check external controls
Fault code
Possible cause
10
Check gas supply, check
flue system, check polarity
7.4
CHECKING THE CO2 AND ADJUSTING THE
GAS VALVE
THE GAS VALVE MUST BE SET-UP OR
ADJUSTED WITH THE AID OF A PROPERLY
CALIBRATED FLUE GAS ANALYSER.
Isolate the appliance from the electrical supply
and remove the appliance casing as described in
4.7.1. Set the flue gas analyser to read CO2 and
insert the probe into the flue analysis test point
(A, B fig. 31). Restore the electrical supply to the
boiler and switch the boiler to the OFF mode. To
adjust the gas valve you must first ensure that
the fan speed potentiometers (trimmers) have been
set correctly (see 7.3).
Remove the 3-selector knobs, locate and press
the CO button (see fig. 32). The appliance will now
operate in CO mode for approximately 15-minutes
(see 7.10).
7.4.1
GAS VALVE MAXIMUM SETTING
Locate and gently turn the HTG trimmer till the
maximum value (fan speed) is obtained and check
that it corresponds with the appropriate CO2 value
(Maximum) for the respective appliance. If the CO2
reading is correct, proceed to gas valve minimum
setting (7.4.2). However, if the CO2 reading is
incorrect, the maximum gas pressure must be
adjusted as follows:
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Using a suitable screwdriver, very slowly turn
the maximum adjustment screw (see fig. 33) –
clockwise to decrease, counter clockwise to
increase – until the correct value is displayed
on the CO2 analyser (allow time for the analyser
to stabilise).
7.4.2
GAS VALVE MINIMUM SETTING
Locate and gently turn the HTG trimmer till the
minimum value (fan speed) is obtained and check
that it corresponds with the appropriate CO2 value
(Minimum) for the respective appliance. If the CO2
reading is correct, rotate the HTG trimmer until the
correct value is obtained for the respective appliance
(see fan speed table) and proceed to 7.4.3.
However, if the CO2 reading is incorrect, the
minimum gas pressure must be adjusted as
follows:
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Using a suitable screwdriver, very slowly turn
the minimum adjustment screw (see fig. 33) –
clockwise to increase, counter clockwise to
decrease - until the correct value is displayed
on the CO2 analyser (allow time for the analyser
to stabilise).
Fig. 33
Maximum
screw
Minimum
screw
Compensation
pipe connection
