25
Fig. 34
FAN SPEED (rpm) TABLE
MODEL MAX
MIN
HTG
IGN
15VHE
4.500
1.300
3.700 3.700
or adjusted prior to making any adjustments to the gas
valve or if the main PCB has been replaced.
ATTENTION
Gas type and appliance fan speed (output)
must be set
according to the specifi c appliance specifi cation. Vokera
accepts no responsibility if the gas type and/or fan speed
is not correctly adjusted according to the respective ap-
pliance specifi cation as detailed on the appliance data
badge.
7.3.1 ADJUSTING THE APPLIANCE FAN SPEEDS
Move the selector switch to the OFF position; remove the
casing as detailed in 4.7 and the two screws of control
panel (fi g. 18).
7.3.2 ABSOLUTE MAX FAN SPEED
Locate the MAX trimmer (fi g. 34) and gently adjust clock-
wise or counter clockwise to achieve the correct fan speed
(see table 7.3.6). NOTE, the display shows the fan RPM
in multiples of 100, i.e. 25 = 2500RPM.
7.3.3 ABSOLUTE MIN FAN SPEED
Locate the MIN trimmer (fi g. 34) and gently adjust clock-
wise or counter clockwise to achieve the correct fan speed
(see table 7.3.6). NOTE, the display shows the fan RPM
in multiples of 100, i.e. 25 = 2500RPM.
7.3.4 IGNITION FAN SPEED
Locate the IGN trimmer (fi g. 34) and gently adjust clock-
wise or counter clockwise to achieve the correct fan speed
(see table 7.3.6). NOTE, the display shows the fan RPM
in multiples of 100, i.e. 25 = 2500RPM.
7.3.5 HEATING FAN SPEED
Lower the controls fascia and remove the cap
(A)
on the
PCB cover (fi g. 35).
Locate the HTG trimmer
and gently adjust clockwise or
counter clockwise to achieve the correct fan speed (see
table 7.3.6). NOTE, the display shows the fan RPM in
multiples of 100, i.e. 25 = 2500RPM.
7.3.6 FAN SPEED TABLE
Use the following table to set the corresponding fan
speeds that are relative to the appliance you are work-
ing on.
Fig. 36
Compensation
pipe connection
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 corre-
sponds with the appropriate CO
2
value (Minimum) for
the respective appliance. If the CO
2
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 CO
2
reading is incorrect, the minimum gas
7.4 CORRECTING THE CO
2
VALUES/ADJUSTING
THE GAS VALVE
THE GAS VALVE MUST BE SET-UP OR ADJUSTED
WITH THE AID OF A PROPERLY CALIBRATED FLUE
GAS ANALYSER.
NOTE
To adjust the gas valve you must fi rst ensure that
the fan speed potentiometers (trimmers) have been
set correctly (see 7.3).
Isolate the appliance from the electrical supply and remove
the appliance casing as described in 4.7.1. Set the fl ue
gas analyser to read CO
2
and insert the probe into the
fl ue analysis test point (fi g. 37). Restore the electrical
supply to the boiler and switch the boiler to the OFF mode.
Remove the PCB cover and the two selector knobs.
Locate/identify the CO button (see fi g. 34). Press the
CO button; the appliance will now operate in CO mode
for approximately 15-minutes (see 7.9).
IMPORTANT
There are 2-sets of CO
2
values for the appliance,
i.e. a value for the casing ‘on’ and a value for the
casing ‘off’.
Use the CO
2
values for ‘casing-off’ when you are
making adjustments to the gas valve.
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 corre-
sponds with the appropriate CO
2
value (Maximum) for
the respective appliance. If the CO
2
reading is correct,
proceed to gas valve minimum setting (7.4.2).
However, if the CO
2
reading is incorrect, the maximum
gas pressure must be adjusted as follows:
Using a suitable screwdriver, very slowly turn the
maximum adjustment screw (see fi g. 30) – clockwise
to decrease, counter clockwise to increase – until the
correct value is displayed on the CO
2
analyser (allow
time for the analyser to stabilise).
Minimum
screw
Maximum
screw
Fig. 35
CASING OFF CASING ON
CO
2
8.8%
9.0%