Supplied By www.heating spares.co Tel. 0161 620 6677
23
7.2.5
HEATING MODE
With the selector switch in the ON position and any
additional controls (time clock, programmer, room
thermostat, etc,) calling for heat, the appliance will
operate in the heating mode. The pump and fan will
be activated via the flow temperature sensor. When
the fan is sensed to be operating correctly (tacho
signal), the ignition sequence commences. Ignition
is sensed by the electronic circuitry to ensure flame
stability at the burner. Once successful ignition has
been achieved, the electronic circuitry increases
the gas rate to 75% of the MAX Heating (set by the
corresponding HTG trimmer) for a period of 15
minutes. The speed of the fan and therefore the
output of the boiler is determined by the tempera-
ture of the water sensed by the flow temperature
sensor, consequently a high temperature at the
flow sensor results in a lower fan speed. As the
water temperature increases, the temperature
sensors – located on the flow pipe of the boiler –
reduce the fan speed via the electronic circuitry.
Depending on the load, either the water tempera-
ture will continue to rise until the set point is
achieved or the water temperature will fall whereby
fan speed will increase relative to the output
required. When the boiler has reached the set point
(+ hysterisis), the burner will switch off. The built-
in anti-cycle device prevents the burner from re-
lighting for approximately 3-minutes. When the
temperature of the flow sensor falls below the set
point (- hysterisis), the burner will re-light.
NOTE
If the spark/sensing electrode does not sense
ignition the appliance will re-attempt ignition a
further 4-times then go to lockout. When the set-
point has been reached (the position of the heating
temperature selector) as measured at the primary
thermistor, the appliance will begin the modulation
phase whereby the fan and gas valve will
continuously modulate to maintain the set-point.
If the temperature continues to rise and exceeds
the set-point by 5°C (hysterisis), the burner will
shut down. A new ignition sequence will be
enabled when the 3- minute anti-cycle has been
performed and the temperature at the primary
thermistor has dropped 5°C (hysterisis) below the
set-point.
NOTES
When the request for heating and/or hot water has
been satisfied, the appliance pump and fan may
continue to circulate to dissipate any residual heat
within the appliance.
7.3
APPLIANCE FAN SPEEDS
The appliance fan speeds require to be checked
and/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 specific appliance
specification. Vokera accepts no responsibility if the
gas type and/or fan speed is not correctly adjusted
according to the respective appliance specification
as detailed on the appliance data badge.
7.3.1
CHECKING/ADJUSTING THE APPLIANCE FAN
SPEEDS
Move the selector switch to the OFF position and
remove the 3-selector knobs.
7.3.2
ABSOLUTE MAX FAN SPEED
Locate the MAX trimmer (fig. 32) 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
1000, i.e. 2.5 = 2500RPM.
7.3.3
ABSOLUTE MIN FAN SPEED
Locate the MIN trimmer (fig. 32) 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
1000, i.e. 2.5 = 2500RPM.
7.3.4
IGNITION FAN SPEED
ATTENTION
Do this operation only after the adjusting of
absolute max and min fan speed.
Locate the IGN trimmer (fig. 32) 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
1000, i.e. 2.5 = 2500RPM.
7.3.5
HEATING FAN SPEED
Locate the HTG trimmer (fig. 32) and gently adjust
clockwise or counter clockwise to achieve the
correct fan speed (see table 7.3.6). speed (see
table 7.3.6).
NOTE
The display shows the fan RPM in multiples of
1000, i.e. 2.5 = 2500RPM.
Fig. 32
7.3.6
FAN SPEED TABLE
Use the following table to set the corresponding
fan speeds that are relative to the appliance you
are working on.
FAN SPEED (rpm) TABLE
MODEL
MAX
MIN
HTG
IGN
12HE
3.700
1.300
3.500
3.700
15HE
4.200
1.300
4.200
3.700
20HE
5.400
1.700
5.400
3.700
25HE
5.500
1.700
5.500
3.700
30HE
5.200
1.400
5.200
3.700
35HE
6.000
1.400
6.000
3.700
