VOKERA Linea Installation & Servicing Instructions Manual - page 33
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29
Linea Max
8.23
Setting Gas Pressures
ALL SETTINGS DONE WITH A SUITABLE
MANOMETER CONNECTED TO GAS
VALVE AS INSTRUCTED IN 6.6.
8.23.1
Setting Maximum Rate
Turn off electrical supply to boiler and follow
instructions in section 8.4 & 8.4.1 to gain
access.
Refer to Fig. 22 & 33.
Turn on the electricity supply and the appli-
ance mode selector switch to Remove gas
pressure adjustment protective cover (fig. 33).
Turn on fully a domestic draw off tap.
The boiler will now light at full flame. Screw the
outer nut (a) on the end of the modulator coil
slowly clockwise until the burner lights.
Adjust the nut until the correct pressure is
obtained on the gauge. The correct reading
should be:
(N/G)
10.1 mbar.
plus or minus 1.0 mbar.
8.23.2
Setting Minimum Rate (DHW)
Remove one of the grey wires connecting to
the modulator coil. The gas pressure will now
be at the minimum rate.
Turn the inner minimum adjusting screw (b)
anti clockwise to decrease the pressure, or
clockwise to increase the pressure until the
minimum gas pressure is achieved, (ensure
when adjusting the inner screw the outer nut
(a) is held in position) the correct reading
should be:
(N/G)
1.3 mbar.
plus or minus 0.13 mbar.
Replace the grey wire back onto the modula-
tor coil together with the protective cover.
8.23.3
Setting Minimum Rate (C/H)
Turn off the hot water draw off tap.
Remove electrical cover plate by removing
6 screws. (Fig. 19).
Turn the mode selector switch to the
position, ensure that the room thermostat
and/or timeclock (if fitted) are calling for
heat. Turn the heating thermostat to maxi-
mum and ensure the appliance ignites.
Identify minimum adjustment button on pcb
(fig. 34).
Press the minimum adjustment button once,
the boiler will operate in central heating
mode at a minimum gas pressure. An LED
on the PCB will flash red to confirm the
appliance is in central heating minimum
mode.
The gas pressure should now be:
(N/G)
1.6 mbar.
plus or minus 0.16 mbar.
If the reading is incorrect it should be adjusted
as follows:
Identify the minimum adjustment potentiometer
on the PCB fig. 34.
With the boiler still in central heating mode and
the burner at the minimum rate, using a small
screwdriver turn the potentiometer clockwise
to increase & anti-clockwise to decrease the
minimum gas pressure.
When all is adjusted, press the minimum
adjustment button once (the appliance will
return to normal operation). Turn the appli-
ance off.
8.23.4
Soft Light Ignition
The Linea range incorporates a fully auto-
matic soft light ignition sequence which is non
adjustable.
When ignition is called for the gas valve is
energised and at the same time 20 m/A is
applied to the modulator coil for a period of
approximately 3 seconds. During this 3 sec-
onds the appliance will ignite.
After the initial 3 seconds power to the modu-
lator coil is gradually increased to a maximum
power of 120 m/A.
120 m/A is applied to the modulator coil for a
further second. If the appliance is operating in
hot water mode the maximum heat input will
be automatically adjusted depending on the
temperature of the appliance.
If the appliance is operating in central heating
mode see 8.23.5.
8.23.5
Maximum Rate in Central Heating Mode.
After initial ingnition (8.23.4), the Linea Max
range does not require any adjustment to
maximum heat requirement of the system
load.
Should the appliance fail to achieve sufficient
temperature rise within this 15 minute period,
the appliance will increase its maximum heat
input to further increase the temperature of the
system.
Once achieved the appliance will modulate to
suit system load.
8.23.6
Combustion Analysis
Incorporated on the appliance is a combustion
switch (fig.1, 35). Once the gas pressures
have been set activation of the combustion
switch automatically fires the appliance at
maximum rate in central heating. The appli-
ance will be held at maximum rate until the
maximum temperature of the appliance is
achieved. The appliance will not modulate
during this period.