61
9 Burner
9.1 Burner Operation
The burner controls the pellet feed
auger, flue fan, boiler temperature and
also the boiler and brazier cleaning
systems. The burner comes with a
display screen and six control buttons.
These buttons are to access the menus
and control the burner functions.
The burner is equipped with a brazier
where the combustion of the wood
pellets takes place within the boiler.
The self cleaning device on the brazier
is automatically activated after the pellet
feed auger run time has exceeded a
predetermined set time. The pellet feed
auger run time for brazier and boiler
cleaning is pre-set in the burner menu.
The temperature of the water within the
boiler is controlled via a thermistor to
the burner. The thermistor is inserted
into the boiler water jacket and is used
by the burner to control the modulation
of the boiler output.
The boiler has a set point temperature.
This is the target flow temperature
from the boiler. As the temperature
of the boiler increases and reaches
the set point less the ‘TEMP DELTA’
temperature (default value 5°C) the
output of the boiler is reduced by one
modulation step.
Each subsequent 1°C increase in boiler
temperature reduces the output of
the boiler by one further modulation
step until the temperature reaches
the set point plus the ‘TEMP DELTA’
temperature.
At this point the boiler output is
‘MINIMUM FLAME’ which is minimum
output setting of the boiler. The
percentage increase or decrease in
power is calculated on the rate of
temperature change. The sequence of
operation is shown in Section 9.3.
9.2 Burner Operating Modes
‘BOILER WAIT THERMOSTAT’:
(operation code 03) Boiler is in standby
awaiting the following;
• A switched live input signal from the
control system.
• The boiler temperature to drop
below the set point less the ‘DELTA
RESTART’ temperature. (‘DELTA
RESTART’ is the temperature below
the set point the burner restarts
after maximum temperature has
been reached).
• If required, the boiler temperature to
drop below the set point less the
‘DELTA RESTART’ temperature.
‘DELTA RESTART’ (default value
5°C) is the temperature below the
set point at which the burner
restarts, after maximum
temperature has been reached).
‘WAIT PRELOAD BRAZIER’:
(operation code 40) Initial loading
of pellets into the brazier to enable
combustion to start.
• Activated with a switched live input
signal and/or temperature drops
below the set point less ‘DELTA
RESTART’ temperature.
• Deactivated after time exceeds 65
seconds.
‘WAIT LIGHTING’ – IGNITION:
(operation code 41) Period of time
given for pellets to light.
• Activated after ‘PRE LOAD’
operation is complete.
• Deactivated once photocell lux
reading reaches 2 lux.
‘WAIT LIGHTING’–FLAME
STABILISATION:
(operation code 45)
Period of time to allow flame to stabilise
after pellets have ignited.
• Activated after ignition mode.
• Deactivated after time exceeds 30
seconds.
‘WAIT LIGHTING’ –LIGHTING FEED
REDUCED:
(operation code 42) Period
of time intermittent quantities of pellets
supplied to the brazier to increase the
flame.
• Activated after -‘WAIT LIGHTING’
flame stabilisation mode.
• Deactivated after time exceeds 120
seconds.
‘PELLET BURNER FIRING’:
Power
100% (operation code 13) Flame is fully
developed and boiler is operating on
full power.
• Activated after –‘WAIT LIGHTING’
lighting feed reduced mode
• Deactivated after boiler temperature
is higher than the set point less
‘TEMP DELTA’.
‘PELLET BURNER FIRING’:
Power
modulating (operation code 13)
Flame is reduced and boiler output is
modulating.
• Activated when the boiler
temperature is higher than the set
point less ‘TEMP DELTA’.
• Deactivated after the boiler
temperature exceeds the set point
plus ‘TEMP DELTA’.
‘PELLET BURNER FIRING’
: Power
minimum (operation code 13) Flame
is reduced and boiler is at minimum
output.
• Activated once the boiler
temperature exceeds the set point
plus ‘TEMP DELTA’.
• Deactivated after the temperature
exceeds ‘TEMP OFF H2o’ (default
value 80°C).
‘TURNING OFF BRAZIER’:
(operation
code 14). Burn down period to remove
any pellets remaining in the brazier.
• Activated when switched live input
signal from control system is
switched off or the boiler
temperature exceeds ‘TEMP OFF
H2o’ setting or the ON/STANDBY
switch on the control panel is set to
the ‘STANDBY’ position.
• Deactivated once photocell lux
reading has dropped to 1 lux.
‘WAIT POST PURGE’:
(operation code
26) Period of time after burn down is
complete to ensure no unburnt pellets
ignite.
• Activated after ‘TURNING OFF
BRAZIER’ is complete.
• Deactivated after time exceeds 180
seconds.
