Section 9: Boiler Operation
Page 40
9.8 Boiler Operating Sequence
The following stages of the boiler operation are displayed on the
control panel LCD screen.
the number shown in brackets [X] indicates the parameter
setting – refer to Section 9.7 and table 9-5.
nOtE
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Standby
Boiler not operating but ready to start in response to the following:
•
A switched live input signal from control system for heating or hot
water.
•
The boiler temperature drops below the ‘Setpoint’ [0] minus
‘Hysteresis On’ (5°C) temperature – if boiler temperature has
exceeded the pre-set ‘Temp Off H
2
O’ setting (80°C).
•
The ON/STANDBY switch on the control panel is set to the ‘ON’
position.
Wait Pre Load Brazier
Initial loading of pellets into the brazier to start the burner.
•
Activated when a switched live input signal and/or temperature
drops below the pre-set ‘Setpoint’ minus ‘Hysteresis On’ value
(5°C).
•
Deactivated when the pre-set ‘Preload Time’ period of 46
seconds has elapsed.
•
Fan is operating at ‘Fan Power Lighting’ speed setting [17].
Lighting
Period of time allowed for pellets to light.
•
Activated after ‘Wait Pre Load Brazier’ stage is completed.
•
Deactivated once photocell lux reading exceeds pre-set ‘Flame
On’ setting of 20%.
•
Note: ignition element remains on until end of pre-set ‘Flame
Stabilisation’ stage (10 seconds).
•
Fan is operating at ‘Fan Power Lighting’ speed setting [17].
Flame Stabilisation
Period of time allowed for flame to stabilise after pellets have ignited.
•
Activated after ‘Lighting’ stage is completed.
•
Deactivated when the pre-set ‘Time Flame Stabilisation’ period of
10 seconds has elapsed.
•
Fan is operating at ‘Fan Power Lighting’ speed setting [17].
Lighting Feed Reduced
Period when pellet feed provides intermittent quantities of pellets to
the brazier to increase the flame.
The auger off period is given by the pre-set ‘Time Pause Lighting’
setting of 22 seconds and the auger on time is given by the pre-set
‘Time Load Lighting’ setting of 1 second.
•
The combustion fan is operating at ‘Fan Power Max’ speed
setting [15].
•
Activated after pre-set ‘Flame Stabilisation’ stage period (10
seconds) is completed.
•
Deactivated when the pre-set ‘Feed Time Reduced’ period of
220 seconds has elapsed.
Modulation Level
The boiler is now firing.
•
Activated after pre-set ‘Feed Time Reduced’ period of 220
seconds has elapsed.
•
Deactivated when either the demand ceases or the temperature
exceeds pre-set ‘Temp Off H
2
O’ [3] setting (80°C).
Initially, the boiler will operate at 25% output – indicated by one
segment showing on the modulation indicator.
After 25 seconds the boiler output will increase to 50% - indicated by
two segments on the modulation indicator.
After a further 25 seconds the boiler output will increase to 75% (three
segments on modulation indicator).
Finally, after a further 25 seconds the boiler output will increase to
100% (four segments on modulation indicator). The boiler is now
operating at maximum output.
After that, the boiler temperature and set point are used to determine
the required output and level of modulation. This in turn controls
the auger operating cycle. Refer to Section 9.2 for details of boiler
modulation.
•
Fan is operating between ‘Fan Power Max’ [15] and ‘Fan Power
Min’ [16] speed settings to suit the modulating burner output.
turning Off Brazier
Burn down period to remove any pellets remaining in the brazier.
Pellet feed auger is switched off.
•
Fan speed changes to pre-set ‘Fan Power Post Purge’ [18]
setting (4500rpm).
•
Activated once switched live input signal is switched off or
the boiler temperature exceeds the pre-set ‘Temp Off H
2
O’ [3]
setting.
•
Deactivated once photocell Lux reading has dropped below pre-
set ‘Flame Off’ setting of 4%.
Wait Post Purge
Burner fan continues to run at pre-set ‘Fan Power Post Purge’ [18]
setting (4500rpm) for a period of time after burn down is completed.
•
Activated after ‘Turning off Brazier’ stage is completed.
•
Deactivated when pre-set ‘Post Ventilation’ period of 120
seconds has elapsed.
