Section 9: Boiler Operation
Page 34
9.1 General
The control system automatically regulates all aspects of the boiler
operation including:
•
Burner start up and shut sequences
•
Output modulation
•
Combustion
It also controls the automatic cleaning sequences for both the burner
and heat exchanger(s) and indicates when a service is required. The
automatic cleaning of the burner brazier and heat exchanger(s) is
activated after the pellet feed auger running time has exceeded the
period pre-set in the burner control settings. Refer to Section 9.3.
The boiler control panel (located on the front panel of the boiler)
features a display screen and six control buttons. These buttons are
used to access and adjust the boiler control parameters. Refer to
Section 9.4.
The control system also has a diagnostic feature, where a fault code
will be displayed on the control panel LCD. Refer to Section 12 – Fault
Finding.
9 Boiler Operation
9.2 Modulation
Adjustable boiler control parameter numbers are shown in square
brackets. Refer to Parameter Menu in Section 9.7.
The boiler has a ‘setpoint’ temperature. This is the target flow
temperature from the boiler. The default ‘setpoint’ temperature is
75°C, but this can be adjusted by the installer if required. The boiler
temperature is monitored by a thermistor located in the water jacket
of the boiler and this is used by the control system to control the
modulation of the boiler output.
When a demand from the heating system controls is detected and the
ON/STANDBY switch is set to ON, the circulating pump runs and the
boiler control checks that the boiler water temperature is cool enough
for the boiler/burner to start. The boiler water temperature must be at
least the ‘Hysteresis On’ temperature value below the ‘Set Point’ (i.e.
boiler temperature < ‘Set Point’ – ‘Hysteresis On’).
If not, the circulating pump continues to run and the boiler water
temperature checked until the conditions to start the boiler/burner are
met.
Figure 9-1:
Boiler modulation
Figure 9-2:
Pellet auger modulation
