Principle Of Operation; Lambda Sensor; Working Phases Of The Controller; 4.2.1 Fire-Up - Tech Controllers ST-976 User Manual

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RINCIPLE OF OPERATION
The regulator controls the fan and the feeder with the aim of reaching the pre‐set temperature value of water
tank and CH boiler. Additionally, it controls CH pump and DHW pump, enabling them after the pre‐defined CH
boiler temperature has been reached.
Depending on the settings, the controller may operate according to standard algorithm, automatic algorithm
or zPID algorithm. It may also use Lambda sensor. The menu layout may also differ depending on settings.
4.1.1
Lambda sensor
Additionally, the controller operation may depend on LAMBDA sensor readings, which provide the information
about the proportion of oxygen in the flue gas. On the basis of this value, the efficiency of the burning process
is assessed. If the amount of oxygen is different than the pre‐set value, the regulator adjusts the fan speed as
well as the amount of fuel fed to the boiler, in order to make the process more efficient.
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ORKING PHASES OF THE CONTROLLER
Parameters of particular working phases of the CH boiler are configured by the user. Fire‐up and damping are
multi‐stage processes described below. The remaining phases depend on the Operation algorithm selected by
the user.
4.2.1 Fire‐up
This phase is initialized by the user in the main menu, or by the controller software in certain situations (e.g.
after periodical cleaning of the furnace during controller operation). There are four stages of the fire‐up
process:
1. Blow‐by
In this stage the fan works at full speed in order to clean the furnace.
2. Initial fuel feeding
In this stage the blow force decreases to its minimum value ‐ 1%. The feeder is enabled and operates
throughout the whole stage. Fuel feeding time is set by the user in the service menu.
3. Heater
In the following stage of the fire‐up process the heater is enabled. It remains active until the sensor detects
flames. The feeder is inactive whereas the fan operates at the speed defined by the fitter in the fitter's menu.
4. Stabilization
Delay is the final stage of the fire‐up process. It starts when the flames have been detected. During this stage
the fire stabilizes. The feeder operates according to operation time and pause time settings. The fan operates
at the speed defined in the service menu.
4.2.2
Standard operation
The feeder and fan operation depend on the user's settings and current CH boiler temperature. If current
temperature is much lower than the pre‐set value (e.g. after the fire‐up), the feeder and the fan operate
according to the settings described as Maximum power. When the CH boiler approaches the pre‐set value, the
controller switches to Minimum power settings.
4.2.3
Automatic operation
Once the fire‐up process has been completed, the controller enters automatic mode. In this mode, the
controller operation is based on the user‐defined parameters concerning the weight and calorific value of fuel
and fan speed before and after reaching the pre‐set temperature value.
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