Principle Of Operation; Temperature Setpoint; Controller Functions (User Menu – Options) - Tech Controllers EU-24 SIGMA User Manual

Principle of operation

Microprocessor-based ST-24 Sigma regulator is intended for controlling CH boilers equipped
with blow and CH pump. Its main task is to maintain the pre-set temperature with the use
of a fan.
In order to fire up the boiler (when the boiler temperature is below 30°C), press EXIT button
– it will enable the fan and both the "manual mode" LED and "fan" LED on the controller will
go on. Pressing the button again disables the fire-up function (i.e. the manual mode). If
enabled, the fire-up process is active until the boiler temperature reaches 30°C (it is the
threshold temperature of pump activation and entering the operation mode). When the
preset temperature is reached, the controller enters the sustain mode. In this mode, the
controller activates blow-by at a frequenz set by the user.

Temperature setpoint

Temperature setpoint is the temperature which the user wants the boiler to reach. Its value
may be changed from the main screen through
pressing button (raising the temperature) and (reducing the temperature)
when the screen is flashing. After 4 seconds the display will show the current boiler
temperature.
Controller functions (user menu – options)
Speed regulation function - (activated through pressing OPTIONS button - "regulacja
obrotów" LED goes on). This function is used to control the fan speed. The setting range is
1-6 or 1-10, depending on the software version ( the values may be regarded as fan gears).
The higher the gear is, the faster the fan works. Gears may be changed using and
buttons. Setting an appropriate gear prevents the fire going out and ensures effective
combustion.
After the preset temperature is reached, the boiler enters the sustain mode (to prevent
further temperature rise). To ensure correct operation of the boiler, the user sets two
parameters – blow-by operation and blow-by pause.
Minimum speed setting – In order to set the minimum fan speed, press OPTIONS button
( "Regulacja obrotów" LED will go on). Next, press the button again ( the LED will start to
flash) and set the minimum fan speed, i.e. the gear in which the fan reaches its minimum
speed when the temperature drops 1°C below the preset value.(see: Automatic speed
control).
Blow-by operation function is activated by pressing OPTIONS button until "praca
przedmuchu" LED goes on. Here, the user should set the blow-by operation time (in seconds)