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54
AST 14 C 255/00
HEATING MODULATION
Upon an operation request in heating mode by thermostat or ambient probe or remote
control, burner ignition sequence is started with the automatic flame control section
enabling, if the water temperature read by the flow NTC probe is lower than the set
temperature value.
At the end of the ignition sequence, gas flow rate goes to its minimum value and then
reaches the value set by parameter P7 (maximum heating output) with a ramp duration
equal to the heating output rising ramp timing which can be set by parameter P12 (default
- one minute).
From now on, the flow water temperature will constantly be read and the rising ramp will
be stopped with a PID-type action upon reaching the set temperature, in order to maintain
the selected flow temperature.
Upon reaching the minimum gas flow rate (Pmin), if the output supplied is still higher than
requested, the burner will be switched off as soon as a flow temperature higher than the
set temperature is reached (set-point +5°C in case of a standard range and set-point +2°C
at a reduced range). The burner is switched off and measuring of burner deactivation time
starts (see section about “Ambient thermostat timer”).
During the heating phase:
-
with
P28 = 0 (pump and deviating valve), the pump is supplied with power and
the deviating valve is in DHW position;
-
with
P28 = 1 (heating pump and DHW pump), the heating pump is supplied with
power whereas the DHW pump is off;
Modulation with P6=0
P7 (%Pmax)
P12 (1 min)
80%
Pmax
