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31
AST 14 C 259/00
AMBIENT THERMOSTAT
With the boiler set on the "CH" or "DHW + CH" operating mode, the closing up of ambient
thermostat electric contact or the heat request by the remote control will result in a request
during heating, thus making heating modulation start.
CENTRAL HEATING MODULATION
Due to ambient thermostat electric contact closing up, if the flow NTC probe water
temperature reading is below the set value, the automatic flame control section consensus
will be disabled and burner ignition sequence will be started.
Once ignition sequence is completed, gas flow rate will go to the min. value and then to
the value set by the P1 parameter (max. heating output) with a ramping time equal to
heating output rising ramp timer to be set by P4 parameter (default setting: 4 minutes).
From now onwards, flow water temperature will be constantly read, and the rising ramp will
be interrupted with a PID action to keep the selected flow temperature once the set
temperature is reached.
Once gas flow rate min. value is reached (Pmin) and with the supplied power above the
requested one, water temperature will obviously increase. Once flow water temperature is
5 °C above the set value, burner will be turned off and the countdown for burner to stay off
will start (see following paragraph). Once this time has elapsed, burner can be turned on
again if, in the meanwhile, flow water temperature is below or equal to the set value.
Modulation with P2=0