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AST 14 C 258/00
Plate DHW modulation temperatures:
DHW temperature setting range: 35 °C ÷ 57 °C
DHW thermostat triggering temperature OFF = set point + 5°C
DHW thermostat triggering temperature ON = set point + 3°C
DHW thermostat triggering temp. upon intake (first 20 sec) OFF = set point + 15° C
DHW thermostat triggering temp. upon intake (first 20 sec) ON = set point + 8° C
Flow water thermostat triggering temperature with DHW OFF: 85°C
Flow water thermostat triggering temperature with DHW: ON 80°C
Flow water PID triggering temperature with DHW: 81°C
Flow water PID deactivating temperature with DHW: 75°C
Note: In case a boiler is combined with a solar plant with instantaneous integration, we
recommend setting the P14 parameter to 1. This increases the modulation range avoiding
boiler hunting (start and stop) with inlet temperature very close to the set-point. In such case
the limit temperatures are as follows:
DHW thermostat triggering temp. OFF with instantaneous solar integr.: set-point + 10° C
DHW thermostat triggering temp. ON with instantaneous solar integr.: set-point + 9° C
TANK HEATER DHW MODULATION
(version KRB only, P3=3)
With the boiler in DHW or DHW+HEATING mode, the tank heater programme activation
time generates a tank heater DHW request.
If the tank heater temperature read by the NTC probe is less than the Tank heater ON
precedence thermostat intervention temperature (set-point 3°C), set on the boiler or
remote control, and the flow temperature is below 70°C, automatic flame control can be
disabled to start the burner ignition sequence.
At the end of this sequence, the power to the burner corresponds to the ignition power
(P6). Subsequently, the power supplied will correspond to the flame modulation value
which, with a PID-type action, allows the flow modulation temperature to be reached
and maintained at the tank heater phase. This is calculated on the basis of the tank heater
temperature requested and the current temperature measured by the probe. The value
must be between a minimum limit (corresponding to the requested tank heater
temperature + 10°C) and a maximum limit (85°C). Maximum flow modulation occurs when
the difference between the requested tank heater temperature and the current tank heater
temperature is greater than or equal to 10°C.
In tank heater DHW mode, the pump is in operation and the electric diverting valve is in
DHW position, while the multifunction relay is in the off-state.
Tank heater DHW modulation temperature:
DHW temperature setting range: 35°C-65°C
Thermostat intervention temperature with tank heater precedence OFF = set-point + 0°C
Thermostat intervention temperature with tank heater precedence ON = set-point - 3°C
Maximum flow modulation temperature at tank heater phase = 85°C
Minimum temperature difference between tank heater request and flow modulation = 10°C
Temperature difference between tank heater request and current value for maximum flow
modulation = 10°C
Temperature difference between tank heater request and current value for minimum flow
modulation = 0°C
Flow thermostat intervention temperature with tank heater DHW OFF = 86°C
Flow thermostat intervention temperature with tank heater DHW ON = 70°C
