Applicatio Manual
Universal Interface 4 DIN/NTC EK- CG2-TP
Revisione 1.0.0 - Aggiornato: 04/09/2017
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Pag. 18
7.2 Controllo a 2 punti con isteresi
Two-point control with hysteresis
This control algorithm, which is also known as On / Off, is the most classic and popular. The control provides for
the on / off switching of the system following a hysteresis loop, i.e. two threshold levels are considered for the
switching instead of a single one.
Heating mode
: when the measured temperature is lower than the value of the difference (T
set
– ΔT
hysteresis
), whereby
ΔT
hysteresis
identifies the differential adjustment of the boilers, the device activates the heating system by sending
a message or KNX telegram to the actuator that handles the heating system; when the measured temperature
reaches the desired temperature (
Setpoint
), the device disables the heating system by sending another
message. In this way, there are two decision thresholds for activation and deactivation of the heating, the first
being the level (T
set
– ΔT
hysteresis
) below which the device activates the system, whereas the second is the desired
temperature above which the heating system is deactivated.
Cooling mode:
When the measured temperature is higher than the value of the difference (T
set
+
ΔT
hysteresis
),
whereby
ΔT
hysteresis
identifies the differential adjustment of the cooler, the device activates the air conditioning
system by sending a message or KNX telegram to the actuator that handles it; when the measured temperature
falls below the desired temperature T
set
the device turns off the air conditioning system by sending another
message. In this way, there are two decision thresholds for activation and deactivation of the cooling: the first
being the level (T
set
+
ΔT
hysteresis
) above which the device activates the system, whereas the second is the desired
temperature below which the air conditioning system is deactivated. In the ETS application program, two different
parameters are available for the hysteresis value for heating and cooling: the values usually differ depending on
the system type and its inertia.
In those applications where floor or ceiling radiant panels are present, it is possible to realize a different 2-point
room temperature control. This type of control must be paired either to a proper regulation system for flow
temperature that takes into account all internal conditions or an optimizer that exploits the thermal capacity of the
building to adjust the energy contributions. In this type of control the hysteresis (
ΔT
hysteresis
) of the room temperature
high limit (T
set
+
ΔT
hysteresis
) represent the maximum level of deviation that the user is willing to accept during plant
conduction.
T ambient
OFF
ON
Tset
Thysteresis
T ambient
OFF
ON
Tset
Thysteresis
T ambient
OFF
ON
Tset
hysteresis
T ambient
OFF
ON
Tset
T
hysteresis