Additional considerations if Absolute Setpoints are used
In order to avoid malfunction of the thermostat, if the Absolute Setpoints method is used
with automatic switching between heating and cooling, an additional limitation is introduced
regarding permanent storage of setpoint changes. Namely, the device will always ensure that
the comfort setpoint for cooling mode is never lower than the comfort setpoint for heating
mode.
2.4.5
Control algorithms
The main function of the Iddero Verso thermostats is to compare the current room temperature
with the desired temperature (setpoint) and send appropriate commands to the KNX actuators
(relay outputs, valve motors, etc.) that control the actual HVAC equipment.
To this end, Iddero Verso thermostats support different control algorithms:
• Two-point control with hysteresis
• P-I control with continuous (analogue) output
• P-I control with PWM (switched) output
These algorithms are described next.
Note
If a thermostat is configured for both heating and cooling, a different control algorithm
can be configured for each function. Thus, for example, a thermostat can be setup to
use two-point control with hysteresis for cooling, and P-I control with PWM output for
heating.
2.4.5.1
Two-point Control with Hysteresis
Two-point control with hysteresis is a simple and well-known control algorithm that is some-
times also referred to as “On/off control”. In this algorithm, the thermostat turns on the heating
when the current room temperature is below the desired setpoint, and turns it off when the
room temperature rises above the desired setpoint. The opposite holds true for cooling.
In order to prevent the output from quickly switching on and off when the room temperature
is close to the setpoint value, different thresholds are considered for switching on and off.
This behaviour is controlled with the
Hysteresis
configuration parameters (upper and lower
hysteresis).
2.4
Thermostats
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