20
Setting the room influence
With weather-dependent control, the flow temperature can
be adjusted if there is a large divergence between the room
temperature and the set temperature.
Offset feed temperature
= ∆ T
v
Set room influence = PI
Setpoint value of room temperature = T
R set
Actual value of room temperature
= T
R act
∆ Tv
= PI (T
R set
– T
R act
)
Example: T
R set
= 20 °C T
R act
= 18 °C PI = 3
∆ Tv
= 3 x ( 20 °C – 18 °C) = 6 K
→
The flow temperature is increased by 6 K.
The higher the selected room influence, the greater the influ
-
ence of the room temperature on the flow temperature.
Connection of an OpenTherm Control Box with relay
output
Behaviour of a PD controller (pulse duration con-
troller)
With adapted heating systems, a PD controller is characte-
rised by its short transient time, minimal overshoot and high
control accuracy.
Behaviour of a hysteresis (on/off) controller
In over or undersized heating systems, a hysteresis controller
is characterised by a minimum switching frequency and low
temperature deviations.
