Note!
The 4-point characteristic
function can only be activated when the
Adaptation
function is not
active (Co1, 2, 3 -> Fb07 = OFF).
5.3 Fixed set point control
During the times-of-use, the flow temperature can be controlled according to a fixed set point.
Outside the times-of-use, this set point is reduced by the
Set-back difference. Both Minimum
flow temperature and Maximum flow temperature parameters are set to identical values.
Parameters
WE
Parameter level / Range of values
Max. flow temperature
90 °C
PA1, 2, 3 / 20 to 130 °C
Min. flow temperature
20 °C
PA1, 2, 3 / 20 to 130 °C
Set-back difference
20 °C
PA1, 2, 3 / 0 to 50 °C
5.4 Differential temperature control using variable weighting factors
This function allows the return flow temperature to be taken into account in addition to the flow
temperature. It can only be used in heating circuits with mixing valves.
The difference between the flow and return flow temperature is specified using the
Intended
temperature difference parameter. It is a measure for the energy consumption in a heating cir-
cuit. The greater the temperature difference, the larger the energy required by a heating circuit.
If the actual temperature difference is not the same as the intended temperature difference, it is
evaluated by the
Kp factor for differential temperature control. After initial signs for a deviation
occur, the flow temperature is raised or reduced by this factor.
When the
Kp factor for differential temperature control is set to 0, the return flow temperature
does not have any affect on the control of the flow temperature.
When the
Kp factor for differential temperature control is set to 1, a pure return flow tempera-
ture limitation takes place (–> section 7.4).
The reset time T
N
determines how fast the deviation of the temperature difference affects the
control circuit (the larger T
N
is, the slower the rate in change).
The
Intended temperature difference parameter is maintained at a constant value by adjusting
the speed of the associated circulation pump in the heating circuit. The pump is controlled by an
analog 0 to 10 V signal, which is applied to the associated analog output (AA) of the controller
(AA1 to AA3). The control signal is displayed in the associated info level. When the differential
temperature control without return flow limitation is active, the actual temperature of the return
flow is nevertheless displayed. After pressing the enter key, the set point is displayed together
with the string "S-r" (for differential temperature control using variable weighting factors).
42
EB 5179 EN
Functions of the heating circuit
