The yellow LED blinks slowly if the flow temperature is reduced due to the
Return flow tem-
perature limitation
function
Function
WE
Configuration
F11 – Return flow temperature sensor
1
F11 - 1
Parameter
WE
Range of values
P13 – Max. return flow temperature
50 °C
10 to 90 °C
P14 – Kp Return flow temperature limitation
1.0
0.1 to 50.0
P15 – Tn Return flow temperature limitation
400 s
0 to 999 s
6.6
Pump forced operation
A deactivated circulation pump is forced-operated every 24 hours for one minute. This func-
tion is disenabled by selecting F10 - 0 or F09 - 1.
Functions
WE
Configuration
F09 – Function of switching output
0
F09 - 0
F10 – Anti-block protection of pump
1
F10 - 1
6.7
External request for heat demand
The controller with electric actuator can issue a heat demand to a higher-level controller
over the binary output BO in rated or reduced operation. In this case, a coupling relay
(contactor relay with floating contact) must be used to adapt the electrical connection.
This function is only possible when the switching output is not configured as a pump output.
Function
WE
Configuration
F09 – Function of switching output
0
F09 - 1
6.8
Control principle
The controller with electric actuator functions with a PI algorithm (three-point stepping con-
trol). The valve reacts to pulses which the actuator receives from the digital controller when a
system deviation occurs. In particular, the length of the first pulse depends on the system de-
viation and the selected gain
Kp flow temperature control (P09) (the pulse length increases as
the Kp rises). Pulse lengths and intervals change until the system deviation is zero again. The
interval between individual pulses is influenced considerably by the reset time
Tn flow tem-
perature control (P10) (the interval time increases as the Tn rises).
The valve transit time
Ty actuator transit time for valve travel (P11) reflects the time that the
25
EB 5757-7 EN
Functions