11
Connection of a circulation line
Activating the DHW circulation pump using the FRISTAR3 controller
Hydraulic circuit diagram with circulation line
Circulation pump (optional)
If an external DHW circulation pump is connected directly to the FRISTAR3 controller, it will operate
in
pulse mode
. While water is being drawn off (once or continually), the DHW circulation pump runs
until the temperature at sensor
T
Zirku
reaches the set temperature (potentiometer on the front of the
controller) minus the set difference (potentiometer inside the controller) (no maximum runtime).
• When water is drawn off (set temp. via potentiometer), DHW circulation runs if: T
Zirku
< set
temp. – differential
• For draw-off (if set DHW circulation temp. specified via DL/CORA-DL): absolute value according
to input variable "Forced DHW circ." or index 3
If a DHW circulation pump is not used, the potentiometer must be set to 0 (= factory setting), as oth
-
erwise the primary pump would run on after every draw-off.
To connect the circulation line, a tee is installed in the secondary circuit cold water pipe.
A PT1000 sensor is used for the
T
Zirku
sensor.
The sensor
T
Zirku
is optional (including when using a DHW circulation pump), but is recommended
for optimal functionality. If it is not connected, the temperature of the sensor
T
KW
is used. If the set
temperature (minus the differential) is reached in this case (not using a
T
Zirku
), pump operation is
only permitted again after a pause of 10 minutes.
Activating the DHW circulation pump using a different switching device
It must be ensured that the flow rate in the DHW circulation line is greater than the flow sensor min
-
imum flow rate (2 l/min or 120 l/h).
When the DHW circulation pump is switched on, the V
KW
sensor measures the flow rate and the pri
-
mary pump is enabled.
Primary pump
Circulation pump
