111
Due to the relatively high power requirement, the "
bus load"
must be considered:
The controller UVR 63 delivers the maximum bus load, 100%. For example, the electronic
sensor FTS4-50
DL
has a bus load of 39%, therefore up to a max. 2 FTS4-50
DL
can be
connected to the DL bus. The bus loads of the electronic sensors are listed in the technical
data of the respective sensors.
Simultaneous power supply to a boot loader and external sensors is not possible. It this case,
the boot loader must be supplied via a power pack (CAN-NT).
Drain-Back Function DRAINB
This additional function may only be activated with programs for a collector field with
a consumer (e.g. program 0, 80 112, 432, etc.) or program 4.
With drain-back solar thermal systems the collector area is emptied outside the circulation
time. In the simplest case, a solar pump is accordingly installed close to an open expansion
tank, which when the pump is stationary receives all the heat transfer medium above the
tank.
System start up is triggered either by a
radiation sensor
or by the exceeding of the
temperature difference
diff
between the
collector-
and
tank sensor
.
During the
filling time
the pump runs at full speed to lift the heat transfer medium above the
highest point of the system. Optionally, a second pump ("booster pump") can be connected
to a free output, so that the filling pressure is increased.
Filling of the collector with cold heat transfer medium leads to the short-term undershooting of
the switching difference
diff
. In the following
stabilisation time
the pump continues to run
irrespective of the temperature difference
diff
at the
calculated speed
.
If the pump is switched off during normal operation (e.g. as a result of undershooting of the
temperature difference
diff
or collector overtemperature switch-off), then the heat transfer
medium runs out of the collector field back to the expansion tank.
A volume flow sensor is suitable for use as low water protection (VSG... or FTS...DL). If the
volume flow falls below a minimum value
after the filling time
, the solar pump is switched off
and the error message
DB ERR
appears in the status menu. The system can only restart
after resetting of the controller by switching it on and off.
For the speed control of pump 1 the pump speed control
PSC
(for standard pumps) or the
control output
COP 1
(for electronic pumps with 0-10V or PWM input) must be activated (see
the corresponding chapter). It makes sense to define a minimum speed
MIN
for the
stabilisation time, that safeguards the circulation.
If an
electronic pump
with a 0-10V or PWM input
is used as a booster pump during the
filling time, the control output
COP 2
must be activated and linked to the input of the booster
pump. During the filling time, the maximum stage is output.
The start function
STARTF
may
not
be activated in conjunction with the drain-back function.
If the drain-back function is activated the frost protection function is blocked (with the
exception of program 4).
