Technische Alternative UVR61-3 User Manual

110
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
cylinder, which when the pump is stationary receives all the heat transfer medium above the
cylinder.
System start up is triggered either by a
radiation sensor or by the exceeding of the
temperature difference
diff  between the collector- and cylinder 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 cylinder.
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).
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Technische Alternative UVR61-3 Specifications

General

Brand	Technische Alternative
Model	UVR61-3
Category	Dryer
Language	English