KT-Elektronik SOL3-3, Installation And Owner'S Manual, Page: 39 / 88

KT-Elektronik SOL3-3
5.4 Collector return flow sensor, Collector flow sensor
In several systems, the sensors for collector temperature and for storage tank
temperature are not really appropriate to decide if the collector pump should be already
turned off or not. It is possible that fluid with a higher temperature than measured by the
storage tank sensor flows from the storage tank to the collector, e.g. because of layering
in the storage tank. It is also possible that the temperature measured by the collector
sensor differs from the one of the heat carrier medium entering the storage tank. Both
can result to a senseless continued operation of the collector pump even without
sunshine, until the temperatures have changed.
A reliable turn-off criteria can be obtained by using a return flow sensor (CRF), and even
better by using both, a flow sensor (CVF) and a return flow sensor (CRF). By activating
the function block CO3-FB08 collector return flow sensor, turning off the collector pump
is not based on the difference between CF and SF any more, but on the difference
between CF and CRF.
If a collector flow temperature sensor is also present (function block CO3-FB08 = On),
the temperature difference between CVF and CRF is also relevant to turn off the pump.
Function FS Description
CVF
CRF 0
0 CO3 -> F07 Collector flow sensor active
CO3 -> F08 Collector return flow sensor active
EB_37383_SOL3-3_EN002
39