PRINCIPLE OF OPERATION
3.2.1 PUMP OPERATION:
In the simplest form the solar system needs two sensors. One is positioned
at the collector (manifold) usually on the roof, which is called the Collector
Sensor . The second is positioned such that it measures the temperature
of the water returning to the collector, after the system has extracted the heat
from it. This is called the Return Sensor .
Two conditions must be satisfied before the pump will run:
1 As the sun shines on the collector, the collector sensor picks up the rise
in temperature, while the return sensor remains at the existing
temperature. The difference between these two temperatures is referred to
as Delta T ( ). For example, when is set to 4, the collector temperature
must rise at least 4°C above the return temperature before the pump
will operate, but only when condition 2 is also satisfied.
2 The collector temperature must be above the minimum collector
temperature set point TC (for example 40°C), before the pump will operate to
optimise the use of the solar collector.