21
6 SYSTEM OPERATION
6.1 WORKING PRINCIPAL - Fig. 26
The solar collector uses the energy of the natural light to heat the water being circulated around the collector. When the
heated water enters the drain back unit, heat is transfer into the stored water via a heat exchanger. Stored domestic hot
water is pumped from the bottom of the solar cylinder through the drain back unit heat exchanger where it is heated and
returned to the cylinder.
When a hot water tap is turned on mains water flows into the bottom of the solar cylinder and hot water flows out of the top
towards the boiler. If the boiler inlet sensor detects that the water from the cylinder is above 60°C the water flows directly
through the boiler to the tap, if the temperature is less than 60°C the boiler heats up the water. As the temperature of the
water entering the boiler is higher than the normal incoming mains water, less gas is required to heat the water to the set
temperature of above 60°C thereby saving energy costs.
Alpha SolarSmart 100 - System Operation
6.2 OPERATION OF THE SOLARSMART SYSTEM - Fig. 26
Control
When the controls detect a collector sensor temperature that is at least 10°C higher than the lower cylinder sensor and the
solar cylinder temperature is less than 65°C, the drain back unit pump will start to circulate water around the collector. At the
same time that the drain back unit pump starts the cylinder pump will start at 10% of full speed to circulate the cylinder water
through the drain back unit heat exchanger. The drain back unit pump will stop when the temperature difference between the
collector sensor and the lower cylinder sensor falls to 3.5°C or the cylinder temperature reaches 70°C. The cylinder pump will
continue to run for 120 seconds to collect any excess heat from the drain back unit then it will also stop.
When the pumps are operating, a flashing pump symbol will be visible in the display (see Fig. 23 and Section 5.4).
If a fault occurs, a flashing warning symbol (see Fig. 23 and Section 5.4) appears in the display and a fault code will be
displayed. Refer to Section 10 for a list of fault codes and possible solutions.
Cold water inlet
Cold water to DBU
Alpha InTec boiler
Warm water
to boiler inlet
Cold water supply if
using thermostatic
mixing valve
Hot water
to taps
Thermostic
mixing valve
Hot water from DBU
Solar cylinder
(case not shown)
Drain back unit
(DBU)
Solar collector
Collector sensor
DBU pump
DBU heat
exchanger
Cylinder sensors
Control unit
Drain
point
System pump
Temperature/pressure
relief valve
Inlet sensor
Pressure
relief
valve
Fig. 26