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8
OPERATION
The
Evolution Solar HDX
boiler is designed to heat a heating installation and provide domestic hot
water by solar collection. Optionally, a second heating circuit, heating circuit 2, may be connected to
the installation to improve its performance.
The boiler also includes a DHW collecting and storage system whereby installation of the solar
collectors supplied with the boiler optimises the use of the solar energy in the collection area, for
economical, environment-friendly domestic hot water production. The solar functioning principle
consists of heating the solar circuit liquid in the solar collectors and then exchanging the heat
absorbed with the domestic hot water in the hot water tank. As an auxiliary source of energy to back
the main source, the oil-fired boiler adds the necessary heat to obtain a suitable domestic hot water
temperature, if the energy collected from the sun is not sufficient.
8.1
Solar circuit functioning
The
Evolution Solar HDX
boiler is equipped with a circuit, separate from the heating circuit, for the
producing DHW using solar energy. This is called the “Solar Circuit”. This circuit basically consists of
a dual-chamber DHW tank, for exchanging heat with the domestic hot water, two solar circulation
pumps, a flow regulator and one or two solar collectors, for exchanging heat with the sun.
The functioning of the solar circuit is based on the drainback principle, whereby the heat-carrying
liquid in the solar circuit does not completely fill the installation, maintaining the solar collector
empty while there is no demand for solar energy and thus preventing freezing or overheating
problems. When there is a demand for solar energy, the solar pumps start up so that all the air in
the solar collector is conveyed towards the dual chamber of the solar hot water tank. The heat-
carrying fluid circulates through the solar collector, collecting the energy provided by the sun and
exchanging it with the domestic hot water stored in the solar hot water tank. When there is no
demand for solar energy, the solar pumps stop and the heat-carrying fluid returns to the dual
chamber of the hot water tank by the force of gravity, and the solar collector drains again
(drainback).
Solar sensor "
Scol
"
Upper solar pump
Lower solar pump
Hot water tank sensor "
Si
"
Air
Air
Heat-carrying fluid
Solar sensor "
Scol
"
Upper solar pump
Lower solar pump
Hot water tank sensor "
Si
"
Air
Heat-carrying fluid
Solar circuit not activated
Solar circuit activated
The boiler’s electronic control system manages the automatic functioning of the solar circuit,
switching on the solar circulation pumps when the temperature difference detected is over 6 ºC.
