Evolution Solar HFD
22
11
OPERATION
The
Evolution Solar HFD
boiler is designed to heat a heating installation and provide domestic hot
water, instantly and/or 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
collector supplied with the boiler optimises the use of the solar energy in the place of installation, for
economical, environment-friendly DHW production. The solar operating principle consists of the
liquid in the solar circuit being heated at the solar collector, followed by exchange of 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.
11.1
Solar circuit functioning
The
Evolution Solar HFD
boiler is equipped with a circuit, separate from the heating circuit, for the
production of domestic hot water using solar energy. This is called the “Solar Circuit”. It basically
consists of a dual-chamber hot water tank, for heat exchange with the domestic hot water, two
solar circulation pumps, a flow regulator and a solar collector, for heat exchange 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
"
Top solar pump
Lower solar pump
Hot water tank sensor "
Si
"
Air
Air
Heat-carrying fluid
Solar sensor "
Scol
"
Hot water tank sensor "
Si
"
Air
Heat-carrying fluid
Top solar pump
Lower solar pump
Solar circuit not activated
Solar circuit activated
