4Nobel Xilinakis D. & Co preserves the right to change all specications of the products and their accessories without prior notice
NOBEL, Xilinakis D. & Co Industry is active in the Solar Energy Field since 1975, always with high-tech equipment,
ultra-modern facilities and certied products of high quality. Our experience and know-how support our co operations,
before and after sales, both in Greece and abroad.
In the present manual you will nd all necessary instructions with regard to the installation, operation and
maintenance of NOBEL Solar Water Heaters.
Nowadays, the necessity for production and saving of energy without at the same time polluting the
environment has become common knowledge. The planet’s conventional energy resources are diminishing to a
threatening level as our society’s energy requirements are increasing, generating pollutants that affect the climate’s
balance.
Renewable energy sources promise a solution to the energy problem as well as to pollution. Gradually, the
international legislation is changing and encouraging - or even imposing - the use of alternative energy products, with
the aim to satisfy energy requirements without endangering the environment.
DOMESTIC HOT WATER CONSUMPTION
Statistically, it is estimated that the mean family consumption is 35 to 50 litres daily per person. If we add the
consumption of a washing machine and a dishwasher, when these are connected to the solar water storage tank,
then each requires 20 litres per day (per wash).
Thus, a family of four, for example, with a mean hot water consumption of 40 litres per person, needs an 160
litres solar water heater. If household appliances connected to the solar water heater are added, then the demand
increases by at least 40 litres daily. In order to take full advantage of the solar water heater, maximum use of hot water
should be made during daytime, so that the system can continuously produce hot water during the daylight hours,
maintaining thus its maximum efciency.
SOLAR WATER HEATER OPERATION - WATER HEATING
The collecting surface absorbs solar energy and heats the liquid (water or antifreeze mixture) that circulates in the
water element. This liquid when heated becomes lighter and is directed to the water storage tank where it heats the
water. The ow of the collector’s liquid is accomplished naturally and not forced (thermosiphonic ow).
The factors that affect the temperature of the water supplied by a solar system are many and their values vary according
to the season, the time of day and the location. Keeping in mind that the solar system is a system that is exposed to
the weather conditions, basic parameters affecting its performance are the mains water temperature, the available
solar energy and the ambient temperature. The mains water does not have a constant temperature throughout the
year, being much colder in winter compared to summer. Considering 45°C as a satisfactory temperature for the
domestic hot water (in order to full the needs of a home) and based on statistic values, in winter the temperature
of the mains water has to be increased by approximately 35°C, whereas during the summer the increase is 20°C.
Similarly, the available solar energy does not remain the same throughout the year, being much less in the winter
months than in the summer months. During periods of reduced sunlight and low ambient temperatures, the solar
water storage tank assures the preheating of the water and is assisted by an electrical heating element or the
central heating water storage tank (triple action solar water storage tanks). As far as night-time temperature losses
are concerned, these are limited as much as possible by the solar system’s powerful thermal insulation. They are
nevertheless affected by ambient temperatures, which vary depending on the location and the weather.