ECOTHERM has developed an innovation in the field of hot water and heating water storage tanks for residential houses: the solar system buffer tank ESSP-B. In the storage tank two from ECOTHERM patented flat heating coils are mounted: one in the middle and one direct above the bottom. These special heat exchangers can use all available sources of energy. "Due to the flat design of these heat exchangers the water in the storage tank can be heated up to the desired temperatures in the upper and lower part of the storage tank," explains Herbert B Bremstaller, CEO and company founder of ECOTHERM Austria GmbH. The lower part is usually heated up to 45?C for heating purpose. Therefore the lower flat heating coil can also be operated by a heat pump. The upper part is heated up to 60?C. Thus the water in the stainless steel sphere is heated up also to this temperature level and is used as domestic water (shower, hand wash basin, etc). Due to the spherical shape the pressure is optimally distributed, the thickness of the steel sheet is minimised and therefore the heat transfer optimised. The two flat heating coils allow also a small solar thermal system to layer the hot water efficiently and without turbulent flows in the storage tank. The compact design of the ESSP-B storage tank reduces the installation costs as well as the operating costs and yield a highly safe operation and best hygiene.

Due to its horizontal design the ECOTHERM flat heating coil lays always completely in one temperature level in the storage tank. Therefore the temperature difference between the water in the heating coil and in the storage tanks is continuously high. So the flat heating coil has an optimal efficiency rate and reduces the time to heat up the water in the storage tank. Conventional spiral tube coils always lay in a zone of mixed temperature levels, which reduces the efficiency. Additionally the flat heating coil has a total height of only 8 centimetres. "If only one flat heating coil is mounted directly above the bottom of the storage tank, 97 percent of the volume of the tank can be heated up to the desired temperature of 60?C. Using spiral tube coils only 70 percent can be heated up to this temperature level. Thus the risk for legionella raises," Herbert B Bremstaller explains. Using an ESSP-B storage tank one can therefore use more hot water at a much better hygiene. Especially during summer more available energy of a solar thermal system can thus be used for the hot water generation.

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