The awareness of the importance of the environment has stimulated the study of new renewed energy sources and less pollutant. Amongst these sources, solar energy stands alone for being perennial and clean. The use of solar energy in systems of agricultural residential water heating, can complement the economy of electric energy, base of the Brazilian energy matrix. Knowing the factors that influence the operation of a system of water heating by solar energy is important in determining their technical viabilities targeting their distribution in agricultural residences. To evaluate equipment of water heating for solar energy, a prototype was constructed in the campus of Assis Gurgacz College, in Cascavel,State of Paraná, Brazil, with similar characteristics to equipment used in residences for two inhabitants, to function with natural circulation or thermosiphon and without help of a complementary heating system. The equipment revealed technical viability, reaching the minimum temperature for shower, of 35 °C, whenever the solar radiation was above the 3,500 Wh m-2, for the majority of the studied days.
hot water; natural circulation; thermosolar
