Device for heating the bacterial proliferation zone of a water heater to prevent legionellosis

摘要

A domestic electric water heater comprises a cylindrical tank having a vertical wall and an inwardly curved bottom, the latter defining with the vertical wall an annular stagnant water zone susceptible of bacterial contamination by, for example, legionella bacteria. The tank is provided with an upper immersion heating element and a lower immersion heating element, the latter being located above to the annular zone of contamination. The tank further comprises an outer electric heating element mounted on the outer surface of the vertical wall at the level of the contamination zone and below the lower immersion element. This outer heating element is capable of bringing water in the contamination zone to a temperature sufficient to eliminate the danger of such bacterial contamination, the temperature being in the order of 46° C.