Programmable thermostat to reduce bacterial proliferation to prevent legionellosis

Abstract

A domestic electric water heater comprises a cylindrical tank having a vertical wall and a 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 programmable thermostat turns on the lower immersion element until the preset temperature is sensed by the temperature sensor at the upper immersion heating element. This concept elevates the whole tank including the annular zone of contamination to a higher temperature setting and thus eliminate the danger of bacterial contamination.

Dependencies are inferred from the claim text.