Patent ID: 7315692

Claim:
An electrical water heater for accurately heating a predetermined amount of water at a predetermined temperature, comprising: a water container which comprises a container body having a water cavity adapted for containing said water therewithin, and a container base provided underneath said container body for supporting said container body; a water heater unit provided in said container base to terminally communicate with said water within said water cavity, in such a manner that said water heater unit is adapted for heating up said water at said predetermined temperature in an accurately controllable manner; a temperature control unit, which comprises: a thermal sensor provided in said container base to accurately detect a temperature of said water within said water cavity, wherein said thermal sensor comprises: a sensor probe supported in said water container to protrude into said water cavity in such a manner that a head portion of said sensor probe is arranged to physically contact with said water for sensitively and accurately detecting a temperature change of said water within said water cavity; and a temperature controller comprising a controlling circuit electrically communicated with said sensor probe, wherein said controlling circuit comprises a central processor unit for being selectively programmed to preset said predetermined temperature, a relay circuit electrically connected between said water heater unit and said central processor unit for selectively diverting an electrical current flowing between said water heater unit; and a bridge rectifier circuit electrically connecting said central processor unit and said relay circuit to external power source to provide an optimal electrical power for said central processor unit and said relay circuit, wherein when said water temperature detected by said sensor probe is below said predetermined temperature, said central processor unit is arranged to deactivate said relay circuit for allowing an electric current flowing through said water heater unit so as to heat up said water within said water cavity until said a temperature of said water reaches said predetermined temperature, and when said water temperature as detected by said sensor probe is above said heat-up temperature, said central processor unit is arranged to activate said relay circuit so as to cut off said electric current flowing through said water heater unit so as to stop heating up said water within said water cavity.