Patent ID: 6465764
Filing Date: 2002-10-15
Classification: F24H

Abstract:
A water heater comprising:(1) a water-tight tank (10); (2) said tank (10) having a cold water inlet (14) and a hot water outlet (16); (3) a first electrical heating element (24) mounted in an upper portion of said tank (10); (4) a second electrical heating element (26) mounted in a lower portion of said tank (10); (5) a first temperature sensor element (28) mounted on the outer surface of said tank (10); (6) a second temperature sensor element (30) mounted on the outer surface of said tank (10); (7) a first relay (32) mounted outside of said tank (10) having a first switch arm (40) and a winding (32a), said first switch arm (40) movable between a first position and a second position; (8) a second relay (34) mounted outside said tank (10) having a second switch arm (42) and a winding (34a), said second switch arm (42) movable between a first closed position and a second open position; (9) a source of high AC voltage connected to said first (24) and second (26) heating elements; (10) a source of low AC voltage connected to said windings (32a and 34a) of said first and second relays (32, 34) respectively; and (11) an electrical control unit (A) electrically connected to said first temperature sensor element (28) and said first relay winding (32a), said control unit (A) also connected to said second temperature sensor element (30) and said second relay winding (34a); (12) said first relay (32) adapted to energize said first electrical heating element (24) when said first relay winding (32a) is in a de-energized condition; (13) said first electrical heating element (24) adapted to actuate said control unit (A) to thereby de-energize said first electrical heating element (24) when the water in the upper portion of said tank (10) reaches a preset temperature; (14) said first relay (32) is further adapted to energize said second electrical heating element (26) when said first arm (40) of said relay is actuated to move from its first position to its second position; and (15) said second temperature sensor element (30) adapted to actuate said control unit (A) to energize said second relay winding (34a) of relay (34) to thereby move said second switch arm (42) to its open position to thereby de-energize said second electrical heating element (26) when the temperature in the lower portion of the tank reaches said preset temperature; wherein said control unit (A) is adapted to sense a temperature rise in the tank (10) at an abnormally high rate, at which time the control unit (A) will operate to open said first and second relays (32, 34) to thereby shut off current to said first and second electrical heating elements (24, 26).