Abstract: An improved system, method and apparatus for control of an instantaneous flow-through fluid heater system is disclosed. The control incorporates a logic control method providing modulation of power in small steps to a plurality of heating elements retaining responsiveness to closed-loop control needs without inducing light flicker. Further, the life of the coils of heating circuit electromechanical relays are extended by energizing the coils with a pulse-width-modulated drive decreasing in duty cycle and thus the latent coil heat when an increase in mains voltage is sensed. The life of the contacts of same relays are extended by inhibiting heating element triac drive immediately upon sensing loss of relay coil power, such as by an over temperature limit switch opening, thus ensuring that relay contacts open with zero heating element current.

Abstract: An electrically powered water heater includes a plurality of heating elements for substantially instantaneous heating of fluid passing through the heater. A controller for powering the plurality of heating elements is responsive to a temperature sensor in fluid communication with the heated fluid. The temperature sensor activates each of the plurality of heating elements for a predetermined period of time that is preferably no more than 32 half cycles. The controller activates a second heating element after a delay of preferably no more than 8 half cycles after activating a first heating element. The predetermined period of time for activating each of the plurality of heating elements may be substantially equal, such that each heating element contributes substantially equally to the heating of fluid. In one embodiment, the heater housing is provided with a plurality of chambers, and a heating element is provided within each of the plurality of chambers.

Abstract: An electrically powered water heater includes a plurality of heating elements for substantially instantaneous heating of fluid passing through the heater. A controller for powering the plurality of heating elements is responsive to a temperature sensor in fluid communication with the heated fluid. The temperature sensor activates each of the plurality of heating elements for a predetermined period of time that is preferably no more than 32 half cycles. The controller activates a second heating element after a delay of preferably no more than 8 half cycles after activating a first heating element. The predetermined period of time for activating each of the plurality of heating elements may be substantially equal, such that each heating element contributes substantially equally to the heating of fluid. In one embodiment, the heater housing is provided with a plurality of chambers, and a heating element is provided within each of the plurality of chambers.