TANKLESS WATER HEATERS

 

United States Patent 5,216,743

Seitz: June 1, 1993

Thermo-plastic heat exchanger

 

Abstract

The present invention provides a flow-through instantaneous fluid heater system designed to satisfy the need for a heater not limited by being connected to a storage tank and which can be made using a plastic casing, incorporating cool-down when out of service and with features of venting and simplified flushing and draining. The system incorporates the use of one or more compartments, usually assembled in two compartment modules connected in series. Each compartment includes a casing having a hollow cylindrical interior region. An inlet aperture is located at one end of the casing and an outlet aperture is located at the other end of the casing. The lower end of each casing is closed by a removable base and the upper end of the casing is closed by a top plate and a heating element. The heating element is positioned axially in the interior region of the compartment. The heating element is activated by a control system which senses and compares temperatures of the water at the compartment outlets. The control system uses temperature comparisons to detect flow through the system to determine whether the heating elements should be activated to maintain the fluid at a stand-by temperature or at an operational temperature.

 

 

United States Patent 5,866,880

Seitz, et al.: February 2, 1999

Fluid heater with improved heating elements controller

 

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.

 

 

United States Patent 6,080,971

Seitz, et al.: June 27, 2000

Fluid heater with improved heating elements controller

 

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.

 

 

United States Patent 6,246,831

Seitz, et al.: June 12, 2001

Fluid heating control system

 

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. In addition to the software "watchdog timer" internal to the microcontroller, a redundant fail-safe circuit external to the microcontroller prevents a program lockup condition from leaving any heating element triac or relay drive in an energized state. A combination of control hardware and program provide self-diagnostic detection of an inoperative thermistor, stuck relay, or a failed triac or heating element. An improved means of sensing water level is disclosed incorporating a low-level, high frequency signal, allowing detection of non-conducting distilled water and the reliable detection of water in the presence of main-frequency currents as would exist in ungrounded sheathed heating elements with electrical leakage or as would exist with bare-elements.

 

 

United States Patent 7,616,873

Seitz: November 10, 2009

Thermo-plastic heat exchanger

 

Abstract

A flow-through instantaneous fluid heater system is designed to satisfy the need for a heater not limited by being connected to a storage tank and which can be made using a plastic casing, incorporating cool-down when out of service and with features of venting and simplified flushing and draining. The system incorporates the use of one or more compartments, usually assembled in two compartment modules connected in series. Each compartment includes a casing having a hollow cylindrical interior region. An inlet aperture is located at one end of the casing and an outlet aperture is located at the other end of the casing. The lower end of each casing is closed by a removable base and the upper end of the casing is closed by a top plate and a heating element. The heating element is positioned axially in the interior region of the compartment. The heating element is activated by a control system which senses and compares temperatures of the water at the compartment outlets. The control system uses temperature comparisons to detect flow through the system to determine whether the heating elements should be activated to maintain the fluid at a stand-by temperature or at an operational temperature.