Instant water heater with PTC plastic conductive electrodes

Abstract

An instant water heater utilizing positive temperature coefficient plastic electrically conductive material structures for electrodes. The heating of the water is not generated by the electrodes, but instead by the resistance of the water to the electrical current flowing between them. The material of the electrodes undergoes a phase change at certain temperatures when whereby it converts from electrically conductive to electrically non-conductive at a predetermined temperature. The output temperature of the water is determined by a combination of the area of the electrodes that confront one another, the water's conductivity, the flow rate of the water and the current limiting capability of the conductive electrode materials positive temperature coefficient, which reduces or stops the heating of the water when the intended water temperature is achieved.

Description

CROSS REFERENCE TO OTHER APPLICATIONS [0001] This is a continuation-in-part of applicant's co-pending U.S. application Ser. No. 11 / 111,670, filed Apr. 21, 2005, which is not being abandoned.FIELD OF THE INVENTION [0002] An instant water heater which heats water flowing between two immersed electrodes, using improved electrodes with positive temperature cutoff (PTC) properties, increased efficiency and longevity. BACKGROUND OF THE INVENTION [0003] This invention relates to water heaters of the type which heats water that flows between two electrodes, rather than by providing a hot element which is contacted by the water. In this invention, the water is heated by electrical current flowing through the water when the water is between the two electrodes. [0004] So-called “instant” water heaters differ from conventional water heaters by their lack of a storage tank for hot water. Instead of heating and storing water for future usage, instant water heaters accept cold or cool water, heat ...

AI Technical Summary

Benefits of technology

[0036] According to a preferred but optional feature of the invention, the polymer electrode is loaded with a “conductive package” comprising two or more of the following: graphite as natural graphite, synthetic graphite, purified graphite, expandable graphite, expanded graphite, graphite flake and graphite fiber, and carbon as carbon black, purified carbon, carbon fiber, carbon fibrils, and carbon nano tubes to reduce the bulk electrical resistance of the material, provide suitable conductivity for the electrode, and to provide for enhanced connectivity with the water. This conductive package is preferably provided in the form of a good packing ratio of assorted sizes and correct proportions to give the best result as will later be described.

Problems solved by technology

Presently-known instant water heaters do have major disadvantages, including short product life, dry-fire burn-out, short service life, liability to water damage, moderate rates of flow, high energy consumption, and release of metal ions into the water.

Another disadvantage of existing instant water heaters is their inability to accommodate varying input voltages and amperage along with water flow that matches their intended use.

A complaint often heard is that the wrong instant water heater was purchased from many different available models.

The necessary wide range of variables, such as voltage, circuit breaker amperage, and service flow in gallons is simply too confusing for many customers.

It is yet another disadvantage of existing instant water heaters that they often burn out or break coils due to water hammering, air in the water lines, or current overloads.

These pose an electrical danger from direct contact of live broken coil ends to the water.

Manifolds that are connected to ground with a grounding wire corrode, and it is only a matter of time before a corroded manifold or a burned out coil releases a full current into the water and out a faucet or other plumbing fixture when in use, to the risk of the user.

It is a disadvantage of conventional electrode water heaters to have to contend with the wide variation of water conductivity of drinking water, both in the United States and in other parts of the world.

The disadvantage occurs when their electrodes must be sized such that they are capable of attaining satisfactory performance with 50 microsiemen water, but must then regulate a potentially hazardous 30 times the current draw when the water is at 1,500 microsiemens.

Since prior to this invention, electrodes could not be resized on the fly, regulating this amount of power has been costly.

However, to regulate the high current potentials of electrode water heaters, these methods are economically and technically unacceptable.

It is yet another disadvantage of electrode water heaters that suggest methods of power regulation using said wave-chopping devices, that such devices can introduce harmonics in the line and heat the wiring without tripping the circuit breaker.

Wires can become extremely hot, causing serious fire hazard.

However, current matching for electrode water heaters and boilers is nearly impossible to accomplish with such a widely varying electrical load without mechanically moving the electrodes as is done in large, expensive industrial electrode boilers.

To do this in a home appliance such as an instant water heater would be too costly and would introduce wear parts that would greatly increase the failure modes of the device.

Yet another disadvantage of electronically regulating high current via AC wave chopping is the electromagnetic emissions that disrupt communications television signals and create radio static interference.

These emissions are not allowed in Europe's “Flicker Standard” and can violate FCC regulations.

It is another disadvantage of electrode water heaters that in order to match the load to the line without the said expensive sine wave chopping devices, the preferred method is to physically move the electrodes via electric motors.

Interestingly, it is not possible to boil water when plastic electrodes are used because when boiling temperatures are reached, cavitation occurs on the surface and prevents the flow of electrical current.

This saves the large cost of temperature and pressure valves for standard water heaters.

For example, many plastic electrodes too quickly become coated with insoluble mineral deposits, such as the carbonates of calcium and magnesium, and other deposits which coat the electrode and limit its useful life.

Other complications are the conductive transmissibility of electrical current from the surface the electrode into the water on its surface.

Still another complication is the need to reduce electrical consumption in the electrodes itself.

Images