Electric resistance heating devices – Heating devices – Tank or container type liquid heater
Reexamination Certificate
2002-05-30
2003-08-12
Campbell, Thor (Department: 3742)
Electric resistance heating devices
Heating devices
Tank or container type liquid heater
C392S441000, C392S449000
Reexamination Certificate
active
06606452
ABSTRACT:
FIELD OF THE INVENTION
The invention herein pertains to corrosible anodes for hot water heaters and particularly pertains to a bi-metallic anode for use in a recreational vehicle (RV) water heater.
DESCRIPTION OF THE PRIOR ART AND OBJECTIVES OF THE INVENTION
Recreational vehicles, motor homes, campers and the like utilize small hot water heaters which are gas or electric powered for the convenience of the occupants. Such water heaters are often made having a metal tank which is lined with a polymeric foam or other material to prevent leaking and to prevent metal contact with the contained water. Particularly when heated, water can be highly corrosive to certain materials and over time can cause a water tank to leak and cause damage, requiring expensive repairs or replacement. To prevent such leaks a sacrificial anode is generally placed in the water tank which will corrode more readily than the metal tank. Anodes in the past have been usually fabricated from metals such as aluminum or magnesium and have steel threads for connecting to the tank fitting. Most manufacturers recommend that such anodes be checked periodically, several times a year to ensure that the anode is still effective and has not totally deteriorated.
Problems have developed in the past, particularly with steel/magnesium bi-metallic anodes in that the corrosive activity of the anode is too near the inner tank wall, whereby the inner tank wall and fitting begins corroding, even while the distal end of the anode which projects into the tank water remains unaffected.
Thus, with the problems and disadvantages of conventional corrosible anodes in hot water heaters, the present invention was conceived and one of its objectives is to provide a corrosible water heater anode which will better protect the inner tank surface and fitting.
It is still another objective of the present invention to provide a corrosible anode which includes a cylindrical shaft of steel which spaces the more corrosible magnesium or other metal a safe distance from the inner tank surface.
It is yet another objective of the present invention to provide a bimetallic anode having a steel, threaded first section and a magnesium second section.
It is still another objective of the present invention to provide an anode for a hot water heater which can be easily positioned in a conventional anode fitting.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed description is set forth below.
SUMMARY OF THE INVENTION
The invention herein pertains to anodes as are used in hot water heaters, particularly small hot water heaters as are found in RVs. Anodes formed of corrosible material such as aluminum, magnesium and the like are commonly used in the industry. However, the use of conventional anodes has caused RV owners problems in that the tanks begin to leak, often near or at the fitting which retains the anode. Conventional bi-metallic anodes are made of a relatively non-corrosive metal such as steel and a highly corrosible metal such as aluminum, magnesium or the like. As the magnesium and steel sections of an anode are usually joined at or very close to the tank fitting, the corrosive activity often causes the fitting and tank inner surface to likewise corrode. Thus, during periodic checks of the anode, for example, on a two or three month basis, the anode may be difficult to remove from the fitting since the threads of the fitting and anode deteriorate. In addition, after a prolonged period the hot water within the tank penetrates the inner tank protective coating and corrodes the metal inner tank surface near the fitting.
The present invention is designed to extend the corrosible section of the anode further into the tank, away from the tank inner surface and fitting, thus distancing the sphere of corrosive activity from the fitting and inner tank surface. The bi-metallic anode described herein includes a first section formed of steel and has a head, threads and a shaft. The second or corrosible anode section of the preferred anode is cylindrically shaped. The second anode section is affixed to the steel shaft, thus the steel shaft spaces or distances the second anode section from the steel threads of the first section and the fitting in the tank wall. The steel shaft thus distances the corrosible section and corrosion activity a safe distance from the tank inner surface.
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patent: 4093529 (1978-06-01), Strobach
patent: 4224126 (1980-09-01), Bidwell
patent: 4773977 (1988-09-01), Houle et al.
patent: 5334299 (1994-08-01), Roden
patent: 5853553 (1998-12-01), Twigg
patent: 5855747 (1999-01-01), Lusk
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