Door insulator with safety plug

Details Door insulator with safety plug Door insulator with safety plug

2002-04-16

2003-12-02

Campbell, Thor (Department: 3742)

Electric resistance heating devices

Heating devices

Tank or container type liquid heater

C392S449000

Reexamination Certificate

active

06658204

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to water heaters, and more particularly to water heaters having doors that provide access to electrical components mounted within the water heaters.
BACKGROUND OF THE INVENTION
It is known to provide water heaters with a tank, a jacket that surrounds the tank, and an electrical component, such as a thermostat or a heating element. The electrical component is coupled to the tank and is accessible through an opening in the jacket. The opening of the jacket is typically covered by a removable door. The door is movable between an open position providing access to the opening and a closed position restricting access to the opening.
It is also known to provide a polystyrene dam that surrounds the electrical component and that extends between the tank and the jacket to protect the electrical component from the insulating foam while the foam is injected between the tank and the jacket. Thus, the dam at least partially defines the opening. In addition, it is known to insert a polystyrene cap into the opening of the jacket and within the dam to further insulate the tank from the environment.
SUMMARY OF THE INVENTION
The water heater of the present invention increases safety and decreases the likelihood of electrocution during water heater maintenance by providing a door assembly that selectively opens and closes an electrical circuit providing electricity to an electrical component of the water heater. More specifically, when the door assembly is removed to gain access to the electrical component, the electrical circuit is opened, and when the door assembly is closed, the electrical circuit is closed.
The door assembly also eliminates the need for a permanently fixed dam around the electrical component by providing a dam that is moldable to a door of the door assembly. The dam is shaped to closely cover and surround the electrical component and to provide the necessary seal against the tank and jacket during the injection of the insulation foam between the tank and the jacket. The dam may optionally be sprayed or coated with a release agent so that the dam does not bond with the injected insulation, thereby allowing the cover assembly to be removed after the insulation foam cures.
In an alternate configuration of the water heater, a conventional foam dam is positioned within an opening in the jacket to protect the electrical component of a water heater from insulating foam during injection of the foam between the tank and the jacket of the water heater. The door assembly includes a ceramic foam insulating cap that is molded to the door and that is insertable in the dam to provide rigidity to the dam and to maintain the shape of the dam under high forces that are generated by injecting a thick layer of insulation between the tank and the jacket. The ceramic foam insulating cap also improves the insulating effect of the door assembly on the water heater.


REFERENCES:
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patent: 5299280 (1994-03-01), Ruark
patent: 5476392 (1995-12-01), Inaba et al.
patent: 5762512 (1998-06-01), Trant et al.
patent: 5820413 (1998-10-01), Yamada et al.
patent: 5848904 (1998-12-01), Kikuchi

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