Abstract: A vessel of substantially uniform curvilinear shape comprising at least one area of a different curvilinear shape that is adapted to closely conform to and engage a number of commonly contoured curvilinear segments on a housing member constructed and arranged to receive an outer covering panel in close fitting relation therewith is disclosed. In addition a method of manufacturing a vessel which comprises at least one area of a different curvilinear shape is also disclosed.

Abstract: Access to the interior of a vessel during fabrication and assembly of the vessel is provided by a channel structure formed around the circumference of the vessel. The channel structure comprises an outer surface that is radially inwardly offset from the exterior surface of the vessel around the circumference of the vessel. The outer surface of the channel structure is bounded by upper and lower circumferential transition areas which join the outer surface of the channel structure to the surface of the vessel. The channel structure is arranged such that when an upper portion of the vessel is separated from a base portion of the vessel by removing the material comprising the upper transition area, the upper portion of the vessel will receive within its inner diameter the outer surface of the channel structure.

Abstract: An improvement in electrical elements for a water heater includes a mass attached to the element for reducing the deposition of hard water scale on element surfaces, particularly in the return bend areas. In one embodiment, a flow accelerator tube encloses the element. The flow accelerator tube has an inlet at one end and an outlet at a higher elevation at the opposite end. Water is induced to flow through the tube because of temperature change. In another embodiment, a solid mass with high surface area encloses the return bend areas to increase heat transfer at a lower temperature to reduce scaling and increase element life.

Abstract: An improvement in electrical elements for a water heater includes a mass attached to the element for reducing the deposition of hard water scale on element surfaces, particularly in the return bend areas. In one embodiment, a flow accelerator tube encloses the element. The flow accelerator tube has an inlet at one end and an outlet at a higher elevation at the opposite end. Water is induced to flow through the tube because of temperature change. In another embodiment, a solid mass with high surface area encloses the return bend areas to increase heat transfer at a lower temperature to reduce scaling and increase element life.

Abstract: An extended life electrical heating element for a water heater includes a coiled heating resistance wire having a uniform power output per coil turn. Where the heating resistance wire passes through the sheath at critical areas, e.g. return bends, the number of coil turns per unit length of element is reduced to reduce thermal power output per unit length of the element. The number of coil turns per unit length of element in bend areas may be reduced by simply stretching the coiled heating wire to attain the desired length of resistance wire per unit length of the element. Resistance wires of differing heat output per unit length may be combined with different degrees of stretching to achieve the desired element temperatures. The reduced power at the bend portions reduces element temperature to reduce hard water scaling and significantly extend the life of the element.

Abstract: A control/safety apparatus and method for an electrical or fuel fired water heater includes one or more temperature sensors strategically located on the water heater vessel at a level at or above a critical water level. The time rate of temperature change is calculated from the sensed temperature. An abnormal value of temperature change rate corresponding to an insufficient water level deactivates the heater to prevent damage to the heater. Water level, projected heating times, heater malfunctions and other operating parameters may be calculated or detected based on the time rate of change in sensed temperature.

Abstract: A port assembly for a non-metallic pressure vessel is joined to a boss which is molded into or otherwise joined to the vessel wall. A bayonet type accessory mount is insertable therein for sealing passage through the vessel wall. The mount includes a simple semicircular locking snap ring with easily manipulable handles. The locking snap ring is configured for retaining and locking an accessory such as a heating element in any desired rotational position within the port. An o-ring is sealingly compressed in a radial direction between the mount and the port assembly. A specific application includes the positioning of a non-linear electrical heating element within a non-metallic water heater.