Water heater apparatus and associated manufacturing and insulation methods

Abstract

A foam dam in the insulation cavity of an electric water heater comprises a plastic bag into which liquid foam insulation is injected, the bag having an essentially closed top edge portion with only a small opening for receiving the injected insulation. A small portion of the insulation injected into the bag is forced outwardly therefrom via small metering holes to form external protrusions on the bag that mechanically interlock with a second batch of insulation subsequently injected into the cavity and prevent the hardened second insulation batch from pulling away from the bag. The substantially closed top edge of the bag permits the insulation injected into the bag to pack therein and increase the top-to-bottom hardened foam density uniformity. Side edges of the bag may be pleated to increase the sealing area of the foam dam.

Description

BACKGROUND OF THE INVENTION [0001] The present invention generally relates to the manufacture of insulated structures and, in a preferred embodiment thereof, more particularly relates to water heater structures and associated manufacturing and insulation methods therefor. [0002] A conventional water heater of either the electric or fuel-fired type normally comprises a water storage tank, typically of a metal construction, adapted to hold a quantity of pressurized, heated water for on-demand delivery to various plumbing fixtures such as sinks, tubs, showers, dishwashers or the like. Outwardly surrounding the tank is a jacket, typically of a metal construction, which defines around the tank a cavity which is filled with a suitable insulation material, usually a hardened foam insulation material which is initially injected into the cavity in liquid form during the fabrication of the water heater. Various control structures, such as thermostats and electric heating element structures pr...

AI Technical Summary

Benefits of technology

The present invention is a method of insulating a tank, such as a water heater tank, by using a flexible bag filled with a liquid foam insulation material. The bag is placed in the tank and positioned around a portion of the tank, with the insulation material being forced into the bag and forming hardened external protrusions on the bag. A second quantity of insulation material is then flowed into the bag and becomes mechanically interlocked with the hardened insulation protrusions, preventing separation between the two insulation materials. This results in a tank with no heat loss gap or void between the insulation materials. The bag has a closed upper end with small openings and the insulation material is pressure-packed into the bag, resulting in a more uniform density of the insulation material. The invention also includes a feature where the opening of the bag has a generally hourglass-shaped configuration with concave opposite vertical side portions that straighten when the bag is expanded by the insulation material.

Problems solved by technology

Several well known problems, limitations and disadvantages are typically associated with this conventional plastic bag-based foam dam construction.

First, after the second or main batch of foamed-in insulation hardens it tends to pull away from the plastic bag in a manner creating a gap between the second foam batch and the bag along the entire length of the water heater.

This gap, caused by shrinkage of the second foam batch, undesirably permits appreciable heat loss from the tank therethrough.

This results in an undesirably decreased foam density in a top portion of the bag, resulting in a lesser insulation efficiency in the top portion of the bag.

Third, bags of this conventional type are typically of a flat construction, but are used to sealingly fill a three dimensional portion of the tank / jack insulation cavity.

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