Water heater apparatus and associated manufacturing and insulation methods

摘要

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.