Abstract: A fuel-fired water heater is provided with a combustion chamber assembly, representatively a sealed combustion chamber assembly, operative to create from combustion air delivered thereto via a circumferentially limited vertical side portion thereof a flow of primary combustion air to the underside of a centrally disposed fuel burner within the assembly via a first location underlying the burner, a first flow of secondary combustion air delivered to the burner via the first location, and a second flow of secondary combustion air delivered to the burner via a second location outwardly circumscribing the first location.

Abstract: A fuel-fired water heater is provided with a combustion chamber assembly, representatively a sealed combustion chamber assembly, operative to create from combustion air delivered thereto via a circumferentially limited vertical side portion thereof a flow of primary combustion air to the underside of a centrally disposed fuel burner within the assembly via a first location underlying the burner, a first flow of secondary combustion air delivered to the burner via the first location, and a second flow of secondary combustion air delivered to the burner via a second location outwardly circumscribing the first location.

Abstract: Electrical components projecting outwardly from the storage tank portion of an electric water heater are shielded from foam insulation material being injected into an insulation space between the tank and an outer jacket portion of the water heater by a hollow, open sided foam dam structure extending through a jacket opening and circumscribing the electrical components. Force exerting projections on the dam engage the interior side surface of the jacket and forcibly hold the inner side of the dam structure in sealing engagement with the tank. The projections also hold an outer side peripheral lip of the dam in a an outwardly and resiliently deflected orientation in which it is sealingly pressed inwardly against the outer side surface of the jacket around the periphery of the opening therein to prevent injected foam from being forced outwardly through the jacket opening.

Abstract: A specially configured fuel-fired water heater production platform may be used as a natural draft water heater. Alternatively, by modifying an upper end portion of the production platform using associated conversion apparatus, the same platform may be converted to a power vented water heater subassembly, a natural draft direct vent water heater subassembly, or a powered direct vent water heater subassembly to thereby lower the overall production costs for these different types of fuel-fired water heaters.

Abstract: Electrical components projecting outwardly from the storage tank portion of an electric water heater are shielded from foam insulation material being injected into an insulation space between the tank and an outer jacket portion of the water heater by a hollow, open sided foam dam structure extending through a jacket opening and circumscribing the electrical components. Force exerting projections on the dam engage the interior side surface of the jacket and forcibly hold the inner side of the dam structure in sealing engagement with the tank. The projections also hold an outer side peripheral lip of the dam in a an outwardly and resiliently deflected orientation in which it is sealingly pressed inwardly against the outer side surface of the jacket around the periphery of the opening therein to prevent injected foam from being forced outwardly through the jacket opening.

Abstract: Electrical components projecting outwardly from the storage tank portion of an electric water heater are shielded from foam insulation material being injected into an insulation space between the tank and an outer jacket portion of the water heater by a hollow, open sided foam dam structure extending through a jacket opening and circumscribing the electrical components. Force exerting projections on the dam engage the interior side surface of the jacket and forcibly hold the inner side of the dam structure in sealing engagement with the tank. The projections also hold an outer side peripheral lip of the dam in a an outwardly and resiliently deflected orientation in which it is sealingly pressed inwardly against the outer side surface of the jacket around the periphery of the opening therein to prevent injected foam from being forced outwardly through the jacket opening.

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.

Abstract: Convective heat traps are installed at the cold water inlet and hot water outlet of a water heater. Each heat trap has a tubular body with two axially spaced apart resilient flapper members transversely extending across the interior of the body and being hinged on opposite sides thereof. The heat trap at the cold water inlet is coaxially disposed within a dip tube. In one alternate structure, flapper members are mounted directly on the dip tube, and in another alternate structure an external annular seal element is mounted on the dip tube or heat trap body, with a flapper member being integrally formed with the seal element.