Abstract: The body structure of a fluid storage apparatus, which may be used for both liquids and gases, is formed from a coaxially and sealingly joined series of one-piece molded polymeric body sections including opposite end sections having closed outer ends. Each one piece molded polymeric body section has tubular inner and outer shell portions that are coaxial with one another and radially separated by a circumferentially spaced series of radially extending ribs molded integrally therewith and defining therebetween a circumferentially extending series of arcuate insulation spaces. In the assembled body structure the inner shell portions entirely define in the apparatus an internal fluid storage vessel portion that is useful in storing both liquids and gases. The interior fluid storage vessel is outwardly enveloped by the insulation spaces and structurally reinforced, via the integral ribs, by the outer shell sections.

Abstract: A fuel-fired, forced draft, down-fired water heater is provided with an improved combustion product flow path that permits the heater to operate with improved fuel efficiency, lowered CO and NOx emissions, and an improved water heat input distribution along the vertical length of the heater. The water heater includes a vertically oriented tank with a vent plenum structure formed at the top end of the tank interior and having an outlet passage connectable to an external combustion product vent pipe. A centrally positioned submerged vertical burner tube extends downwardly from the vent plenum and has an open lower end extending into a submerged turn bowl disposed at the bottom end of the tank interior. Extending upwardly from the turn bowl within the tank interior, and symmetrically arranged about the centrally disposed burner tube, are a plurality of vertical flue tubes that communicate the interiors of the turn bowl and the vent plenum.

Abstract: An electric water heater has a body structure formed in a manner eliminating the need for a separate metal water storage tank therein. The body structure is formed from a coaxially and sealingly joined series of one-piece molded plastic body sections including opposite end sections having closed outer ends. Each one piece molded plastic body section has tubular inner and outer shell portions that are coaxial with one another and radially separated by a circumferentially spaced series of radially extending ribs molded integrally therewith and defining therebetween a circumferentially extending series of arcuate insulation spaces. In the assembled body structure the inner shell portions entirely define in the water heater an internal water storage vessel portion that is outwardly enveloped by the insulation spaces and structurally reinforced, via the integral ribs, by the outer shell sections.