Abstract: Disclosed is a water heater that has a water storage tank, a first pass flue tube extending from a top of the water storage tank to a bottom of the water storage tank, a down-fired burner assembly positioned to direct combustion gases into the first pass flue tube, a plurality of second pass flue tubes extending from the bottom of the water storage tank to a top of the water storage tank, and an expansion chamber positioned below the bottom of the water storage tank. The expansion chamber receives the combustion gases from the first pass flue tube and delivers the combustion gases to the second pass flue tubes. The water heater operates with a non-positive vent static pressure and with a vent gas temperature that avoids or reduces excessive condensate production in an exhaust vent connected to receive combustion gases from the water heater.

Abstract: Disclosed is a water heater that has a water storage tank, a first pass flue tube extending from a top of the water storage tank to a bottom of the water storage tank, a down-fired burner assembly positioned to direct combustion gases into the first pass flue tube, a plurality of second pass flue tubes extending from the bottom of the water storage tank to a top of the water storage tank, and an expansion chamber positioned below the bottom of the water storage tank. The expansion chamber receives the combustion gases from the first pass flue tube and delivers the combustion gases to the second pass flue tubes.

Abstract: A cold water inlet for a tank of a water heater is provided. The inlet includes an inlet conduit configured to extend toward a flue extending upwardly through the tank. The inlet conduit includes a proximal, intermediate, and distal conduit portion, the distal portion terminating at a closed end configured to reduce the amount of the water flow directed toward the flue. The cold water inlet further includes flow openings defined in the distal portion to permit the water flow to exit the inlet conduit. Deflectors are positioned along the distal portion proximal respective ones of the flow openings, and are oriented for deflecting the water flow. The closed end and the deflectors of the inlet conduit coact, as the water flows into the tank, to direct the water flow away from the flue and toward the side wall and bottom of the tank, thereby reducing an accumulation of scale.