HIGH EFFICIENCY, WET-BASE, DOWNFIRED MULTI-PASS WATER HEATER

摘要

A fuel-fired water heater has a three-pass condensing type heat exchanger disposed within its tank and having a central vertical first pass flue pipe separated into upper and lower portions by an internal dividing structure. Respectivel y coupled to the upper and lower first pass flue pipe portions are circumferentially spaced series of vertical second and third pass flue pipes which circumscribe the central flue pipe within the tank. During firing of the water heater, combustion gases fr om a power burner are sequentially forced downwardly through the upper portion of the first pass flue pipe, upwardly through the second pass flue pipes to an uppe r plenum external to the tank, and then downwardly through the third pass flue pipes and the lower central pipe portion into a bottom plenum external to the tank for discharge from the water heater.