MULTIPLE U-TUBE DOWN FIRED WATER HEATER

摘要

The top storage tank end wall of a down-fired water heater has a first circumferentially spaced series of circular openings formed therethrough and centered about the tank axis, and a second circumferentially spaced series of circular openings centered about the tank axis and spaced radially outwardly of the first series of openings. Vertically disposed within the tank is a circumferentially spaced series of hollow U-tube immersion heating members each having a first open upper end secured to one of the first series of openings, and a second open upper end secured to one of the second series of openings. Shot-type fuel burners extend downwardly into the second open upper tube ends and are supplied with gaseous fuel via a manifold ring positioned atop the water heater. Hot combustion gases from the burners are drawn through the U-tubes by a draft inducer fan having an inlet connected to the first open upper ends of the tubes. In an alternate embodiment of the water heater, air-driven power fuel burners are connected to the first open upper tube ends and are supplied with driving air through a manifold structure connected to the outlet of a supply air blower. Combustion gases forced out the second tube ends are collected in an exhaust manifold structure for venting to atmosphere.