Wet-base, down-fired water heater

摘要

A fuel-fired, forced draft water heater is provided with a specially designed burner structure and combustion product flow path that permit 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 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 are a plurality of vertical flue tubes that communicate the interiors of the turn bowl and the vent plenum. A vertically elongated perforated conical burner is disposed within the burner tube and is supplied with a throughflow of a pressurized fuel/air mixture that is ignited by an igniter mounted on the top end of the burner. During operation of the water heater, hot combustion products discharged from the conical burner are sequentially flowed downwardly through the burner tube into the submerged turn bowl, upwardly through the flue pipes into the vent plenum, and then outwardly through the vent plenum outlet passage.