| 摘要 |
A fuel-fired, forced draft, down-fired water heater is provided with an improved combustion product flow path thar 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 hater. 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 plenumand 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. A suitable fuel burner is disposed within the burnern tube and is supplied with a throughflow of a pressurized fuel/air mixture which is ignited to create a downwardly directed flame and associated hot combustion products. During operation of the water heater, the hot combustion products are sequentially flowed downwardly through the burner tube into the submerged tunr bowl, upwardly through the flue tubes into the vent plenum, and then outwardly through the vent plenum outlet passage.
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