Abstract: A water heater includes a water tank having an inlet and an outlet, and a flue extending through the tank. A nozzle is positioned near a first end of the flue, arranged so as to emit a fuel stream into the flue, and a flame holder is located within the flue in a position to receive the fuel stream and to hold a flame entirely within the flue.

Abstract: A water heater includes a water tank adapted to contain water; a flue extending through the water tank and having a first end communicating with the water heater's combustion chamber for the flow of products of combustion through the tank; a damper communicating with the flue; and an apparatus for creating a flow of air proximate the second end of the flue to resist the flow of warm air out of the second end of the flue due to standby convection. The apparatus for creating airflow may be a fan or an ionic wind generator. Additionally, the airflow may be directed into or across the end of the flue at the top of the water heater to either create a downdraft or an air curtain for containing warm air within the flue.

Abstract: An efficiency and safety and economy-improved water heating system with a water-containing casing around a coaxially central upright flue having a combustion chamber at the bottom which is open for the purpose and a closed upper end, and, connecting with the upper end of the upright flue, a plurality of downdraft flue elements passing helically downward through the water-containing casing to a power-exhaust element which positively draws combustion by-products up through the flue and down through the flue elements for heating water flowed through the casing; improved, readily removable perforate basket burner structure produces diverse, well ventilated combustion paths in the combustion chamber further enhancing efficiency and safety and ability to use the unit with gas or oil.