Water heating system with oxygen sensor

A method for controlling a water heating system, comprising the steps of:

• Providing an upright boiler, including a combustion chamber, comprising an enclosed housing including a first plate at its top, and a mesh burner mounted to the first plate, said burner housing side the combustion chamber, at least one conduit fluidly coupled to the combustion chamber to channel gas into the combustion chamber, wherein the burner causes combustion of gas to produce products of combustion, an oxygen sensor coupled to a top plate of the combustion chamber and positioned within the combustion chamber to detect an amount of oxygen in the products of combustion, wherein the oxygen sensor outputs data representative of the amount of oxygen in the products of combustion, a control unit for feedback control of the water heating system, wherein the control unit receives the data from the oxygen sensor and wherein the combustion of the gas in the combustion chamber is controllable by the control unit based on the data, a heat exchanger system coupled the combustion chamber to heat water in the heat exchanger system with products of combustion, the heat exchanger system positioned below the combustion chamber and comprising a plurality of substantially straight vertical tubes through which the products of combustion flow, wherein the top plate is mounted to and positioned on the first plate, wherein the top plate and the first plate define a recess, a surface of the recess within said combustion chamber defined by the first plate, the oxygen sensor positioned within the recess and the sensing element of the oxygen sensor is entirely within the recess;
• channeling gas through at least one conduit fluidly coupled to a combustion chamber of a boiler;
• combusting the gas with a burner housed inside the combustion chamber to produce products of combustion;
• sensing an amount of oxygen in the products of combustion with an oxygen sensor coupled to the combustion chamber;
• outputting data representative of the amount of oxygen in the products of combustion to a control unit of the water heating system;
• controlling feedback control of the water heating system at least responsive to the data from the oxygen sensor;
• directing the products of combustion from the combustion chamber to a heat exchanger system coupled to the combustion chamber;
• heating water with the products of combustion in the heat exchanger system;
• and
• directed the products of combustion out of the heat exchanger system through a flue.