Cooking system with burner assembly and heat exchanger

A heat exchanger, comprising:

• a top wall, a bottom wall, a right side wall, and a left side wall, the top, bottom, right side, and left side walls defining a duct, the duct configured to receive combusted fuel and/or combusted air/fuel mixture;
• a first fluid circuit fluidly coupled to a vessel, the first fluid circuit including:
• top headers positioned on a top side of the duct,
• bottom headers positioned on a bottom side of the duct, first tubes fluidly coupled to and extending through the top and bottom walls to the bottom headers and the top headers;
• and
• a second fluid circuit fluidly coupled to the vessel, the second fluid circuit including:
• left headers positioned on a left side of the duct,
• right headers positioned on a right side of the duct, and
• second tubes fluidly coupled to and extending through the right side and left side walls to the left headers and the right headers,
• wherein the first and second tubes are positioned within the duct,
• wherein at least some of the second tubes are located between a first plurality of the first tubes and a second plurality of the first tubes,
• wherein the second plurality of first tubes is located between a first plurality of the second tubes and a second plurality of the second tubes, and
• wherein a first top header of the top headers includes a first end and a second end, wherein the first top header is attached at the first end to the top wall directly above a first position of the first plurality of second tubes in the duct, wherein the first top header is further attached at the second end to the top wall directly above a second position of the second plurality of second tubes in the duct, wherein the first and the second plurality of first tubes are positioned in the duct between the first plurality and the second plurality of second tubes, and wherein a third plurality of second tubes is located between the first and the second plurality of first tubes.

A heat exchanger comprising:

• a top wall, a bottom wall, a right side wall, and a left side wall, the top, bottom, right side, and left side walls defining a duct,
• a first fluid circuit fluidly coupled to a vessel, the first fluid circuit including:
• top headers positioned on a top side of the duct,
• bottom headers positioned on a bottom side of the duct,
• upward tubes fluidly coupled to and extending through the top and bottom walls to the bottom headers and the top headers, wherein the upward tubes are downstream from the bottom headers, and wherein the upward tubes are positioned within the duct, and
• downward tubes fluidly coupled to and extending through the top and bottom walls to the top headers and the bottom headers, wherein the downward tubes are downstream from the top headers, and wherein the downward tubes are positioned within the duct;
• and
• a second fluid circuit fluidly coupled to the vessel, the second fluid circuit including:
• left headers positioned on a left side of the duct,
• right headers positioned on a right side of the duct,
• rightward tubes fluidly coupled to and extending through the right side and left side walls to the left headers and the right headers, wherein the rightward tubes are downstream from the left headers, and
• leftward tubes fluidly coupled to and extending through the right side and left side walls to the right headers and the left headers, wherein the leftward tubes are downstream from the right headers, and
• wherein a first top header of the top headers includes a first end and a second end, wherein the first top header is attached at the first end to the top wall directly above a first position of a first plurality of leftward or rightward tubes in the duct, wherein the first top header is further attached at the second end to the top wall directly above a second position of a second plurality of leftward or rightward tubes in the duct, wherein a first and a second plurality of upward or downward tubes are positioned in the duct between the first plurality and second plurality of leftward or rightward tubes, and wherein a third plurality of leftward or rightward tubes is located between the first and the second plurality of upward or downward tubes.