High-efficiency heating apparatus

A deep fryer, comprising:

• a fry tank for holding a cooking medium, the fry tank comprising:
• a cooking zone;
• and
• a lower chamber located beneath the cooking zone, the lower chamber comprising:
• a front wall and a back wall;
• and
• a right side wall and a left side wall;
• and
• a combustion system comprising:
• a gas supply system for receiving and distributing a combustion gas;
• two or more burners, each burner being in fluid communication with the gas supply system;
• two or more generally horizontal combustion chambers, each combustion chamber being in fluid communication with a corresponding burner, at least one combustion chamber being affixed to an exterior surface of the right side wall and at least one combustion chamber being affixed to an exterior surface of the left side wall, each combustion chamber being in heat transfer communication with either the exterior surface of the right side wall or the exterior surface of the left side wall;
• at least one flue in fluid communication with each combustion chamber for exhausting the combustion gas;
• and
• wherein each combustion chamber comprises:
• an inlet portion located near the front wall of the lower chamber;
• and
• an outlet portion located near the back wall of the lower chamber;
• wherein the right side wall and the left side wall form interior walls of the combustion chambers;
• wherein the combustion gas flows continuously in a generally horizontal direction along the right side wall and the left side wall of the lower chamber from the inlet portion to the outlet portion and thereafter is exhausted through the flue;
• and
• wherein the burners are disposed at the inlet portion of each combustion chamber.